ND-ft19 107 TRMITION METRL 11 COMPLEXES OF DXTHIACYCLOPNUNS(U) 1Iv~SOUTHERN UNIV RATON ROUGE LA DEPT OF CHEMISTRYE DOONES ET AL. 25 NAR 86 ARO-19740. I-CM-H
UNCL ASS I FIEDDARG29-82-0-00133FO ?/3 .N
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TRANSITION METAL (II) COPLEX(ES OF DITrHIACYCLOPHANES
FINAL TECHNl'ICAL REPORT
1 EFARL DOOES, THORNTON RHODES AND DERALD C-iRISS
25 Mlarch 1986
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Final TechnicalTransition Metal (11) Complexes 20 Sept 198Lto 19 Sept 1985of Dithiacyclophanes 6. PERFORMING ORG. REPORT NUMBER
7. AUTHOR(e) 8. CONTRACT OR GRANT NUMBER(a)
Earl Doomes, Thornton Rhodes and Derald Chriss DAAG29-82-G-0013
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Southern University-Baton Rouge AREA & OK UNIT NUMBERSChemistry Department
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p ,, r~d~'rht-r cnin~tAi19. KEY WORD' (Contnu t revere, aide It necessary and identify by block number)
Oxadithiapyri~dinophanes, trithiapyridinophanes, oxaparacyclophanes, oxameta-cyclophanes, -Mixed crown ethers, coordination compounds cobalt (II),copper (II), nickel (II), magnetic susceptibilities, - siolet-visiblespectra, electrolytic conductivities
21. AISSTRACTr st s rer . Ff w sees d n'deidfy by block ncuffbar)
See item 20. on reverse side of page """
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20. A BSTRACT
--This- investigation is related to our recent report on thesynthesis and characterization of cobalt (II). copper (II). andnickel 'JI) complexes of the new macrocyclic ligand,7-oxa-2.12-dithia[l3) (2.6)pyridinophane (1). r1., Thecoordination chemistry of a series of structurally relatedmacrocyiclic ligands (1-8) was investigated. Macrocycles studiedinclude oxa-, dioxa-, and thia- dithiapyridinophanes, (2a. ")b. and3. respectively). ox-a-, dioxa-, trioxa- and polymethylene-dithiaparacyclophanes (4a and 5. 4bq 4c and 4) and2,.10-dithia[3.3(2,6)pyridinophane (9). Th yidinophans (a2b. *..a and 9) formed stable crystalliine complexes when treat edwith methanol solutions of cobalt (II). copper (II). and nickel(II) salts. However. cobalt (II) and nickel (II) salts did notform crystalline complexes when combined with the paracylcophanes(4, 5, and 6). Electronic spectra. electrolytic conductivitiesand magnetic susceptibilities data. and elemental analyses wereSutilized in the characterization of these complexes. Solutionand solid state effective magnetic moments were identical foreach complex derived from the oxapyridinophane 1. indicating thatthe same species exists in both phases. Overall, physical datasupport monomeric structures of general formula M(II)LX2 (whereM(II) = the transition metal (11) cation. L= macrocycle. and X S
halogen or thiocyanate) for all complexes studied.
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TRANSITION IETAL (II) COP-2L=(S OF DITHIACYCLOPHANS
FINAL TEC-NIC Ai REPORT
EARL DXO1,1S, THORNTON RHODES AID DERAIL CHFJSS -
25 March 1986
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ABSTRACT
This investigation is related to our recent report on thesynthesis and characterization of cobalt (II), copper (II). andnickel (II) complexes of the new macrocyclic ligand,7-oxa-2,12-dithiat13] (2,6)pyridinophane (1). Ell The ?
coordination chemistry of a series of structurally relatedmacrocylclic ligands (1-8) was investigated. Macrocycles studiedinclude oxa-, dioxa-, and thia- dithiapyridinophanes (2a, 2b, and
* 3a, respectively), oxa-, dioxa-, trioxa- and polymethylene-dithiaparacyclophanes (4a and 5, 4b, 4c and 1) and2,10-dithia[3.3](2,6)pyridinophane (9). The pyridinophanes (2a,2b, 3a and 9) formed stable crystalline complexes when treatedwith methanol solutions of cobalt (II), copper (II). and nickel(II) salts. However., cobalt (II) and nickel (II) salts did notform crystalline complexes when combined with the paracylcoohanes(4, 5. and 6). Electronic spectra, electrolytic conductivitiesand magnetic susceptibilities data, and elemental analyses wereutilized in the characterization of these complexes. Solutionand solid state effective magnetic moments were identical foreach complex derived from the oxapyridinophane 1, indicating thatthe same species exists in both phases. Overall, physical datasupport monomeric structures of general formula M(II)LX2 (whereM(II) = the transition metal (II) cation, L= macrocycle, and X =halogen or thiocyanate) for all complexes studied. However, theseries includes some non-electrolytes and so,.e 1:1 electrolytes.
