- Email: [email protected]
Pentacoordinated complexes of organotellurium(IV) halides with tertiary phosphine selenides
Polyhedron Vol. 6, No. 2, pp. 219-223, 1987 0
Printed in Great Britain
0277-5387187 $3.00+.00 1987 Pergamon Journals Ltd
PENTACOORDINATED COMPLEXES OF ORGANOTELLURIUM(JV) HALIDES WITH TERTIARY PHOSPHINE SELENIDES T. N. SRIVASTAVA,”
JAI DE0 SINGH and SANJAY KUMAR SRIVASTAVA
Chemistry Department, (Received
University of Lucknow, Lucknow 226007, India 17 April 1986 ; accepted 28 May 1986)
Abstract-The pentacoordinated tellurium(IV) complexes [R2TeC12* L] [R = C6HS or pCH30CgH4; L = Ph,PSe, (p-MeC,H,),PSe, Bu,PSe or Ph2P(Se)(CH2),(Se)PPh2] were obtained by the reaction of R,TeC12 with L under anhydrous conditions. The complexes have been characterized by spectral (IR, ‘H NMR and 3’P NMR) studies. The reaction of RTeCl, and L, however, yields tellurium/selenium metal. ‘5(31P-77Se) coupling constant data suggest complexation. In case of bidentate donor bases only one donor site is used in coordination. The complexes possess distorted octahedral geometry around a central tellurium atom which is surrounded by five groups and one vacant site occupied by a lone pair.
The coordination chemistry of phosphine selenides is little known compared to that of phosphine, phosphine oxides and sulfides.’ There are only a few reports on the complexes of P=Se bases with some soft acceptors*-6 such as Pt(II), Pd(II), Ag(I), Zn(II), Cd(H) and Hg(I1). A few coordination compounds of the main-group metals Pb(II), Sn(I1) and Sn(IV) have also been reported>* but the corresponding reactions with organometals have not been studied. There is a single paper describing the coordination behaviour of P=Se with (PhTeBr).’ In continuation of our interest in the synthesis and reactivity of organotellurium(IV) compounds,” we report herein the synthesis of such complexes with organotellurium(IV). EXPERIMENTAL All manipulations were carried out under dry nitrogen. TeCl, (BDH) was used as such. Ph2TeC12,” @-MeOC&)2TeC12,‘2 Me2TeI,,13 (pMeOC6H4)TeC13,‘4 and Ph,Te(OCOCF,), and Me2Te(OCOCF3)2’5 were prepared by literature methods. Tertiary phosphine selenides were prepared from the phosphine and KSeCN in CH3CN16 or by direct reaction of elemental selenium (red) with phosphines in refluxing toluene.17 ‘H NMR spectra of the compounds were recorded in CDC&, *Author to whom correspondence should be addressed.
using TMS as the internal standard on a Varian 90D spectrometer. 31P NMR spectra were obtained using a JEOL-PFT 400 Fourier transform spectrometer operating at 40.5 MHz. Samples were contained in spinning IO-mm tubes with CDC13 as the solvent system with a l-mm capillary tube containing 85% H3P04 as a reference. The molecular complexes were obtained by the direct interaction of the Lewis acids and bases in dichloromethane. Reaction of R2TeC12 (R = Ph or p-MeOC,H,) bases
with
In a typical experiment a mixture of Ph2TeC12 (3.52 g, 10 mmol) and Ph,PSe (3.41 g, 10 mmol) in dichloromethane (-30 cm3) was refluxed for 4 h, and the excess solvent distilled off. The solution was concentrated to crystallization, yielding [Ph,TeCl* . SePPh,]. Similar products were obtained using Ph,P(Se)(CH,),(Se)PPh, as a base and Me,Te(OCOCF,), as an acceptor. Reaction of (p-MeOC,H,)TeCl,
with bases
In a representative experiment, a mixture of (p-MeOC6H4)TeC13 and Ph,PSe in a 1: 1 molar ratio was stirred in dichloromethane at room temperature. The reaction mixture after a few minutes deposited selenium and tellurium metals. Similarly, MqTe12 and Me2TeClz with Ph,PSe
219
ph2TeClz * SePBu,]
[phzTeC& - Ph2P(Se)(CH,),(Se)PPhd
ph,TeC& - SeP(p-CH,OC&,)J
[(p-MeOCsHJ2TeC12 * SePPh,]
[@-MeOCsH3,TeC12 * SePBu,]
[(p-MeOCsH,),TeC1, - SeP(p-CH,OC,H&]
[(p-MeOC&I.,)2TeC12* Ph,P(Se)(CH,),(Se)PPh~
[2@MeOC,H&TeCl,
2
3
4
5
6
7
8
9
85
11 [Ph2Te(OCOCF,), *PhzP(Se)(CH,),(Se)PPhJ
’ v, in ligand and v, in complex.
