Synthesis and characterization of zinc and cadmium compounds with arenephosphinothiol ligands.

Article abstract of DOI:10.1021/ic981405b

The electrochemical oxidation of a metallic anode (zinc or cadmium) in an acetonitrile solution of a series of arenephosphinothiol ligands, 2-(Ph₂P)C₆H₄SH, 2-(Ph₂P)-6-(Me₃Si)C₆H₃SH, 2-(Ph₂PO)-6-(Me₃Si)C₆H₃SH, and PhP-(C₆H₄SH-2)₂ [abbreviated RP-CSH)_x, x = 1 or 2], affords [M(RP-S)₂] and [M(RP-S₂)], M = Zn, Cd. Adducts of several of these compounds with 1,10-phenanthroline and 2,2′-bipyridine have also been obtained by addition of these coligands to the electrolysis phase. The compounds obtained have been characterized by microanalysis, IR, UV-visible, FAB spectrometry and ¹H, ³¹P NMR spectroscopic studies.

Full text of DOI:10.1021/ic981405b

Inorg. Chem. 1999, 38, 3709-3715
3709
Synthesis and Characterization of Zinc and Cadmium Compounds with
Arenephosphinothiol Ligands. Crystal and Molecular Structures of
[Cd2{2-(Ph2PO)C6H4S}4], [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2],
[Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2(CH3OH)], and [Zn{PhPO(C6H4S-2)2}(bipy)]
Paulo Pe´rez-Lourido, Jaime Romero,* Jose´ A. Garc´ıa-Va´zquez, and Antonio Sousa*
Departamento de Qu´ımica Inorga´nica, Universidad de Santiago de Compostela,
15706 Santiago de Compostela, Spain
Kevin P. Maresca and Jon Zubieta*
Department of Chemistry, Syracuse University, Syracuse, New York 13244
ReceiVed December 8, 1998
The electrochemical oxidation of a metallic anode (zinc or cadmium) in an acetonitrile solution of a series of
arenephosphinothiol ligands, 2-(Ph2P)C6H4SH, 2-(Ph2P)-6-(Me3Si)C6H3SH, 2-(Ph2PO)-6-(Me3Si)C6H3SH, and PhP-
(C6H4SH-2)2 [abbreviated RP-(SH)x, x ) 1 or 2], affords [M(RP-S)2] and [M(RP-S2)], M ) Zn, Cd. Adducts of
several of these compounds with 1,10-phenanthroline and 2,2′-bipyridine have also been obtained by addition of
these coligands to the electrolysis phase. The compounds obtained have been characterized by microanalysis, IR,
1
UV-visible, FAB spectrometry and H, 31P NMR spectroscopic studies. The compounds, [Cd2{2-(Ph2PO)-
C6H4S}4]CH3CN (1), [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2] (2), [Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2(CH3OH)] (3), and
[Zn{PhPO(C6H4S-2)2}(bipy)] (4), have been also characterized by single-crystal X-ray diffraction. Compound 1
is binuclear with a {Cd2S2} core and distorted trigonal bipyramidal {CdO2S3} geometry about the Cd sites.
Compounds 2, 3, and 4 are mononuclear with distorted tetrahedral {ZnP2S2}, distorted square pyramidal {CdO3S2},
and distorted trigonal bipyramidal {ZnON2S2} geometries, respectively. Crystal data: 1, C42H37N3O2P2S2Cd,
triclinic, P1h, a ) 13.5780(2) Å, b ) 13.8505(2) Å, c ) 13.9526(2) Å, R ) 106.622(1)°, â ) 109.693(1)°, γ )
107.137(1)°, V ) 2133.30(5) Å3, Z ) 2, 9560 reflections, R ) 0.0483; 2, C46H50N2P2S2Si2Zn, monoclinic, C2/c,
a ) 21.332(4) Å, b ) 9.391(2) Å, c ) 25.938(5) Å, â ) 113.84(3)°, V ) 4753(2) Å3, Z ) 4, 2564 reflections,
R ) 0.0377; 3, C43H48CdO3P2S2Si2, triclinic, P1h, a ) 12.1237(4) Å, b ) 14.0568(4) Å, c ) 15.0938(2) Å, R )
70.836(2)°, â ) 83.410(2)°, γ ) 65.397(2)°, V ) 2208.7(1) Å3, Z ) 2, 4936 reflections, R ) 0.0738; 4, C29H22-
Cl3N2OP2S2Zn, triclinic, P1h, a ) 8.9556(3) Å, b ) 12.7911(4) Å, c ) 14.0598(5) Å, R ) 82.671(1)°, â )
73.140(1)°, γ ) 74.113(1)°, V ) 1480.44(9)(1) Å3, Z ) 2, 3820 reflections, R ) 0.0511.
Introduction
As a continuation of this work this paper reports the synthesis
of zinc and cadmium complexes with phosphinothiols, ligands
Neutral thiolate complexes of zinc or cadmium [M(SR)2] form
in general infinite lattices with bridging ligands and tetrahedral
metal centers.1-3 Their polymeric nature renders these materials
of low volatility and unsuitable for deposition of metal chal-
cogenides under typical MOCVD conditions. Volatility may be
improved by modifying the degree of aggregation of these
species by blocking some coordination sites either with donor
atoms from the thiolate ligand or with coligands, such as 2,2′-
bipyridine or 1,10-phenanthroline. In previous studies we have
used this strategy for the synthesis of monomeric4 and dimeric
compounds5 of zinc and cadmium with heterocyclic thiones.
incorporating both thiolate sulfur and tertiary phosphorus atoms
as donor groups, following an electrochemical procedure where
the metal is the anode of a cell containing the ligand in an
acetonitrile solution. This method is simple and high-yielding,
and the presence in the cell of coligands such as 1,10-
phenanthroline or 2,2′-bipyridine allows the synthesis of mixed-
ligand complexes in one step.
