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R E V I E W A R T I C L E

Interplay of thermochemistry and Structural Chemistry,the journal (volume 21, 2010) and the discipline

Maja Ponikvar-Svet Joel F. Liebman

Received: 24 January 2011 / Accepted: 16 February 2011 / Published online: 5 March 2011

Springer Science+Business Media, LLC 2011

Abstract In the current review the content of the journal

Structural Chemistry for the calendar year 2010 is relatedto thermochemistry. To a short summary of each article in

this volume of the journal a thermochemical comment is

added.

Keywords Structural Chemistry Thermodynamics Physical Chemistry Thermochemistry Enthalpy of

formation Chemical reactions Phase transitions

Introduction

The current review ofStructural Chemistry for the calendar

year 2010 has become tradition as this is already the 10th

review and as such, constitutes a jubilee review. Let us

add that we have been told that these reviews in which an

attempt is made to link experiments and theory of all of the

articles in a given chemistry/physics/material science

periodical, represents a unique and appreciated approach.

This adds to our enthusiasm to continue with this annual

project.

This review is conceptually and organizationally very

much the same as the reviews of previous volumes of this

journal [110] in which each article has been reviewed and

summarized by us from our personal perspectives as well

as knowledge, facilitated wherever possible by the originalauthors choice of key words. Of course, our perspectives

are often very much different as is also our basic scientific

educationit is interesting to observe how scientists

working in different areas consider the same subject.

Therefore, it is perhaps also educational how we handle the

same area of investigation from our perspectives of theo-

retical and analytical chemistry and then combine the

comments into a logical unit. The review is supplemented

by adding thermochemical comments. Occasionally, it is

found that the investigations presented in the articles doc-

ument inadequacy of current knowledge by the scientific

community and that additional studies enlightening the

investigated area would be highly desirable. As such, hints,

suggestions, and encouragement for possible future

research are often given.

Thermochemical data are occasionally given as part of

our added material as well. All data for inorganic com-

pounds with otherwise unreferenced enthalpies of forma-

tion will be assumed to be taken from the Wagman

compendium [11], while corresponding unreferenced

enthalpies of formation of organic compounds will be

assumed to be taken from the Pedley compendium [12].

Issue 1

Volume 21 begins with the editorial by Hargittai [13] on

Linus Pauling and his work on the structure of proteins and

eventual discovery of the alpha-helix. Pauling postulated

that the amino acid units are linked to each other in the

folded protein molecule not only by the normal peptide

bond but also by hydrogen bonding that is facilitated by

this folding of the protein. His quantum chemical theory of

M. Ponikvar-Svet (&)

Department of Inorganic Chemistry and Technology, Jozef

Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia

e-mail: [email protected]

J. F. Liebman (&)

Department of Chemistry and Biochemistry, University of

Maryland, Baltimore County, Baltimore, MD 21250, USA

e-mail: [email protected]

123

Struct Chem (2011) 22:717740

DOI 10.1007/s11224-011-9769-0


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resonance contributed to his understanding of other scien-

tific phenomena, although at the same time, this theory was

attacked in Soviet Union as an ideological aberration.

In the first of the theoretical papers that follow Xu and

Chen [14] described use of density functional theory (DFT)

to predict the structural parameters, IR spectra, and ther-

modynamic properties of tetrazole derivatives. The total

energies, heats of formation, and enthalpies of combustionindicate the following order of stability: 5-(2,4,6-trinitro-

phenyl)-2H-tetrazole[ [5-(2,4,6-trinitrophenyl)-1H-tetra-

zole[ [5-(2,4,6-trinitrophenyl)-5H-tetrazole. A similar

result is found for the corresponding three isomers of

5-(2,4,6-trinitrobenzyl)-tetrazole. While there is a consid-

erable body of experimental data that allow for the com-

parison of the stability of 1Hand2H-tetrazoles, we know of

no corresponding study for 5H-tetrazoles. Indeed, we know

of but few thermochemically relevant studies of species

with a N=NN=N substructure. One was the study of

species [15] of the type ArN=NN=NAr as part of the

comparison of the dimerization of, and N2 loss by, tran-siently formed ArN2 radicals. Another is the suggestion that

5-nickelatetrazoles may enjoy significant stability [16].

Liu et al. [17] then used DFT to study the correlation

between regioselectivity and site charge in propene poly-

merization by single-site metallocene catalysts such as

[Cp2ZrMe]?. The activation energy for 1,2-insertion was

shown to be lower than that for 2,1-insertion in agreement

with the experimental data. Let us ask now if there is any

steric repulsion between the methyl group of the propene

and the cyclopentadienyl rings that contributes to the reg-

ioselective addition? How different are the activation

energies for Z- and E-2-butene from that of propene

wherein this methyl/cyclopentadienyl repulsion in these

4-carbon olefins is unavoidable?

Chapkanov [18] studied 2-aminopyridinium tetrachlo-

rocuprate (II) salt both in solution and in the solid-state

using IR and UVVis spectroscopy 1H-NMR, TGV, and

DSC methods. A change of aromatic character was

explained by the Npy protonation that leads to weak charge

redistribution in the pyridinium ring and thereby changes in

geometrical parameters. Thermodynamically, the stability

of the aminopyridines decreases in the order 2-[ 4-[

3- and span a 25 kJ mol-1 range. The proton affinities [19]

of the aminopyridines decrease in the order 4-[ 3-[ 2-

and span a 33 kJ mol-1 range. From these data we find that

the stability of the aminopyridinium ions decreases in the

order 2-[4-[ 3-. Is this change in enthalpy of formation,

and presumably aromaticity, reflected in the properties of

the corresponding aminopyridinium salts such as the above

cuprates?

For typical concentrations found in solutions the number

the solvent molecules outnumber the solute molecules

which makes the analysis of solute molecular structure

difficult. Lee and Ihee [20] used time-resolved X-ray

solution scattering for determining structures of small

molecules and proteins in solution. The difference scat-

tering curves generally exhibit much higher structural

sensitivity to the solute structure than the original scatter-

ing curves. The authors discuss solutions of iodine in

methanol and dissociation to form atomic iodine. We note

that the enthalpy of solution of gaseous I2 in methanol is54 kJ mol-1; we know of no corresponding data for the

atomic iodine as solute.

Stem and Ellzey [21] studied organotin(IV) molecules

using computational optimization modeling (COM) which

enables the prediction of molecular properties and struc-

tures. The data were compared to the experimental data as

obtained by X-ray crystallography and solid-state NMR.

Hyperconjugation-derived stabilization is suggested to be

an important force in these molecules. The lack of vali-

dation of computational optimization treatments for many

organotin(IV) molecules remains a limiting factor against

generating accurate COMs. These authors explicitlyinvestigated species with SnS bonds. The enthalpy of

formation of the simplest condensed phase species of

tin(IV) with sulfur, namely the binary sulfide and inorganic

material, SnS2 has been reported [22] but comparison with

organotin sulfides remains unexplored.

Suleymanoglu et al. [23] describe synthesis and char-

acterization, including crystal structure analysis, of 2-pro-

pylamino-5-[4-(2-hydroxy-3,5-dichlorobenzylideneamino)

phenyl]-1,3,4-thiadiazole. The experimentally determined

molecular geometry was compared to the geometry

obtained by DFT calculations. The results showed that the

Schiff base, which contains a thiadiazole ring, prefers the

E-configuration. A thermochemical comparison of 1,2,3-,

1,2,4-, and 1,3,4-thiadiazole, their amino analogs and

derived Schiff bases is welcomed.

Six new salicylic acid derivatives were prepared by

Djurendic et al. using conventional heating or microwave-

assisted synthesis [24]. Comparison of structures obtained

from X-ray analysis and molecular mechanics calculations

for three of these synthesized compounds, N-(2-hydrox-

ybenzoyl)-2,20-bis(2-hydroxybenzoyloxy)diethylamine,

2,20,200-tris(2-hydroxybenzoyloxy)triethylamine and N-phenyl-

2,20-bis(2-hydroxybenzoyloxy)diethylamine revealed that

the intramolecular hydrogen bonds play an important role in

stabilizing the conformation of the molecules. The antioxi-

dant activity and cytotoxicity tests showed strong activity

against hydroxyl radical, as well as exhibiting promising

lipid peroxidation inhibition. Comparison with the 3- and

4-hydroxybenzoic acid isomers is welcomed: it is to be

noted that the enthalpies of formation of the three isomeric

hydroxybenzoic acids spans but 6 kJ mol-1 in the solid

state. Does this mean the effect of the OH groups on stability

and conformation is rather negligible?

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In the experimental paper by Zhang et al. [25] the syn-

thesis and characterization of complex [Co(Imazameth)3]

0.5DMF4H2O (Imazameth = ()-2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-5-methyl-3-

pyridinecarboxylic acid) by IR spectroscopy, elemental

analysis, thermal gravimetric analysis, fluorescence prop-

erties, and single crystal X-ray structure analysis is reported.

Octameric water clusters were observed. We know of nodirect measurement as to the enthalpy of formation differ-

ence of the tautomeric 4,5-dihydro-4(5)-oxo-imidazole and

imidazole-4(5)-ol or even between their methylated deriva-

tives [26]: synthetic chemists [27, 28] have provided useful

information.

In the following experimental study by Kruszynski [29],

2,20-bipyridine complexation properties of the dichloroac-

etates of zinc and cadmium is reported. [Zn(C10H8N2)

(CHCl2COO)(H2O)3][Zn(C10H8N2)(CHCl2COO)3]

? and

[Cd(C10H8N2)2(CHCl2COO)2] were synthesized and char-

acterized by elemental and thermal analyses, IR and

UVVIS spectroscopy, and crystal X-ray structure analysis.The zinc compound is a rare example of a salt containing

complex anions and complex cations in which the same

organic ligands and anions are in the inner coordination

spheres. Consider now Zn(C10H8N2)(CHCl2COO)2(H2O)2[30]. Forgetting now the differences of Zn and Cd, do the

three compounds in this paragraph compose a homologous

series of hydrates with regards to nearly constant enthalpy

of formation differences, cf. [31]?