80
87
85
83
79
80
75
80
85
82
W)
Yield
10 [Me,Te(OCOCF,),*Ph,P(Se)(CH,),(Se)PPhJ
.Ph*P(se)(CH,),(se)PPhzl
[Ph,TeCl, * SePPh,]
1
Complex
135 118
117
158
114 152
131
134
149
109
119
M.D.
(Z) 42.5 (42.9)
(G)
(::a 52.4 (52.9) 49.3 (49.5)
51.6 (51.9) 45.0 (45.5) 50.1 (50.2) 53.6 (53.8) 50.7 (50.9)
C
(Z)
(3.2)
3.1
(E) (E) (E) (E) (E) (E) (2) (E) ;I;)
H
(Z) 10.1 (10.3)
(&
(Z) 10.1 (10.2)
(Z) 16.1 (16.3) 11.2 (11.4) 16.3 (16.8) 14.4 (14.8)
(10.7) 10.3 (10.5) 11.3 (11.4)
(Z)
(G)
11.2 (11.4) 12.1 (12.5) 17.2 (17.4) 10.1
Se
10.2 (10.2) 11.1 (11.2)
Cl
(Z) 13.7 (14.0) 17.2 (17.3) 16.8 (16.9) 18.2 (18.4) 15.6 (16.0) 13.1 (13.2) 18.4 (18.5) 13.3 (13.6) 11.6 (12.0)
18.1 (18.4)
Te
Elemental analysis : found (talc.) (%)
Table 1. Analytical data for R,TeCl, - L
537
537
537
537
544
511
562
544
537
511
562
VI
523
526
525
527
535
501
551
534
528
503
553
v2
IR absorptions of P=Se (cm-‘)
-14
-11
-12
-8
-9
A(+v2)
w 0
Pentacoordinated complexes of organotellurium(IV) halides and PhzP(Se)(CH&(Se)PPh2 deposited metals and failed to yield stable adducts. RESULTS
free
AND DISCUSSION
The analytical data for the adducts (Table 1) correspond to a 1: 1 (M : L) stoichiometry except for [2@ - MeOC,H&TeCl, * PhzP(Se)(CH,),(Se)PPhz] which has a 2 : 1 (M : L) mole ratio and possesses a bridging ligand. All complexes are white crystalline solids having sharp melting points. They are normally stable but deposit selenium metal on standing for a long time. The complexes possess very offensive odours. They are soluble in common organic solvents such as MeOH, EtOH, CH2C12, MeCN, Me$O, Me*NCHO and PhNO*. The molar conductances of lop3 M solutions of the complexes in MeOH and MeCN at room temperature indicate their non-electrolytic nature. All known organoselenophosphorus compounds belong to the P(IV)-Se(I1) class. Thus, selenium can be bonded to a phosphorus atom by a single (a) bond or by a double bond of p,-d, (Se 4pn+P 3d,) type. P=Se can be considered as essentially a double bond because 3d orbitals of phosphorus are available for n-bonding. The p,-d, bonding arises from donation of non-bonding 4pn electrons of the selenium atom into vacant 3d orbitals of phosphorus. This double-bond character in these ligands and the presence of valence s-electron density at the nucleus of the selenium atom is more than twice that for phosphorus, which would normally lead to a larger coordinating centre. Depending upon the relative importance of the two resonating hybrid structures the selenium atom will effectively retain from one to two electron lone pairs which have most of the selenium s-character, and thus may coordinate to a metal atom in one of the following ways : R,P=Se
: + M f+ R,P’SeT-+
M.