• Tentative structures have been proposed for the variouscoordination compounds. We have been unable to obtain crystalsof any of these complexes that would be suitable for X-raycrystallographic structural analyses. The electrochemistry ofthis series will be examined within the next three months inorder to complete our characterizations. A significant
* achievement during the grant support period was development of ageneral scheme for synthesis of trithiapyridinophanes utilizingdiisothiorouium salts (derived from simple n-haloalkanols) as keyintermediates.
Outline of Research Findings
Statement of Problem: Physical data on transition metal (II)complexes of macrocyclic ligands containing the donor sets SNSO.SNSOO. SNSOOO, SNS. SNSN. SOS and SS will be collected. We shallutilize these data to assess whether geometrically restrictedmacrocycles with selected donor sets generate unusual ligandfields (e.g.! similar to the ligand field in blue copperproteins).
a. Synthesis of Ligands. Previously, we utilized the highdilution method of Vogtle to synthesize a series ofdithiaparacyclophanes. [2.Z] The general method for synthesis ofcyclophane ligands is through the high dilution reaction of theappropriate bis-(halomethyl)arene with a 1.n-alkalenedithiolate(0.040 mole scale in two liters of solution). The
* -- " .
1,n-al~anedithiolates are generated conveniently from thecorresponding diisothiouronium dihalides. providing an excellentmethod for handling exact quantities of precursors of the
dithiacyclophanes. This approach has been utilized in the
synthesis of several known dithia- and trithiapyridinophanes (2and 3a, respectively) and the new trithiapyridinophane 3b.
Fx S _3aS
Ar +)- Ar)
NN
S S S S
2a x =0 3a 3b\)2b x = 1
2c x = 2
A significant achievement during this period of support isthe development of an approach for conversion of n-haloalkanols
to the corresponding thiaether dithiols via dilsothiouroniumdihalides. The n-haloalkanol is treated with sodium sulfide inaqueous alcohol to yield the dihydroxy thiather. The dihydroxythiather is allowed to react with excess thionyl chloride toyield the bis-(chloroalkyl) thiather. These intermediate •compounds were not isolated, and the latter was treated with twomolar equivalents of thiourea in ethanol to yield the crystalline
diisothiouronium dichlorides. The overall scheme is outlined inthe equations that follow. The availability of thethialkane-ln-ditholates opens the possibility for synthesis of awide range of trithiacyclophanes. The various newdithiacyclophanes that were synthesized by this gereral methodwill be described under the section that deals with the
associated coordination chemistry.
HO-(CH2)n-X 0 HO-(CH 2 )n-S-(CH2)n-OH
* Cl-(CH2 )-S-(CH 2 )-CI - . HC1.HN-C-S-(CH)-S- (CH2)-S--NH.HC1
NH NH2 2
HS-(CH 2 )n-S-(CH2 )n-SH 0
IC? , ,, % _ • '.V " ..- . . * , . * . . . .. • . .*. - " -.,' ' . . • • •
It
-m
b. Characterization of Transition Metal (II) Complexes of5-Oxa-2.,8-dithiapyridinophane (2a) and 2,5.8-Trithiapyridinophane(3a). The previously synthesized [3,4] ligands, 2a and 3a. were
synthesized in high yield by the high dilution reaction ofbis-2,6-(chloromethyl)pyridine with the appropriatei.n dithiolate. Physical data for 2a and 3a were identical tothose reported for these substances in the literature. C3,43 Thetransition metal (II) halide complexes and the cobalt (II)thiocyanate complexes were synthesized as outlined in Scheme I. .
The designations for ligands (see below) indicate the potentialdonor set and bridge size between the methanethio groups of thecyclophanes. Specific transition metal (II) complexes
synthesized, and their properties are listed in Table I.
