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Masters Theses Student Theses & Publications
1995
The Synthesis and Characterization of [RuII (bpy)2 (biphen) ] (PF6)2 and [ (bpy) 2RuII (biphen)RuII (bpy) 2] (PF6)4Mei-Yueh ChangEastern Illinois UniversityThis research is a product of the graduate program in Chemistry at Eastern Illinois University. Find out moreabout the program.
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Recommended CitationChang, Mei-Yueh, "The Synthesis and Characterization of [RuII (bpy) 2 (biphen) ] (PF6)2 and [ (bpy) 2RuII (biphen) RuII (bpy) 2](PF6)4" (1995). Masters Theses. 1966.https://thekeep.eiu.edu/theses/1966
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The Synthesis and Characterization
of [Ru II (bpy) 2 (biphen) ] (PF 6 ) 2
and [ (bpy) 2RUII (biphen) RuII (bpy) 2] (PF5) 4
(TITLE)
BY
Mei-Yueh Chang
THESIS
SUBMITIED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
MASTER OF SCIENCE IN CHEMISTRY
IN THE GRADUATE SCHOOL, EASTERN ILLINOIS UNIVERSl1Y
CHARLESTON, ILLINOIS
1995 YEAR
I HEREBY RECOMMEND THIS THESIS BE ACCEPTED AS FULFILLING THIS PART OF THE GRADUATE DEGREE CITED ABOVE
7-2 /-C,{"" DATE
DATE
The Synthesis and Characterization of
[Ru11 (bpy2 ) (biphen)](PF6 ) 2 and
[(bpy) 2Ru11 (biphen)Ru11 (bpy) 2 J (PF6 ) 4
Thesis Approved
}-Z/- 1J.-
Abstract
A new bidentate polypyridine bridging ligand (biphen),
produced by the condensation of 1,10-phenanthroline-5,6-dione
with 5,6-diamino-phenanthroline has been synthesized and
characterized. In addition
[ (bpy) 2RUII (biphen)] (PF5) 2 and
the
the
monometallic
bimetallic
complex
complex
[ (bpy) 2Run(biphen)Run(bpy) 2] (PF6 ) 4 have been prepared. The
complexes were characterized by elemental analysis, by 1H-NMR
spectroscopy and by cyclic voltsmmetry(CV).
The results of these analyses seem to indicate that
biphen acts like two independent units when attached to a -
Run (bpy) 2 fragment. a bipyridine portion and a phenazine
portion. Moreover, CV data on the bimetalllic complex
indicated no special stability for the mixed-valence form,
ruling out any significant metal-metal interaction.
ACKNOWLEDGEMENT
I would like to express my sincere appreciation to Dr.
Mark E. McGuire, my research advisor, for his patience and
help during this study.
I would like to thank the faculty and staff of the
Chemistry Department of Eastern Illinois University and
Kaohsiung Noble University and the other members of our
research group for their encouragement and assistance.
II
Table of Contents
Introduction ........................................... 1
References ................................ 10
Experimental Section .................................. 12
Materials ................................. 12
Measurement ............................... 13
Methods ................................... 14
References ................................ 2 0
Results and Discussion ................................ 21
Biphen .................................... 21
[Run (bpy) 2 (biphen)] (PF6 ) 2 and
References ................................ 42
Summary ............................................... 67
Appendix
III
List of Tables
Table 3-1 1H NMR Spectra Data of Ligands ............ 32
Table 3-2 UV-Vis Data of Ligands .................... 33
Table 3-3 UV-Vis Data of [Run (bpy) 2 (biphen)] (PF6 ) 2
in CH3CN .................................. 35
Table 3-4 UV-Vis Data of
[ (bpy) 2RUII (biphen) RuII (bpy) 21 (PF5) 4
in CH3CN .................................. 36
Table 3-5 UV-Vis Data of Analogous
Ru Complexes .............................. 3 7
Table 3-6 UV-Vis Data of Mono- and Bi-metallic
Complexes ................................. 3 8
Table 3-7 Cyclic Voltammetry Data of Ruthenium
Complexes ................................. 39
Table 3-8 Oxidation Potentials of Ruthenium
Complexes ................................. 40
IV
List of Tables
Table 3-9 Redox Properties of Analogous
Ruthenium Complexes ....................... 41
v
List of Figures
Figure 2-1 The 1 H-NMR Spectrum of
5-N02-l,10-phenanthroline ................ 43
Figure 2-2 The 1H-NMR Spectrum of crude
5,6-diamino-1,10-phenanthroline .......... 44
Figure 3-1 The Structure and Numbering of
1,10-phenanthroline ...................... 45
Figure 3-2 The Structure and Numbering of
1,10-phenanthroline-5,6-dione ............ 46
Figure 3-3 The Structure and Numbering of biphen .... 47
Figure 3-4 The Structure of Pptd .................... 48
Figure 3-5 The Structure of
Dipyro[3,2-a;2',3'-c]phenazine ........... 49
VI
List of Figures
Figure 3-6 The Structure of
2,3-bis(2-pyridyl)-pyrazine .............. 50
Figure 3-7 The Structure of
2,5-bis(2-pyridyl)-pyrazine .............. 51
Figure 3-8 The 1H-NMR Spectrum of
1,10-phenanthroline in CDC1 3 ••••••••••••• 52
Figure 3-9 The 1H-NMR Spectrum of
1,10-phenanthroline-5,6-dione in CDC1 3 ••• 53
Figure 3-10 The 1H-NMR Spectrum of biphen in CDC13 .. 54
Figure 3-11 The UV-Vis Spectrum of biphen in CHC1 3 •• 55
Figure 3-12 The UV-Vis Spectrum of biphen in CH3CN .. 56
VII
List of Figures
Figure 3-13 The UV-Vis Spectrum of 2,2-bipyridine
in CH3CN ................................. 57
Figure 3-14 The UV-Vis Spectrum of phenazine in
CH3CN .................................... 5 8
Figure 3-15 The Structure of
[Ru II (bpy) 2 (biphen) ] (PF 6) 2 ••••••••••••••••• 59
Figure 3-16 The Structure of
Figure 3-17 The 1H-NMR Spectrum of
[Run (bpy) 2 (biphen) ] (PF 6 ) 2 in CD3CN ........ 61
VIII
List of Figures
Figure 3-18 The 1H-NMR Spectrum of
in CD3CN ................................. 62
Figure 3-19 The UV-Vis Spectrum of
[RuII (bpy) 2 (biphen)] (PF6) 2 in CH3CN ........ 63
Figure 3-20 The UV-Vis Spectrum of
in CH3CN ................................. 64
Figure 3-21 The Cyclic Voltammogram of
[RuII (bpy) 2 (biphen)] (PF6) 2 ••••••••••••••••• 65
Figure 3-22 The Cyclic Voltammogram
[ (bpy2 ) Run (biphen) Run (bpy) 2 ] (PF6) ......... 66
IX
List of Figures
Figure A-1 The UV-Vis Spectrum of
5,6-diamino-1,10-phenanthroline ......... A-I
Figure A-2 The IR Spectrum of
5,6-diamino-1,10-phenanthroline ........ A-II
Figure A-3 The 1 H-NMR Spectrum of
5,6-diamino-1,10-phenanthroline ....... A-III
x
:Introduction
Electron transfer (ET) reactions are very common in
inorganic, organic and biological systems. Attempts to study
the fundamental chemistry of ET reactions have involved
simplified model systems. In particular, much research has
been devoted to the design and synthesis of molecular systems
comprised of electron donors and acceptors that mimic the
charge separation function of proteins involved in
photosynthesis.
In the past 30 years, long range ET between donor (D) and
acceptor (A) molecules has been studied in several systems in
which D and A are held apart by rigid spacer groups. The
rigid spacer groups are usually structures normally thought of
as good "molecular wires" such as aromatic and/or conjugated
systems1 • However, a variety of compounds can serve the same
function (rigid or semi-rigid spacer) such as proteins2 ,
steroids3 , and other saturated framework structures. In fact,
despite initial perceptions Pasmen et al. 4 have suggested that
through-bond interaction between the electron donor (D) and
the electron acceptor (A) separated by bridge a-bonds can
still lead to strong charge-transfer.
An electron donor and acceptor separated by a rigid
spacer ( --- ) can be depicted as in Scheme 1.
1
A --------- D
Scheme 1
If both A and D are metal centers the system in Scheme 1 could
be depicted as in Scheme 2.