The shift is attributed to a weakening of the secondary p,-d, bonds between the selenium and the phosphorus atom in the complexes. It is observed that only a small change in the Me stretching frequency occurs compared to the corresponding v(P=O) and v(P=S) absorptions” in the corresponding complexes. This is reasonable since the vibrations involving the relatively heavy selenium atom would be less sensitive to coordination than those with the lighter phosphorus, oxygen or sulphur atoms. ‘H NMR spectral studies The ‘H NMR values are given in Table 2. The salient features of the spectra are discussed below. In the ‘H NMR spectra of [(p-MeOCJI&TeCl, * Ph,P(Se)(CH,),(Se)PPhz] (1 : 1 M : L) and [2(pMeOC6H.&TeC12 * PhzP(Se)(CH,),(Se)PPhd (2 : 1 M : L), the -CH, protons are doubled due to coupling with the 31P nucleus. The methyl protons of thep-MeOC,H, group show a doublet in the 1: 1 complex. In the 2 : 1 complex the two methyl singlets are separated and are centred at 3.15 and 3.68. However, the two complexes show a single spot in TLC, ruling out the presence of a mixture of the 2 : 1 and 1: 1 adducts. The structural change may be due to participation of both selenium atoms of the bidentate ligand in coordination, giving rise to a bridging ligand between the two tellurium atoms. The structure of bis(diphenylphosphinoselenide)ethane favours more a bite and an orientation of the lone pairs for bridging two metals atoms
Table 2. ‘H NMR spectral data
Complexes
5
7 8
with phosphine selenides
reported in various phosphine selenides lies in the range 51 l-562 cn- ‘, and undergoes a negative shift of 8-14 cm-’ on coordination. A shift of 10-20 cm- ’ in v(P=Se) has been reported for zinc, cadmium, mercury and nickel complexes.3*‘8 The
v(P=Se)
Chemical shift (Ppm)
Complex”
IR spectra
The IR spectra of the complexes were recorded in the range 4000-400 cm- ‘. The diagnostic absorptions are discussed below.
221
3.72, s, 6H @-CH,O); 6.88, d, 4H (metaprotons) ; 7.94, d, 4H [ortho protons of @CH,OC.&J] ; 7.2-7.85, m, 15H (C,H,),P 2.3, s, 9H (C&-(X3); 3.73, s, 6H (pCH,O) ; 6X-8.0, m, 20H (phenyl protons) 2.84, d, 4H (-CH,CH,--) ; 3.76, d, 6H (pCH,O) ; 6.92, d, 4H (meta protons) 7.95, d, 4H [ortho protons of (p-CH,OC&+] ; 6.5-8.0, m, 20H lphenyl protons of
%WWl 9
2.82, d, 4H (-CH,CHJ; 3.75, 3.68, s, 12H @CH30) 6.90, d, 8H [ortho protons of (pCH,OC&F]; 668.0, m, 20H lphenyl protons of Ph,P(Se)-]
“See Table 1.
222
T. N. SRIVASTAVA
et al.