Scheme I
L + hotL + M(II)X 2 IN MLX2
methanol
M(II) Co(II), Ni(ll) or Cu(lI)
X C1, Br or SCN
L 1, 2a or 3a
0 0S 0 S S
1 SNSO-9 2a SNSO-5 3a = SNSS-5
Electrolytic conductivity data (equivalent conductancesequaling 38-89 ohm-1 cm2 mole-i) indicate that complexes of _aand 3a investigated are lil electrolytes or non-electrolytes.Also, magnetic moments for this series of complexes fall withinthe expected range for the central metal cations (Table I).Ultraviolet-visible spectra for the series of SNSO-5 complexesare reported in Table II. The analogous data for complexes ofSNSS-5 are reported also. Although the affinities of the metal(II) cations for a thiather sulfur atom would be expected to begreater than their affinities for ether oxygen, the complexes ofSNSO-5 and SNSS-5 appear to have analogous structures. Thesedata suggest that each ligand is tetradentate. and that one ofthe halide ions enter the inner coordination sphere. Spectraland electrolytic conductivity data ( r,.-25 ohm-1 cm2 mole-I)indicate that the thiocyanate complexes are six coordinatewherein both monodentate thiocyanate ligands enter the inner
-- t * * **** *** **** *** **** ** ~ * -"'.
W- ..- .7 . W. -
'1coordination sphere. The ultraviolet-visible spectra ofpreviously reported polymethylene dithiapyridinophanes (SNSligand) show maxima at different wavelengths than the oxa- andthia- dithiapyridinophanes reported here [6).
Table I. Physical Properties of Transition Metal (II) Complexesof 2a and 3a (SNSO-5 and SNSS-50 respectively)
Compound (a) Color eff (b) NJ (c)
Co(SNSO-5)2CI bright purple 5.1 53
Co(SNSO-5)2(SCN) purple 5.0 38
Ni (SNSO-5)2CI bright green .3 62
Ni(SNSO-5)2Br green 3.3 54
Cu(SNSO-5)2C1 dark green 1.6 35
Cu(SNSO-5)2Br pale green 2.3 54
Co(SNSS-5)2Cl purple 5.3 34
Co(SNSS-5)2(SCN) dark purple 4.8 17
Ni(SNSS-5)2C1 blue-green 3.3 (d)
Ni(SNSS-5)2Br blue 3.2 61
Cu(SNSS-5)2CI greenish-brown 1.7 42
Cu (SNSS-5)2Br olive green 1.7 69
Co(SNSO-9)2(SCN) purple 5.0 55
(a) the ligands are designated by donor set and number of• members between methanethio groups, (b) Bohr magnetons. room
temperature, (c) in ohm-1 cm2 mole-1 for 2 x 10-4 M nitromethaneor dimethylformamide solutions. (d) insoluble.
• ,-.
'
• :", , o :.". -.-. .' . .. < 2.;. -?.i.". '. ,-"-.".... -"-./. ,:.."- .-.. "- ... "- .i' '-?..---..?. <. <"""' ;""0 "
TABLE II. Electronic Spectral Data of CompIes Z) f -
5-0x a-2,8-di thi apyri di nophane (2) and o.2, 5,8-Trithiapridinophane (3)
Complex Absorption Bands. Frequencies, kK (F) s-
In nitromethane
Cu(SNSO-5)2CI 15.2 (300)
Cu(SNSO-5)2Br 14.9 (370)
Ni(SNSO-5)2Cl 15.7 (40), 25.1 (93), 27.0 (82)
Ni(SNS-5)2Br 15.9 (62), 24.2 (116), 26.8 (184)
Co(SNS-5)2CL 15.3 (307), 16.9 (308); 19.0 (73), 26.8 ,22) -
Cu (SNSO-5)2C1 14.5 (228)
In acetonitrile
Cu(SNSO-5) 2Br 14.3 (305)
Ni(SNSO-5)2C1 15.6 (55). 25.6 (98), >30 (strong)
Ni (SNSO-5)2Br 15.6 (69). 26.6 (150). >30 (strong)
Co(SNSO-5)2(SCN) 15.2 (198), 16.0 (150). 17.6 (209) ., .. 70(strong)
In dimethylformamide %
Cu(SNSS-5)2Br 16.9 (94), 262 (1,073)
Ni(SNSS-5)2Br 15.2 (98). 35.1 (7,680)
Co(SNSS-5)2C1 14.8 (296), 16.4 (19())
Co(SNSS-5)2(SCN) 16.0 (221). 32.8 (811)
Co(SNSO-9)2(SCN) 16.0 (608), 16.7 (355)
Co(SNSO-5)2(SCN), Cu(SNSS-5) 2C1, and Ni(SNSS-5)2CI weresynthesized also.
*...... .. %\\~-. ."