Using the MP2 method Qiu et al. [32] studied hydrogen

bonding patterns of the base pairs between 4-thiouracil,

analogue of uracil and four RNA bases, adenine, uracil,

guanine, and cytosine. The order of stability is s4U : guan-

ine[ s4U : adenine[ s4U : uracil * s4U : cytosine and

the calculated interaction energies for the complexes vary

from -7.4 to-13.3 kcal mol-1. What about the difference

of their interaction energies with other nucleobases? What is

the enthalpy of formation difference of 4-thiouracil and the

isomeric 2-thiouracil?

Tomura and Yamashita [33] successfully synthesized the

2:1 co-crystal of 1,2,5-thiadiazole-3,4-dicarboxylic acid and

4,40-bipyridine, which has been widely used as a ligand in

supramolecular architecture in crystal engineering. A unique

two-dimensional ladder-type molecular network in the

co-crystal is built using intermolecular OHN hydrogenbonds and SO heteroatom interactions. The 1,2,5-thiadia-

zole ring is expected to be aromatic by the criterion of having

6 p electrons. Comparison of the aromaticity of its ring

annelated qunoxaline and dihydroquinoxaline derivatives

has recently been reported [34]. How do these species

compare with the parent 1-ring heterocycle?

Gossypol is a polyphenolic terpene that is found in the

cotton plant. Four new solid-state forms, two polymorphic

and two solvated, of the likewise naturally occurring

derivative, 6,60-dimethoxygossypol were synthesized and

their structures determined by X-ray diffraction by Zelaya

et al. [35]. We note that gossypol and its dimethoxy

derivative may be recognized as 2,8-dihydroxy-1-napthal-

dehydes. What is the enthalpy of formation difference

between the aldehyde hydrogen-bonded species involving

the 2-hydroxy group and the ring closed lactol isomer

formed with the 8-hydroxy?In the following study, Qi et al. [36] studied the silyle-

noid 2-NH2CH2C6H4(CH3)SiLiF using DFT to get more

insight into the structures, and properties and solution

phase reactions of pentacoordinate silylenoids. 2-NH2CH2C6H4(CH3)SiLiF is more stable than corresponding silyl-

ene NH2CH2C6H4(CH3)Si. The insertion of 2-NH2CH2C6H4(CH3)SiLiF into CF bonds is similar to that of

NH2CH2C6H4(CH3)Si. The activation barrier for the for-

mer is 62.9 kJ mol-1 higher than that for the latter. What

are the corresponding values for the 3- and 4-isomers of

NH2CH2C6H4(CH3)SiLiF and the corresponding silylene,

and what are the differences of enthalpies of formationwithin sets of isomers?

Trzesowska-Kruszynska [37] synthesized, characterized

by spectroscopic and thermogravimetric analyses, and

determined the crystal and molecular structures of

N-(2-carboxyphenyl)-4-dimethylaminebenzylideneimine penta-

hydrate, which is an example of Schiff base compound

existing as the zwitterion, stabilized by the intramolecular

N?HO- hydrogen bond. As shown by NBO analysis this

form is energetically unfavorable for the free molecule but in

the solid and solution states the intermolecular interactions

support the presence of the zwitterionic form. How many

waters are needed to stabilize the zwitterionis it neces-

sarily at least five?

In the theoretical study by Macaveiu et al. [38] the

effects of NO2 groups on intramolecular interactions were

studied using chloromethane, ClCH3. NO2 groups were

successively introduced to form chloronitromethanes.

Corresponding CN and F derivatives were also checked.

Shortening of the carbonchlorine bond in chloronitrome-

thanes was explained by the changes in the attractive ClOelectrostatic interactions. Following up on this investiga-

tion of chlorotrinitromethane, Klapotke and Liebman [39]

studied the energetics of chlorotrinitromethane and other

trinitromethyl derivatives.

Ghosh et al. [40] synthesized mononuclear nickel(II)

and copper(II) complexes with the tetradentate Schiff base

biacetyl bis(benzoylhydrazone) (H2babh) with the general

formula [M(babh)] and characterized them by microanal-

ysis, magnetic susceptibility, spectroscopically, and X-ray

crystal structure analysis. Both compounds form one-

dimensional self-assemblies via pp interaction and

hydrogen bonding. Considering the partial double bond

character of amides, the above species are seen to have four

Struct Chem (2011) 22:717740 719

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contiguous p bonds not counting the terminal benzene

rings. What is their conjugation energy?

In the next article, Khalaji et al. [41] report the synthesis

of the Schiff base 6-[(5-bromopyridin-2-yl)iminometh-

yl]phenol, and additionally characterized this species by

elemental analysis and spectroscopic methods. X-ray

crystal structure analysis showed a monoclinic structure.

DFT analysis showed that conformer in which the hydroxylgroup and imine nitrogen participate in an intermolecular

hydrogen bonding and pyridine nitrogen is in the other side

of the N1C7 bond is the most stable of four isomers. How

are the relative isomer stabilities modulated by 5-substit-

uents, such as bromine in the current species?

An et al. [42] in their study describe thermal synthesis,

characterization, and crystal structures of 3-D supramo-

lecular compounds [Co(phen)(tdc)(H2O)3]5H2O and [Co(phen)(Htdc)(H2O)3](Htdc)2H2O (phen = 1,10-phenan-

throline, H2tdc = thiophene-2,5-dicarboxylate). While in

the former compound water layers were found to enable

overall 3-D supramolecular architecture by H-bond inter-actions, they were not observed in the latter compound.

What is the equilibrium constant of the reaction

Co phen tdc H2O 3

5H2O H2tdc, Co phen Htdc H2O 3

Htdc 2H2O 3H2O

1

In the following paper, Ye et al. [43] report on the syn-

thesis of four new lanthanide complexes (Ln(3,4-DMBA)3phen)2 (Ln(III) = Nd, Sm, Tb, Dy, 3,4-DMBA = 3,4-

dimethylbenzoate, phen= 1,10-phenanthroline). Compounds

were characterized by elemental and thermal analyses, IR

spectroscopy and X-ray crystal structure analysis. Kinetic

and thermodynamic parameters were calculated which

reveal that the decomposition of the complexes is not

spontaneous. Four of fourteen lanthanides are discussed

above. What periodic trends would be exhibited for these

kinetic and thermodynamic parameters had all these

lanthanide species were to be studied?

Using DFT and Baders theory of Atoms in molecules

(AIM) theory Maecka [44] investigated the nature of

resonance-assisted NHO hydrogen bonds for 3-amino-

methylene-2-methoxy-5,6-dimethyl-2-oxo-2,3-dihydro-

2k5-[1,2]oxaphosphinin-4-one and its derivatives at the

bond critical points. Analysis of the ellipticity parameters

indicated p-delocalization over all six ring atoms. How is

this delocalization manifest in terms of resonance stabil-

ization? We note that there are no thermochemical data for

any [1, 2]phosphinin derivative.

Obtaining single crystals suitable for single crystal

X-ray crystallography of bile acid derivatives is difficult.

Ahonen et al. [45] studied solid state structures of litho-

cholyl-N-(2-aminoethyl) amide. One pure polymorph along

with four solvates were isolated. 13C and 15N CP/MAS

NMR and powder X-ray diffraction (PXRD) was a useful

structural determination strategy. We note few determina-

tions of the enthalpy of few steroids have been made. Does

this mean that samples for calorimetry are likewise hard to

find? More precisely, the thermochemical review by Do-

malski [46] gives a collection of results but the later

compendium, our organic archive by Pedley, inexplicablyfails to include most of these data.

As part of the study toward extraction of heavy metals

and the inclusion of diorganodithiophosphates in activated

composite membranes (ACM) as carriers in the selective

transport of mercury, Perez-Garca et al. [47] synthesized

and characterized five Sn-alkyl (O,O0)-diorganodithio-

phosphates RS2P(OC6H4)2. Structure elucidation showed

that the crystal packing of these compounds is stabilized by

cation-p, weak hydrogen bonding CHO, as well as aro-

matic non-bonded interactions. What is found for the iso-

meric RO2P(SC6H4)2 derivatives and both of the mixed

O- and S-alkylated RO(S)P(OC6H4C6H4S) and RS(O)-P(OC6H4C6H4S) species. Indeed, what are the relative

stabilities of the various isomers?

Theoretical work by Liu et al. [48] is aimed toward

investigation of bonding character of noble-gas com-

pounds of the type CH3NgF (Ng = He, Ar, Kr, or Xe) at

the MP2 level of theory. NgF bond lengths of the

CH3NgF species are all longer than those of the corre-

sponding HNgF species and infrared intensity of the CNg

and NgF stretching vibrations are larger than that of the

other vibrations. The AIM analysis indicated that the

NgF bond (Ng = He, Ar, or Kr) bonds are dominated by

electrostatic interaction and the two CNg (Ng= Ar or

Kr) bonds by covalent interaction. The bond length anal-

ysis seems to indicate that both the NgF and the CNg

bonds are dominated by covalent interaction. No CH3NgF

have yet been observed. However, except for Ng = He,

all the related CH3Ng? are known from experiment and

indeed, their CNg bond energies have been determined

[49, 50].

The following paper by Wang et al. [51] deals with the

synthesis and characterization of new silver coordination

polymers with high packing coefficients. Reactions of sil-

ver squarate, including a new polymorph, and silver tar-

trates with pyrazine resulted in three products which have

been structurally characterized. The crystal structures and

the space-filling properties with respect to the information

retrieved from the Cambridge Structural Database (CSD)

are discussed. The enthalpy of formation of silver squarate

has been determined [52]; now, how we appraise the aro-

maticity of this species with its 2 p-electron anion [53]

especially confounded because of the presence of the Ag?

counterion?