Compounds with arenephosphinothiol ligands have been
previously reported by Dilworth and Zubieta, mainly of the
heavier transition metals, such as molybdenum,6 technetium and
rhenium,7 ruthenium,8 and rhodium and iridium9 metals. In
contrast, the chemistry of the main group metals remains
* Authors to whom correspondence should be addressed.
(1) Dance, I. G. Polyhedron 1986, 5, 1037.
(2) Craig, D. C.; Dance, I. D.; Garbutt, R. Angew. Chem., Int. Ed. Engl.
1986, 25, 165.
(3) Dance, I. G.; Garbutt, R. G.; Graig, D. C.; Scudder M. L. Inorg. Chem.
1987, 26, 4057.
(4) Castro, R.; Dura´n, M. L.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa,
A.; Castin˜eiras, A.; Hiller, W.; Strahle, J. Z. Naturforsch. 1992, 47b,
1067.
(6) Block, E.; Kang, H.; Ofori-Okai, G.; Zubieta, J. Inorg. Chim. Acta
1989, 166, 155.
(7) Dilworth, J. R.; Huston, A. J.; Morton, S.; Harman, M.; Hursthouse,
M. B.; Zubieta, J.; Archer, C. M.; Kelly, J. D. Polyhedron 1992, 11,
2151.
(8) Dilworth, J. R.; Zheng, Y.; Lu, S.; Wu, Q. Transition Met. Chem.
1992, 17, 364.
(5) Castro, R.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa, A.; Castin˜eiras,
A.; Hiller, W.; Strahle, J. Inorg. Chim. Acta 1993, 211, 47.
(9) Dilworth, J. R.; Lu, S.; Miller, J. R.; Zheng, Y. J. Chem. Soc., Dalton
Trans. 1995, 1957.
10.1021/ic981405b CCC: $18.00 © 1999 American Chemical Society
Published on Web 07/15/1999

3710 Inorganic Chemistry, Vol. 38, No. 16, 1999
Pe´rez-Lourido et al.
2H), 8.4 (d, 2H), 7.9 (m, 2H), 7.7 (m,2H), 7.4-6.6 (m, 28H). 31P NMR
(CDCl3, ppm): δ 37.6 ppm.
unexplored, and compounds of zinc or cadmium with these
ligands have not been reported previously.
[Cd{2-(Ph2P)C6H4S}2(phen)]. A similar experiment (10 mA, 10
V, 1.5 h) using 0.166 g (0.333 mmol) of 2-(Ph2P)C6H4SH (0.565 mmol)
and 0.060 g (0.282 mmol) of 1,10-phenanthroline dissolved 31 mg of
cadmium from the anode, Ef ) 0.49 mol F-1. The color of the solution
changed from colorless to yellowish. At the end of the reaction yellow
needles were recovered, washed with acetonitrile, and dried (0.18 g,
75%). Anal. Calcd for C48H36N2P2S2Cd: C, 65.6; H, 4.10; N, 3.19; S,
7.28. Found: C, 65.0; H, 4.02; N, 3.14; S, 7.18. IR (KBr, cm-1): 1587
(m), 1569 (s), 1513 (m), 1479 (m), 1435 (s), 1416 (s), 1242 (m), 1091
(s), 847 (m), 748 (s), 731 (m), 696 (s). 1H NMR (CDCl3, ppm): δ 9.1
(d, 2H), 8.1 (d, 2H), 7.6 (s, 2H), 7.4 (m,2H), 7.3-6.4 (m, 28H). 31P
NMR (CDCl3, ppm): δ 36.6.
Experimental Section
General Considerations. All manipulations were carried out under
an inert atmosphere of dry nitrogen. Zinc and cadmium (Aldrich
Chemie) were used as plates (ca. 2 × 2 cm). All other reagents,
including 1,10-phenanthroline and 2,2′-bipyridine, were used as sup-
plied. Syntheses of ligands were carried out using minor modifications
of the standard literature procedure.10
Elemental analyses were performed in a Carlo-Erba EA microana-
lyzer, and IR spectra were recorded as KBr mulls on a Brucker IFS-
66V. FAB mass spectra were recorded on a Kratos-MS-50T connected
to a DS90 data system, using 3-nitrobenzyl alcohol (3-NBA) as matrix
material. 1H NMR spectra were recorded on a Brucker AMX 300 MHz
instrument and 31P in a Brucker 500 MHz, using CDCl3 or DMSO-d6
[Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2]. A solution of acetonitrile (50 cm3)
containing 2-diphenylphosphino-6-trimethylsilylbenzenethiol (0.273 g,
0.746 mmol) was electrolyzed at 10 mA, 20 V, during 2 h, and 24 mg
of zinc metal was dissolved from the anode, Ef ) 0.49 mol F-1. A
white crystalline compound was obtained directly from the cell at the
end of the reaction. The crystals were recovered by filtration, washed
with acetonitrile, dried, and identified by elemental analysis (0.24 g,
82%). Anal. Calcd for C42H44P2S2Si2Zn: C, 63.4; H, 5.53; S, 8.05.
