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Substitution reactions of [CuI(AsPh3)3X] (X = Cl, Br or I) with 3-phenyl-2-thioxoimidazolidin-4-one (ptiH) and 5-mercapto-1-phenyl-1,2,3-4-tetrazole (mptH)
Polyhedron Vol. 12, No. 7, pp. 75%763, Printed in Great Britain
1993 0
0277-5387/93 %6.00+.00 1993 Pergamon Press Ltd
SUBSTITUTION REACTIONS OF [CuI(AsPh&X] (X = Cl, Br OR I) WITH SPHENYLr2-THIOXOIMlDAZOLIDlN4ONE (ptiH) AND 5-MERCAPTO-l-PHENYL-1,2,3,4-TETRAZOLE (mptH) RAMSHARAN
SINGH and S. K. DIKSHIT*
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India (Received 10 August 1992 ; accepted 20 November 1992)
Abstract-Reactions
of [Cu(AsPh,),X] with the title ligands yield [Cu(AsPh,),(LH)X] 0 N=N
!-CH LH = ptiH,
Ph-N
/ \
2
;
or mptH,
Ph-N
\
C-N !
/
‘H
C-N !
‘H
These complexes have been characterized on the basis of analytical, IR, electronic (UVvis), ‘H NMR, conductivity and magnetic measurements. In all cases there is a distorted tetrahedral environment around copper(I), and the ligands (LH) bind through the thione sulphur atom to copper(I).
The application of heterocyclic thioamides in and the biological imcorrosion protection’ portance of copper-sulphur interactions’.3 have stimulated much of the research efforts exemplified by reports on the ligating behaviour of heterocyclic thiones.“16 Moreover, the copper(I) complexes may adopt di-, ” tri-, ’ 8 tetra-2*’’ and penta-coordination,2o which basically depends upon the bulk as well as the electronic properties of the ligands. This has stimulated many workers to study the ligating behaviour of heterocyclic thiones, possessing an a-nitrogen heteroatom. Specifically, in this field of research the group of Karagiannidis has characterized structurally a number of mixed-ligand coordination compounds of copper(I) with heterocyclic thiones, possessing an m-nitrogen heteroatom and triaryl-phosphines7-‘4 and -arsines. ‘5,‘6 The properties of triphenylphosphine, heterocyclic thione mixed-ligand complexes are fairly well known, but their arsine, stibine and bismuthine analogues are not well studied. Following our interest in coordination properties of the ligands having the H-&--&S
gro~p,~,~J-~~we
* Author to whom correspondence should be addressed.
have recently reported the phosphine counterpart6 of the complexes. For the sake of comparison and in view of the unique properties of copper coordinated triphenylarsine,24~25 we describe the syntheses and characterization of novel copper(I) distorted tetrahedral complexes, [Cu(AsPh,),(LH)X], with the title ligands, which behave as monodentate thione sulphur donors. EXPERIMENTAL Starting materials
All the chemicals used were either of Analar or chemically pure grade. Complexes of the type [Cu(AsPh3)3X],26 (X = Cl, Br or I) and the ligands 3-phenyl-2-thioxoimidazolidin-4-one6 (ptiH) and 5mercapto- 1-phenyl- 1,2,3,4-tetrazole6 (mptH) were prepared by literature methods. Physical methods
Snlphur, halide and copper were determined gravimetrically. The carbon, hydrogen and nitrogen analyses were performed at the Microanalytical
759
760
R. SINGH
and S. K. DIKSHIT
Table 1. Analytical data of the complexes with colours, melting points (M.p.) and yields
Compound
Colour
C
[Cu(AsPh,),(ptiH)Cl]
Maroon
[Cu(AsPh,),(ptiH)Br]
White
[Cu(AsPh,),(ptiH)I]
White
[Cu(AsPh,),(mptH)Cl]
White
[Cu(AsPh,),(mptH)Br]
White
WAsPh&GW-U~1
Orange
54.5 (54.3) 50.6 (50.5) 47.2 (47.1) 51.2 (51.5) 47.2 (47.8) 44.3 (44.5)
Analytical data : Found (Calc.) (%) H N cu S
Halide
F$
10.8
(if) (2;)(10.6) (2) (E) 95d 140d 3.5 12.3 (E) (Z) (::%(12.5) (3.6) 18.6 9.5 135d (Z) (E) (Z) (18.4) (9.2) 158d 10.7 (E) (10.9) (E) (Z) (E) 12.9 158d 10.3 (E) (10.1) &) :::, (12.7) 18.7 160d (E) (E) (E) (ii) (18.8)
Yield (%) 82 85 80 45 58 46
“d = decomposed.