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Avc et al. [54] compared results of HartreeFock (HF)

and DFT for computed and experimental IR vibrational

frequencies and chemical shifts of 3-[(1E)-N-ethylethanim-

idoyl]-4-hydroxy-6-methyl-2H-pyran-2-one. The B3LYP

DFT studies, which include the effects of electron correla-

tion, show a better fit to the experimental vibrational fre-

quencies and 13C NMR chemical shifts than those using HF.

We recognize this species as the N-ethylamide of dehydra-cetic acid, a highly substituted pyrone. No enthalpies of

formation of either 2- or 4-pyrone, or any simple derivatives,

have been determined experimentally to compare with

recent high level theoretical predictions [55]. We note the

enthalpy of dimerization of diketene to dehydracetic acid has

been measured [56], but as we said the latter species is highly

substituted and therefore, comparisons are problematic [57].

In the theoretical work by Oliveira et al. [58] DFT was

used to study trimolecular properties of bifurcated

BeH22HX and linear HXBeH2HX dihydrogen-bon-ded complexes with X = CN and NC. The geometries of

these systems are well-defined wherein the linear com-plexes present shorter dihydrogen bond distances and the

bifurcated complexes present the larger ones. Vibrational

effects were interpreted by the quantum theory of atoms in

molecules (QTAIM) parameters. We may ask what is the

difference of the enthalpies of formation of the ligating

HCN and HNC; only once answered should we ask about

the above beryllium complexes later. Ionmolecule reac-

tions result in ca. 75 kJ mol-1 [59, 60], to be compared

with the calorimetrically determined 90 kJ mol-1 for

CH3CN and CH3NC, and 63 kJ mol-1 for 2,4,6-(CH3)3C6

H2CN and its corresponding isonitrile [61].

A series of experimental papers then follows. As little is

known about multiple bonds linking two reactive centers

Kassaee et al. [62] continued their related investigations

using DFT on unstable and experimentally difficult to

obtain the (nitrenoethynyl)halomethylenes, NC:CCX

(X = H, F, Cl, Br). Triplet minima are 5456 kcal mol-1

more stable than their corresponding quintets. No reac-

tive intermediate is observed through connecting singlet

states of carbene and nitrene subunits and show about

70 kcal mol-1 greater stability than the corresponding

triplet states. We recognize these species as excited states

of cyanoacetylene and its substituted derivatives. An

enthalpy of formation of ca. 85 kJ mol-1 has been reported

in the ion molecule literature [63] for cyanoacetylene itself,

very discrepant from a value by interpolating those calo-

rimetrically determined for acetylene and dicyanoacety-

lene. So, is this value for cyanoacetylene correct? Not

enough is known about the thermochemistry of cyano-

acetylenes and the isomeric polyacetylenes to appraise this.

Lu et al. [64] studied rarely investigated complexes that

contain an asymmetrically 3,5-disubstituted 1,2,4-triazole.

Syntheses, characterization, and single crystal structures of

trans-[CuL2(ClO4)2] and cis-[CoL2(H2O)2](ClO4)2H2OCH3OH (L = 3-methyl-4-(p-bromophenyl)-5-(2-pyri-

dyl)-1,2,4-triazole) which have a similar pseudo-octahedral

[MN4O2] core, two ClO4 ions in the trans position in the

former and two H2O molecules in the cis arrangement of

the latter compound. What are the respective cistrans

isomerization enthalpies and why are they of opposite

sign?In the next paper, Eimann et al. [65] report syntheses

and X-ray crystal structure analyses of 5-iodocytosine and

of three different derivatives of bromo substituted nucleo-

sides. The packing structures reveal aggregations created

via networks of hydrogen bonds involving NHN,NHO, and OHO interactions between the nucleobase

and ribose units. A further support stems from weak

CHO contacts. These species all contain C, H, N, O, andeither I or Br. We know of comparatively few species with

C, H, N, O, and Br for which the enthalpy of formation is

known, e.g., bromotrinitromethane [66] and 5,7-dibromo-

8-hydroxyquinoline [67], and with C, H, N, O, and I,the iodo analog of these species, respectively [66, 67].

Other species are the parent and n-butanoate of the two

3,5-dihalo-4-cyanophenols [68].

Then Jiet al. [69] describe the synthesis, characterization,

and crystal structures of [Cu2(HL)2](ClO4)26H2O and[Zn2(HL)2](ClO4)22H2O (H2L = di(2-pyridylcarbalde-

hyde)-6,60-dicarboxylic acid hydrazone-2,20-bipyridine)

which revealed to be bimetallic molecular squares. We know

of no enthalpy of formation data for any bipyridine carbox-

ylic acid derivative; by contrast this quantity has been

determined for several biphenyl carboxylic acid derivatives

[70] including the 2,20-dicarboxylic acid anhydride [71].

Lah and Leban [72] show in their study on the syntheses

and crystal structures of three new Cu(II) complexes

comprising three simple pyridine alcohol ligands, 3-pyri-

dinepropanol, 2-pyridineethanol, and 2-pyridinemethanol

in their neutral forms. This study documented considerable

structural diversity within the system limited to simple

pyridine alcohols and Cu(II) halides. The solution phase

complexation enthalpy of Cu(II) with the latter two alco-

hols has been directly determined [73]; we know of no such

measurement for the first species. The sole enthalpy mea-

surement we know of for this species is that involving its

intra- and intermolecular hydrogen bonding, a study that

involves the other two pyridine alcohols as well [74].

Styczen et al. [75] describe the syntheses, characteriza-

tion, and crystal structures of manganese and cobalt tetrab-

romometallates(II), [(C2H5)4N]2[CoBr4] and [(C4H9)4N]2[MnBr4]. Magnetic measurements suggest weak anti-

ferromagnetic intermolecular interactions between the

divalent metal ions in the crystal lattice. Consider tetrae-

thylammonium and tetrabutylammonium halides. There is a

nearly constant 200 kJ mol-1difference for the enthalpies of

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formation of these chlorides, bromides, and iodides. Is the

difference (per cation) found for the above tetrabromomet-

allates affected by this antiferromagnetic coupling?

The issue closes with the paper by Szekely et al. [76]

who studied crown ethers containing an alkyl diary-

lphosphinate or diarylphosphinic acid unit. Crystals for

X-ray analysis of the achiral and chiral methyl phosphi-

nates as well as the achiral phosphinic acid which wasfound to form hydrogen bonded dimers in the crystal were

successfully prepared. The calculated electronic circular

dichroism spectrum shows a reasonable agreement with the

spectra obtained in solution which shows that the structure

observed in the crystal is predominant in solution as well.

The thermochemistry of organophosphorus compounds has

been largely ignored when compared to that of sulfur-

containing species; indeed, the Pedley archive includes

none of the former data, Domalskis compendium [46] but

a few. We note that the enthalpies of formation of phe-

nylphosphinic, diphenylphosphinic, and phenylphosphonic

acids have been measured [77].

Issue 2

This issue is devoted to the Polish chemist Adam Bartecki

on the occasion of his 90th birthday. The first paper is an

editorial by Cieslak-Golonka [78] who gives a short

introduction on the work of Adam Bartecki whose interests

range from coordination chemistry to practical applica-

tions, where especially worth mentioning is his expertise in

electronic spectroscopy and his successful work on color.

Following is a paper by Warnke et al. [79], who report onthe synthesis and crystal structure of the new Fe(III) com-

plex [(C2H5)4N][FeCl4] crystallizing in the hexagonal sys-

tem. The magnetic susceptibility measurements revealed

suggests weak antiferromagnetic coupling. Results of

electron paramagnetic resonance spectroscopy indicate

symmetric arrangement of the chloride ligands in the

coordination sphere of Fe(III). The enthalpies of formation

of (C2H5)4NCl, KFeCl4 and KCl are well-established; that

of [(C2H5)4N][FeCl4] remains unknown. We wonder how

close to thermoneutral is the following solid state exchange

reaction

C2H5 4NCl KFeCl4 ! KCl C2H5 4N

FeCl4

2

The related halogen exchange reactions (X = Br, I)

C2H5 4NCl KX ! KCl C2H5 4NX 3

are exothermic by ca. 20 and 40 kJ mol-1, respectively.

In the next paper, Griffiths et al. [80] describe catalyst-

enhanced molten salt oxidation, which is an extension of

molten salt oxidation originally employed in the 1960s. As

revealed, by addition of nitrate catalyst the concentration of

the oxidizing species, superoxide, and peroxide ions that

are produced from the oxygen entering the carbonate melt

could be increased and maintained. Further characteriza-

tion of possible adducts between nitrate and nitrite with

oxygen and peroxide has been done by employing DFT.

While the enthalpy of formation of peroxynitrate and its

covalent hydrogen and alkyl derivatives has only now beenunderstood [81], the enthalpy of formation of peroxynitrite

ion is solidly established [82].

Radecka-Paryzek et al. [83] synthesized, characterized,

and determined the X-ray crystal structure of 2,6-diace-

tylpyridinediphenylhydrazone perchlorate. Spectroscopic

and analytical data of its chelating behavior toward lan-

thanum(III), praseodymium(III), and neodymium(III)

showed 1:2 metal to ligand stoichiometry. What are the

relative stabilities of the isomeric diacetylpyridines? Is it

the same order as recently found for the related pyridine-

dicarboxylic acids [84] wherein COOH replaces COCH3?

The enthalpies of formation of the three monoacetylatedpyridines have all been reported [85].