Found: C, 62.4; H, 5.59; S, 8.15. IR (KBr, cm-1): 3053 (m), 2949
(m), 2893 (m), 1555 (m), 1482 (m), 1436 (m), 1352 (s), 1243 (m),
1
as solvents; H NMR chemical shifts were recorded against TMS as
internal standard while 31P chemical shifts were determined against
H3PO4 (85%).
Electrochemical Synthesis. The complexes were obtained following
an electrochemical procedure. An acetonitrile solution of the ligand
containing about 15 mg of tetramethylammonium perchlorate as a
current carrier was electrolyzed using a platinum wire as the cathode
and a metal plate as the sacrificial anode. For the synthesis of mixed
complexes, the corresponding coligand, 1,10-phenanthroline or 2,2′-
bipyridine, was also added to the solution. Applied voltages of 10-15
V allowed sufficient current flow for smooth dissolution of the metal.
During electrolysis, nitrogen was bubbled through the solution to
provide an inert atmosphere and also to stir the reaction mixture. The
1
1096 (m), 853 (s), 743 (s), 692 (s). H NMR (CDCl3, ppm): δ 8.1-
6.8 (m, 26H), 0.5 (s, 18H). 31P NMR (CDCl3, ppm): δ 43.2.
X-ray quality crystals of [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2]‚2CH3CN
(2) were obtained by crystallization from CH3CN.
[Cd{2-(Ph2P)-6-(Me3Si)C6H3S}2]. A similar experiment (16 V, 10
mA, 2 h) with 0.273 g (0.746 mmol) of the ligand 2-(Ph2P)-6-(Me3-
Si)C6H3SH in 50 cm3 of acetonitrile dissolved 42 mg of cadmium, Ef
) 0.50 mol F-1. A white microcrystalline solid was obtained at the
end of the reaction. The solid was collected, washed with cool
acetonitrile and diethyl ether, and dried under vacuum (0.27 g, 86%).
Anal. Calcd for C42H44CdP2S2Si2: C, 59.8; H, 5.22; S, 7.60. Found:
C, 59.2; H, 5.21; S, 7.66. IR (KBr, cm-1): 3055 (m), 2947 (m), 2893
(m), 1553 (m), 1480 (m), 1435 (m), 1351 (s), 1243 (m), 1095 (m), 851
cell can be summarized as Pt(-)/CH3CN + RP-(SH)x/M(+)
.
[Zn{2-(Ph2P)C6H4S}2]. Electrochemical oxidation of a zinc anode
in a solution of 2-diphenylphosphinobenzenethiol, 2-(Ph2P)C6H4SH
(0.220 g, 0.748 mmol), in acetonitrile (50 cm3), at 16 V and 10 mA
for 2 h caused 25 mg of zinc to be dissolved, Ef ) 0.51 mol F-1. During
the electrolysis process, hydrogen was evolved at the cathode, and at
the end of the reaction white crystalline needles appeared at the bottom
of the vessel. The solid was filtered off, washed with acetonitrile and
ether, and dried under vacuum (0.21 g, 87%). Anal. Calcd for C36H28-
ZnP2S2: C, 66.3; H, 4.30; S, 9.82. Found: C, 66.03; H, 4.25; S, 9.70.
IR (cm-1): 1572 (m), 1480 (m), 1436 (s), 1421 (m), 1248 (m), 1096
1
(s), 743 (s), 693 (m). H NMR (CDCl3, ppm): δ 7.8-6.5 (m, 26 H),
0.35 (s, 18H). 31P NMR (CDCl3, ppm): δ 37.3.
[Zn{2-(Ph2PO)-6-(Me3Si)C6H3S}2]. The electrochemical oxidation
of zinc in a solution of 2-(Ph2PO)-6-(Me3Si)C6H3SH (0.214 g, 0.560
mmol) in acetonitrile (60 mL) for 1.5 h at 10 V and 10 mA resulted in
the loss of 19 mg of zinc from the anode, Ef ) 0.52 mol F-1. At the
end of the electrolysis the reaction mixture was filtered to remove any
precipitated particles of metal, and the filtrate was left to concentrate
by evaporation at room temperature. A white crystalline product was
isolated and identified by elemental analysis (0.190 g, 82%). Anal.
Calcd for C42H44ZnP2O2S2Si2: C, 60.9; H, 5.32; S, 7.73. Found: C,
61.3; H, 5.43; S, 7.70. IR (KBr, cm-1): 3057 (m), 2951 (m), 2893
(m), 1556 (m), 1438 (s), 1354 (s), 1242 (m), 1128 (s), 1060 (m), 854
1
(m), 743 (s), 693 (s). H NMR (DMSO-d6, ppm): δ 8.0-6.8 (m, 28
H). 31P NMR (DMSO-d6, ppm): δ 42.3.