M1 --------- M2
Scheme 2
Here, M1 and M2 may or may not be identical. If in fact M 1 and
M2 are the same metal center differing by one unit in
oxidation state (e.g. M1 = Mrr and M 2 = M rrr ) , a "mixed-valence"
system results (Scheme 3).
MII -------- MIII
Scheme 3
In this case, the conversion of the system in Scheme 3 to its
"redox-isomer" can occur by an ET mechanism (Scheme 4).
--- MII
Scheme 4
2
According to Robin and Day5 , intramolecular interactions
in mixed-valence systems like that shown in Scheme 3 can be
divided into three different types or classes. Class I
compounds refer to the case where there is little or no
electronic interaction between the metal centers. [The
perturbation Hamiltonian Hab coupling the initial (Mn --- Mrn)
and the final (Mrrr --- Mr states is equal to zero]. In
Class I compounds, the two metal centers act as independent
units. Class II compounds refer to an intermediate case (weak
to moderate interaction) . In class III compounds there is
very strong interaction and consequent delocalization of
charge over the entire supramolecule. In class III, the
individual characteristics of each metal are non-existent (the
transferring electron is considered to be delocalized) .
Strictly speaking, according to Fermi's golden rule (Eq.
1-1) 6 , the rate constant for the ET process shown in Fig. 1-4
(electron-exchange) can be determined:
kET = 2rr/h Hab2 FCWD (Eq. 1-1)
Here Hab is the electron coupling matrix element and FCWD is
the Franck-Condon weighted density of states.
As can be observed from Eq. 1-1, the magnitude of Hab is
directly proportional to kET and thus is a good measure of the
amount of electronic communication between Mn and Mrrr .
3
Hush7 has derived a relationship between Hab for the ET process
depicted in Scheme 4 and the energy and intensity of the
optical transition shown in Scheme 5
Scheme 5
Here, E0 P is the energy of what is referred to as an
intervalence charge transfer (IVCT) or a metal-to-metal
charger transfer (MMCT) band * vibrationally excited
state). For many mixed-valence systems, the MMCT band can be
observed in the red to near-IR portion of the spectra.) The
relationship between Hab and Et,P derived by Hush is shown in
Eq. 1-2.
(Eq. 1-2)
Solving eq.1-2 for Hab giving
0 ( E · /\v ) = 2 3 8 0 r 2 H 2 "'max op Ll 1/2 ab
4
Here, E0 P and E'1nax are the energy (cm-1 ) and molar extinction
coefficient (M-1 cm1 ) of the MMCT band, respectively. The
metal-metal distance (A) is depicted by r, and Llu112 (cm-1 ) is
the bandwidth at half-height. According to Hush Llu112 is
related to E0 P and to the internal energy difference between
the two redox isomers (LlE) .
Llu112 = 2310 (E0 P - LlE) (Eq. 1-3)
An intense (large e) MMCT band is indicative of significant
communication between the metal centers. Class I compounds do
not have any stability in the mixed valence form and hence
show no IVCT bands. Class II compounds show relatively weak
bands with larger bandwidth (e < 5000 M-1 cm-1 ; Llu112 > 2000 cm-
1) • Class III compounds show intense IVCT bands that are
fairly narrow (e > 5000 M-1 cm-1 ; Llu112 < 2000 cm-1 ).
Electrochemical data can also be used in a qualitative
way to either rule out the existence of any significant
electronic interaction in systems like that shown in Scheme 3
or infer (but not prove) the existence of such interaction.
The stability of the mixed-valence species shown in Scheme 3
can be described by measuring the comproportionation constant,
Kc, for its formation.
5
MII --- MII + MIII --- MIII ----+ 2 MII --- MIII
If the Mn --- Mn mixed-valence form has no special
stability, Kc = 4 (statistical limit). However, if Kc > 4, the
mixed-valence state shows some extra stability compared to the
Mn - - - Mn and Mnr MIII precursors.
This could be due to a number of factors. 8
1. Entropic factor (greater disorder possible in
mixed-valence form.)
2. Electrostatic effects (depend on molecular shape,
structure and solvent)
3. Synergistic factors (Mn stabilized by Mnr , etc.)
4. Electron delocalization
Since electron delocalization is only one factor determining
the size of Kc, the possibility of its existence is only
inferred if Kc > 4. If Kc = 4, however, then any significant
electron delocalization in the mixed valence form can be ruled
out.
It has been shown9 that when the difference in standard
reduction (Mn1 /Mn) potentials between the two ends of the
Mn --- Mn complex is sufficiently large (> 250 mV), a value
of Kc can be calculated from the electrochemical data.
6
(Eq. 1-5)
E1 ------- MIII --- MII
E2 ------- MII - - - MII
Qualitatively, then, the difference in reduction
potentials t.E1 , 2 ( = E1 - E 2 ) can be used to either rule out the
existence of electronic interaction or infer the possibility
of its presence. In this thesis, cyclic voltammetry (and
half-wave potentials, E112 ), will be used to observe whether or
not the reduction (or oxidation) of one end of a bimetallic
compound can affect the ease of the reduction (or oxidation)
of the other end.
Ruthenium(II) polypyridine complexes {ie. [Ru(bpy) 3 ] 2+;
bpy = 2,2'-bipyridine and derivatives) have been extensively
used for the elucidation of the factors that govern the rates
of ET reaction. 10 This class of compounds has many
advantageous properties:
1) Ru(II) polypyridine compounds can be used as light
absorption sensitizers in excited state and
photochemical reactions.
2) These complexes can be used as catalysts in
important processes such as the reduction of C02 •
3) Ru(II) polypyridine complexes tend to be stable in
7
both the oxidized and reduced forms. ([Ru (bpy) 3 ] 2+
can be stored in aqueous solutions for months 11 and
is unaffected by boiling cone. HCl or 50% aqueous
sodium hydroxide solutions12 .)
4) Ru(II) polypyridine complexes are well suited for
the study of the relationship between
electrochemical and spectroscopic properties.
In addition a large number of such complexes can be
synthesized with varying electrochemical and spectroscopic
properties.
Recently, a large number of bimetallic Run complexes
(Rurr-Rurr) have been studied where the rigid bridging group is
a bidentate polypyridine ligand. As is typical for
polypyridine ligands, these bridging ligands possess both o
donor and rr-acceptor properties. A number of such compounds
have been synthesized. Dose and Wilson13 reported the
preparation and properties of [Ru (bpy) 2 (bpm)] 2 + and
{[Ru (bpy) 2 ] 2bpm} 4 + (bpm = 2, 2 '-bipyrimidine and bpy =
bipyridine) . Gafney and co-workers14 reported the preparation
of monometallic and bimetallic ruthenium complexes based on
the ligand 2,3-bis(2-pyridyl) pyrazine (bpp). See Fig. 1-1
for structure diagrams of the bridging ligands bpm and bpp.
In this work the preparation and properties of the
monometallic and bimetallic Run complexes of a new bidentate
polypyridine bridging ligand tetrapyridophenazine (biphen) are
8
described. The structure of biphen is shown in Fig. 1-1. The
complexes were characterized by UV-Vis and NMR spectroscopy.
In addition, cyclic voltammetry was used to measure whether or
not the possibility of electron communication between the
ruthenium centers (across biphen) existed. Finally, the
results will be compared to other similar systems.
9
Reference
1. (a) Guarr, T.; McGuire, M. E.; McLendon, G. J. J. Am.
Chem. Soc. 1985, 107, 5104-5111.
(b) Kira, A. and Imanura, M. J Phy. Chem. 1984, 88,
1865-1871.
(c) Miller, J. R.; Beitz, J. V.; Huddleston, R. K . .iI.....
Am. Chem. Soc. 1984, 106. 5057-5068.
2. McLendon, G. Acc. Chem. Res. 1988, 21, 160-167.
3. Closs, G. L.; Calcaterra, L. T.; Green, N. J. Penfield,
K. W.; Miller, J. R. J. Phy. Chem. 1986, ..2...Q, 3673-3683.
4. Pasman, P. Verhoeven, J. W.; Boer, Th. J. de
Tetrahedron Lett. 1977, 207-210.
5. Robin, M. B.; Day. P. Adv. Inorg. Chem. Radiochem.
1967, 1...Q_,__ 247.
6. Yonemoto, E. H.; Saupe, G. b.; Schmehl, R.H.; Hubig,S.
7 .
M.; Riley, R. L.; Iverson, B. L.; Mallouk T. E. J. Am.