As showed in the study by Staszak et al. [86] 3-methyl-

4-nitropyridine-N-oxide (3-mnpn) interacts with copper(II)

acetate to form a solid, crystalline, dinuclear copper(II)

complex with formula [Cu(OAc)2(3-mnpn)]2. New bands

observed at 16000 and 24000 cm-1 in the electronic

spectra were plausibly ascribed to metalmetal interactions

and solid state effects. We wonder how different are the

spectroscopic and thermochemical properties of 3-methyl-

4-nitropyridine-N-oxide and 4-methyl-3-nitropyridine-N-

oxide, and of related complexes; the enthalpy of formation

of only the former N-oxide is available from the literature

[87].

Phenytoin complexes of Co(II) and Ni(II), [Ni(H2O)4(pht)2] and [Co(H2O)4(pht)2]1.5NH3H2O (pht = phenot-oinate anion) were synthesized by Puszynska-Tuszkanow

et al. [88]. The compounds were characterized by spec-

troscopic, thermal, and magnetic measurements. X-ray

structural analysis revealed that the environment around

the nickel and cobalt ions can be described as a distorted

octahedron. Although the first measurement of the com-

bustion enthalpy of a hydantoin (5-ureidoimidazolin-2,4-

dione, the so-called allantoin) was first reported over

100 years ago [89] that of phenotoin (the 5,5-diphenyl-

derivative) remains unmeasured despite its biomedical

importance. The thermochemistry of hydantoins remains

problematic [90] and incompletely studied.

Nowak et al. [91] report the synthesis of several

new compounds of the flavonoid, rutin, with Fe(II) and

Fe(III) ions. This study gains relevance because selective

inhibitory effect of rutin under pathologic conditions

induced by iron overload is thought to be due to the forma-

tion of inactive ironrutin complexes. Complexes having

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formulas FeOH(C27H29O16)5H2O, Fe2OH(C27H27O16)9H2O,Fe(OH)2(C27H29O16)8H2O, [Fe6(OH)2(4H2O)(C15H7O12)-

SO4]10H2O were synthesized. Their composition wasdetermined by elemental analysis and thermogravimetric

measurements. These species were additionally character-

ized by spectroscopic and magnetic properties. A thermo-

dynamic study of metal-flavonoid interactions has been

reported [92].In the next paper, Adach et al. [93] report synthesis,

characterization, and X-ray crystal structure of a novel

cobalt(II) complex [Co(L)Cl]2[CdI4] (L = tris(1-(3,5-

dimethylpyrazolylmethyl)amine) obtained in situ from the

redox system (Co0, CdCl2, NH4I, 1-hydroxymethyl-3,5-

dimethylpyrazole). Diverse isomers exchanging the halo-

gens Cl and I may be suggested: what determines the

formation of the above iodocadmate? We do note that the

solid state reaction

CoI2 CdCl2 ! CoCl2 CdI2 4

is exothermic by ca. 45 kJ mol-1 suggesting [Co(L)Cl]2[CdI4] is plausibly more stable than [Cd(L)Cl]2[CoI4].

However, this ignores all contributions from metal-N

bonding.

Wojciechowska et al. [94] reported the new crystalline

Cu (II) complex Cu(phen)2OCrO3](phen)0.54H2O, derived

from the [Cu(II)-phen-K2CrO4] system (phen = 1,10-phe-

nantroline) system. The compound was characterized by

spectroscopic (NIRVisUV) methods and its structure

determined by X-ray diffraction. The chromate unit was

found to be monodentate. Consider now the simpler, i.e.,

uncomplexed, CuCrO4. Comparison of its enthalpy of

formation with the other mixed copper chromium oxides,Cu2Cr2O4, and CuCr2O4 [95] is welcomed; a study of their

Gibbs energies has been reported [96].

In the study by Kamecka et al. [97] systems Cu(II)L1L2(L1 = ethylenediamine (en), diethylenetriamine (dien) or

N,N,N0,N0,N00-pentamethyldiethylene triamine (Me5dien)

and L2 = (aminomethyl)phosphonic acid (glycinephos-

phonic acid, Gly(P)) were investigated using potentiomet-

ric, spectrophotometric, and EPR methods. The EPR

parameters obtained correspond to a five-coordinate spe-

cies. The enthalpies of formation of ethylenediamine,

diethylenetriamine [98, 99], and triethylenetetramine [98]

have all been determined as well as that of tetraethylene-pentamine [100], the last value should solvation enthalpies

be ignorable.

As part of continuing investigations on interpretation of

the electronic spectra of the copper(II) complexes with

Schiff bases, Kurzak and Kuzniarska-Biernacka [101]

synthesized the bis(salicylidene-2-amino-3-methylpyridine)

copper(II) complex, which was characterized by elemental

analysis, conductivity measurements, and UVVis spec-

troscopy. Coordination properties of donor atoms and their

bonding abilities, as well as solvatochromism were studied

by electronic spectra. The angular overlap model (AOM)

calculations were carried out within the framework of the

simplest model. Colorimetry and calorimetry have occa-

sionally been combined to enhance understanding of sol-

vatochromic systems, e.g. [102].

Further Radtke et al. [103] describe synthesis, spectral

characterization, thermal properties, and X-ray crystalstructures of the novel Zr(IV) b-ketodiester complexes of

general formulas [Zr(dtbacdc))4], [Zr(dmacdc)3(OiPr)]2,

and [Zr(dtbacdc)3(OiPr)]2 (dtbacdc = di-tert-butyl-1,3-ac-

etonedicarboxylato, dmacdc = dimethyl-1,3-acetonedi-

carboxylato ligands). As the synthesized compounds have

potential application in the technique of chemical vapor

deposition, the most often used method in the preparation

the high quality of ceramic materials and thin metal oxide

layers, thermal decomposition pathways were discussed.

The enthalpies of formation of the related homoleptic

8-coordinate zirconium complexes with acetylacetone and

its 1,1,1-trifluoro derivative have been reported [104].With interest in cobalt(II) complexes with tetrahedral or

pseudo-octahedral geometries with Schiff bases derived

from salicylaldehyde and amines in a variety of solvents,

Kurzak et al. [105] prepared [Co(sap)2] (Hsap = salicyli-

dene-2-aminopyridine) and characterized it by elemental

analysis, molar conductivity, cyclic voltammetry, and Vis

NIR spectroscopy. A tetrahedral geometry was suggested

in the solid state and in solution. Electronic spectroscopy

was used to study the ligandfield parameters and solva-

tochromism. The authors describe electrochemical reduc-

tion and the addition of the electron to the metal and

pyridine ring. What does that tell us about the conjugation

of the endo and exocyclic nitrogens? The thermochemistry

of 2-aminopyridine metal complexes has been explored,

e.g., the enthalpy of formation of bis(2-aminopyridine)zinc

chloride has recently been reported [106] .

Zeolites or related materials have been widely used as

catalysts, cation exchangers, and adsorption media. In the

paper by Roth and Dorset [107], it is shown that the

symmetry principles may govern and rationalize formation

of different zeolite frameworks from corresponding layered

zeolite precursors. Despite their seeming complexity as

defined by the large number of atoms per formula unit,

enthalpies of formation of zeolites are encouragingly well-

understood [108].

With the purpose to provide better understanding of the

interactions between explosives and surfaces of selected

porous metalorganic frameworks that possess the catalytic

activity, Petrova et al. [109] theoretically studied the

interactions between the adsorption of 1,3,5-trinitro-s-tri-

azine (RDX) and triacetone triperoxide (TATP) on repre-

sentative fragments of metal organic framework (IRMOF-1).

Comparison of these species with their respective

Struct Chem (2011) 22:717740 723

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oligomers is welcomed: we note the enthalpies of forma-

tion of RDX and the corresponding tetramer (HMX) are

both known. The value for neither TATP nor for the

corresponding dimer, tetramethyl-1,2,4,5-tetroxane, are

known from experiment. However that of several other

tetroxanes such as the parent species [110], and the

3,6-bis(butanal) [111], 3,6-bis(butanoic acid) [112] and

3,6-diphenyl [113] derivatives have been reported.Dro_zd_zewski et al. [114] reexamined the X-ray crystal

structure of bis(4-hydroxybenzhydrazide)copper(II) sulfate

dihydrate complex. The two water molecules are not coordi-

nated to the metal, but rather stabilize the sulfate group ori-

entation and link the layers of complex molecules by strong

hydrogen bonds. DFT calculations were used to interpret IR

and Raman spectra that had been enhanced by deuteration and

copper stable isotope substitutions. Copper (II) sulfate exists

as the anhydrous and the mono-, tri-, and pentahydrateso,

why not also the dihydrate [115] here as well?

New mixedligand lanthanide complexes of Er(III),

Yb(III), and Lu(III) with 4,40-bipyridine and dichloroace-tates were prepared by Czylkowska et al. [116]. X-ray

crystal structures of the complexes were determined as well

as elemental, IR spectroscopic analysis, conductivity

measurements, and thermal studies (TG-DTA-DTG)

were performed. The intermolecular OHO, OHN,CHO, CHCl, and p p interactions link complex

and organic molecules to the three-dimensional network.

The relative acidity of haloacetic acids, e.g., dichloroacetic

acid, or conversely, the relative basicity of haloacetate

anions is an exemplary exercise in the relative importance

of substituent steric and inductive effects and solvation

energies of ions and related neutrals [117, 118]. How are

complexation energies and enthalpies of the diverse halo-

acetates affected by halogens?

Kulesza et al. [119] synthesized the new neodymium(III)

complex NaNd(SP)4 chelate (SP = C6H5S(O)2NP(O)

(OCH3)2) and determined it X-ray crystal structure. Large

intensity of the 4I9/2 ?4G5/2;

2G7/2 transition with a rela-

tively high symmetry has been found. The high-resolution

absorption, emission, and excitation spectra and accompa-

nying crystal-field calculations have been performed and

compared with the earlier reported compound NaNd-

Wo4H2O(Wo = CCl3CONP(O)(OCH3)2)).Weknowofnoenthalpy of formation data for any acylphophoramide;

indeed, the only phosphoramides with known enthalpies of

formation are the parent species P(O)(NH2)3 [120] and the

alkylphosphonic dianilides, CH3P(O)(NHC6H5)2 and

C2H5P(O)(NHC6H5)2 [121]. Likewise, we know of only one

unequivocal example of the enthalpy of formation of an

acylsulfonamide, namely that of saccharin [122].