[Cd{2-(Ph2P)C6H4S}2]. A similar experiment (12 V, 10 mA, 2 h)
with cadmium as anode and 0.220 g (0.748 mmol) of 2-(Ph2P)C6H4-
SH in 50 cm3 of acetonitrile dissolved 40 mg of metal, Ef ) 0.47 mol
F-1. At the end of the electrolysis white crystals deposited in the cell
were recovered, washed with cool acetonitrile and diethyl ether, and
dried under vacuum (0.19 g, 77%). Anal. Calcd for C36H28CdP2S2: C,
61.9; H, 4.01; S, 9.16. Found: C, 61.9; H, 4.00; S, 8.97. IR (KBr,
cm-1): 1570 (m), 1479 (m), 1435 (s), 1418 (m), 1247 (m), 1094 (m),
743 (s), 693 (s). 1H NMR (CDCl3, ppm): δ 8.0-6.5 (m, 28). 31P NMR
(CDCl3, ppm): δ 32.4. Air concentration of the resulting solution
yielded crystals of [Cd2{2-(Ph2PO)C6H4S}4]‚3CH3CN (1) suitable for
X-ray studies.
1
(s), 748 (m), 692 (s). H NMR (CDCl3, ppm): δ 7.7-6.5 (m, 26H),
0.35 (s, 18H). 31P(CDCl3, ppm): δ 45.1.
[Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2]. Electrolysis of an acetonitrile
solution (50 cm3) containing 2-(Ph2PO)-6-(Me3Si)C6H3SH (0.214 g,
0.560 mmol) using 10 mA, 10 V electric current for 1.5 h caused the
dissolution of 32 mg of cadmium (Ef ) 0.51 mol F-1). The final reaction
mixture was concentrated to produce a white solid (0.20 g, 80%). Anal.
Calcd C42H44CdP2O2S2Si2: C, 57.6; H, 5.03; S, 7.32. Found: C, 58.0;
H, 5.17; S, 7.25. IR (KBr, cm-1): 3055 (m), 2952 (m), 2895 (m), 1555
(m), 1438 (s), 1353 (s), 1242 (s), 1130 (s), 1065 (m), 845 (s), 748 (s),
[Cd{2-(Ph2P)C6H4S}2(bipy)]. Electrochemical oxidation of cad-
mium in an acetonitrile solution (50 cm3) containing 2-(Ph2P)C6H4SH,
0.220 g, 0.748 mmol, and 2,2′-bipyridine, 0.060 g, 0.384 mmol, using
a current of 10 mA, 11 V, for 2 h resulted in the dissolution of 44 mg
of metal, Ef ) 0.52 mol F-1. As the reaction proceeded the solution
color changed from colorless to yellow, and a microcrystalline solid
was deposited in the cell. The solid was recovered, washed with
acetonitrile, dried under vacuum, and identified by elemental analysis
(0.21 g, 67%). Anal. Calcd for C46H36CdN2P2S2: C, 64.6; H, 4.21; N,
3.27; S, 7.49. Found: C, 64.5; H, 4.19; N, 3.19; S, 7.39%. IR (KBr,
cm-1): 1588 (m), 1568 (m), 1479 (m), 1435 (s), 1419 (m), 1246 (m),
1095 (m), 761 (m), 747 (s), 695 (s). 1H NMR (CDCl3, ppm): δ 8.8 (d,
1
692 (s). H NMR (CDCl3, ppm): δ 7.7-6.6 (m, 26H), 0.35 (s, 18H).
31P(CDCl3, ppm): δ 40.7. Crystals of [Cd{2-(Ph2PO)-6-(Me3Si)-
C6H3S}2(CH3OH)] (3) suitable for X-ray studies were obtained by
crystallization from CH2Cl2/CH3OH.
[Zn{PhP(C6H4S-2)2}]. The electrochemical oxidation of zinc in a
solution of PhP(C6H4SH-2)2 (0.122 g, 0.374 mmol) in acetonitrile (40
mL) for 2 h at 20 V and 10 mA resulted in the loss of 24 mg of zinc
from the anode, Ef ) 0.49 mol F-1. A white insoluble solid precipitated
in the cell within a few minutes. This solid was washed with acetonitrile
and ether, dried under vacuum, and identified by elemental analysis
(0.13 g, 94%). Anal. Calcd for C18H13PS2Zn: C, 55.5; H, 3.34; S, 16.4.
(10) Block, E.; Ofori-Okai, G.; Zubieta, J. J. Am. Chem. Soc. 1989, 111,
2327.

Zn and Cd Compounds with Arenephosphinothiol Ligands
Inorganic Chemistry, Vol. 38, No. 16, 1999 3711
Table 1. Summary of Crystallographic Data for the Compounds [Cd2{2-(Ph2PO)C6H4S}4]‚3CH3CN (1),
[Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2]‚2CH3CN (2), [Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2(CH3OH)] (3), and [Zn{PhPO (C6H4S-2)2}(bipy)]‚CHCl3 (4)
1
2
3
4
empirical formula
fw
C42H37N3P2S2O2Cd
854.10
298(2)
0.710 73
triclinic
P1h
C46H50N2P2S2Si2Zn
878.49
293(2)
1.541 78
monoclinic
C2/c
C43H48P2O3S2Si2Cd
907.4
298(2)
0.710 73
triclinic
P1h
C29H22N2POS2Cl3Zn
681.30
296(2)
0.710 73
triclinic
P1h
temp (K)
wavelength (Å)
cryst syst
space group
unit cell dimens
a (Å)
13.5780(2
13.8505(2)
13.9526(2)
106.622(1)
109.693(1)
107.137(1)
2133.30(5)
2
1.329
0.713
0.0517
0.1613
21.332(4)
9.391(2)
25.938(5)
12.1237(4)
14.0586(4)
15.0938(2)
70.836(2)
83.410(2)
65.397(2)
2208.7(1)
2
1.364
0.752
0.0885
0.1553
8.9556(3)
12.7911(4)
14.0598(5)
82.671(1)
73.140(1)
74.113(1)
1480.44(9)
2
1.528
1.322
0.0567
0.1322
b (Å)
c (Å)
R (deg)
â (deg)
113.84(3)
γ (deg)
vol (Å3)
Z
4753(2)
4
1.228
2.899
0.0396
0.0953
d
cal, g cm-3
µ, mm-1
Ra
Rw
b
2
a R ) ∑(|Fo| - |Fc|)|∑|Fo|. b Rw) [(|∑w(|Fo| - |Fc|)2|∑w|Fo| ]1/2
.