Laboratory, I.I.T. Kanpur, India. The IR spectra were recorded in KBr in the range 400&400 cm- I on Perkin-Elmer and Shimadzu IR-420 spectrophotometers. The electronic (UV-vis) spectra were recorded on a Shimadzu double beam W-160 spectrophotometer. The’ ‘H NMR spectra were recorded on a JEOL JN -PMX 60 SI NMR spectrometer in the range d-20 ppm in CDCl, using TMS as an internal calibrant at room temperature. Conductivity measurements were performed on an Elico conductivity bridge type CM 82T in acetonitrile solution. Magne ’ measurements were performed using a parallel- eld vibrating sample magnetometer (VSM), mod % -150A (Princeton Applied Research Corporation, ~Princeton, NJ). Melting points of the complexes were recorded on a FisherJohn melting point apparatus and are uncorrected.
M
zene solution (30 cm’) of [Cu(AsPh,),X] (0.2 mmol) was added an equivalent amount (0.2 mmol) of the ligand mptH and the resulting clear solution was stirred for cu 3 h. During the stirring some crystals of the complex were separated. The volume of the reaction mixture was reduced to ca 5 cm3 under vacuum and excess petroleum ether (60-8OC) (50 cm3) was added to ensure the maximum precipitation of the complexes. These complexes were centrifuged and washed several times with petroleum ether and dried in vucuo. All these compounds are stable in air for several days but a few complexes are susceptible to air oxidation when left in air for more than a week. The air-oxidized products were not further studied. Melting points, yields and colours of the complexes are given in Table 1 along with the analytical data.
Preparation of compounds Preparation of [Cu(AsPh,),(ptiH)X].
To a benzene solution (30 cm3) of the air-stable compound [Cu(AsPh,),X] (0.2 mmol) was added an equivalent amount (0.2 mmol) oft the ligand ptiH and the solution/suspension wa heated under reflux for ca reaction mixture became 2 h. During refluxing t almost clear. After cooli g, the solution was filtered through a Whatman N . 1 filter paper to remove any insoluble particles. t he resulting solution was concentrated under reduced pressure to half its volume. The addition of petroleum ether (6&8O”C) (50 cm3) resulted in the brecipitation of the microcrystalline products on s anding for 2-3 h. The complexes were centrifuged 1and washed several times with petroleum ether a dried in vacua. Preparation of To a ben-
RESULTS AND DISCUSSION
The analytical data are in good agreement with the stoichiometry proposed as [Cu(AsPh,),(LH)X] (Table 1). These compounds are soluble in most of the organic solvents like CsH6, CHC13, CH2C12, DMSO, DMF, CH,CN, etc. All the compounds are diamagnetic at room temperature. The conductivity of the complexes was found in the range 50-65 R- ’ cm2 mol- ’ in acetonitrile and, consequently, were interpreted according to Geary27 as being nonelectrolytes. The IR spectra of the ligands and complexes are summarized in Table 2. All the ligands adopt the thione form both in the free state and in their complexes. This is evident by the absence of the v(SH) band in the 2500 cm-’ region in each, and by
761
Substitution reactions of [Cn’(AsPh~)~XJ Table 2. Major fR bands of the ligands and complexes (cm- ‘)
v(C==o) Ligand CptiH) [Cu(AsPh~)~~ti~)Cl] [Cu(AsPh,),(ptiH)Br] [Cu(AsPh~)~~tiH)I] Ligand (mptH) [Cu(AsPh,)~(mptH)Cl] [Cu~AsPh~)~(mptH)Br] [Cu(AsRhMnptH)Il