The general pattern of solvatochromic behavior for a

variety of iron(II) complexes has been documented by

Burgess and Hubbard [123]. The emphasis of this study was

diimine complexes and their behavior in a variety of ternary

aqueous solvent media. Enthalpy and entropy changes

associated with the redox chemistry of two different types

of iron diimine complexes have been reported [124, 125].

Two contributions by Sobczyk and Dro_zd_zynski then

follow. In the first contribution [126] U(III)-doped LaBr3single crystals were synthesized and their high-resolution

low temperature emission spectra were studied. The emis-sion from the 2K15/2,

2H11/2, and4F9/2 levels to the ground

state, 4I9/2, and from2K15/2 to the first excited state

4I11/2have been investigated and discussed with respect to vib-

ronic transitions. The assignment has been proposed. In the

following contribution [127], synthesis of U(IV)-doped

KPb2Cl5 single crystal and its unpolarized absorption,

excitation, and emission spectra studied. Good agreement

was found between theoretical lifetimes calculated by

JuddOfelt intensity analysis of 5f25f2 transitions calcu-

lated and experimentally measured for this compound. Here

are U(III) and U(IV)can U(II) be likewise studied? U(II)

has been observed in alkaline earth halide matrices [128]and in salt melts [129] for which a redox potential, and

hence a Gibbs energy from the Nernst equation, has been

assigned.

The last paper in this issue is by Godlewska et al. [130],

who studied IR and Raman spectra of Dy, Ho, Er, and Lu

phthalocyanine of the type PcLn(OAc). The changes of the

structure and symmetry of the axially substituted metall-

ophthalocyanine complexes have been checked and dis-

cussed on the basis of group theory. As concluded, this

analysis can assist in gaining information on the molecular

structure of this type of compounds. How strong is the

LnO bond? We wonder about the stability of divalent

PcLn species formed by the formal cleavage of the bond,

and are they better described as PcLn(III). After all,Pc2Ln species have been studied as neutral species and as

radical cations and anions. When do they contain trivalent

lanthanides [131]?

Issue 3

Issue 3 of 2010 review opens with the obituary written by

Hargittai [132] for Lev V. Vilkov (19312010), a premier

scientist interested in the structures of relatively small

organic molecules and the techniques capable of this

determination. Following this essay, Hargittai [133] wrote

an obituary for Torvard C. Laurent (19302009). Laurent

was an expert in X-ray diffraction technique of macro-

molecular structures that led him to do the pioneering

research on the structural chemistry of hyaluronan. He

determined many of the physicochemical properties of

hyaluronan and their relationship to the versatile biological

functions.

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In the next contribution, Notario et al. [134] discuss the

enthalpy of formation of acrylonitrile, which despite the

industrial importance of this species, is still not accurately

known from experiment. Using defining reactions, G2 and

G3 quantum chemical calculations, and using literature

sources, values between 185 and 191 kJ mol-1 were sug-

gested with a recommended average of (188 7) kJ

mol-1. A delocalization stabilization energy of but4 kJ mol-1 has been suggested, a small value in accord

with the value for acrylic acid earlier discussed by these

authors [135].

Using one- and two-dimensional NMR spectroscopy

Silva et al. [136] completed the 1H and 13C NMR signal

assignments for four luminescent 1,2,4-oxadiazole con-

taining light-emitting liquid crystals. Experimental chemi-

cal shift calculations were in rather good agreement with

the signals as calculated by DFT incorporated with GIAO.

The thermochemical literature of 1,2,4-oxadiazoles and

their 1,3,4- and 1,2,5-isomers is surprisingly rich albeit

seemingly only for solid state species. We note that theenthalpies of formation of the diphenyl derivatives of these

three heterocycles span a ca. 160 kJ mol-1 range.

Organophosphorus inhibitors are among the most dan-

gerous compounds developed by man as they inhibit acetyl-

cholinesterase (AChE). Post-treatment regimens involve also

oxime AChE reactivators. Skorska-Stania et al. [137] syn-

thesized (E)-1,4-bis(4-hydroxyiminomethylpyridinium)-

but-2-ene (K075) and 4,40-bis(hydroxyiminomethyl)-1,10-

(1,4-phenylenedimethyl)-bispyridinium (K114) bromides and

determined their structure by X-ray single crystal analysis.

Hydrogen bonds were shown to be of considerable impor-

tance in stabilizing these crystals and in the reactivation of

AChE. Despite their importance, enthalpies of formation

data for oximes is scarce and generally not particularly

reliable [138].

Nicola and Mahe [139] prepared the solvated form of

biclotymolN,N-dimethylacetamide 1:1 solvate and deter-

mined its crystal structure, which was then compared to

the crystal structures of the DMSO and DMF 1:1 solvates

of biclotymol. Two conformers have been observed

experimentally although conformational analysis con-

ducted by employing semiempirical and ab initio tech-

niques of the isolated biclotymol molecule revealed that

there are six possible conformers. Biclotymol is a

p-chlorophenol derivative. The enthalpy of formation of

both m- and p-chlorophenol has been determined; sur-

prisingly, there are no such data for the o-isomer given

there are also measurements for all six dichlorophenols

[140]. We know of no data for the enthalpy of formation

of any of their solvates.

Husak et al. [141] determined crystal structures of two

new polymorphs of simvastatin, a drug for the treatment

hypercholesterolemia, by X-ray powder diffraction and

solid-state NMR spectroscopy. The main differences

among three polymorphs, the two new and the one earlier

described, is only in the O4C20C21C22 and C20C21

C22C23 torsion angles describing the rotation of the side

group. It is interesting to note that the phase changes are

fully reversible. Simvastatin is a hexahydronaphthalene

derivative. The relative enthalpies of formation of the

parent hexahydronaphthalenes have been studied [142,143]; we know of no analogous relative biomedical activ-

ities of their analogous simvastatin isomers.

Due to the interest in the IIVI semiconductors Xu et al.

[144] studied CdTe nanocrystals by DFT. After optimizing

Cd3Te3, (Cd3Te3)2, (Cd3Te3)3, and Cd4Te4 structures

TeCdligand clusters were optimized to further discuss

the bond and optical spectrum qualities of CdTe nano-

crystals. The sublimation enthalpy of CdTe and other group

12 chalcogenides was recently explained in terms of atom-

based thermochemistry [145].

Ponikvar-Svet et al. [6] in the next paper relate ther-

mochemistry to the content of the articles contained inStructural Chemistry for the year 2005 and so this paper

represents a conceptual ancestor of the current study.

The Kuhn segment, varying in polyheteroarylenes from

10 to 15 A to ?, links the geometric structure of a

monomer unit of polyheteroarylenes to its physical prop-

erties. In the paper by Ronova [146], a volume factor that

serves as a good proxy for the geometric structure of a unit

of aliphatic polymers has been suggested. This factor

correlates with those physical properties that depend on the

free volume. The simplest polyarylene is polyphenylene,

(C6H4)n. The enthalpies of formation of the p-isomer

[147] and its monophenylated derivative have been deter-

mined [148].

The family of plants known as Clusiaceae (Guttiferae)

shows a diversity of metabolites, such as oxygenated xant-

hones which have been widely studied due to their potential

biological activities. Correa et al. [149] managed to iso-

late 1-hydroxyxanthone, 1-hydroxy-7-methoxyxanthone,

1,5-dihydroxy-3-methoxyxanthone, and 1,7-dihydroxy-3,8-

dimethoxyxanthone, to determined their X-ray crystal

structures and study molecular interactions. Important

bonding is represented by hydrogen bonds and the crystal

self-assemblies are kept together bypp interactions. While

the enthalpy of formation of the parent species xanthone has

been determined multiple times [150152], we know of no

measurements at all for the above (or for that matter, any)-

substituted derivatives.

Huang et al. [153] studied the nature of hydrogen bonds

through structures, energies, frequencies, and electron

density topological analysis in (CH3OH)n (n = 28) clus-

ters using DFT, natural bond orbital (NBO), and QTAIM

approaches. The strengths of OHO H-bonds in (CH3OH)nclusters increase from n = 2 to 8, along with the increasing

Struct Chem (2011) 22:717740 725

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of DEprep (the amount of energy required to deform the

separate bases from their free monomer structure to the

geometry that they acquire in the pair cluster) due to

the deformations during the formations of clusters. At what

stage does the cluster become effectively indistinguishable

from the bulk liquid? From the bulk solid?

Using DFT approach, Contreras et al. [154] studied

nitrogen-containing exohydrogenated carbon nanotubesformed by covalently arranging 210 and 20 layers of

identical cyclic units having a pyrimidine backbone.

Structural and electronic properties were investigated.

Calculated band gap values were small (around 0.2 eV) for

all the studied structures and were dependent on the

number of layers and the configurations. Recently, the

energetics of carbon nitrides (and carbon oxides) was dis-

cussed [155]: no thermochemical data yet exist for these

nitrogenated carbon nanotubes.

Geometric and electronic changes of a series of

poly(carbosilysilanes) induced by varying the size and

species of the substituting groups was investigated by Dinget al. [156] using DFT combined with AM1 method. While

the bias-trans conformation is preferred if the side chain

contains fewer than three carbons, the all-trans confor-

mation with a loose-helix backbone is a preference with

more than four carbons in side chain. The enthalpy of

formation of solid SiC is well-established. How does this

number relate to enthalpies of formation for these polymers

and discrete organosilicon compounds such as the meth-

ylated silanes?