Found: C, 55.3; H, 3.35; S, 16.2. IR (KBr, cm-1): 1574 (m), 1440
solution allowed a second crop of compound. The product was identified
as [Cd{PhP(C6H4S-2)2}(bipy)] (0.17 g, 80%). Anal. Calcd for C28H21N2-
PS2Cd: C, 56.7; H, 3.54; S, 10.8; N, 4.72. Found: C, 56.5; H, 3.62;
S, 10.5; N, 4.67. IR (KBr, cm-1): 1593 (m), 1572 (m), 1478 (m), 1439
(s), 1420 (m), 1251 (m), 1098 (s), 1041 (m), 744 (s), 696 (m). 1H
NMR (CDCl3, ppm): δ 8.6-6.6 (m, 21H). 31P NMR (CDCl3, ppm):
δ 39.9.
[Cd{PhP(C6H4S-2)2}(phen)]. A similar experiment (10 mA, 10 V,
1.5 h) using 0.18 g of PhP(C6H4SH-2)2 (0.552 mmol) and 0.10 g (0.55
mmol) of 1,10-phenanthroline dissolved 32 mg of cadmium from the
anode, Ef ) 0.51 mol F-1. The color of the solution changed from
colorless to yellow. At the end of the reaction yellow needles were
recovered, washed with acetonitrile, and dried (0.13 g, 74%). Anal.
Calcd for C30H21N2PS2Cd: C, 58.40; H, 3.41; N, 4.54; S, 10.38.
Found: C, 58.27; H, 3.36; N, 4.53; S, 9.87. IR (KBr, cm-1): 1589
(m), 1570 (s), 1512 (m), 1479 (w), 1435 (w), 1424 (s), 1245 (m), 1098
(s), 844 (m), 743 (s), 729 (m), 700 (m). 1H NMR (CDCl3, ppm): δ 9.2
(d, 2H), 8.3 (d, 2H), 7.8 (s, 2H), 7.7 (m,2H), 7.6-6.5 (m, 13H). 31P
(CDCl3, ppm): δ 37.4.
X-ray Crystallography. Compounds [Cd2{2-(Ph2PO)C6H4S}4] (1),
[Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2(CH3OH)] (3), and [Zn{PhPO(C6H4S-
2)2}(bipy)] (4) were studied on a Siemens Smart diffractometer, and
compound [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2] (2) was studied on a
Nicolet P3 apparatus. Data collections were carried out under ambient
conditions, using graphite-monochromated Mo KR radiation (λ )
0.710 73 Å) for 1, 3, and 4 and Cu KR radiation (λ ) 1.541 78 Å) for
(2). The crystal parameters and other experimental details of the data
collection are summarized in Table 1. A complete description of the
details of the crystallographic methods is given in the Supporting
Information. The structures were solved by direct methods and refined
by a full-matrix least-squares procedure. Neutral atom scattering factors
were taken from Cromer and Waber,11 and anomalous dispersion factors
were taken from Cromer.12 Data were corrected for absorption using
SADABS (Tmax/Tmin: 0.935/0.786 (1); 0.928/0.735 (2); 0.894/0.562 (3);
0.954/0.876 (4)). All calculations were performed using SHELXTL
PLUS (PC version)13 for 1, 3, and 4, and using DECMicroVAX 3500
computer for 2. Refinements were based on F2. No anomalies were
encountered in the refinements of any of the structures. In the case of
1, an acetonitrile molecule of crystallization is disordered over three
1
(s), 1421 (s), 1253 (m), 1101 (s), 744 (s), 694 (m). H NMR (CDCl3,
ppm): δ 7.9-6.6 (m, 13H). 31P (CDCl3, ppm): δ 47.7.
[Zn{PhP(C6H4S-2)2}(bipy)]. Electrolysis of an acetonitrile solution
(50 cm3) containing PPh(C6H4SH-2)2 (0.122 g, 0.374 mmol) and 2,2′-
bipyridine (0.060 g, 0.384 mmol), using a 10 mA, 12 V electric current
for 1.5 h caused the dissolution of 18 mg of zinc from the anode, Ef )
0.50 mol F-1. The solid obtained was washed with acetonitrile and
ether and dried under vacuum. A second crop of the compound was
obtained by concentration of the resulting solution (0.12 g, 73%). Anal.