3180 3177 3180 3240 3023,2904,2745 2900 2900 2950
1770 1771 1776 1775 -
v(C===S) I 1165 1080 1077 1075 1050 1040 1045 1050
Thioamide bands II III
1530 1300 1020 1532 1324 1140 1530 1320 1139 1525 1320 1145 1492 1279, 1298 1002,993 1495 1300 995 1495 1300 995 1505 1310 1000
IV ‘780 745sh 746sh 760 751,793 754 752 751
sh = shoulder. the presence of v(NH) in the 2900-3300 cm-’ region.2s The Iigands contain a thioamide group
the complexes. The discernible v(N-H) bands of the ligand mptH (Table 2) shift a little on complexation, indicating the non-involvement of the (H-I&--&S) and give rise to four characteristic thioaxnide bands, namely, I, II, III and IV, N-H group in the coordination. Bonding via sulphur is also favoured in the comin the regions 1500, 1300, 1000 and 800 cm-’ and have contributions from &N-H)+ v(C---N), plexes because copper(I), being a soft acid, should prefer to interact with a soft base such as sulphur v(W) -I-v(C=N) + v(C-H), v(C-N) + v(C-S) and v(C-S) modes of vibrations, respectiveIy6~2p-31and, indeed, the presence of a sulphur--copper(I) bond was confirmed by X-ray single-crystal struc(Table 2). All complexes exhibited the characteristic bands ture of many complexes having a heterocyclic of t~phenylarsine. 32In the case of coordination of thione ligand possessing an ol-nitrogen heterothe ligand with a carbonyl group, namely ptiH, atom . 7-16*34Very recently the mixed-ligand coordination compounds of copper(I) with heterocyclic through the carbonyl oxygen atom the v(C=O) band should shift to a lower wave number and the thiones and triphenylarsine’ ’ have been synthesized thioamide band I [&N-H) + v(C-N)] should shift and their X-ray crystal structural characterization to a higher wave number. However, if coordination is through the nitrogen atom the thioamide band I I ’ I ’ will shift to a lower wave number. However, the position of the band at ca 1770 cm-“, assigned to v(C=O), remains almost unaffected or slightly shifts to the higher wave number (cu Av = 1-6 cm-‘) in the complexes, ruling out coordination through the carbonyl group. The band at cla 1165 cm- ‘, assigned to v(C=S) in the spectra of the ligand ptiH, either splits or shifts to a lower wave number (ca Av = 10-15 cm- ‘) on coordination. The thioa~de band IV, which contains a major contribution from v(C!=S), splits or shifts to the lower region by cu Av = 41-42 cm-‘, which indicates the involvement of the C&S group in the coordination (Fig. 1). On complexation v(C=S) of the l&and mptH (Fig. 2) at 1050 cm-’ splits. The thioamide band I at 1492 cm- ’ undergoes a blue shift by 3-16 cm- I. The thioamide band IV at 793 cn- ’ undergoes a red shift (lit.33 value 785 cm-‘). These observations support the bond formation between the metal and thione sulphur. +i7 (cm-‘) The band at 3 180 cm- ‘, assigned to v(N-H), for Fig. 1. The IR spectra of the ligand ptiH (--) and the the ligand ptiH becomes weak in the IR spectra of complex [Cu(AsPh,)&tiH)Br] (---- -).
-3iAr4e
762
R. SINGH and S. K. DIKSHIT I
I
--
t-
-.-
[Cu(AsPh3)2(ptiH)Ba
A.*.-..
[Cu(AsPh3)2(ptiH)
‘\ ‘. 200
I
ptiH [Cu(AsPhg)p(ptiH)CI]
_-._
300
I 500
400
Ahm)
‘i
I,,,
1400
,
1000
1200 e
,
-
-
Fig. 3. The electronic (UV-vis) spectra of the ligand ptiH and its complexes.
i! il III 1600
I]
I
800
,
600
~(CrIi’)
I
I
Fig. 2. The IR spectra of the figand mptH (-) complex [Cu(AsPh,)d(mptH)Cl] (---).
=
and the
;$kt$,(mptH)C,]
-.