. .. p
v'- ;, . w .-. _ _wrr _ wr, 6'. gwrrr •r wr .r i_? r r .' ,-.- . .-I
c. Characterization of Copper (II) Complexes Derived -rom
Oxa-. Dioxa-, Trioxa- and Folymethyleneparacyclophanes (4a. and5, 4b. 4c, and 6, respectively). Dithiaparacyclophanes weresynthesized in good yield (40-80%) by adapting the high dilutionmethod of Vogtle. The l.n-alkane-dithiolates andoxaalkane-ln-dithiolates were generated conveniently in situfrom the corresponding diisothiouronium dihalides. Reaction ofthe dithiolates with appropriate bis-(halomethyl)arenes yield theligands outlined below. We synthesized five new oxacyclophaneligands (4. 5 and 7) along with four previously reportedpolymethylene cyclophanes.
V/%%0 (CH2ns Om'J - S S S 2) S
4a m = 1, SOS-5 5, SOS-9 6 n = 7 or 9
4b m = 2, SOOS-8 SS-7 or SS-9_4- m = 3, SOOOS-li
0S
2 n
7 8 n = 7 or8
The coordination chemistry of the new oxadithiametacyclophane 7and of the previously reported dithiamethcyclophanes (9) were
investigated in order to examine structural effects on the easeof formation and stability of copper (II) complexes within the 0series. Neither oxadithiaparacyclophene 4a (containing a ninemembered bridge) nor dithiametacyclophanes (7 and 8) yieldedsolid insolable copper (II) chloride comple," es in methanolsolution. On the other hand, oxadithiaparacyclophanes (4b. 4c, 5and 6) and polymethylenedithiaparacyclophanes (6, containingbridges of ten or more members) yielded green crystallinecomplexes that are sparinglyl soluble in anhydrous methanol.Complexes may be formulated as shown in Table III. These copper(II) complexes exhibit relatively low melting points, and theirequivalent conductances suggest neutral mol ecul ar structures.The failure of 4a and of 7 and 8 to form stable crystallinecomple:es indicate a steric requirement in the ligand structure.In the absence of :-rav crystallographic data on a representati,.ecomplex, a folded structure (A) is proposed wherein copper I)is in its usual square planar geometry. An interesting alternatestructure (B). although Unlikely. is one in which copper (II)
7q
Table III. Physical Data for Copper (I I) Cr- om 1e. es 0-±
Dithiaparacyclophanes (4b. 4c. 5 and 6)
Compound (a) mp. C .A'(b) UV-visible, kK (c)
Cu(SOS-9)2C1 137-138 17 22.8 (288)
Cu(SOOS-8)2C1 1 3-6-13 7 17 22. 8 (285)
Cu(SOOS-8)2Br 120-122 30 16.8 (196)
CU(SOOOS-11)2C1 143-145 20 22.9 (278)
Cu(SOOOS-11)2Br 1 d25-127 J. 16.9 (157)
Cu (SS-7)2':Cl 140-141 15 22.9 (244)
*Cu(SS-9)2C1 142-14-3 27 22.9 (249)
* (a) See previous page for structures; notation indicatespotential donor set. (b) In ohm-i cm2 mole-i for 1 " io-3- M
solutions in dimethylformamide. (c) spectra were determined indimethylformamide solution.
*CuC12. + Ligand Cu(Ligand)2Cl. green solid
would occupy the cavity between the aliphatic bridge and the
aromatic nucleus. A tetrahedral structure for copper (II) as
shown in structure C appears remote.
I .U,. CU .,. ...,
X
A B C
square planar, cis X groups square planar, trans X groups tetrahedral
While effective magnetic moments for this series of complexes arerelatively low ( k-eff = 1.4-1.7 B.M.), the experimental valuesN9
support monomeric structures (as apposed to polymeric or clustercomplexes) for these crystalline substances. Characteristics ofvisible spectra within this series of copper(t1)-dithiaparacyclophane complexes (in dimethylformamide)
depended on the monodentate halide ions primarily, as shown inthe data summary in Table III. Since conductivity and electronic
spectral data were obtained in the same solvent, identical
species were examined in each case. Thus the electrolytic
conductivity data assures us that complexes do not dissociate in
dimethylformamide (complexes are non-electrolytes).
d. Complexes of 2,10-Dithia[3.3](2.6) pyridinophane (3).The pyridinophane _? was reported previously. However, we areunaware of any reports on the coordination chemistry of thistetradentate ligand. The bipyridyl ligand (9) reacted with metal(II) salts in methanol solution to yield crystalline comple~es
with high melting points (>30)0 degrees Celsius) and lowsolubilities in polar aprotic solvents (nitromethane anddimethylformamide). Electrolytic conductivity on dilutesolutions indicate that the series of complexes arenon-electrolytes. suggesting a six-coordinate octahedral
structures (10). Elemental analyses on these complexes supportthe general formula. M(SNSN)X2.
x
M(lI) = Cu(II)S S C N,M- --N N = Co(Il)
N --- --S_. = Ni(II)X = C1
X = Br
9 = SCN
designated SNSN 10 M(SNSN)X2
2p
.m €. _,.,- , ; ', " . - *-.1.•. . . .. ., ." . . ° . . .,. ' . , , " , - . . . . -. .