Chem. Soc. 1994, ~ 4786-4795.
a. Allen, G. C.; Hush, N. S. Prog. Inorg. Chem. 1967,
..a..,_ 357.
b. Hush, N. S. Prog. Inorg. Chem. 1967, ..8._,_ 391.
c. Hush, N. S. Electrochimical Acta. 1968, .lJ...,__ 1005-
1023.
8. Creutz, C. In Prog. Inorg. Chem.; Lippard, S. J.; Ed.;
John Wiley & Sons: New York, 1983; pp 1-73.
10
9. Richardson D. E.; Taube H. Inorg. Chem. 1981, 20, 1278-
1285.
10. Kavarnos, G. J.; Turro, N. J. Chem. Rev. 1986, ~ 481-
490.
11. Brandt, W.W.; Smith, G. S. Anal. Chem. 1949, ~ 1313-
1319.
12. Burstall, F. H. J. Chem. Soc. 1936, 173-175.
13. Dose, E. V.; Wilson, L. Inorg. Chem. 1978, .11..i._ 2660-
2666.
14. Fuchs, Y.; Lofters, S; Dieter, T.; Shi, W.; Morgan, R.;
Strekas, T. C.; Gafney, H. D.; Baker, A.D. J. Am. Chem.
SQQ..._ 1987, ~ 2691-2697.
11
Experimental Section
Materials. l, 10-Phenanthroline (phen, 99+%), hydroxylamine
hydrochloride (NH20H·HC1, 99%), ammonium hexafluorophosphate
99.9%), acetonitrile 3 (CH CN, 99%) and sodium
hydrosulfite (Na2 S20 4 , 85%) were purchased from Aldrich
Chemical Co. and used without further purification. Fuming
sulfuric acid (H2S04 , 30% S03 ), cone. nitric acid (HN03 , 69-71
%) and glacial acetic acid (CH3COOH, 99.7%) were all reagent
grade and purchased from Fisher Chemical Co. and used as
received. The solvent ethylene glycol (HOCH2CH20H) was
purchased from Eastman Kodak Company. Dichloromethane (CH2Cl2 ,
99. 5%), ethanol (C2H50H, 95%), methanol (CJi OH), chloroform
(CHC1 3 ) and potassium hydroxide (KOH, 85+%) were purchased
from E.M. Science and used as received. Absolute ethanol
(C2H50H) was purchased from Midwest Grain Products and used as
received. The deuterated solvents chloroform (CDC1 3 , 99.8
atom% D), acetonitrile (CD3CN, 99. 8 atom% D), and methyl
sulfoxide ((CD3 ) 2SO, 99.9 atom% D) were purchased from
Cambridge Isotope Laboratories and used as received.
Polarographic grade tetrabutylammonium hexaf luorophosphate
(TBAH) was purchased from Bioanalytical Systems Inc. Chemicals
and used as received. Acetonitrile used for UV-Vis spectra
was spectrophotometric grade and was purchased from E. M.
Science. All water used for reactions was purified from a
12
Millipore "Milli-Q" water system. Acetoni trile used for
electrochemical experiments was stored over 4 A "Molecular
Sieves" purchased from MCB Manufacturing Chemists or from
Aldrich Chemical Co. Some electrochemical experiments used
acetonitrile (E.M. Science, HPLC grade) that had been
distilled over CaH2 (Aldrich Chemical Co. , 95+%) and then
stored over 4 A Sieves (activated at 350 °C for 24 h.)
Measurements. Melting point measurements were performed on a
Laboratory Devices MEL-TEMP. 1H NMR spectra were recorded
using a General Electric QE-300 FT-NMR. UV-Vis spectra were
recorded on either a Shimadzu UV-160U or a Shimadzu UV-3100
recording spectrophotometer. IR was obtained on a Nicolet 20
DXB FT-IR spectrometer. Electrochemical measurements were made
using either a Ag wire or a saturated sodium chloride calomel
electrode (SSCE, Bioanalytical System, Inc.) as a reference
(room temperature). A 1.5 mm platinum button electrode was
used as the working electrode and a platinum wire was used as
the auxiliary electrode. The electrolyte was
tetrabutylammonium hexaf luorophosphate (TBAH) . Cyclic
voltammetry measurements were obtained using an EG&G PAR Model
173 potentiostat for potential control with a Model 175
universal programmer as a sweep generator. Voltammograms were
recorded on a The Recorder Company Model 200 xy-recorder. The
E112 values from the cyclic voltammograms were calculated from
13
the average of the Ev {potential at current maximum) values
for the anodic and cathodic waves. Elemental analyses were
performed by Atlantic Microlabs, Norcross, GA.
Methods.
1,10-phenanthroline-S,6-dione (phendione) and 5-nitro-1,10-
phenanthroline (5-N02-phen): These compounds were synthesized
by using a method analogous to that reported by Amouyl et.
al 1 • In a typical preparation, 1,10-phenanthroline (9.1133 g,
0.0505 moles) and fuming H2 S04 (55 mL) were mixed in a three
neck RB flask. The mixture was heated to 110 °C and cone. HN03
(10 mL) was added drop by drop (using a separatory funnel) to
the oleum/phenanthroline solution. The reaction mixture was
heated to 145 °C and cone. HN03 (29 mL) was added over 0.5 h.
At the end of this addition the temperature had dropped to 120
°C. Then the yellow reaction mixture was cooled to room
temperature and left stirring for 2 h. The reaction mixture
was then poured into 100 mL of ice and neutralized with 30%
NaOH to around pH 3 to 5. The yellow precipitate was removed
by filtration using a 150 mL M frit. The solid in the frit
was thoroughly washed with water. The filtrate and water
washes were saved and set aside. The solid (mostly 5-N02 -
phen) was dried in vacuo.
g (57.64%, based on phen).
Yield of crude 5-N02 -phen: 6.1263
The dried solid was triturated with 100 mL of water (to
14
remove any remaining phendione) , and the resulting suspension
was filtered. The filtrate was saved and set aside. The
solid was suspended in 35 mL of hot ethanol (95%), and the hot
solution was filtered using a 30 mL M frit. The filtrate was
cooled slowly to room temperature and precipitate formed. The
mixture was filtered using a 60 mL F frit. The solid obtained
was dried in vacuo. Yield of pure 5-N02 -phen: 3.3505 g (32%,
based on phen) m.p. 198-200 °C (lit2 m.p 202-204 °C). 1 H NMR
(CDC1 3 , Fig. 2-1), ppm (TMS): 7.60 (dd, lH), 7.83 (dd, lH),
8.46 (d, lH), 8.71 (s, lH), 9.12 (d, lH), 9.32 (d, lH), 9.36
(d, lH) .
The filtrate (water washes) from the trituration, and the
filtrate and water washes from the 5-N02 -phen synthesis were
combined and extracted with CH2Cl2 (in two batches) in a 500
mL separatory funnel.
with 50 mL of CH2Cl 2 •
Each batch was extracted four times
The combined ~H ~l extracts were
evaporated overnight in the hood. Yield of crude phendione
(2.5510 g, 23.99 %, based on phen). m.p. 242-248 °C.
Methanol (120 mL) was heated in a 200 mL RB flask
equipped with a stir bar and a reflux column. The crude
phendione from the previous step was then added quickly. The
yellow solution was boiled about 5 min until the solid almost
all dissolved. The hot solution was filtered through a warm
150 mL M frit. The filtrate was cooled to room temperature
and crystals formed. The mixture was filtered using a 60 mL
15
F frit and the solid was washed with 15 mL of cool CH30H. The
bright yellow solid was dried in vacuo. Yield of pure
phendione: 1.2791 g (10.6% based on phen) m.p 252-254 °C. (lit
3 m.p. 258 °C). 1H NMR (CDCL3) I ppm (TMS): 7. 60 (m, 2H) I 8. 52
(dd, 2H) I 9.13 (dd, 2H).
5,6-diamino-1,10-phenanthroline (diamino-phen): The procedure
of Pesin4 and coworkers (for the preparation of 4,5-
diaminobenzo-2,1,3-thiadiazole) was followed with slight
modification. In a typical preparation, a solution of
potassium hydroxide (4.0163 g, 71.6 mmol) in 13 mL of absolute
ethanol was gradually added to a stirring mixture of 5-N02 -
phen (1.0063 g, 4.47 mmol), hydroxylamine hydrochloride
(2.0016 g, 28.8 mmol) and 13 mL of ethanol. The mixture was
stirred for 1 h, and then 53 mL of water was added. After
heating to 70 °C, sodium hydrosulfite (8.0376 g, 46.16 mmol)
was added. The mixture was heated to boiling and then cooled
to room temperature, resulting in a yellow suspension. The
product was collected on a fine glass frit, washed with a
small amount of cool water and dried in vacuo. Yield: 1.0313
g (109%, based on 5-N02-phen). This crude product (1H-NMR in
Fig.2-2) was used in the preparation of biphen. ( A small
amount of analytically pure diamino-phen was isolated from
these preparations. Appendix I contains details about the
procedure and analysis.)