In the theoretical paper by Kassaee et al. [157], DFT was

used to investigate the effects of different sized rings

(cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl sub-

stituents) on the stability of spirocyclic (alkyl)(amino)carb-

enes (CAACs). The cyclopropyl-substituted CAAC shows

higher DEs-t and DEHOMO-LUMO than the others (54.2 and

116.7 kcal mol-1, respectively). The ring inversion energy

barriers were assigned which do not show a considerable

difference with those of the bare cyclohexane, cyclopentane,

andcyclobutane;enthalpies of formationare known for these

cycloalkanes but none of these carbenes derivatives.

In the experimental paper by Prathapachandra Kurup

et al. [158] synthesis and characterization including the

X-ray crystal structure determination of oxovanadium(IV/V)

complexes of 2-hydroxyacetophenone-3-hydroxy-2-naph-

thoylhydrazone (H2L) along with the crystal structure of

an oxovanadium(V) complex [VOL(OCH3)] existing in

two polymorphic forms is reported. Consider the related

VOL(OH) complex. What is the gas acidity of this species?

On which oxygen does VOL(OH) protonate and what is the

corresponding gas phase basicity? The enthalpy of forma-

tion of aqueous VO2? and VO2? are well-established.

Using single crystal X-ray analysis and quantum chemi-

cal calculations Fukin et al. [159] analyzed the basic

geometrical, kinetic, and energetic properties features of 4,5-

disubstituted 3,6-di-tert-butyl-o-benzoquinones. Identified

contacts of the C=OH(tBu)-type (2.373.83 kcal mol-1)can be interpreted as intramolecular hydrogen bonds. These

hydrogen bonds were not considered in the analysis of

enthalpies of formation of the parent and t-butylated o-ben-

zoquinones [160]. Should the literature analysis be redone?

Clozapine and haloperidol are two common antipsy-chotic agents. With the purpose to develop compounds

with the clozapine-like profile of high dopamine D4 and

serotonin 5-HT2A receptor affinity for the treatment of

schizophrenia Capuano et al. [161] synthesized, charac-

terized, and determined X-ray crystal structures of three

new prospective antipsychotic agents, one originating from

the structural hybridization of the commercial therapeutics,

clozapine, and haloperidol, while the others possess an

alternative tricyclic nucleus derived from JL13, a cloza-

pine-like atypical antipsychotic. Clozapine is a dibenzo-

1,4-diazepine derivative; haloperidol is a piperidine-4-ol

derivative. No thermochemical data is seemingly availablefor 1,4-diazepines, save from a study of their basicity

[162]. Piperidine-4-ols have been discussed in the context

of enthalpies of formation [163, 164] and of their enzy-

matic interconversion with the related 4-piperidiones [165].

Gholivand et al. [166] synthesized and characterized by

IR, 1H-, 13C-, 31P-NMR spectroscopy and CHN elemental

analysis four new phosphoric triamides derived from iso-

nicotinamide with the general formula 3-NC5H4C(O)NH-

P(O)XY (X = Y = Cl; X = Y = NHC(CH3)3; X =Y =

N(C4H9)2; X = Cl, Y = N(C2H5)2. Two new polymorphs

of the compound with X = Y = NHC(CH3)3 for which

X-ray crystal structure were determined were obtained.

These compounds form centrosymmetric dimers via inter-

molecular hydrogen bonds. Due to different strengths of

hydrogen bonds a three-dimensional polymeric cluster is

formed in the first while two-dimensional polymeric chain

is formed in the case of second compound. The enthalpies

of formation of isonicotinamide and its 2- and 3-pyridin-

ecarboxamide isomers (nicotinamide and picolinamide),

and also of isonicotinamide and nicotinamide Npy-oxides

have been reported [167]. Picolinamide Npy-oxide has

seemingly not been studied by thermochemists. Its photo-

chemistry shows [168] rearrangement to N-formylpyrrole-

2-carboxamide, a likewise thermochemically uncharacterized

species.

A new ruthenium arsine complex with pyrazole ligand

[RuCl3(AsPh3)(C3H4N2)2]0.5CH3OH complex has beenprepared and characterized by X-ray structure analysis and

IR and UVVis spectroscopy by Maecki and Kruszynski

[169]. Next to DFT and time-dependent DFT methods also

natural bond orbital (NBO) analysis were used to calculate

the electronic structure and UVVis spectrum. Good

agreement between experimental and calculated UVVis

726 Struct Chem (2011) 22:717740

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spectra was obtained. There are three isomers

RuCl3(AsPh3)(C3H4N2)2: the isomer with the two pyra-

zoles cis to each other and the arsine trans to one of them is

the one that was studied. What is the relative energy of this

species and the other two isomers in which the arsine and

the two pyrazoles are all cis, and the pyrazole is cis to the

two pyrazoles which are trans to each other?

In the theoretical study by Chermahini et al. [170] DFTand ab initio calculation were employed to study the

hydrogen bond interactions of dimer of difluoroacetic acid.

Eight different conformers were considered. The calcula-

tions predict the order of stability in monomeric difluro-

acetic acid: EHC[EFC[EHT. The interaction energy of

dimer of difluoroacetic acid is enough to overcome the

relative stability of the monomers and dimer formation

proceeds. As well understood as the hydrogen bonding in

the dimer is as well as conformational preferences from

this study, reliable information as to the value of the

enthalpy of formation of difluoroacetic acid itself is still

lacking, cf. [171, 172].In the theoretical study by He et al. [173], periodic DFT

calculation was used to investigate crystalline 2,6-diamino-

3,5-dinitropyridine-1-oxide, an important explosive and

raw materials for preparing high energetic explosive. The

insight into chemical molecular properties was obtained by

analyzing band structures, densities of states and charge

distributions. The theoretical lattice energy of the crystal

was predicted to be -166.03 kJ mol-1. How does this

lattice energy compare with this quantity for the 1,4-

dioxide, the unoxygenated heterocycle and the isomeric

4-oxide?

In the article by Zhu and Xiao [174] recent papers on

first-principles band gap predictions of the impact sensi-

tivity for different classes of energetic crystals were

reviewed. It was shown that the first-principles band gap

criterion is applicable to different series of energetic

crystals with similar structure or with similar thermal

decomposition mechanism and therefore this principle

could be used for molecular design of high-energy den-

sity materials. These authors discuss metal azides. We

note a recent paper that discusses the anomalously high

electron affinity of azido radical [175] and thus the sta-

bility of species with the azide ion such as these metal

azides.

Issue 4

Issue 4 of the 2010 review begins with an editorial written

by Hargittai [176] on the occasion of publishing the new

book by Victor McElheny Drawing the Map of Life

describing the huge importance and background of Human

Genome Project (HGP) completed in 2003 by succeeding

to determine the entire DNA sequence.

In the theoretical study by Wu et al. [177], DFT was

used for the purpose of studying the structures and elec-

tronic properties of endohedral metallofullerenes TM@C24and TM@C24H12 (TM = Cr, Mo, W). The results show

that TM atoms bind over the pentagon ring inside the C24

cage. The analyses of dissociation energy and energy gapindicate that these compounds are not only thermody-

namically, but also considerably kinetically stable. We note

that the simplest species involving Cr, Mo, and W, the

bis-cyclopentadienyl or ocene derivatives Cp2TM, are

all known. The enthalpy of formation of the Cr species is

well-established [178, 179], while that with Mo and W

remain unmeasured except as oxidized (higher metal

valence) form with affixed ligands [180].

In the experimental paper by Petek et al. [181], synthesis

and X-ray crystal structure of o-hydroxy Schiff base deriv-

ative, (E)-2-ethoxy-6-[(2-methoxyphenylimino)methyl]phe-

nol was synthesized and its molecular geometries at thedifferent stages in tautomerism of (E)-2-ethoxy-6-[(2-

methoxyphenylimino)methyl]phenol studied. The Harmonic

Oscillator Model of Aromaticity (HOMA) indices were

calculated for each step of a potential energy surface (PES)

scan. This showed that there is a dynamic equilibrium

between the aromaticity level of the phenol and chelate ring.

How do the alkoxy groups affect the aromaticity? We recall

a study comparing the enthalpies of formation of the iso-

meric methoxy and dimethoxyphenols [182].

In the following theoretical paper, Farmanzadeh and

Ashtiani [183] proposed single molecular wire, 4,40-[eth-

ane-1,2-diylidenedi(nitrilo)] dibenzenethiol and studied

electric field effects on the structural and electronic prop-

erties by employing DFT. The results show that the elec-

tronic structure is more sensitive than geometric structure

to both directions of the applied electric field and that with

increasing the electric field X component of electric dipole

moment and total dipole moment increase continuously.

We note the NC6H4S substructure of the above key

species and that there are but three species containing

this thioaniline functionality with a measured enthalpy of

formation, phenothiazine, 1,3,7,9-tetranitrophenothiazine-

5-oxide and cis-5a,6,11a,12-tetrahydro[1, 4]benzothiazino

[3,2-b][1, 4]-benzothiazine [184]. None of these, however,

have the p-N,S substitution pattern found in the above

benzenethiol derivative.

Aghabozorg et al. [185] report the synthesis and charac-

terization including X-ray crystal structures of three new

metal compounds (H2bda)[Mn(pydc)2]3H2O, (H2bda)[Zn(pydc)2]3H2O, and (H2bda)3[Ce(pydc)3]24H2O (bda =butane-1,4-diamine, pydcH2 = pyridine-2,6-dicarboxylic

acid). In the crystalline network hydrogen bonds, pp

stacking, and ion pairing play important roles in the

Struct Chem (2011) 22:717740 727

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12/24

formation of supramolecular structures. The complexation

studies on these compounds in addition to Ni(II), Cu(II), and

Cd(II) compounds including the (H2bda)(pydc) ion pair have

also been performed. What about other diamines? It is

perhaps surprising that there are no thermochemical data for

butane-1,4-diamine. Then again, of all the a,x-diaminoalk-

anes, only the ethane and hexane [186] derivatives have

been so-investigated.A series of theoretical studies then follow. In the first

Wanno and Ruangpornvisuti [187] report use of DFT for

studying electronic properties and structural properties of

helical thiophene carbonsulfur oligomers, H2(C2S)nC2H2(n = 120). It was found that helix of the icosamer

(H2(C2S)20C2H2) makes one full turn for every approxi-

mately 3.493 A along its length and its inner diameter is

approximately 4.04 A. It may be asked how the aromaticity

varies with n. Then again, it must be asked are we using the

thermochemical, magnetic, or geometric criterion for aro-

maticity (see [188] for a study of the n = 2 case).