-
[C u(AsPh$2(mptH)Ba
.....“’
has been performed, in whidh exactly the same type of coordination environment and stoichiometry have been observed. The ‘H NMR and electronic (W-vis) spectra of the complexes and free li&nds are given in Table 3, with assignments. The I’H NMR spectra of the complexes clearly show Reaks due to the ligands and triphenylarsines. The NMR signal of the > NH
200
I
300 A
-
[Cu(AsPh3)2(mptH)I]
I
I
400
500
600
(nm)4
Fig. 4. The electronic (UV-vis) spectra of the ligand mptH and its complexes
Table 3. Electronic spectra of the ligands and the complexes in CH,CN and ‘H NMR spectra of the ligands and complexes in CDCl,
Compound
Band position A,, (nm)
Ligand (ptiH)
227.0 265.0
[Cu(AsPh,),(ptiH)Cl]
226.5 270.0 305.0sh 225.0 263.0 225.0 249.5 227.0
[Cu(AsPh,),(ptiH)Br] [Cu(AsPh,),(ptiH)I] Ligand (mptH)
IL IL IL IL IL IL IL
259.5
[Cu(AsPh,),(mptH)Cl] [Cu(AsPh,),(mptH)Br] ]Cu(AsPh 3)&@H)Il
uThese are the literature ‘These are the literature
225.0 245.0sh 226.5 251.5 224.0 247.0
‘H NMR signal with assignments (6)
Assignment
IL IL IL IL IL IL
4.30 (s, 2H, >CH, ring); 7.28 (m, 3H, orfho_H of --C,H,); cu 7.46 (m, meta- andpara-H of -C6H5); 10.37 (s, lH, :NH group) 4.00 (s, 2H, >CH, ring); 6.83-7.67 (m, 35H, -CsHS groups);
4.10 (s, 2H , >CH, ring); 7.00-7.67 (m, 35H, -C&H, groups); 10.27 [s(broad), lH, >NH group] 4.00 (s, 2H, : CH, ring); 6.83-7.67 (m, 35H, -C6H, groups); 9.47 [s(broad), 1H, > NH group] 7.63 (m, 3H, ortho- andpnra-H of -C,H,); 7.89 (m, 2H, metaH of -C,H,); 10.5Ck13.50 (s, lH, -SH)b 6.83-7.67 (m, -C,H, groups) 6.83-7.67 (m, -C,H,
groups)
7.0&7.67 (m, 35H, -CsH,
group1
from ref. 35, in DMSO-d, ; sh = shoulder. from ref. 36, in DMSO-d,.
groups); 9.37 [s(broad), lH, >NH
Substitution
reactions of [Cu’(AsPh,),X]
proton of the complexes appeared as a broad signal. The broadening of the signals may be due to hydrogen bonding. 8,I5,’6 The 6 values become lower as the halogen atomic radius increases (10.27 and 9.47 in the bromine and iodine complexes of the ligand ptiH, respectively). l6 The proportions of the protons, observed by integration, exactly match the proposed stoichiometry of the complexes. As expected, only UV absorption bands are observed, which are assigned as intraligand (IL) transitions (Figs 3 and 4).
REFERENCES 1. B. Donnelly, T. C. Downine, R. Grzeskowiak, H. R. Hamburg and D. Short, Corros. Sci. 1978,18, 109. 2. P. J. Colman, H. C. Freeman, J. M. Gun, M. Murata, V. A. Norris, J. A. M. Ramshow and M. P. Venkatappe, Nature (London) 1978272,319. 3. K. D. Karlin and J. Zubieta (Editors), Copper Coordination Chemistry : Biochemical and Inorganic Perspectiues. Adenine Press, Guilderland, NY (1983). E. S. Raper, Coord. Chem. Rev. 1985,61, 115. R. Singh and S. K. Dikshit, Polyhedron 1992, 11,
2099. R. Singh and S. K. Dikshit, Synth. React. Znorg. Met.-Org. Chem. 1992, 22, 1141 and refs therein. P. Karagiannidis, P. Aslanidis, S. Papastefanou, D. Mentzafos, A. Hountas and A. Terzis, Znorg. Chim. Acta 1989, 156, 265.
8. P. Karagiannidis, P. Aslanidis, D. P. Kessissoglon, B. Krebs and M. Dartmann, Znorg. Chim. Acta 1989, 156,47 and refs therein. 9. S. Skoulika, A. Aubry, P. Karagiannidis, P. Aslanidis and S. Papastefanou, Znorg. Chim. Acta 1991, 183, 207. 10. C. Leconite, St. Skoulika, P. Aslanides, P. Karagiannidis and S. Papastefanou, Polyhedron 1989. 8. 1103. 11. S. K. Hadjikakou, P. Aslanidis, P. Karagiannidis, A. Hountas and A. Terzis, Znorg. Chim. Acta 1991,184, 161. 12. P. Karagiannidis, S. K. Hadjikakau, P. Aslanidis and A. Hountas, Znorg. Chim. Acta 1990, 178,27. 13. S. K. Hadjikakou, P. Aslanidis, P. Karagiannidis, D. Mentzafos and A. Terzis, PoI.vhedron 1991.10.935. 14. P. Karagiannidis, P. Aslanidis, S. Papastefanou, D. Mentzafos, A. Hountas and A. Terzis. Polvhedron 1990, 9, 981.