16
Biphen (C12 H24 N6 ) : This ligand was prepared by condensation
of the crude diamino-phen with phendione. In a typical
preparation, diamino-phen (0.1090 g, 0.52 mmol) was reacted
for 20 minutes with phendione (0.0813 g, 0.387 mmol) in 20 mL
of hot glacial acetic acid. The mixture was allowed to cool
to room temperature. An orange-brown solid was collected on
a fine glass frit and washed with 2 mL of glacial acetic acid
and then dried in vacuo. Yield. 0.1113 g (74.95% based on
phendi one) .
The crude sample was then stirred with 50 mL of
chloroform for 1 h and then filtered through a fine glass frit
to remove insoluble materials. The filtrate was then allowed
to evaporate to dryness in the hood. Yield: 0.336 g (22.63%
based on phendione). m.p. > 380 °C. 1H NMR (CDCL1 , 300 MHz),
ppm (TMS) : 7. 85 (dd, 4H), 9. 34 (dd, 4H), 9. 66 (dd, 4H) . Anal.
Calcd for C12H 2!J 6: C 74.99%, H 3.15%, N 21.86%.
74.57%, H 3.61%, N 21.66%.
. . (0.1056 g, 0.203 rnrrrol)
Found C
and biphen
(0.0380 g, 0.0989 mmol) were refluxed in 30 mL of ethylene
glycol for 3 h. The mixture was cooled to room temperature
and 3 0 mL of H20 was added. The insoluble solids were
filtered out through a fine glass frit and 0.4690 g of NH4PF6
was added and the product precipitated very fine red crystals.
17
The product was collected on a 15 mL F frit, washed with a
small amount of cold water and dried in vacuo. Yield: 0.1912
g (107.93%, based on biphen).
The crude product was purified by using a two-step
procedure. First, it was dissolved in 9 mL of acetone and
filtered using a 2 mL F frit. Chloroform (15 mL) was added to
the filtrate resulting in the precipitation of solid. The
mixture was filtered, and the solid washed with 1 mL of
chloroform and 1 mL of ether and then air-dried overnight.
The dried solid was suspended in 15 mL of hot water (@ 70 °C)
and then acetonitrile was added dropwise to this solution
until the solid just dissolved. The solution was cooled to
room temperature slowly and orange-red solid was formed. The
solution mixture was filtered and the solid collected and
dried in vacuo. Yield: 0.0928 g (52.40% based on biphen).
Anal. Calcd for [bpy) 2Rurr(biphen)Rurr(bpy) 2 ] (PF6 ) 4 : C 42.92% H
2.48% N 10.95%. Found C 43.01%, H 2.52%, N 10.87%. 1H NMR
(CD3CN, 300 MHz), ppm (TMS): 9.6 (d, 4H), 8.55 (m, 8H), 8.29
(d, 4H), 8.14 (m, 4H), 8.02 (m, 8H), 7.86 (d, 4H), 7.74 (d,
4H) , 7. 4 7 (m, 4H) , 7. 26 (m, 4H) .
[RuII (bpy) 2 (biphen](PF6 ) 2 : Biphen (0.1235 g, 0.321 mmol)
and 130 mL of ethylene glycol were heated in a 200 mL 3-neck
RB flask for 1 h. A solution of cis-Rurr (bpy) 2c12 ·2H20 (0. 0513
g, 0.0985 mmol ) in 2 mL of ethylene glycol was added dropwise
18
over 1. 5 h. The mixture was heated at reflux for 2 h (The
orange color turned eventually to an orange-red.) . The
mixture was then cooled to room temperature, 130 mL of H20 was
added, and this mixture was filtered using a 30 mL F frit.
Addition of NH4PF6 • (0.1046 g) to the filtrate produced a solid
consisting of very fine red crystals. The suspension was left
covered overnight and then filtered using a 60 mL M frit. The
solid collected was washed with 20 mL of H20 and 5 mL of ethyl
ether and dried in vacuo. Yield: 0.0558 g (52.08% based on
Run (bpy) 2Cl2·2H20) ·
The crude product was purified using a solution of
ethanol:water (1:1). The ethanol/water solution (50 mL) was
heated in a 100 mL RB flask equipped with a stir bar and a
reflux column. After adding the crude product, the mixture was
boiled about 5 min until the solid almost all dissolved. The
hot mixture was filtered using a warm 15 mL F frit. The
filtrate was slowly cooled to room temperature resulting in
precipitation of an orange-red solid. The solid was collected
and dried in vacuo. Yield: 0.0200 g (18.66%, based on
Rurr(bpy) 2Cl2·2H20). 1H NMR (CD 3CN, 300 MHz), ppm (TMS): 9.48 (d,
2H), 9.24 (d, 2H), 8.60 (d, 2H), 8.57 (d, 2H), 8.32 (s, 2H),
8.27 (d, 2H), 8.20 (d, 2H), 8.16 (d, 2H), 8.05 (m, 2H), 7.93
(d, 2H), 7.84(dd, 2H), 7.72 (dd, 2H) 7.53 (m, 2H), 7.37 (m,
2H). Anal. Calcd for [Rurr(bpy) 2(biphen)] (PF6 ) 2: C: 48.58%, H:
2.59%, N: 12.88%. Found: C: 48.97%, H:3.09%, N: 12.07%.
19
Reference
1. Amouyl, E.; Homsi, A. J. Chem. Soc. Dalton Trans.
1990, 1841-45.
2. Aldrich Catalog Hand.book of Fine Chemicals Aldrich
Chemical Company, Inc.; 1992-1993; pp.929.
3. Smith, G.F.; Cagle, F.W. J. Org. Chem. 1947, 12, 781.
4. Pesin, V. G.; Sergeev, V. A.; Nikulina, M. G. Chem.
Heterocylic Compounds 1968, ~' 186-188.
5. cis-Rurr(bpy) 2Cl2 was previously prepared & purified by
Greg Juriga using the following procedures: (a)
Sullivan, B. P.; Salmon, D. J.; Meyer, T. J. Inorg.
Chem. 1978, 17, 3334. (b) Sprintschnik, G.;
Sprintschnik, H. W.; Kirsch, P. P.; Whitten, D. G. i.L..
Am. Chem. Soc. 1977, .2.2, 4947.
20
Results and Discussion
Biphen: This is a condensation product of crude diamino-phen
and phendione and is a light yellow solid. The structures and
numbering schemes for phenanthroline, phendione and biphen are
given in Fig. 3-1 to Fig. 3-3. The actual 1H-NMR spectra for
these three ligands are shown in Fig. 3-8 to Fig. 3-10,
respectively, and their NMR spectral data listed in Table 3-1.
In the 1H-NMR spectrum of biphen (Fig. 3-10), there are three
sets of peaks with the area ratio 1:1:1. This peak pattern
(two sets of doublets of doublets and one quartet) appear to
be typical for 1,10-phenanthroline symmetrically substituted
at positions 5 and 6.
(Fig. 3-9) shows the
For example, the 1H~NMR of phendione
same peak pat tern. Moreover, 1, 10-
phenanthroline itself (Fig. 3-8) shows the same pattern except
for the singlet at 7. 78 ppm which is assigned to the two
equivalent hydrogens at positions 5 and 6. The 1H-NMR for
biphen (Fig. 3-10) is therefore consistent with a structure
having two equivalent phenanthrolines fused (at positions 5
and 6) through a structure containing no hydrogens (in this
case pyrazine) .
The peak assignments and chemical shift values list in
Table 3-1 reveal that the biphen ligand appears to be fairly
electron deficient when compared to either phendione or phen.
Evidence for this comes from the fact that all three sets of
peaks for biphen are shifted downf ield from those of the other
21
two ligands. The most dramatic shift occurs for the peaks
assigned to H4 , 7 , these protons being the closest to the
pyrazine bridge.
The UV-Vis spectrum of biphen in CHC1 3 is shown in Fig.