Mohajeri and Alipour [189] next describe use of con-ceptual DFT with the aim to compare the site selectivity in

the complete series of dichloropyridines as ambiphilic

molecules toward the reactivity and regioselectivity.

Nucleophilic and electrophilic characters were analyzed.

Of the six position isomers only 2,5-dichloropyridine is not

a dually active molecule and is just prone to nucleophilic

attack while remaining five are ambiphilic. The enthalpy of

formation of diverse chloropyridines is discussed in Refs.

[190, 191].

In the following paper, Deng and Zhou [192] used DFT

to study two complexes with significant antitumor activity,

[Ti(g5-C5H4{CMe2CH2CH2CH=CH2})2Cl2] and [Ti{Me2Si(g5-C5Me4)(g

5-C5H3{CMe2CH2CH2CH=CH2})}Cl2],

which have different substituent monofunctional bindings

to the purine bases and phosphate group which are poten-

tial binding targets. Results reveal that the monoaquated

complex binding to guanine shows the smallest activation

free-energy with 15.3 kcal mol-1 for the former and

21.5 kcal mol-1 for the latter complex. In the first dia-

quated compound, the lowest activation-free energy is

16.7 kcal mol-1 for the guanine closely followed by the

phosphate group by 18.3 kcal/mol, while the lowest acti-

vation-free energy is 16.9 kcal mol-1 for the second

complex binding to the phosphate group. Additionally,

major electronic characteristics were investigated. Are we

right to assume there is but a negligible effect of the p

electrons in the dimethylpentenyl substituent?

Then experimental paper by Zhang et al. [193] follows

in which synthesis and characterization by elemental

analysis, spectroscopic methods, and X-ray crystal analysis

of a series of dinuclear and trinuclear half-sand-

wichzirconocene complexes derived from (diphenyl-,

dibenzyl-)phosphate and methylphenylphosphinic acid is

reported. The results reveal the importance of experimental

conditions for the design of molecular structures. The tri-

nuclear species contain a central l3 oxygen. How strong is

the ZrO bond for these triply bridged species as opposed

to the more customary doubly bridging oxygen? There are

but few cases of multiply bridging oxygen for which the

thermochemistry is known. Among them are the so called

basic beryllium salts or beryllium oxy salts of the genericformula Be4OX6 with a l

4-oxygen at its core (X = nitrate

[194], acetate [195], and propionate [193]).

Alkorta and Elguero [196] investigated the absolute 13C

shielding of 13 methane derivatives (CH3X, X = CH3, CN,

NH2, NO2, OH, F, Cl, Br, SH, SeH, PH2) and proposed a

method for correction of chemical shifts obtained by DFT

calculations for carbon atoms directly linked to heavy

atoms that takes into account a quadratic variation with the

atomic number. It is well-established that the CO bond in

CH3OH is different than in (CH3)2O as shown by their

different proton affinities [19].

Machura et al. [197] managed to synthesize and char-acterize by IR, UVVis spectroscopy, magnetic measure-

ments, and X-ray crystallography a novel rhenium(III)

complex [ReBr3(dppt)(OPPh3)] (dppt = 5,6-diphenyl-3-(2-

pyridyl)-1,2,4-triazine). Using DFT approach the electronic

structure was determined. Spectroscopic and magnetic

properties were revealed to be characteristic of mononu-

clear complexes with d4 low-spin octahedral Re(III) com-

plexes (3T1g ground state). How different is the binding of

3-(2-pyridyl)-1,2,4-triazine and the isomeric 3,30-bis(py-

ridazines)? Insufficient is known about the energetics of

substituted pyridazines and triazines to attempt answering

this about metal complexes.

Systematic investigation by X-ray structural and thermal

analysis of solvates of nevirapine used in combination with

other antiretroviral drugs to treat HIV-1 infection and

AIDS, with the homologous series of primary alcohols

CH3(CH2)nOH with n = 27 is then reported by Steiger

et al. [198]. Nevirapine is a tetraaza derivative of diben-

zosuberane. The parent heterocycle is thermochemically

uncharacterized; only recently, the enthalpy of formation

of the corresponding carbocycle was reported [199].

In the paper by Kaczmarek et al. [200] synthesis and

characterization by spectroscopic methods and X-ray

structural analysis of (La(III), Eu(III), Gd(III), Er(III),

Tm(III), and Lu(III) complexes containing N,N0-bis(sali-

cylidene)-4-methyl-1,3-phenylenediamine (H2L) ligand is

presented formed by self-assembly formation of dinuclear

lanthanide salicylaldimines. Crystal structure determina-

tion revealed a rare coordination pattern of salen-type

ligand. There is a 12 kJ mol-1 spread in the enthalpies of

formation of the three isomeric phenylenediamines, as

solids. Now, how different are thus the related isomeric

salen-type ligands or any such complexes.

728 Struct Chem (2011) 22:717740

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Hamza [201] report on the synthesis of 5,6,11,12-tetra-

hydrodibenzo[a,e]cyclooctene (THDC) and its two selec-

tively deuterated isotopomers which were studied by

resonance-enhanced two-photon ionization spectroscopy in

a supersonic jet expansion. The results showed that about

90% of THDC in the gas phase exists in the twist-boat and

the remaining 10% in chair conformation. The enthalpy of

formation of the 5-keto species has been measured [202]but not that of the parent, three-ring compound mentioned

above. We welcome that of this species and note the

comparison of the enthalpies of formation of ben-

zocycloalkanes the corresponding keto compounds is of

continuing interest, e.g. [203] for a study of indane and the

isomeric indanones.

In the study by Kaynak et al. [204] synthesis, character-

ization including X-ray structural characterization and

theoretical investigations of two novel derivatives of 1,2,4-

triazolo[3,4-b]-1,3,4-thiadiazine, 3-[2-(4-methoxyphenyl)

ethyl]-6-phenyl-7H-1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazine

and 3-[2-(3,4,5-trimethoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazine having analgesic

anti-inflammatory activity is reported. The six-membered

thiadiazine ring adopts the screw boat conformation in both

compounds. Potential energy surface scans were drawn. We

know of no thermochemical studies for thiadazines. For

dithiazines, admittedly 1,3,5- and not 1,3,4-derivatives,

there is none but the over 100-year-old study [205] which is

simultaneously suspect and suggestive.

Campanelli et al. [206] in their contribution describe

advantages and limitations of gas-phase electron diffrac-

tion for determining molecular structure of five different

benzene derivatives, 1,4-difluorobenzene, 1,3,5-trifluoro-

benzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, and

silylbenzene. The report is rather unique, as it is only rarely

possible that the analyses can be repeated independently by

the same technique in two different laboratories. Except for

the last species, the enthalpy of formation of each of these

species is known. As such, we are thwarted from com-

paring the energetics of the phenyl transfer reaction

4C6H5EH3 ! C6H5 4E 3EH4 5

for E = C and Si.

Ethyl 2-methyl-4-(4-methylbenzoyl)-5-(4-methylphenyl)-

7-oxo-3,3a-dihydropyrazolo[1,5-c]pyrimidine-3-carboxylate

and ethyl 2-methyl-4-(4-methylbenzoyl)-5-(4-methylphenyl)-

7-thioxo-3,3a-dihydropyrazolo[1,5-c]pyrimidine-3-carbox-

ylate are interesting because of diverse medical and

biological activities of pyrimidine derivatives. These species

were successfully synthesized and characterized by Onal

et al. [207] by reactions of 1-amino-5-(4-methylbenzoyl)-4-

(4-methylphenyl)pyrimidin-2(1H)-one/-thione with ethyl

acetoacetate. Theoretical calculations (DFT, NBO analysis,

and Fukui function) revealed the former compound is more

stable than the latter. We note the initial synthetic step

involves furan-2,3-diones. To the extent that furan is aro-

matic, are these species at least antiaromatic because of

their nominal 4 p electrons as discussed for the isomerically

related furan-2,5-dione (more commonly known as maleic

anhydride) [208]?

Isomerization of azobenzene derivatives is important

from the perspective of their applications. Using DFT Zhuet al. [209] studied cistrans isomerization mechanisms in

the S0 and T1 states of 3,30-azobenzene disulfonate. In the

S0 state the energy barrier is 22.79 kcal mol-1 and it con-

cerns mainly the rotational pathway around the NN double

bond while the energy barrier of T1 state is 5.02 kcal mol-1

and requires a change in spin-multiplicity. The strength of

NN bonds in azo compounds shows considerable depen-

dence on the affixed groups [210]. How is that reflected in

the rotational barriers of these azo compounds?

Picolinic acid derivatives form a group of bidentate

ligands effectively complex the tricarbonyltechne-

tium(I) and rhenium(I) cations and form promising radio-pharmaceutical precursors. Using DFT, Fuks et al. [211]

proved that in vitro behavior of tricarbonylrhenium(I) and

tricarbonyltechnetium(I) complexed by the N-methyl-2-

pyridinecarboxyamide and chloride, water or tert-butyl-3-

isocyanopropionate is thermodynamically controlled. The

energy of formation of the complexes containing tert-

butyl-3-isocyanopropanoate ligand is more negative by a

few kcal mol-1 than energy of those having a coordinated

water molecules instead. The energetics ofp-complexes of

the valence isoelectronic tricarbonylmanganese(I) cation

has recently been reviewed [212]. Comparison with the

above technetium and rhenium species is welcomed.