Table 3. 31PNMR data for [R2TeC!12- L] L in the complex (pMeOC,H.,),TeCl, *L Ph,PSe Ph2P(Se)(CH,),(Se)PPhz
g(P) (Ppm)
d(P) (Ppm)
1J(3’P-“Se) (Hz)
A(“P-“Se) (Hz)
35.3 (32.9) 3598 (33.6)
2.4
700.4 (736) 635.1 832.2 (736)
- 35.6
2.38
- 100.9 +96.2
a Free-ligand values”
than forming a chelate ring around a single metal.lg It is concluded that diphosphine selenide acts as a bridging ligand between two tellurium atoms, as reported for diphosphine complexes with other metals.20-u rather
3’P NMR spectra 31P NMR spectra of a few complexes were obtained at room temperature and the data are listed in Table 3. From the 31P NMR data the following facts are deduced : (i) Jr_&3’P-77Se) is sensitive toward coordination and possesses a lower value compared to that for the free ligand. Such a change is attributed to coordination of P=Se to the metal atom through selenium.23,24 (ii) In the complex [(p-MeOC6HJ2TeClz * SePPh,] the 8(P) and 1J(3’P-77Se) decrease on coordination, indicating Se + Te bonding.‘7,23 (iii) In the complex [(p-MeOC6HJ2TeC12 Ph,P(Se)(CH,),(Se)PPh,] two sets of 77Se satellites of equal intensity, with 1J(31P-77Se)= 635.1 and 832.2 Hz, are observed. The former coupling constant [A1J(3’P-77Se = - 100.9 Hz] is due to coordination from the selenium atom, while the other, being higher (A’J = +96.2 Hz) than that in the free ligand, may be due to an uncoordinated selenium atom.25 Thus, from spectral data it may be concluded that the complexes possess an octahedral geometry around a tellurium atom with one site being occupied by a lone pair of elec-
i R\TC R’I’L
X
Sb’I’R
R/r<& xII
IIX PPh,
Ph2P ‘(CH,
R = Cl%, &l-l5 or p-MeOC,Hq;
,(
X = CL or OCOCF3
trons. The structures of the complexes may be as shown below.
AcknowledgementsFinancial assistance from the Council of Scienti6c and Industrial Research, New Delhi, and the University Grant Commission, New Delhi, in support of the present work is gratefully acknowledged. REFERENCES 1. N. M. Karayannis, C. M. Mikulski and L. L. Pyrlewski, Znorg. Chim. Acta, Rev. 1977,5, 69. 2. T. Allman and R. G. Geol. Can. J. Chem. 1984,60, 615, 621. 3. A. J. Blake and G. P. McQuillan, J. Chem. Sot., Dalton Trans. 1984, 1849. 4. D. J. Williams and K. J. Wynne, Znorg. Chem. 1976, 15, 1449. 5. E. W. Abel, S. K. Bhargwa, K. G. Ore11and V. Sik, Znorg. Chim. Acta 1981, 49,25. 6. I. J. Colquhoun and W. McFarlane, J. Chem. Sot., Dalton Trans. 1981,658. 7. M. J. Fernandezcid, M. P. Pazos Perez, J. Sordo, J. S. Casas, M. R. Bermego and M. Gayoso, An. Quim., Ser. B 1982,78, 190. 8. P. A. W. Dean, Can. J. Chem. 1982,60,2921. 9. S. Hauge and 0. Vikane, Acta Chem. Stand. 1973, 27, 3596. 10. T. N. Srivastava, Jai Deo Singh and Shashi Mehrotra, Indian J. Chem. 1985,24A, 849. 11. R. C. Paul, K. K. Bhasin and R. K. Chadha, J. Znorg. Nucl. Chem. 1975,37,2337. 12. J. Bergman, Tetrahedron 1972, 28, 3323. 13. R. H. Vernon, J. Chem. Sot. 1920,117,86. 14. G. T. Morgan and R. E. Kellett, J. Chem. Sot. 1926, 1089. 15. T. N. Srivastava and Jai Deo Singh, Indian J. Chem. (communicated). 16. P. Nicpon and D. W. Meek, Znorg. Chem. 1966, 5, 1297. 17. S. 0. Grim, E. D. Walton and L. C. Satek, Can. J. Chem. 1980,58,1476. 18. M. G. King and G. P. McQuillan, J. Chem. Sot. A 1967,898. 19. C. H. Lindsay, L. S. Benner and A. L. Balch, Znorg. Chem. 1980,19,3503.
Pentacoordinated
complexes of organotellurium(IV)
20. M. M. Olmstead, C. H. Lindsay, L. S. Bearer and A. L. Balch, J. Organomet. Chem. 1979, 179,289. 21. V. G. Kumar Das, J. Znorg. Nucl. Chem. 1976, 38, 1241. 22. F. A. Cotton, G. G. Stanley and R. A. Walton, Znorg. Chem. 1978,17,2099.
halides
223
23. P. A. W. Dean, Can. J. Chem. 1979,57,754. 24. S. 0. Grim, E. D. Walton and L. C. Satck, Znorg. Chim. Acta 1978,27, L115. 25. P. A. W. Dean and M. K. Hughes, Can. J. Chem. 1980,58, 180.