3-11. There are two main areas of absorption. The first is
between 250 nm and 300 nm and the second is in the range 350
nm to 400 nm. It is the second set (lower energy) peaks which
give biphen its characteristic light yellow color. The peak
maxima and absorption coefficients for biphen in CHC1 3 are
listed in Table 3-2. It should be noted that CHC1 3 was the
only solvent found in which biphen had a high enough
solubility to allow accurate determinations of absorption
coefficients. The UV-Vis spectrum of biphen was also taken
using CH3CN as the solvent (Fig. 3-12; Table 3-2).
The UV-Vis spectra of 2,2'-bipyridine (bpy) and phenazine
(both in CH3CN) are shown in Fig. 3-13 and 3-14, respectively.
In addition, peak maxima for both spectra are summarized in
Table 3-2. Not surprisingly, the UV-Vis spectrum of biphen is
roughly equivalent to the sum of the spectra of bpy and
phenazine (the two structural components of biphen) . It
should be noted that although both phenazine and biphen are
yellow in color (and show lower energy absorptions), the low
energy maximum for biphen is red-shifted about 25 nm as
compared to phenazine. This may simply reflect the effect of
the larger ring system in biphen.
22
The monometallic and bimetallic Ru complexes are both
orange-red solids whose structures are shown in Fig. 3-15 and
Fig. 3-16. The actual 1H-NMR spectra in CD3CN are shown in
Fig. 3-17 and Fig. 3-18, respectively. The spectrum of the
monometallic complex [Run(bpy) 2 (biphen)] (PF6 ) 2 (Fig. 3-17) can
be integrated to 28 hydrogens, the expected number for two bpy
ligands (2 x 8H) and one biphen (1 x 12H) . The spectrum of
the bimetallic complex [ (bpy) 2Run (biphen) Run (bpy) 2 ] (PF6 ) 4 (Fig.
3-18) can be integrated to 44 hydrogens: four bpy ligands (4
x 8H) and one biphen (1 x 12H). A comparison of the 1H-NMR
spectra of the monometallic and bimetallic complexes reveals
striking differences at chemical shift values greater than 9
ppm. The monometallic complex shows two doublets between 9.1
and 9.6 ppm, representing 4 H, while the bimetalllic complex
show one doublet, also representing 4 H, at close to 10 ppm.
These are expected differences for the H2 , 9 and H2 ., 9 • positions
(Fig. 3-3) of the bridging biphen ligand. For the
monometallic complex, these two positions would not be
equivalent, since -Ru (bpy) /+ is bound to only end of the
biphen. In this case, it would be expected that the doublet
at -9. 5 ppm represents the H2 , 9 positions biphen near the point
of attachment of the -Ru (bpy) /+ fragment. On the other hand,
the bimetallic complex might be expected to show the H2 , 9 and
H2 ., 9 • position as equivalent, since a -Ru (bpy) /+ fragment is
23
bound at both ends of biphen, forming a symmetric species.
The downf ield shift for this doublet compared to either
doublet in the monometallic case most likely represents the
effects of a total 4+ charge from the two -Ru(bpy)/+
fragments.
As is typical for hexafluorophosphate salts of Ru (II)
polypyridyl complexes, both the monometallic and bimetallic
Ru(II) complexes of biphen were quite soluble in acetonitrile
and acetone and partially soluble in water. The UV-Vis
spectra of both complexes (Fig. 3-19, Fig. 3-20) were taken in
CH3CN, and the absorption bands that were observed are listed
in Tables 3-3 and 3-4 along with transition assignments. The
UV-Vis spectra of the monometallic and bimetallic complexes
both show very similar peak patterns. Each spectrum shows
three main areas of absorption. The first is between 240 nm
and 340 nm, the second from 340 nm to 400 nm and the third
from 400 nm to 500 nm. It is the third set (lower energy) of
peaks which give the complexes their characteristic red-orange
color.
The first absorption area (240 nm to 340 nm) is
characteristic of rr ~-> rr* transitions of the bpy and the
biphen ligands. This assignment is reasonable based on
comparisons with the spectra of free biphen and bpy (Fig. 3-12
and Fig. 3-13), and transition assignments from the
literature1. The ratio of the e values for the bimetallic and
monometallic complexes (eb/em) at 282 nm is 1.7:1. This is an
24
expected result (at least qualitatively), since the bimetallic
complex contains two additional bpy ligands.
The second absorption area (340 nm to 400 nm) is
characteristic of transitions of the biphen ligand (in the
phenazine portion) . This can be seen by comparing the spectra
in Fig. 3-19 and Fig. 3-20 with those of free biphen (Fig. 3-
12) and phenazine (Fig. 3-14). The ratio eb/em in this area
of the spectrum is only about 1.2:1. This is an expected
result, since both complexes contain only one biphen ligand
each.
The third absorption area (400 nm to 500 nm) is
characteristic of overlapping MLCT bands from Ru(drr) ~->
biphen(rr*) and Ru(drr) ~-> bpy(rr*) transitions. The ratio of
eb/em is approximately 2.2:1. Once again, this is an expected
result, based on the ratio of the number of Run centers in
the two complexes.
The energies of the MLCT bands of both the mono- and
bimetallic complexes give some information about the
electronic structure of the bridge ligand biphen and some
indication of the extent of metal-metal interaction in the
bimetallic case. The expected energy of the MLCT bands can be
calculated from the absolute value of the measured energy
difference between the oxidation potential of Run and the
reduction potentials of either biphen or bpy.
25
EMLcT ( eV) = E (RuIIr /II ) - E (biphen°11-) (Eq. 3-1)
EMLCT ( eV) = E (RuIIr /II ) - E (bpyDll-) (Eq. 3-2)
Using Eq. 3-1 (and cyclic voltammetry data from Table 3-7
(vide infra)) and converting the resulting energy units to nm
for both the monometallic and bimetallic complexes results in
a predicted .A.MLcT = 582 nm. This lower energy .A.MLcT value
is not observed experimentally for either complex. Doing the
same calculation for bpy in Eq. 3-2. the A. values result in
predicted A. = 454 nm for both complexes. The .A.MLcT values
observed experimentally seem to correspond to these higher
energy RuII to bpy MLCT transitions. Thus, it appears that
the molecular orbitals in biphen that are reduced
electrochemically (most likely centered in the phenazine
portion) are electronically isolated from those that are
reduced photochemically (bpy portion) . These observations are
consistent with behavior reported in the literature for other
similar ligands, such as pptd2 , and dppz3 (Fig. 3-4 and Fig.
3-5) .
The experimentally observed .A.MLcT values for the
monometallic and bimetallic complexes reported here are nearly
identical. This implies that the metal-metal interaction in
the bimetallic complex is negligible. For example, it would
be expected that addition of the second Ru II center in the
bimetallic species would make the phenazine portion of biphen
26
easier to reduce, thus lowering the energy of the MLCT band in
the complex. Since this is not observed, it appears that both
ends of the bimetallic complex act as independent
(bpy)Ru(bpy)/+ units.
Table 3-6 lists .\nax values for both Run complexes
and bimetallic reported here and values for other mono-
systems. As can be seen from the data, red shifts in .A.MLcT
values (20-80 nm) usually accompany formation of bimetallic
complexes from their monometallic precursors. This is usually
taken as evidence for at least a small amount of metal-metal
interaction. These red-shifts are not observed for the
bimetallic Run biphen complex reported here. The results of
cyclic voltammetry experiments on monometallic and bimetallic
complexes in acetonitrile with 0 .1 M TBAH as supporting
electrolyte are listed in Table 3-7. E112 values were
calculated from the average of the anodic and cathodic peak
potentials [E112 = (~a+Epc) /2] at a scan rate of 100 mV · s-1 •
Reduction of [Rurr(bpy) 2 (biphen)] (PF6 ) 2 results in three
waves: -1.26 V, -1.78 V and -1.99 V (vs Fe/Fe+; Ag wire ref.,
Fig 3-21 b) . The first wave is assigned to the reduction of
biphen and appears to be complicated by adsorption in the
cathodic scan. The peaks at -1.78 and -1.99 (barely visible)
are assigned as reductions of the bipyridine ligands. These
processes to do not appear to be reversible.
Reduction of [ (bpy) 2 Run (biphen) Run (bpy}i ] ( PF6 )4
results in two waves : -1.21 V and -1.78 V (vs. Fe/Fe+; Ag
27
wire ref., Fig. 3-22 b) . The first wave most likely
corresponds to the reduction of biphen and the second wave
corresponds to the reduction of bipyridine ligands. The wave
assigned as bipyridine reduction is larger and this is most
likely due to the fact that two 1 e- reductions are occuring
simultaneously. One bpy- being produced at each end of the
bimetallic complex. The E112 values of biphen in the
monometallic and bimetallic complexes are nearly identical.