763
15. P. Karagiannidis, P. Akrivos, A. Aubry and S. Skoulika, Znorg. Chim. Acta 1991,188,79. 16. P. Karagianmdis, P. Akrivos, D. Mentzafos and A. Terzis, Znorg. Chim. Acta 1991, 181,263. 17. T. N. Sarrel and D. L. Jameson, J. Am. Chem. Sot. 1983,105,6013. 18. J. C. Dyason, P. C. Healy, C. Pakawatchai, V. A. Patrick and A. H. White, Znorg. Chem. 1985, 24, 1957 and refs therein. 19. L. M. Engelhardt, C. Pakawatchai, A. H. White and P. C. Healy, J. Chem. Sot., Dalton Trans. 1985, 125 and refs therein. 20. B. C. Green, C. H. L. Kennard, G. Smith, M. M. Elcombe, F. H. Moore, B. D. James and A. H. White, Znorg. Chim. Acta 1984,83, 117. 21. S. K. Dikshit and V. Chauhan, Trans. Met. Chem. 1986, 11, 223. 22. S. K. Dikshit and V. Chauhan, Trans. Met. Chem. 1986, 11, 403. 23. S. K. Dikshit and V. Chauhan, Bull. Chem. Sot. Japan 1987,60,3005.
24. S. J. Lippard and P. S. Welcker, Znorg. Chem. 1972, 11. 6. 25. S. Sakaki, K. Ohkubo, H. Fujiwara and A. Ohyoshi. J. Molec. Catal. 1982, 16, 181.
26. S. J. Lippard and D. A. Ucko, Znorg. Chem. 1968,7, 1051.
27. W. J. Geary, Coord. Chem. Rev. 1971,7,81. 28. L. K. Ramachandran, E. P. P. Agues and W. B. McConnel, Analyt. Chem. 1955,27, 1734. 29. C. N. R. Rao and R. Venkataraghvan, Spectrochim. Acta 1962, 18. 541.
30. C. N. R. Rao, R. Venkataraghvan and T. R. Kartruri, Can. J. Chem. 1964,42,36.
31. I. Suzuki, Bull. Chem. Sot. Japan 1962, 35, 1286, 1449, 1456.
32. J. C. Sheldon and S. Y. Tyree Jr, J. Am. Chem. Sot. 1958,80,2120.
33. B. Singh and R. D. Singh, J. Znorg. Nucl. Chem. 1977,39, 25.
34. E. S. Raper, J. R. Creighton, J. D. Wilson, W. Clegg and A. Milne, Znorg. Chim. Acta 1989, 115, 77. 35. Hand book of Proton-NMR Spectra and Data (Edited by Asahi Research Center Co., Ltd, Tokyo. Japan), Vol. 3, Spectra No. 2153. Supervised by Shin-ichi Sasaki, Academic Press, Tokyo (1985). 36. Hand book of Proton-NMR Spectra and Data (Edited by Asahi Research Center Co., Ltd, Tokyo, Japan). Vol. 3, Spectra No. 1315. Supervised by Shin-ichi Sasaki, Academic Press, Tokyo (1985).
1993 0
0277-5387/93 %6.00+.00 1993 Pergamon Press Ltd
SUBSTITUTION REACTIONS OF [CuI(AsPh&X] (X = Cl, Br OR I) WITH SPHENYLr2-THIOXOIMlDAZOLIDlN4ONE (ptiH) AND 5-MERCAPTO-l-PHENYL-1,2,3,4-TETRAZOLE (mptH) RAMSHARAN
SINGH and S. K. DIKSHIT*
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India (Received 10 August 1992 ; accepted 20 November 1992)
Abstract-Reactions
of [Cu(AsPh,),X] with the title ligands yield [Cu(AsPh,),(LH)X] 0 N=N
!-CH LH = ptiH,
Ph-N
/ \
2
;
or mptH,
Ph-N
\
C-N !
/
‘H
C-N !
‘H
These complexes have been characterized on the basis of analytical, IR, electronic (UVvis), ‘H NMR, conductivity and magnetic measurements. In all cases there is a distorted tetrahedral environment around copper(I), and the ligands (LH) bind through the thione sulphur atom to copper(I).