Printed in Great Britain
0277-5387187 $3.00+.00 1987 Pergamon Journals Ltd
PENTACOORDINATED COMPLEXES OF ORGANOTELLURIUM(JV) HALIDES WITH TERTIARY PHOSPHINE SELENIDES T. N. SRIVASTAVA,”
JAI DE0 SINGH and SANJAY KUMAR SRIVASTAVA
Chemistry Department, (Received
University of Lucknow, Lucknow 226007, India 17 April 1986 ; accepted 28 May 1986)
Abstract-The pentacoordinated tellurium(IV) complexes [R2TeC12* L] [R = C6HS or pCH30CgH4; L = Ph,PSe, (p-MeC,H,),PSe, Bu,PSe or Ph2P(Se)(CH2),(Se)PPh2] were obtained by the reaction of R,TeC12 with L under anhydrous conditions. The complexes have been characterized by spectral (IR, ‘H NMR and 3’P NMR) studies. The reaction of RTeCl, and L, however, yields tellurium/selenium metal. ‘5(31P-77Se) coupling constant data suggest complexation. In case of bidentate donor bases only one donor site is used in coordination. The complexes possess distorted octahedral geometry around a central tellurium atom which is surrounded by five groups and one vacant site occupied by a lone pair.
The coordination chemistry of phosphine selenides is little known compared to that of phosphine, phosphine oxides and sulfides.’ There are only a few reports on the complexes of P=Se bases with some soft acceptors*-6 such as Pt(II), Pd(II), Ag(I), Zn(II), Cd(H) and Hg(I1). A few coordination compounds of the main-group metals Pb(II), Sn(I1) and Sn(IV) have also been reported>* but the corresponding reactions with organometals have not been studied. There is a single paper describing the coordination behaviour of P=Se with (PhTeBr).’ In continuation of our interest in the synthesis and reactivity of organotellurium(IV) compounds,” we report herein the synthesis of such complexes with organotellurium(IV). EXPERIMENTAL All manipulations were carried out under dry nitrogen. TeCl, (BDH) was used as such. Ph2TeC12,” @-MeOC&)2TeC12,‘2 Me2TeI,,13 (pMeOC6H4)TeC13,‘4 and Ph,Te(OCOCF,), and Me2Te(OCOCF3)2’5 were prepared by literature methods. Tertiary phosphine selenides were prepared from the phosphine and KSeCN in CH3CN16 or by direct reaction of elemental selenium (red) with phosphines in refluxing toluene.17 ‘H NMR spectra of the compounds were recorded in CDC&, *Author to whom correspondence should be addressed.
using TMS as the internal standard on a Varian 90D spectrometer. 31P NMR spectra were obtained using a JEOL-PFT 400 Fourier transform spectrometer operating at 40.5 MHz. Samples were contained in spinning IO-mm tubes with CDC13 as the solvent system with a l-mm capillary tube containing 85% H3P04 as a reference. The molecular complexes were obtained by the direct interaction of the Lewis acids and bases in dichloromethane. Reaction of R2TeC12 (R = Ph or p-MeOC,H,) bases
with
In a typical experiment a mixture of Ph2TeC12 (3.52 g, 10 mmol) and Ph,PSe (3.41 g, 10 mmol) in dichloromethane (-30 cm3) was refluxed for 4 h, and the excess solvent distilled off. The solution was concentrated to crystallization, yielding [Ph,TeCl* . SePPh,]. Similar products were obtained using Ph,P(Se)(CH,),(Se)PPh, as a base and Me,Te(OCOCF,), as an acceptor. Reaction of (p-MeOC,H,)TeCl,
with bases
In a representative experiment, a mixture of (p-MeOC6H4)TeC13 and Ph,PSe in a 1: 1 molar ratio was stirred in dichloromethane at room temperature. The reaction mixture after a few minutes deposited selenium and tellurium metals. Similarly, MqTe12 and Me2TeClz with Ph,PSe
219
ph2TeClz * SePBu,]
[phzTeC& - Ph2P(Se)(CH,),(Se)PPhd
ph,TeC& - SeP(p-CH,OC&,)J
[(p-MeOCsHJ2TeC12 * SePPh,]
[@-MeOCsH3,TeC12 * SePBu,]
[(p-MeOCsH,),TeC1, - SeP(p-CH,OC,H&]
[(p-MeOC&I.,)2TeC12* Ph,P(Se)(CH,),(Se)PPh~
[2@MeOC,H&TeCl,
2
3
4
5
6
7
8
9
85
11 [Ph2Te(OCOCF,), *PhzP(Se)(CH,),(Se)PPhJ
’ v, in ligand and v, in complex.