Hayvali et al. [213] report the synthesis and character-

ization of the substituted benzyloxybenzaldehyde deriva-

tives by reaction of the appropriate hydroxy benzaldehydes

with p-nitrobenzyl bromide in DMF and NaOH. After 5 h

of reflux with furfuryl amine the corresponding imine

compounds were formed, and the crystal structures were

determined. After longer reflux time, cyclization reaction

with a CO bond occurs and corresponding benzofuran

derivatives are formed. Quoting a recent review [214],

de-benzoannnelation resulting in an aromatic one-ring

species (e.g., benzofuran) is generally more favorable than

processes involving non- or antiaromatic species. This

was discussed in context of heterocyclic analogs of indene

and indane, cyclopentadiene and cyclopentene, with benzo-

annelated 5-membered rings. What about other size rings,

e.g., the 6-membered ring containing analogs of naphtha-

lene and its hydrogenated derivatives?

A series of theoretical papers then follows. Using DFT,

Zhu and Xiao [215] studied substituent effects on the

electronic structure and properties of the 1H-tetrazole

crystal and variously substituted derivatives. The

Struct Chem (2011) 22:717740 729

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calculated thermodynamic properties show that the order

of their thermodynamic stability is 5-amino-1H-tetrazole

\5-methyl-1H-tetrazole\5-azido-1H-tetrazole\1H-tetra-

zole and that their decomposition reactions are favorable at

high temperature. An attempt to correlate the impact sen-

sitivity of the four crystals with their band gaps showed

that the first-principles band gap criterion can be used to

predict impact sensitivity for the substituted 1H-tetrazoles.Do the same substituent trends for stability apply to the

isomeric triazoles, diazoles and parent pyrroles?

In the subsequent paper by Huang et al. [216] use of

DFT, the QTAIM and NBO analyses to study hydrogen

bonds and the interaction characteristics in cysteineprop-

anoic acid complexes are reported. More than 10 kinds of

H-bonds including intra- and intermolecular H-bonds have

been found. The results show that the important factors for

the stability of complexes are strength of H-bonds and the

deformations. What about alanine and serinepropanoic

acid complexes? When can we ignore hydrogen bonding

involving SH groups?Further Huang et al. [217] report use of DFT, QTAIM,

and NBO to study geometries, energies, and IR charac-

teristics of the intermolecular hydrogen bonds in com-

plexes formed between N-protonated adrenaline and

dimethyl sulfoxide. While the H-bonds involving amino or

hydroxyls as H-donor are dominant in complexes and

considered as strong H-bonds, weak H-bonds, such as p

H-bonds and H-bonds involving methyl or methenyls

(C2H6 and C5H7 of AdH?) as H-acceptors were found in

complexes as well. The reader will note we said N-pro-

tonated earlier in this paragraph. Was there a choice? For a

discussion of the alternative N and O protonation sites in

aminoalcohols, the reader is referred to Ref. [218].

Using DFT the structures and properties of the planar

double hydrogen-bonded imidazoleadenineimidazole

trimer were studied by Cui et al. [219]. The H-bond gen-

erated by NH group of adenine decreases significantly in

length upon oxidation to form the radical cation and sig-

nificant IR spectra red-shift occurs upon oxidation for all

NHH bonds. The molecular orbital analysis was effec-tive to reveal the geometry variations and the IR spectral

shifts. We note that while the ionization energy of imid-

azole is greater than that of purine as the authors point out,

the proton affinities are in the reverse order [19].

The theoretical study by Qi et al. [220] follows with a

study of the insertions of the p-complex silylenoid H2SiLiF

into CX bonds of CH3XHn-1 (X = F, Cl, Br, O, N;

n = 1, 1, 1, 2, 3) using DFT is the following. The results

revealed that substituted silanes H2Si(XHn-1)CH3 and LiF

are formed. The reaction barriers for the insertion of the

p-complex into CX bond increase for the same-row ele-

ment X from right to left in the periodic table and do not

change much for the insertion of the same family element

X. All this is sensible except that we also note there are no

reliable measurements of the CF bond strength in CH3F or

equivalently, of the enthalpy of formation of methyl

fluoride.

Alkorta and Elguero [221] report conformational anal-

ysis of medium-sized rings, namely four derivatives of

cyclooctadiene bearing two aromatic or heteroaromatic

rings. Good agreement between experimental results andtheoretical results was reached. We look forward to studies

comparing the findings of Hamza [201] to this article.

In the last paper in this issue Zhan and Feng [222] report

on synthesis of two 3D supramolecular complexes con-

structed from p-thioacetatebenzoic acid (H2L), [Mn(HL)2(bpp)2(H2O)2]n and [NiL(4,4

0bipy)(H2O)3]nnH2O (bpp =

1,3-bi(4-pyridyl)propane, 4,40-bipy = 4,40-bipyridine). The

former compound exhibits intense structure-related fluo-

rescent emission bands. The latter exhibits irreversible

redox processes. The enthalpy of formation of numerous

substituted benzoic acids has been studied. We know of no

examples where the substituent is bonded to the benzenering by a sulfurhowever, enthalpy of hydrolysis studies

discussing CH3C(O)O- and CH3C(O)S-substituted benzoic

acids is recalled [223, 224].

Issue 5

Issue 5 of the present volume opens with the editorial by

Hargittai [225] written in honor of Gyorgy Kepes, designer

and art theorist. Although not a chemist Kepes managed to

influence chemistry and science with his visionary

approach in design and so ultimately accomplishing design

in science.

The next paper is a theoretical study by Beheshtian et al.

[226] in which the DFT approach was used to study the

interaction of water with the outer layer of single-walled

boron nitride nanotubes. The results suggest that water can

be adsorbed on the surface through BO interactions by asignificant charge transfer and NHO hydrogen bond

interactions, and that the water is better adsorbed as the

cluster size increases. As an archetypical study, we ask

what is the interaction energy of borazine with water and is

B or N-bonding to water preferable? What is the hydration

energy of borazine to form the saturated B,B0,B00-tri-

hydroxyborazane? We note that borazine photochemically

reacts with water to form the B-hydroxy derivative and the

corresponding ether [227], the latter being shown to be

more stable. By contrast, for the isoelectronic benzene

derivatives, phenol is rather much more stable than the

corresponding ether (?water).

In multiple types of non-bonded interactions it is intui-

tively expected that they would be formed hierarchically

based on energetic gains. In the paper by Rathore et al.

730 Struct Chem (2011) 22:717740

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[228], synthesis of derivatives of 3-azabicyclo[3.3.1]

nonan-9-one, namely 10,12-bis(2-fluorophenyl)-11-azatri-

cyclo[7.3.1.02,7]trideca-2,4,6-trien-13-one, and its bis(2-

methylphenyl) and bis(2-methoxyphenyl) counterparts, is

reported and the interactions studied. Preferences for

weaker interactions over strong hydrogen bonds were

observed. How strong are the nitrogencarbonyl transan-

nular interactions in these species and how are theseinteractions impacted by the above substitution of the two

phenyl groups?

What follows is a theoretical study by Goodarzi et al.

[229], who investigated energies of the gas phase reaction of

SewithO3 using DFT. As calculationally shown, SeO3(D3h)

and (SeO ? 3O2) products are obtained via transformations

of the linear chain SeO3 isomer. Both reactions are at

atmospheric pressure and temperature of 298.15 K exo-

thermic and exergonic (DH\ 0,DG\ 0).WenoteSeO2 is a

classic oxidizing agent in organic chemistry; presumably

SeO3 would be even more oxidizing. Sulfur dioxide is an

occasional reductant. This is reflected in some 70 kJ mol-1

difference in the enthalpies of formation of selenium diox-

ide, as solid, and sulfur dioxide, as gas (where the solid is

unequivocally even more stable by an unstated enthalpy of

sublimation). The difference is over 200 kJ mol-1 for the

trioxides for the same choice of phases. Why do the dioxides

and trioxides differ by so much?

He et al. [230] in their experimental paper report on

synthesis and characterization including X-ray single crystal

analysis of 3d4f heterometallic coordination polymers

based on 2,5- and 2,6-pyridinedicarboxylic acid, [Cu3Eu2(2,5-pydc)6(H2O)12]4(H2O), [Zn2Eu2(2,5-pydc)5(H2O)2]

3(H2O), and [Co3Ln2(2,6-pydc)6 (H2O)6]4(H2O) (Ln = Eu,3; Dy, 4) (H2pydc = pyridinedicarboxylic acid) under

hydrothermal conditions. The results, which indicate that

compounds generate 3D heterometallic coordination frame-

works containing 1D channels that are occupied by lattice

water guest mole, are important from the perspective of

further construction of novel 3D lanthanidetransition metal

heterometallic coordination frameworks. We note the tran-

sition metal is always divalent while the lanthanide is always

trivalent. Some transition metals are naturally trivalent while

some lanthanides enjoy the divalent oxidation state. Can

related species be prepared with these reversed oxidation

states and how does that effect the structure, and thereby

properties, of these complexes?

With the aim to investigate influence of oxidation

damage on the guanine:cytosine base pairs Qiu et al. [231]

studied structures of their derivatives with MllerPlesset

perturbation theory. Marked differences in the interaction

energy were shown: among the hydrogen bond complexes

ranging from-24.1 to-13.0 kcal mol-1 for derivatives of

the guanine bonded to cytosine derivatives and from-24.5

to -9.7 kcal mol-1 for cytosine bonded to guanine

derivatives. Thermochemical data for the free component

nucleobases and their derivatives are almost totally absent

in the experimental literature (see Domalski [46] but not

Pedley). We note that the unmodified

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