The application of heterocyclic thioamides in and the biological imcorrosion protection’ portance of copper-sulphur interactions’.3 have stimulated much of the research efforts exemplified by reports on the ligating behaviour of heterocyclic thiones.“16 Moreover, the copper(I) complexes may adopt di-, ” tri-, ’ 8 tetra-2*’’ and penta-coordination,2o which basically depends upon the bulk as well as the electronic properties of the ligands. This has stimulated many workers to study the ligating behaviour of heterocyclic thiones, possessing an a-nitrogen heteroatom. Specifically, in this field of research the group of Karagiannidis has characterized structurally a number of mixed-ligand coordination compounds of copper(I) with heterocyclic thiones, possessing an m-nitrogen heteroatom and triaryl-phosphines7-‘4 and -arsines. ‘5,‘6 The properties of triphenylphosphine, heterocyclic thione mixed-ligand complexes are fairly well known, but their arsine, stibine and bismuthine analogues are not well studied. Following our interest in coordination properties of the ligands having the H-&--&S
gro~p,~,~J-~~we
* Author to whom correspondence should be addressed.
have recently reported the phosphine counterpart6 of the complexes. For the sake of comparison and in view of the unique properties of copper coordinated triphenylarsine,24~25 we describe the syntheses and characterization of novel copper(I) distorted tetrahedral complexes, [Cu(AsPh,),(LH)X], with the title ligands, which behave as monodentate thione sulphur donors. EXPERIMENTAL Starting materials
All the chemicals used were either of Analar or chemically pure grade. Complexes of the type [Cu(AsPh3)3X],26 (X = Cl, Br or I) and the ligands 3-phenyl-2-thioxoimidazolidin-4-one6 (ptiH) and 5mercapto- 1-phenyl- 1,2,3,4-tetrazole6 (mptH) were prepared by literature methods. Physical methods
Snlphur, halide and copper were determined gravimetrically. The carbon, hydrogen and nitrogen analyses were performed at the Microanalytical
759
760
R. SINGH
and S. K. DIKSHIT
Table 1. Analytical data of the complexes with colours, melting points (M.p.) and yields
Compound
Colour
C
[Cu(AsPh,),(ptiH)Cl]
Maroon
[Cu(AsPh,),(ptiH)Br]
White
[Cu(AsPh,),(ptiH)I]
White
[Cu(AsPh,),(mptH)Cl]
White
[Cu(AsPh,),(mptH)Br]
White
WAsPh&GW-U~1
Orange
54.5 (54.3) 50.6 (50.5) 47.2 (47.1) 51.2 (51.5) 47.2 (47.8) 44.3 (44.5)
Analytical data : Found (Calc.) (%) H N cu S
Halide
F$
10.8
(if) (2;)(10.6) (2) (E) 95d 140d 3.5 12.3 (E) (Z) (::%(12.5) (3.6) 18.6 9.5 135d (Z) (E) (Z) (18.4) (9.2) 158d 10.7 (E) (10.9) (E) (Z) (E) 12.9 158d 10.3 (E) (10.1) &) :::, (12.7) 18.7 160d (E) (E) (E) (ii) (18.8)
Yield (%) 82 85 80 45 58 46
“d = decomposed.
Laboratory, I.I.T. Kanpur, India. The IR spectra were recorded in KBr in the range 400&400 cm- I on Perkin-Elmer and Shimadzu IR-420 spectrophotometers. The electronic (UV-vis) spectra were recorded on a Shimadzu double beam W-160 spectrophotometer. The’ ‘H NMR spectra were recorded on a JEOL JN -PMX 60 SI NMR spectrometer in the range d-20 ppm in CDCl, using TMS as an internal calibrant at room temperature. Conductivity measurements were performed on an Elico conductivity bridge type CM 82T in acetonitrile solution. Magne ’ measurements were performed using a parallel- eld vibrating sample magnetometer (VSM), mod % -150A (Princeton Applied Research Corporation, ~Princeton, NJ). Melting points of the complexes were recorded on a FisherJohn melting point apparatus and are uncorrected.
M
zene solution (30 cm’) of [Cu(AsPh,),X] (0.2 mmol) was added an equivalent amount (0.2 mmol) of the ligand mptH and the resulting clear solution was stirred for cu 3 h. During the stirring some crystals of the complex were separated. The volume of the reaction mixture was reduced to ca 5 cm3 under vacuum and excess petroleum ether (60-8OC) (50 cm3) was added to ensure the maximum precipitation of the complexes. These complexes were centrifuged and washed several times with petroleum ether and dried in vucuo. All these compounds are stable in air for several days but a few complexes are susceptible to air oxidation when left in air for more than a week. The air-oxidized products were not further studied. Melting points, yields and colours of the complexes are given in Table 1 along with the analytical data.
Preparation of compounds Preparation of [Cu(AsPh,),(ptiH)X].