This information, along with the apparent single reduction
wave for bipyridines at either end of the bimetallic complex,
implies that "end-to end" electron communication in
bimetallic species is very small. The asssignment of
the
both
the biphen and bpy reduction waves here compares well with
reduction waves assigned in the literature3 to bpy and dppz (a
monodentate analog of biphen) in the complexes [Rurr (bpy) 3 ] 2+
and [Rurr (bpy) 2 ( dppz) ] 2+. It should be notedbiphen is more
easily reduced than bypyridine by ca. 0.5 V, due to the lower
energy rr* orbital of the biphen moiety.
Oxidation of the monometallic complex results in one wave
at +0.97 V (vs. Fe/Fe+; Ag wire ref., Fig. 3-21a). This is
assigned as arising from a le- oxidation of the metal center
(Rurr --> Rtlrr ) . The peak height for a 1 mM solution of
complex corresponds to a current of approximately 1. 8 µA.
Oxidation of the bimetallic complex results in one wave at
+0.93 V (vs. Fe/Fe+; Ag wire ref., Fig. 3-22a) This wave is
assigned as arising from a two electron oxidation of the metal
28
centers (Run --> Run at each of two sites). The peak
height for a 1 mM solution of complex corresponds to a current
of 4.8 µA.
Comparison of the oxidation waves for the mono- and
bimetallic complexes reveals some interesting information.
First of all, the peak heights (in µA) show that, for equal
concentrations of complex, about twice as much current is
observed for the bimetallic complex. This is expected if both
Run sites are oxidized at the same or nearly the same
potential.
A second observation is that the E112 values for the
monometallic and bimetallic complexes are nearly identical.
This is somewhat surprising, since it might be expected that
a 4+ complex would be somewhat harder to oxidize than a 2+
complex.
A third observation involves the oxidation of the
bimetallic complex. As stated in the introduction, the mixed
valence form of this complex would be produced after the first
electron is removed (at potential E1 ) •
form was
[ (bpy) 2RUII-biphen-RuII (bpy) 2] 4+
If the mixed-valence
Ei ------>
-le-
[ (bpy) 2RUII-biphen-Ru1 II (bpy) 21 S+
29
very stable relative to the Run /Run or Runr /Runr form, it
would be expected that the second electron would be harder to
remove (at potential E2) .
E2 [ (bpy) 2RUII-biphen-RuIII (bpy) 2] S+ ~~~~~~~->
-le-
[ (bpy) 2RUIII_biphen-RuIII (bpy) 2] G+
In other words, if the comproportionation constant (Kc) were
large, E2 > E1 and two well-spaced le- waves would be observed
for the bimetallic complex. Since only one wave is observed,
E1 = E2 and Kc is not large. The two metal centers do not seem
to communicate very well.
Despite the above analysis, it should be noted that the
oxidation wave for the bimetallic complex shows a peak
separation (~EP) of about 80 mV. This is much larger than
expected for a 2e- process (30 mV) . Therefore, there is some
evidence for stabilization of the Run /Rurn mixed-valence
species, even though two well-resolved le- oxidation waves
were not obtained. The 2e- oxidation may consist of two
closely spaced le- oxidations. Therefore the value of Kc,
while small, is still most likely greater than 4. It is not
clear, from this analysis, however, whether any of the
stabilization of the Run /Rurn state is due to any
delocalization.
It should be noted that the oxidations of both the mono-
30
and bimetallic complexes were also carried out referenced to
an SSCE electrode. The E112 values obtained were +1. 23 V for
the monometallic complex, and +1.34 V for the bimetallic. In
actual fact, the monometallic complex probably has an E112 ~
1.33 V (identical to the bimetallic). This is because the
Fe/Fe+ couple in the monometallic CV appeared to be about 0.10
V too low (probably due to axis calibration error or some
problem with the reference electrode). For this reason, Table
3-9 lists the E112 (RurII III ) for the monometallic complex as
+1. 33 V vs. SSCE. The E112 (RuIIr III ) values for the mono
and bimetallic complexes seem reasonable when compared to
similar RuII complexes seem reasonable when compared to similar
RuII complexes (Table 3-9). Reductive scans were not taken for
the two complexes vs SSCE.
31
ligand
phen
phendione
biphen
Table 3-1
1H NMR Spectra Data of Ligandsa,b
9.20(d) 7.63(q)
9.13(dd) 7.60(q)
9.67(dd) 7.86(q)
8.24(dd) 7.78(s)
8. 52 (dd)
9. 35 (dd)
achemical shifts are given in ppm (vs TMS) in CDC1 3 •
bs, d, dd and q = singlet, doublet, doublet of doublets and
quartet, respectively.
32
Ligand
biphen
biphen
Table 3-2
UV-Vis Data of Ligands
Solvent ~ (run)
(e x 10-3 M-1 cm-1 )
CHC1 3 390.4 (29.2)
380.8 (14.9)
370.2 (16.4)
361. 5 (8.97)
351. 8 (7.18)
(sh) 335.0 (9.10)
(sh) 324.7 (14.1)
(sh) 308.9 (20.2)
276.8 (66.2)
CH3CN 389.0
379.8
368.8
360.7
350.8
274.5
33
Table 3-2 (Cont'd)
Ligand Solvent Aman (nm)
( e x 10-3 M-1 cm-1 )
bpy CH3CN 281. 5
236.5
phenazine CH3CN 362.8
(sh) 359.8
(sh) 357.9
(sh) 348.0
(sh) 324.2
248.0
208.0
34
(sh)
(sh)
Table 3-3
UV-Vis Data of [Ruu (bpy) 2 (biphen)] (PF6 ) 2 in CH3CN
Amax (nm)
(e x 10-3 M-1 cm-1 )
449.9 (14.0)
422.7 (12.5)
380.5 (24.4)
362.3 (17.3)
314.1 (36.1)
282.5 (86.4)
246.0 ( 51. 2)
Run
Transition
assignments
( dII) --> biphen (II*) MLCT
Run (dII) --> bpy ( rr*) MLCT
Run ( drr) --> biphen (II*) MLCT
Run (dII) --> bpy (II*) MLCT
ligand biphen II --> II*
ligand biphen II --> II*
ligand biphen II --> II*
ligand biphen II --> II*
ligand bpy II --> II*
ligand biphen II --> II*
ligand bpy II --> II*
35
Table 3-4
UV-Vis Data of [ (bpy)2RUII(biphen)RuII(bpy)2l (PF6)4 in CH3CN
Amax (nm)
( e x 10-3 M- 1 cm-1 )
442.0 (31.8)
(sh) 420.0 (27.6)
370.0 (29.6)
351. 3 (23.9)
(sh) 322.0 (40.1)
282.5 (146)
44.5 (58.2)
Rull
Transition
assignments
( dII) --> biphen (II*)
Rull ( dII) --> bpy (II*)
Rull ( dII) --> biphen (II*)
Rull ( dII) --> bpy (II*)
ligand biphen II --> II*
ligand biphen II --> II*
ligand biphen II --> II*
ligand biphen II --> II*
ligand bpy II --> II*
ligand biphen II --> II*
ligand bpy II --> II*
36
Table 3-5
UV-Vis Data of Analogous Ru Complexes
Compound
[Ru (bpy) 2 (dppz)] 2+c
[Ru (bpy) 2 (biphen) ] 2+
Amax (nm) a
(e x 10-3 M-1 cm-1 )
448(1.57), 366(1.55), 357(1.56)
352(sh), 342(sh), 315(sh),
284(9.36), 255(4.18) I 212(5.00)b
449.9(14.0), 422.7(sh), 380.5(24.4)
362.3(17.3), 314.1(36.1), 282.5(86.4)
246.0(51.2)
452 (1. 45) I 345 (sh) I 323 (sh) I
285(8.71), 250(2.51), 238(2.95),
208 (sh) I 185 (8 • 91)
aunless otherwise noted, the absorptions are taken in CH3CN.
bin EtOH.