Calcd for C28H21N2PS2Zn: C, 61.6; H, 3.85; S, 11.7; N, 5.12. Found:
C, 61.9; H, 4.05; S, 11.8; N, 5.17. IR (KBr, cm-1): 1597 (m), 1573
(m), 1473 (m), 1441 (s), 1417 (m), 1246 (m), 1094 (m), 1046 (m),
1020 (m), 768 (s), 742 (s), 699 (m). 1H NMR (CDCl3, ppm): δ 8.7 (d,
2H), 8.1 (d, 2H), 7.9 (s, 2H), 7.6 (m,2H), 7.4-6.7 (m, 13H). 31P (CDCl3,
ppm): δ 48.4. Crystals of [Zn{PhPO(C6H4S-2)2}(bipy)]‚CHCl3 (4)
suitable for X-ray studies were obtained by recrystallization from
CHCl3/CH3OH.
[Zn{PhP(C6H4S-2)2}(phen)]. A similar experiment (10 mA, 10 V,
1.5 h) using 0.122 g (0.374 mmol) of PhP(C6H4SH-2)2 and 0.08 g (0.44
mmol) of 1,10-phenanthroline dissolved 19 mg of zinc from the anode,
Ef ) 0.51 mol F-1. The color of the solution changed from colorless
to yellow. At the end of the reaction a yellow crystalline solid was
recovered, washed with acetonitrile, and dried, 0.14 g (85%). Anal.
Calcd for C30H21N2PS2Zn: C, 63.2; H, 3.69; N, 4.93; S, 11.2. Found:
C, 63.0; H, 3.72; N, 5.02, S, 10.2%. IR (KBr, cm-1): 1574 (m), 1544
(w), 1516 (m), 1477 (w), 1422 (s), 1247 (m), 1095 (s), 849 (m), 744
1
(s), 727 (m), 699 (s). H NMR (CDCl3, ppm): δ 9.0 (d, 2H), 8.4 (d,
2H), 7.9 (s, 2H), 7.7 (m, 2H), 7.6-6.7 (m, 13H). 31P (CDCl3, ppm):
δ 45.3.
[Cd{PhP(C6H4S-2)2}]. An acetonitrile solution (50 mL) containing
0.122 g (0.374 mmol) of PhP(C6H4SH-2)2 was electrolyzed using a 10
mA, 14 V electric current for 2 h, resulting in the loss of 41 mg of
cadmium from the anode, Ef ) 0.49 mol F-1. A white insoluble solid
precipitated in the cell within a few minutes (0.14 g, 88%). This solid
was washed with acetonitrile and ether, dried under vacuum, and
identified as [Cd{PhP(C6H4S-2)2}]. Anal. Calcd for C18H13CdPS2: C,
49.5; H, 2.98; S, 14.7. Found: C, 50.1; H, 2.95; S, 15.0. IR (KBr,
cm-1): 1572 (m), 1440 (s), 1421 (s), 1252 (m), 1098 (s), 1042 (m),
1
744 (s), 695 (m). H NMR (CDCl3, ppm): δ 7.8-6.5 (m, 13H). 31P
(CdCl3, ppm): δ 38.1.
(11) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2A.
(12) Cromer, D. T. International Tables for X-ray Crystallography; The
Kynoch Press: Birmingham, England, 1974; Vol. IV, Table 2.3.1.
(13) Sheldrick, G. M. SHELXTL-PLUS program package (PC Version) for
the determination of crystal structures, Release 4.0; Siemens Analytical
X-ray Instruments, Inc.: Madison, WI, 1990.
[Cd{PhP(C6H4S-2)2}(bipy)]. Electrolysis of an acetonitrile solution
(60 cm3) containing 0.120 g (0.374 mmol) of PPh(C6H4SH-2)2 and
0.060 g (0.0384 mmol) of 2,2′-bipyridine using a 10 mA, 17 V electric
current for 2 h caused the dissolution of 41 mg of cadmium from the
anode, Ef ) 0.49 mol F-1. At the end of the experiment a white
insoluble solid was recovered from the cell. Concentration of the filtered

3712 Inorganic Chemistry, Vol. 38, No. 16, 1999
Pe´rez-Lourido et al.
sites with concomitant large thermal parameters. Atomic positional
parameters and isotropic temperature factors for the structures are
presented in the Supporting Information.
Results and Discussion
Arenephosphinothiolate complexes of zinc and cadmium, and
some adducts with 2,2′-bipyridine (bipy) or 1,10 phenanthroline
(phen), are easily prepared in good yield, by the simple one-
step electrochemical procedure described above.
The electrochemical efficiency, defined as the amount of
metal dissolved per Faraday of charge, was in all cases close to
0.5 mol F-1. This and the evolution of hydrogen at the cathode
are consistent with the following reaction scheme:
cathode:
anode:
2RP-SH + 2e- f 2RP-S- + H2
2RP-S- + M f [M(RP-S)2] + 2e-
2RP-S- + M + L′ f [M(RP-S)2L′]
M ) Zn, Cd; L′ ) bipy, phen
Figure 1. Molecular structure of [Cd2{2-(Ph2PO)C6H4S}4].
A similar mechanism is proposed for the synthesis of metal
complexes with the RP-(SH)2 ligand.
The incorporation of additional bidentate ligands to the cell
allows the synthesis of cadmium mixed-ligand complexes such
as [Cd{2-(Ph2P)C6H4S}2(bipy)] and [Cd{2-(Ph2P)C6H4S}2-
(phen)]. These complexes show IR bands characteristic of the
coordinated phosphinothiolate ligand and also bands at 761 and
747 cm-1 and 748 and 731 cm-1 typical of coordinated 2,2′-
[M{2-(Ph2P)C6H4S}2] Compounds. The electrochemical
oxidation of anodic zinc or cadmium in a cell containing
2-(Ph2P)C6H4SH in acetonitrile gave the complexes [Zn{2-
(Ph2P)C6H4S}2] and [Cd{2-(Ph2P)C6H4S}2] in good yield. The
compounds are insoluble in the reaction solvent and are obtained
as crystalline white air-stable solids in the bottom of the cell.