To a benzene solution (30 cm3) of the air-stable compound [Cu(AsPh,),X] (0.2 mmol) was added an equivalent amount (0.2 mmol) oft the ligand ptiH and the solution/suspension wa heated under reflux for ca reaction mixture became 2 h. During refluxing t almost clear. After cooli g, the solution was filtered through a Whatman N . 1 filter paper to remove any insoluble particles. t he resulting solution was concentrated under reduced pressure to half its volume. The addition of petroleum ether (6&8O”C) (50 cm3) resulted in the brecipitation of the microcrystalline products on s anding for 2-3 h. The complexes were centrifuged 1and washed several times with petroleum ether a dried in vacua. Preparation of To a ben-
RESULTS AND DISCUSSION
The analytical data are in good agreement with the stoichiometry proposed as [Cu(AsPh,),(LH)X] (Table 1). These compounds are soluble in most of the organic solvents like CsH6, CHC13, CH2C12, DMSO, DMF, CH,CN, etc. All the compounds are diamagnetic at room temperature. The conductivity of the complexes was found in the range 50-65 R- ’ cm2 mol- ’ in acetonitrile and, consequently, were interpreted according to Geary27 as being nonelectrolytes. The IR spectra of the ligands and complexes are summarized in Table 2. All the ligands adopt the thione form both in the free state and in their complexes. This is evident by the absence of the v(SH) band in the 2500 cm-’ region in each, and by
761
Substitution reactions of [Cn’(AsPh~)~XJ Table 2. Major fR bands of the ligands and complexes (cm- ‘)
v(C==o) Ligand CptiH) [Cu(AsPh~)~~ti~)Cl] [Cu(AsPh,),(ptiH)Br] [Cu(AsPh~)~~tiH)I] Ligand (mptH) [Cu(AsPh,)~(mptH)Cl] [Cu~AsPh~)~(mptH)Br] [Cu(AsRhMnptH)Il
3180 3177 3180 3240 3023,2904,2745 2900 2900 2950
1770 1771 1776 1775 -
v(C===S) I 1165 1080 1077 1075 1050 1040 1045 1050
Thioamide bands II III
1530 1300 1020 1532 1324 1140 1530 1320 1139 1525 1320 1145 1492 1279, 1298 1002,993 1495 1300 995 1495 1300 995 1505 1310 1000
IV ‘780 745sh 746sh 760 751,793 754 752 751
sh = shoulder. the presence of v(NH) in the 2900-3300 cm-’ region.2s The Iigands contain a thioamide group
the complexes. The discernible v(N-H) bands of the ligand mptH (Table 2) shift a little on complexation, indicating the non-involvement of the (H-I&--&S) and give rise to four characteristic thioaxnide bands, namely, I, II, III and IV, N-H group in the coordination. Bonding via sulphur is also favoured in the comin the regions 1500, 1300, 1000 and 800 cm-’ and have contributions from &N-H)+ v(C---N), plexes because copper(I), being a soft acid, should prefer to interact with a soft base such as sulphur v(W) -I-v(C=N) + v(C-H), v(C-N) + v(C-S) and v(C-S) modes of vibrations, respectiveIy6~2p-31and, indeed, the presence of a sulphur--copper(I) bond was confirmed by X-ray single-crystal struc(Table 2). All complexes exhibited the characteristic bands ture of many complexes having a heterocyclic of t~phenylarsine. 32In the case of coordination of thione ligand possessing an ol-nitrogen heterothe ligand with a carbonyl group, namely ptiH, atom . 7-16*34Very recently the mixed-ligand coordination compounds of copper(I) with heterocyclic through the carbonyl oxygen atom the v(C=O) band should shift to a lower wave number and the thiones and triphenylarsine’ ’ have been synthesized thioamide band I [&N-H) + v(C-N)] should shift and their X-ray crystal structural characterization to a higher wave number. However, if coordination is through the nitrogen atom the thioamide band I I ’ I ’ will shift to a lower wave number. However, the position of the band at ca 1770 cm-“, assigned to v(C=O), remains almost unaffected or slightly shifts to the higher wave number (cu Av = 1-6 cm-‘) in the complexes, ruling out coordination through the carbonyl group. The band at cla 1165 cm- ‘, assigned to v(C=S) in the spectra of the ligand ptiH, either splits or shifts to a lower wave number (ca Av = 10-15 cm- ‘) on coordination. The thioa~de band IV, which contains a major contribution from v(C!=S), splits or shifts to the lower region by cu Av = 41-42 cm-‘, which indicates the involvement of the C&S group in the coordination (Fig. 1). On complexation v(C=S) of the l&and mptH (Fig. 2) at 1050 cm-’ splits. The thioamide band I at 1492 cm- ’ undergoes a blue shift by 3-16 cm- I. The thioamide band IV at 793 cn- ’ undergoes a red shift (lit.33 value 785 cm-‘). These observations support the bond formation between the metal and thione sulphur. +i7 (cm-‘) The band at 3 180 cm- ‘, assigned to v(N-H), for Fig. 1. The IR spectra of the ligand ptiH (--) and the the ligand ptiH becomes weak in the IR spectra of complex [Cu(AsPh,)&tiH)Br] (---- -).