80
87
85
83
79
80
75
80
85
82
W)
Yield
10 [Me,Te(OCOCF,),*Ph,P(Se)(CH,),(Se)PPhJ
.Ph*P(se)(CH,),(se)PPhzl
[Ph,TeCl, * SePPh,]
1
Complex
135 118
117
158
114 152
131
134
149
109
119
M.D.
(Z) 42.5 (42.9)
(G)
(::a 52.4 (52.9) 49.3 (49.5)
51.6 (51.9) 45.0 (45.5) 50.1 (50.2) 53.6 (53.8) 50.7 (50.9)
C
(Z)
(3.2)
3.1
(E) (E) (E) (E) (E) (E) (2) (E) ;I;)
H
(Z) 10.1 (10.3)
(&
(Z) 10.1 (10.2)
(Z) 16.1 (16.3) 11.2 (11.4) 16.3 (16.8) 14.4 (14.8)
(10.7) 10.3 (10.5) 11.3 (11.4)
(Z)
(G)
11.2 (11.4) 12.1 (12.5) 17.2 (17.4) 10.1
Se
10.2 (10.2) 11.1 (11.2)
Cl
(Z) 13.7 (14.0) 17.2 (17.3) 16.8 (16.9) 18.2 (18.4) 15.6 (16.0) 13.1 (13.2) 18.4 (18.5) 13.3 (13.6) 11.6 (12.0)
18.1 (18.4)
Te
Elemental analysis : found (talc.) (%)
Table 1. Analytical data for R,TeCl, - L
537
537
537
537
544
511
562
544
537
511
562
VI
523
526
525
527
535
501
551
534
528
503
553
v2
IR absorptions of P=Se (cm-‘)
-14
-11
-12
-8
-9
A(+v2)
w 0
Pentacoordinated complexes of organotellurium(IV) halides and PhzP(Se)(CH&(Se)PPh2 deposited metals and failed to yield stable adducts. RESULTS
free
AND DISCUSSION
The analytical data for the adducts (Table 1) correspond to a 1: 1 (M : L) stoichiometry except for [2@ - MeOC,H&TeCl, * PhzP(Se)(CH,),(Se)PPhz] which has a 2 : 1 (M : L) mole ratio and possesses a bridging ligand. All complexes are white crystalline solids having sharp melting points. They are normally stable but deposit selenium metal on standing for a long time. The complexes possess very offensive odours. They are soluble in common organic solvents such as MeOH, EtOH, CH2C12, MeCN, Me$O, Me*NCHO and PhNO*. The molar conductances of lop3 M solutions of the complexes in MeOH and MeCN at room temperature indicate their non-electrolytic nature. All known organoselenophosphorus compounds belong to the P(IV)-Se(I1) class. Thus, selenium can be bonded to a phosphorus atom by a single (a) bond or by a double bond of p,-d, (Se 4pn+P 3d,) type. P=Se can be considered as essentially a double bond because 3d orbitals of phosphorus are available for n-bonding. The p,-d, bonding arises from donation of non-bonding 4pn electrons of the selenium atom into vacant 3d orbitals of phosphorus. This double-bond character in these ligands and the presence of valence s-electron density at the nucleus of the selenium atom is more than twice that for phosphorus, which would normally lead to a larger coordinating centre. Depending upon the relative importance of the two resonating hybrid structures the selenium atom will effectively retain from one to two electron lone pairs which have most of the selenium s-character, and thus may coordinate to a metal atom in one of the following ways : R,P=Se
: + M f+ R,P’SeT-+
M.