cdppz=dipyrido[3,2-a;2',3'-c]phenazine ref.4
37
Table 3-6
UV-Vis Data of Mono- and Bimetallic Complexes
Complexes Amax (nm) color
[Ru (bpy) 2 (biphen) 12+a 450, 423 (sh) t 381, red-orange
362, 314(sh), 283, 246
{[Ru (bpy) 212 (biphen) }4+a 442, 420 (sh) t 370, red-orange
351, 322(sh), 283,
245
[ (bpy) 2Ru ( dpp) 12+b 436, 465, 475 dark-red
{ [ (bpy) 2Ru1 2 (dpp) }4+b 425, 436, 525 reddish-purple
[Ru (2, 3-dpp) (CO) 21 Cl2c 384 yellow
(µ-2,3-dpp) [Ru(C0)2Cl212c 409 red-brown
[Ru(2,5-dpp) (C0) 21Cl2c 405 red-brown
(µ-2, 5-dpp) [Ru (CO) 2Cl212c 448 yellow
[Ru (bpy) 2 (HAT) 12+a 207, 277, 432, 484 yellow
{[Ru (bpy) 212 (HAT) l 4+a 206, 243, 252(sh), aubergine
276, 405, 490, 572
{[Ru (bpy) 213 (HAT) 2}6+a 206(sh), 244, 251, deep blue
278, 364' 401, 525,
580
cin CH3CN. ref. 6 µ-2, 3-
dpp=2,3- (2-pyridyl)-pyrazine (Fig. 3-6), µ-2,5-dpp=2,5-bis(2-
pyridyl)-pyrazine (Fig. 3-7). ain H20. ref.7
HAT=hexatriphenylene
38
Table 3-7
Cyclic Voltanunetry Data of Ruthenium Complexesa
Complexb Solvent Ei12
.0.EP, mV)
[Run (bpy) 2 (biphen)] 2+c CH3CN/O .1 M TBAH +0.97 (60)
-1. 26
-1.78
-1. 99
[Run (bpy) 2 (biphen)] 2+a CH3CN/0 .1 M TBAH +0.40 (60)
+1.33 (55)
[ (bpy) 2Run (biphen) Run (bpy) 2] 4 +c CH3CN/0 .1 M TBAH +0.93 (65)
-1.21
-1.78
[ {bpy) 2RUn (biphen) Run (bpy) 2J 4 +d CH3CN/O .1 M TBAH +0.40 (65)
+1.34 (80)
aPotentials are in volts. Scan rate = 100 mV/s.
TBAH=tetrabutylammonium hexafluorophosphate. Values in
parentheses indicate peak separations (.0.EP = Eanodic- Ecathodic) in
mV. bAll complexes were PF 6 - salts. cPlatinum working electrodes
were used, along with a Pt auxiliary electrode, and a silver
reference electrode. E112 values are reported vs a
ferrocene/ferrecinium (Fe/Fe+) internal standard. aPlatinum
working electrodes were used, along with a Pt auxiliary
electrode, and a saturated sodium chloride calomel (SSCE)
reference electrode.
39
Table 3-8
Oxidation Potentials of Ruthenium Complexes
Complex
[Ru II (bpy) 2 ( tpbq) ] 2 +
[Run (bpy) 2 ( dppz) ] 2+
{ [Run (bpy) 2 ] 2 ( tpbq) } 4 +
{ [RUII (bpy} 2 ] 2 (dpq) }4+
{ [RUII (bpy) 2J 2 (dpp} }4+
El/2 (V vs SCE)
(no. electron)
+l.41 (le)
+1.24 (le)
+l.42 (2e)
+1. 47 ( 2e)
+1.39 ( 2e)
tpbq=2,2'-3,3'-tetra-2-pyridyl-6,6'-biquinoxaline. ref.4
dppz=dipyrido[3,2-a;2',3'-c]phenazine ref.3
dpq=2,3-bis(2-pyridyl)quinoxaline ref.8
dpp=dipyridyl pyrazine ref .5
40
Table 3-9
Redox Properties of Analogous Rutheniwn Complexes
complex oxidation Reduction
(mV) (mV)
1 2
[Ru II (bpy) 3] 2+a +l.29 -1. 33 -1.52
[Rurr (bpy) 2 (dppz)] 2 +a +l.24 -1.02 -1. 44
[Rurr (bpy) 2 (biphen) ] 2+ +l.38
{ [Rurrbpy) 2 ] 2 (biphen) } 4+ +l.34
adppz=dipyrido[3,2-a;2' ,3'-c]phenazine ref. 3
All data was taken in CH3CN
41
3
-1.76
-1. 67
4
-2.40
-2.07
References
1. Crutchley, R. J. Lever, A. B. Inorg. Chem. 1982, 21,
2276-2282.
2. Black, K. J.; Huang, H.; High, S.; Starks, L.; Olson,
M. and McGuire, M. E. Inorg. Chem. 1993, 32, 5591-5596.
3. Amouyl, E.; Homsi, A. J. Chem. Soc. Dalton. Trans.
1990, 1841-1845.
4. Rillema, D. P., Callahan, R. W.; Mack K. B. Inorg.
Chem. 1982, 21, 2589.
5. Braunstein, C. H.; Baker, A. D.; Streakas, T. C.;
Gafney, H. D. J. Inorg. Chem. 1984, 23, 857-864.
6. Campagna, S.; Denti, G.; Rosa, G. De; Sabatino, L.;
Ciano, M.; Balzani, V. Inorg. Chem. 1989, .£8., 2565-
2570.
7. Masschelein, A.; Mesmaeker, A. K.; Verhoeven C.;
Nasielski- Hinkens R. Inorg. Chim. Acta. 1987, ~'
L13-L16.
8. Carlson, D. L.; Murphy, W. R. Inorg. Chim Acta. 1991,
.1.8..L.. 61.
42
Fig
ure
2
-1
Th
e 1
H-N
MR
S
pectru
m
5-N
02 -l,1
0-p
hen
an
thro
line in
l ..
! I ,
,!u· ---:;~
J '
-
\ I I
( 1! 1 J Ii 111,
' i:11i1 •!I
.1 1 ~ : .
: ! ~ ;. .... '' '; i.: ... 1 ·
. ·11::.;
I 1
·"'
ii! I !)Jll i
' ' ~
~
___ __) l I
I I
I I
1 '
1 I
I I
I I
I I
I I
' I
' I
I I
I T
CD
Cl3
9.5
9
.0
8.5
8
.0
1.5
PPM
rt')
""'
Fig
ure
2-2
T
he
1H-N
MR
S
pectru
m o
f cru
de 5
,6-d
iam
ino
-1,1
0-p
hen
an
thro
line in
DM
SO
!1 fj •: I· :· I: 11 1: I
I I,: ;; f ., !. t t j;
t ~
' I ! ' I I I I
i
•I (
. . Jlj i.. •. i. ... ..I .._... ................ ",J.....-
.. .. ....... "
: ,
L _
_ j
f •
-..
1 ,
i i
i i
t i
j t
I I
j I
I I
I
ti,,,.; ...• :
·i •
I :
1 C
hi
qt
qt
Flg. 3-1
The St1uctu1e and Numbe1lng of I .J IO-phenanth10 I l ne
3
2 4
N s
6
8
45
Fig. 3-2
The St1uctu1e and Numbe1ing of 1,J 10-phenanthio Ii ne-5,J 6-d i one
3
2 4
1 N 0 s
1 0 0 6
g 7
8
46
Fig, 3-3
The St1uctu1e and Numbe1lng of biphen
3 3 '
2 4 4 ' 2 '
N S N S , N 1 ,
1 0 6 ' 1 0 '
g 7 7 ' g '
8 8 '
47
Fig, 3-4
CH3
N N
0
48
Fig, 3-5
The st1uctu1e of Dlpy11do[J,)2-a~2 '3 '-c] phenazlne (dppzJ
N N
49
Fig, 3-6
THe St1uctu1e of 2,) 3-b Is( 2-pyr I dy I)
--py1az1 ne
N
N
50
Fig. 3-7
The St1uctu1e of 2,J 5-b ls( 2-pyi i dy I)py1az 1 ne
N
51
N
/
N
/
N
Fig
ure
3
-8
Th
e 1
H-N
MR
S
pectru
m o
f 1
,10
-ph
en
an
thro
line in
C
DC
13
• l
I
1-,--T
---.-1
-,T
--i--.-'I
I
I I
I I
I I
I I
I I
I I
I I
I ,--, -,
9.5
9
.0
8.5
8
.0
7.5
7
. 0 P
PM
N
lf)
Fig
ure
3
-9
~-
-J.
J ~
J
I I
I I
I I
I -.---.