The compounds are sparingly soluble in chloroform and in a
range of other chlorinated organic solvents.
1
bipyridine and 1,10-phenanthroline, respectevily.15,16 The H
NMR spectra of these mixed complexes also show additional
signals due to coordinated 2,2′-bypiridine at δ 8.8, 8.4, 7.9, and
7.7 ppm and 1,10-phenantroline at δ 9.3, 8.3, 7.9, and 7.7 ppm.17
The FAB mass spectra of these cadmium mixed-ligand com-
pounds do not show the molecular ion, but show peaks at m/z
563 (17%) and m/z 587 (30%) corresponding to [Cd{2-(Ph2P)-
C6H4S}(bipy)]+ and [Cd{2-(Ph2P)C6H4S}(phen)]+, respectively.
The presence of additional ligands in the coordination sphere
of the metal leads us to suggest an octahedral monomeric
structure for these complexes.
Attempts to obtain mixed-ligand complexes in the case of
zinc were unsuccessful, as the analytical data did not show the
incorporation of the additional coligand. In all cases, the
recovered compound was [Zn{2-(Ph2P)C6H4S}2]. This behavior
can be ascribed to the different atomic sizes of zinc and
cadmium, which makes the zinc atom more reluctant than the
cadmium atom to achieve octahedral environments, especially
in the case of bulky ligands such as the arenephosphinothiolate
ones.
The IR spectra of these complexes do not show the band
attributed to ν(S-H), which in the ligand appears at 2494 cm-1
.
This is indicative of the anionic thiolate form of the ligand in
the complex. The spectra also show bands in the aromatic
region, 1580-1500 cm-1, characteristic of the ν(CdC) vibra-
tions and also a band at 720-730 cm-1 attributable to ν(P-C).
The room temperature 1H NMR spectra of complexes exhibit
only multiplet resonances in the aromatic region, δ 8.0-6.5
ppm, as the signal attributable to the SH hydrogen, which in
the free ligand appears at δ 4.0 ppm as a doublet due to the
coupling to the phosphorus atom, is now absent. The 31P NMR
spectra show a single signal at δ 42.3 and 32.4 ppm for the
zinc and cadmium complexes, respectively. This signal appears
in the free ligand at δ -14.6 ppm. The downfield shift is a
consequence of the coordination of the phosphorus atom to the
metal.
The FAB mass spectrum of the cadmium compound shows
a peak at m/z 699 (23%), due to the molecular ion, but also a
signal at m/z 1102 (56%) due to [Cd2{2-(Ph2P)C6H4S}3]+,
formed by loss of one ligand from the dimer species. This can
be taken as indicative of a dimeric structure for this compound,
similar to that found in the case of complex 1, vide infra. For
solubility reasons, the FAB spectra of the zinc complex could
not be recorded, but the structure of this compound is presum-
ably analogous to that of the trimethylsilyl derivative complex
2 discussed below.
Concentration of the mother liquor from the synthesis of [Cd-
{2-(Ph2P)C6H4S}2] in air yielded crystals of the dimeric
phosphine oxide complex [Cd2{2-(Ph2PO)C6H4S}4] (1). Such
facile oxidation of phosphine to phosphine oxides has been
observed in other complexes containing this type of ligand.14
Crystal Structure of [Cd2{2-(Ph2PO)C6H4S}4] (1). Figure
1 shows a view of the molecule together with the atomic
numbering scheme. Bond lengths and angles with the standard
uncertainties are listed in Table 2. The structure consists of
dimers in which two thiolate sulfur atoms of two ligands bridge
both cadmium atoms. The molecule possesses a crystallographic
inversion center. In addition, each cadmium is coordinated to
an oxygen atom of the bridging ligand and to the thiolate sulfur
atom and the oxygen atom of an additional ligand. The value
of 0.63 for the geometrical parameter τ (τ ) â - R/60)18
suggests that the cadmium atom is in a distorted [CdO2S3]
(15) Inskeep, R. G. J. Inorg. Nucl. Chem. 1962, 24, 763.
(16) Schilt, A. A.; Taylor, R. C. J. Inorg. Nucl. Chem. 1959, 9, 211.
(17) (a) Yamazaki, S. Polyhedron 1985, 4, 1915. (b) Annan, T. A.; Chadha,
R. K.; Tuck, D. K.; Wadson, K. D. Can. J. Chem. 1987, 65, 2670.
(18) Addison, A. W.; Rao, T. N.; Reedijk, J.; van Rinj, J.; Verschoor, G.
C. J. Chem. Soc., Dalton Trans. 1984, 1349.
(14) Pe´rez-Lourido, P.; Romero, J.; Garc´ıa-Va´zquez, J.; Sousa, A.; Maresca,
K.; Rose, D. J.; Zubieta, J. Inorg. Chem. 1998, 37, 3331.