-3iAr4e
762
R. SINGH and S. K. DIKSHIT I
I
--
t-
-.-
[Cu(AsPh3)2(ptiH)Ba
A.*.-..
[Cu(AsPh3)2(ptiH)
‘\ ‘. 200
I
ptiH [Cu(AsPhg)p(ptiH)CI]
_-._
300
I 500
400
Ahm)
‘i
I,,,
1400
,
1000
1200 e
,
-
-
Fig. 3. The electronic (UV-vis) spectra of the ligand ptiH and its complexes.
i! il III 1600
I]
I
800
,
600
~(CrIi’)
I
I
Fig. 2. The IR spectra of the figand mptH (-) complex [Cu(AsPh,)d(mptH)Cl] (---).
=
and the
;$kt$,(mptH)C,]
-.
-
[C u(AsPh$2(mptH)Ba
.....“’
has been performed, in whidh exactly the same type of coordination environment and stoichiometry have been observed. The ‘H NMR and electronic (W-vis) spectra of the complexes and free li&nds are given in Table 3, with assignments. The I’H NMR spectra of the complexes clearly show Reaks due to the ligands and triphenylarsines. The NMR signal of the > NH
200
I
300 A
-
[Cu(AsPh3)2(mptH)I]
I
I
400
500
600
(nm)4
Fig. 4. The electronic (UV-vis) spectra of the ligand mptH and its complexes
Table 3. Electronic spectra of the ligands and the complexes in CH,CN and ‘H NMR spectra of the ligands and complexes in CDCl,
Compound
Band position A,, (nm)
Ligand (ptiH)
227.0 265.0
[Cu(AsPh,),(ptiH)Cl]
226.5 270.0 305.0sh 225.0 263.0 225.0 249.5 227.0
[Cu(AsPh,),(ptiH)Br] [Cu(AsPh,),(ptiH)I] Ligand (mptH)
IL IL IL IL IL IL IL
259.5
[Cu(AsPh,),(mptH)Cl] [Cu(AsPh,),(mptH)Br] ]Cu(AsPh 3)&@H)Il
uThese are the literature ‘These are the literature
225.0 245.0sh 226.5 251.5 224.0 247.0
‘H NMR signal with assignments (6)
Assignment
IL IL IL IL IL IL
4.30 (s, 2H, >CH, ring); 7.28 (m, 3H, orfho_H of --C,H,); cu 7.46 (m, meta- andpara-H of -C6H5); 10.37 (s, lH, :NH group) 4.00 (s, 2H, >CH, ring); 6.83-7.67 (m, 35H, -CsHS groups);
4.10 (s, 2H , >CH, ring); 7.00-7.67 (m, 35H, -C&H, groups); 10.27 [s(broad), lH, >NH group] 4.00 (s, 2H, : CH, ring); 6.83-7.67 (m, 35H, -C6H, groups); 9.47 [s(broad), 1H, > NH group] 7.63 (m, 3H, ortho- andpnra-H of -C,H,); 7.89 (m, 2H, metaH of -C,H,); 10.5Ck13.50 (s, lH, -SH)b 6.83-7.67 (m, -C,H, groups) 6.83-7.67 (m, -C,H,
groups)
7.0&7.67 (m, 35H, -CsH,
group1
from ref. 35, in DMSO-d, ; sh = shoulder. from ref. 36, in DMSO-d,.
groups); 9.37 [s(broad), lH, >NH
Substitution
reactions of [Cu’(AsPh,),X]
proton of the complexes appeared as a broad signal. The broadening of the signals may be due to hydrogen bonding. 8,I5,’6 The 6 values become lower as the halogen atomic radius increases (10.27 and 9.47 in the bromine and iodine complexes of the ligand ptiH, respectively). l6 The proportions of the protons, observed by integration, exactly match the proposed stoichiometry of the complexes. As expected, only UV absorption bands are observed, which are assigned as intraligand (IL) transitions (Figs 3 and 4).
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