Table IV. Transition Metal (II) Complexes of
2,10-Dithia[3.J](2,6)pyridinophane (1).
Compound eff ohm-I cm2 mole-1 UV-Visible
Cu(SNSN)2C1 2.0 27 (b)
Cu(SNSN)2Br 1.4 47 (b)
Co(SNSN)2Cl 4.8 13 (b)
Co(SNSN)2(SCN) 4.5 23 (b)
(a) obtained on 2 x 10-4 M dimethylforamide solutions. (b)no significant absorption was observed in the visible spectra at
these concentrations.
We have begun the preparation of two manuscripts forpublication of portions of this work. The comparative chemistryof structurally related ligands and the physical properties oftheir complexes will be discussed. Measurement of theoxidation-reduction potentials of the complexes will allow us todetermine wheth-.r ligand structure (as well as donor set) canalter significantly the ease of reduction of copper (II). Wehave the equipment and reagents on hand to make thesemeasurements. Our efforts to obtain crystals suitable for x-ray ' .-crystallographic analyses continue. We have made arrangementswith the crystallography group at Lousiana State University fordetermination of crystal structures of representative exampleswithin our series of complexes, and they provided tips on how
suitable crystals may be grown. The critical literature reviewconnected with our experimental findings will be included inforthcoming manuscripts. We plan to complete two manuscriptsbased on data included in this report by August. 1986.
PUBLICATIONS: None
4.o,1
777
9-,.
F- °
SCIENTIFIC PERSONNEL:
Earl Doomes, Principal Investigator, 20 Septimber 1982 through 19September 1985.
Thornton Rhodes, Co-principal Investigator, 20 September 1982through 5 November 1984 (unable to continue due to illness).
Derald Chriss, Research Associate, 20 January 1984 through 17 May1985.
Sylvester Burton, Graduate Student, 19 August 1983 through 19September 1985; Mr. Burton will receive ar M. S. degree inchemistry in May 1986.
Verlinda Allen, Undergraduate student, 20 August 1984 through 17may 1985; Ms. Allen expects to receive a B. S. degree inchemistry in May 1986.
Batool Tadayoni, Research Assistant, 1 June through 8 August1985. Ms. Tadayoni is now a graduate student who is supported by Sa Chemistry Department assistantship, and expects to receive anM. S. degree in May 1986 (organic research problem). 1*.
ip.
Depaak Mohanty, Undergraduate Research Assistant, 20 Septemberthrough 19 December 1983.
Hillary Wynn. Research Assistant, 9 June through 18 August 198.
BIBLIOGRAPHY AND REFERENCES
1. "Cobalt (II), Nickel (II), and Copper (II) Halide complexes of7-Oxa-2,12-dithiaE13(2,6) pyridinophane," S. Lu and E. Doomes,J. Coord. Chem., 13, 1(1983)
2. "Copper (II) Complexes Bis-2,6-(methylthiomethyl)pyridine andthe Dithia(2.6) pyridinophanes." P. Bryan and E. Doomes, J.Coord. Chem., 6, 97 (1976)
3. "Synthesis and Spectra of Paracylclophane Dienes," E. Doomesand R. M. Beard, Tetrahedron Letters, 1243 (1976).
4. "Novel Ligand Systems for Complexing Alkali Metal Ions." F.Vogtle and E. Weber, Angew. Chem. Internat. Edit., 13. 149(1974).
5. "Versatility of the Cyclic Ligand 5,8,11-Trioxa-2, 14-dithia[153(2,6) pyridinophane; Crystal and Molecular Structures of itsComplexes with Barium Isothiocyanate and with Copper (II)Chloride," G. Weber, Inorganica Chimica Acta, 58. 27 (1982)."2,5.8-Trithia 9 (2.6) pyridinophane," Acta Cryst. 389 (1983).
6. See references 1 and 2 for a brief discussion of this point.
i0
ttA..%.%*~.t *r~r!%r. rr~r .-. .w:-~ .r*.< -.
'a