The shift is attributed to a weakening of the secondary p,-d, bonds between the selenium and the phosphorus atom in the complexes. It is observed that only a small change in the Me stretching frequency occurs compared to the corresponding v(P=O) and v(P=S) absorptions” in the corresponding complexes. This is reasonable since the vibrations involving the relatively heavy selenium atom would be less sensitive to coordination than those with the lighter phosphorus, oxygen or sulphur atoms. ‘H NMR spectral studies The ‘H NMR values are given in Table 2. The salient features of the spectra are discussed below. In the ‘H NMR spectra of [(p-MeOCJI&TeCl, * Ph,P(Se)(CH,),(Se)PPhz] (1 : 1 M : L) and [2(pMeOC6H.&TeC12 * PhzP(Se)(CH,),(Se)PPhd (2 : 1 M : L), the -CH, protons are doubled due to coupling with the 31P nucleus. The methyl protons of thep-MeOC,H, group show a doublet in the 1: 1 complex. In the 2 : 1 complex the two methyl singlets are separated and are centred at 3.15 and 3.68. However, the two complexes show a single spot in TLC, ruling out the presence of a mixture of the 2 : 1 and 1: 1 adducts. The structural change may be due to participation of both selenium atoms of the bidentate ligand in coordination, giving rise to a bridging ligand between the two tellurium atoms. The structure of bis(diphenylphosphinoselenide)ethane favours more a bite and an orientation of the lone pairs for bridging two metals atoms
Table 2. ‘H NMR spectral data
Complexes
5
7 8
with phosphine selenides
reported in various phosphine selenides lies in the range 51 l-562 cn- ‘, and undergoes a negative shift of 8-14 cm-’ on coordination. A shift of 10-20 cm- ’ in v(P=Se) has been reported for zinc, cadmium, mercury and nickel complexes.3*‘8 The
v(P=Se)
Chemical shift (Ppm)
Complex”
IR spectra
The IR spectra of the complexes were recorded in the range 4000-400 cm- ‘. The diagnostic absorptions are discussed below.
221
3.72, s, 6H @-CH,O); 6.88, d, 4H (metaprotons) ; 7.94, d, 4H [ortho protons of @CH,OC.&J] ; 7.2-7.85, m, 15H (C,H,),P 2.3, s, 9H (C&-(X3); 3.73, s, 6H (pCH,O) ; 6X-8.0, m, 20H (phenyl protons) 2.84, d, 4H (-CH,CH,--) ; 3.76, d, 6H (pCH,O) ; 6.92, d, 4H (meta protons) 7.95, d, 4H [ortho protons of (p-CH,OC&+] ; 6.5-8.0, m, 20H lphenyl protons of
%WWl 9
2.82, d, 4H (-CH,CHJ; 3.75, 3.68, s, 12H @CH30) 6.90, d, 8H [ortho protons of (pCH,OC&F]; 668.0, m, 20H lphenyl protons of Ph,P(Se)-]
“See Table 1.
222
T. N. SRIVASTAVA
et al.
Table 3. 31PNMR data for [R2TeC!12- L] L in the complex (pMeOC,H.,),TeCl, *L Ph,PSe Ph2P(Se)(CH,),(Se)PPhz
g(P) (Ppm)
d(P) (Ppm)
1J(3’P-“Se) (Hz)
A(“P-“Se) (Hz)
35.3 (32.9) 3598 (33.6)
2.4
700.4 (736) 635.1 832.2 (736)
- 35.6
2.38
- 100.9 +96.2
a Free-ligand values”
than forming a chelate ring around a single metal.lg It is concluded that diphosphine selenide acts as a bridging ligand between two tellurium atoms, as reported for diphosphine complexes with other metals.20-u rather
3’P NMR spectra 31P NMR spectra of a few complexes were obtained at room temperature and the data are listed in Table 3. From the 31P NMR data the following facts are deduced : (i) Jr_&3’P-77Se) is sensitive toward coordination and possesses a lower value compared to that for the free ligand. Such a change is attributed to coordination of P=Se to the metal atom through selenium.23,24 (ii) In the complex [(p-MeOC6HJ2TeClz * SePPh,] the 8(P) and 1J(3’P-77Se) decrease on coordination, indicating Se + Te bonding.‘7,23 (iii) In the complex [(p-MeOC6HJ2TeC12 Ph,P(Se)(CH,),(Se)PPh,] two sets of 77Se satellites of equal intensity, with 1J(31P-77Se)= 635.1 and 832.2 Hz, are observed. The former coupling constant [A1J(3’P-77Se = - 100.9 Hz] is due to coordination from the selenium atom, while the other, being higher (A’J = +96.2 Hz) than that in the free ligand, may be due to an uncoordinated selenium atom.25 Thus, from spectral data it may be concluded that the complexes possess an octahedral geometry around a tellurium atom with one site being occupied by a lone pair of elec-
i R\TC R’I’L
X
Sb’I’R
R/r<& xII
IIX PPh,
Ph2P ‘(CH,
R = Cl%, &l-l5 or p-MeOC,Hq;
,(
X = CL or OCOCF3
trons. The structures of the complexes may be as shown below.