9.5
Th
e 1H
-NM
R S
pectru
m o
f 1,1
0-p
hen
an
thro
line-5
,6-d
ion
e in
CDC1
3
J
J .L
L
r· r .. ,
,..,. .. _,..
_)
•I
, I
'I
..
I I
I I
I I
I I
I I
I I
,---, -T
l r ~
9.0
8
.5
8.0
7
. 5 P
PM
r'l ll'l
_, I
I
1 I
·1
I
l p 1 ·~·· 1 ·o -1
1 1
"' l ·1 ~ i
l (0 1----r-~ l
i CP i ~1
0
Vl
--
54
w I
1--' 0
1)\JC. 0 002·0 '.)O., ·o ~-~~~~~~~~~~ ......... ~~~~~~~~~_,_~~~~~~~~~~ t.,r I ! -=> r .. ,
I I
i v. I ':::> ...... ':::> I
I
· [
J 0 0
VI 0 0
t
I ~1 o 'I I.
" r. H 11
"
-----'"--·-----"--·-~-~--·--- .... .....a......l-1.-.. . • ----"-"-~·-· -- •.•• 1. •• -··' --·--·.
55
I i l
l i j
( .:. :J ":' ) )•)0 • <) ')·;.:;'.. j ).) ., . ) ; p. )
Ji J ~ J
~, ·.:>
I I L. --c____ I '"r:l ' ..... I
l!l c . -N Ii
(D
VI w 0 0 I
I-' N
1
8 ::r (I)
~ 1 I ........
< ~ ..... 0 0 {ll
en ttj (I)
~ 0 :I rT 3 11 c a 0
V' Hi 0
tr 0 .....
1 ttj ::r (I)
i ::s
i ..... ::s (')
1 ::r:
-j w
.:]- (') ':::> z :>
'
I . ________ ..__·--·--·-···' -·-·-·--- ..... - _ _I
56
( ·_,·J~) it)') . fJ ') ~2 .. .} j i". j Vi'-" . ') )•) ·; ') J , , ,.,
':> -- ---0
!. I
~ '1j I-'· I
t.Q ~ s::
Ii I CD r w
; I I,,;
..... 0 ... 0 I w I I
i i 8 i ::r I CD j Cl I <: I I
1 <: I-'· ~
j rn 0 0
C/l 'O
CD 0
i rt ~
11 :;, i:: 3
i a
j 0 HI
lJ'I f\J 0
l 0
f\J I tr I-'· 'O ~ Ii I-'· 0. I-'· ::l CD
·:J' I-'· :> -t ::l ::> ! (') :I:
w (') z
57
C '.iO\;' 1
o•Vi ·o ')')2 · c) •.)').., . ) ;..n·) )j•=J.)
-0 ~-r-s ":> -1 "tJ I-'·
!· c_ lQ
I c I ~
1 ro w I
I I-'
i .::.
l.-4 0
1-3 0 :;:,' (I)
c: <: I
j <: ....... I rn
Ul ~
~ (I) 0 0 0 rt t-f ~ - s
:J 3 0
Hi
~ :;:,' (I) ::s
V1 ~ 0 N 0 ....... ::s (I)
I
i .......
i ::s I (') 1 ::x:
w (')
a- I z I •.J
1 ::;,
I
j
..• ='
-~------'- - i..___ .• _ ..... _ ' L
58
Fig.3-15
The St1uctu1e of [ Ru(bpyJ 2 (b i phenJ] C PF 6 J 2
N N
Ru(bpyJ 2
59
Fig. 3-16
The St1uctu1e of [Ru(bpy) 2 (biphen)J 2 CPF 6 J 4
Ru(bpyJ 2
60
"!j ..... "°
I ~ 11 (1)
' I I
w I
! I-' I I ...J I I I
I 8 ::r (1)
I-' ::c I
l "'\
~ l ~
o"l
~ ~
en ta (1) 0 rt
a
Ul I
s
1
0 HI
,.......,
a' -~ "< -N -(X) tr .....
0 ta ::r (1) :l -....... -......., "'d "!j
°' 'Jl -N
} I
..... :l
-....J 1 f \
(') :I:
w '::>
(') z
"'J '""J ?" .....
61
Fig
ure
3
-18
: T
he
1H
-NM
R S
pectru
m o
f [(b
py
2)R
u(b
iph
en
)Ru
(bp
y)
2](P
F6
)2
. I ,, ,, i: r! !1' ,, I I
f
I ··I :, r11
11 I I A.' ,, !
I I I I I I
,J,-
. : 'I
I' I.
! I '·
' 11
11 I
., 'lj1I
1i I ' .~[
: ll I
, jl.
J l~;I ~., ' '·~·.' I .. ;' ~
j.1., I~
•: r
~·I 1.; Ii
:j ll!
~I ~:
~11
, -,
-1
I -
, T
'-1
I I
I I
I I
I I
I I
I I
I I
I I
I I
I I
I I
I I
I ,-----,
N
\D
( :>Q~!
000·0 002·0 00""0 ()09. •j 009. :.i )1)1;. t '"':I
g f I-'· lO c "i "i
w I
..... \0
"' .. "'
.. "" '"3 0 ::r 0
(1)
c: < I < I-'· rn Cll
"a (1)
~ 0 rt 0 t'1 0
s:: s 0 - Hi ::i
3 ,....., ~ s:: -tr
"a I.JI "< 0 0 -"" -tr
I-'• "a ::r (1) ~ -........
~! ~ -"C "'%j
0
°' ':> -"" I I-'·
I ~ j I n I ::i::
I w n
I ·Z
'·I . .., ~-----·-
)
11 1 ) )• j ., '• ')1) .. ;, ... , . j·);
63
Fig
ure
3
-20
: T
he U
V-V
is Sp
ectr-um
of
[(bp
y2
)Ru
(bip
hen
)Ru
(bp
y)
2](P
F6
)2in
CH3
CN
L'
D
" ~.....,
t.r .--.
r·-
-----r·-
-r
-T
•
-,.--,--~--.,. -
· -
·-r·
--
r-
---1-
, I
0 •
0 20
0
30
0
40
0
50
0
60
0
~
<nm>
I .
\ I I
fro
f) ~.
.q< \D
Figure 3-21 The Cyclic Voltammogram [Ru(bpy) 2 (biphen)] (PF6 ) 2
a) J 1 µA
+1.80 mV 0.00
b)
11 µA
0.00 -1.70 m'
65
Figure 3-22 : The Cyclic Voltammogram
[ (bpy2 ) Ru ~biphen) Ru (bpy) 2 ) (PF6 ) 4
I 4 µA
+l.80mV
I 4 µA
... "":
0.00
66
0.00
-1. so mv
Fig
ure A
-I :
The
UV
-Vis
Sp
ectrum
of
S,6
-dia
min
o-1
,10
-ph
en
an
thro
line in
cH
3 CN
+1
.20
A
0.2
00
<
A/O
JI.).)
/ +0
.00
A,
20
0.0
I•
_,,,,.-;
,.,.
10
0 .0
< N
M/D
IU.)
,
•v_,,,.
-.... -.;;t
fl(
70
(
Fig
ure
A
-II T
he
IR
Sp
ectru
m o
f 5
,6-d
iam
ino
-1,1
0-p
hen
an
thro
line in
K
Br
I' N
~
: 1 NICOL
ET
ex.
•AM
PL
E
FIL
E
~ i I' I
Ill u 2
<I I
~ t <
lfl
I-II
I-..
... . I:
~
~
II z ~q " Ill II
" WI
nl 0 II
ID ..
---
-----+-----------
•oco
.o
3-'2
2. 2
28
44
.4
l.
12
/22
/94
1
21
39
10
9
'I
·--+---~....__ _
__
-----t 2
28
9.7
1
8-4
4. 4
1 !SS
!S. !S
12
99
.7
97
7.7
11
eaa.a
a
40
0.0
0
WA
VEN
UM
BR
R9
<CM
-1>
--id!
Fig
ure A
-III The
1 H
-NM
R S
pectru
m o
f 5
,6-d
iam
ino
-1,1
0-p
hen
an
thro
line in
DMSO
l ':• 1
!1
ji•! I·
i.:· . ,
l.
I•
• l
.·
l l
• I'
. 11,
LJL
~
J l
.,. T
T
' ·1
-'T
. ... '"T
... -.,.-----,-·-· T··-·,-·--·-,-----,----...,.---T
·--,----.--,---.--··--
,_, ,_, 1-f
<