AcknowledgementsFinancial assistance from the Council of Scienti6c and Industrial Research, New Delhi, and the University Grant Commission, New Delhi, in support of the present work is gratefully acknowledged. REFERENCES 1. N. M. Karayannis, C. M. Mikulski and L. L. Pyrlewski, Znorg. Chim. Acta, Rev. 1977,5, 69. 2. T. Allman and R. G. Geol. Can. J. Chem. 1984,60, 615, 621. 3. A. J. Blake and G. P. McQuillan, J. Chem. Sot., Dalton Trans. 1984, 1849. 4. D. J. Williams and K. J. Wynne, Znorg. Chem. 1976, 15, 1449. 5. E. W. Abel, S. K. Bhargwa, K. G. Ore11and V. Sik, Znorg. Chim. Acta 1981, 49,25. 6. I. J. Colquhoun and W. McFarlane, J. Chem. Sot., Dalton Trans. 1981,658. 7. M. J. Fernandezcid, M. P. Pazos Perez, J. Sordo, J. S. Casas, M. R. Bermego and M. Gayoso, An. Quim., Ser. B 1982,78, 190. 8. P. A. W. Dean, Can. J. Chem. 1982,60,2921. 9. S. Hauge and 0. Vikane, Acta Chem. Stand. 1973, 27, 3596. 10. T. N. Srivastava, Jai Deo Singh and Shashi Mehrotra, Indian J. Chem. 1985,24A, 849. 11. R. C. Paul, K. K. Bhasin and R. K. Chadha, J. Znorg. Nucl. Chem. 1975,37,2337. 12. J. Bergman, Tetrahedron 1972, 28, 3323. 13. R. H. Vernon, J. Chem. Sot. 1920,117,86. 14. G. T. Morgan and R. E. Kellett, J. Chem. Sot. 1926, 1089. 15. T. N. Srivastava and Jai Deo Singh, Indian J. Chem. (communicated). 16. P. Nicpon and D. W. Meek, Znorg. Chem. 1966, 5, 1297. 17. S. 0. Grim, E. D. Walton and L. C. Satek, Can. J. Chem. 1980,58,1476. 18. M. G. King and G. P. McQuillan, J. Chem. Sot. A 1967,898. 19. C. H. Lindsay, L. S. Benner and A. L. Balch, Znorg. Chem. 1980,19,3503.
Pentacoordinated
complexes of organotellurium(IV)
20. M. M. Olmstead, C. H. Lindsay, L. S. Bearer and A. L. Balch, J. Organomet. Chem. 1979, 179,289. 21. V. G. Kumar Das, J. Znorg. Nucl. Chem. 1976, 38, 1241. 22. F. A. Cotton, G. G. Stanley and R. A. Walton, Znorg. Chem. 1978,17,2099.
halides
223
23. P. A. W. Dean, Can. J. Chem. 1979,57,754. 24. S. 0. Grim, E. D. Walton and L. C. Satck, Znorg. Chim. Acta 1978,27, L115. 25. P. A. W. Dean and M. K. Hughes, Can. J. Chem. 1980,58, 180.