Zn and Cd Compounds with Arenephosphinothiol Ligands
Inorganic Chemistry, Vol. 38, No. 16, 1999 3713
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
[Cd2{2-(Ph2PO)C6H4S}4] (1)a
Cd-O(2)
2.219(3)
2.5351(9)
2.8700(9)
1.511(3)
1.758(4)
1.809(4)
Cd-S(1)
2.508(1)
2.374(3)
2.5351(9)
1.509(3)
1.787(4)
1.806(4)
Cd-S(2)#l
Cd-S(2)
Cd-O(1)
S(2)-Cd#l
P(2)-O(2)
S(2)-C(41)
P(1)-C(36)
P(1)-O(1)
S(1)-C(11)
P(1)-C(16)
O(2)-Cd-O(1)
O(1)-Cd-S(1)
O(1)-Cd-S(2)#1
O(2)-Cd-S(2)
S(1)-Cd-S(2)
86.68(9)
90.63(7)
97.31(6)
79.67(7)
97.72(3)
O(2)-Cd-S(1)
O(2)-Cd-S(2)#l
S(1)-Cd-S(2)#l
O(1)-Cd-S(2)
S(2)#1-Cd-S(2)
106.44(8)
125.75(8)
127.47(4)
165.56(7)
86.97(3)
a Symmetry transformations used to generate equivalent atoms: (#1)
-x + 1, -y + 1, -z + 1.
trigonal bipyramidal environment with O(1) and S(2) at axial
sites and O(2), S(1), and S(2A) in the equatorial plane. The
cadmium metal is 0.085 Å out of the equatorial plane. Angular
distortions are observed both in the equatorial plane, with bond
angles in the range 106.44(8)-127.47(4)°, and along the axial
direction of the bipyramid with an O(1)-Cd-S(2) angle of
165.56(7)°.
Figure 2. Molecular structure of [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2].
The four-membered ring Cd-S(2)-S(2A)-Cd(A) is planar,
and the thiolate bridge is clearly asymmetric, with Cd-S bond
distances of 2.5351(9) and 2.8700(9) Å. Although asymmetric
bridging thiolate bonds have been found in dimeric pentacoor-
dinated cadmium complexes, for instance 2.667(2) and 2.597-
(2) Å in [Cd2(3-Me3Si(pyt))4] (pyt- ) pyridinethionate),5 the
value of 2.8700(9) Å is considerably larger than the sum of the
covalent radii of tetrahedral cadmium and sulfur atoms, 2.52
Å.19 This is indicative of weak interaction between the metal
and this donor atom. The other bridge bond distance, 2.5351-
(9) Å, and the cadmium-terminal sulfur bond distance, 2.5082-
(11) Å, are normal and agree with those found in other dimeric
cadmium complexes with pentacoordinated environments around
the cadmium, such as in [Cd2(3-Me3Si(pyt))4], and with Cd-
(µ-SR) bond distances in general.20
The Cd-O bond distances, 2.219(3) and 2.374(3) Å, are also
different, with the Cd-O(1) for the chelating ligand longer by
0.155 Å. However, for example, both distances are in the range
found in 3, vide supra, and similar to those found in other
pentacoordinated cadmium complexes involving O-donor ligands,
e.g., 2.34 Å in [Cd(thiourea)3(SO4)],21 or 2.387(9) and 2.353-
(9) Å in dinitrato bis(2-methylmercaptoaniline) Cd(II).22
[M{2-(Ph2P)-6-(Me3Si)C6H3S}2] Compounds. In order to
evaluate the possible steric effects upon the metal-phosphi-
nothiolate system, anodic zinc and cadmium were oxidized in
a solution of 2-(diphenylphosphino)-6-trimethylsilylbenzenethiol
in acetonitrile. In both cases the compounds are obtained directly
from the cell as microcrystalline solids deposited at the bottom
of the cell.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
[Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2] (2)a
Zn-S
2.2791(9)
2.387(1)
1.768(3)
1.808(3)
Zn-S#
2.2791(9)
2.387(1)
1.804(3)
1.821(3)
Zn-P
Zn-P#
S-C(1)
P-C(7)
P-C(2)
P-C(13)
S-Zn-S#1
S#1-Zn-P#1
S#1-Zn-P
122.82(5)
87.60(3)
119.12(3)
S-Zn-P#1
S-Zn-P
119.12(3)
87.60(3)
124.62(5)
P#1-Zn-P
a Symmetry transformations used to generate equivalent atoms: (#1)
1
-x + 1, y, -z + /2.
characteristic of the ν(Si-C) group. The 1H NMR spectra show
the aromatic resonances at δ 8.0-6.5 ppm and singlets at δ
0.55 and 0.35 ppm for zinc and cadmium complexes, respec-
tively, characteristic of the SiMe3 group. The 31P NMR spectra
show a singlet at δ 43.2, M ) Zn, and 37.3 ppm, M ) Cd.
The FAB mass spectra of both compounds show the molec-
ular ion at m/z 795 (12%) and 843 (4%) for the zinc complex
and the cadmium complex, respectively. None of them show
peaks of m/z higher than that of the molecular ion, suggesting
that both compounds are monomeric molecular species. The
X-ray structure of [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2], vide infra,
confirms this conclusion. In the case of cadmium, the mono-
meric structure can be taken as a consequence of the steric
hindrance introduced by the trimethylsilyl group, which prevents
the formation of dimeric species.
Crystal Structure of [Zn{2-(Ph2P)-6-(Me3Si)C6H3S}2] (2).
Figure 2. shows a view of the molecule together with the atomic
numbering scheme. Bond lengths and angles with the estimated
standard deviations are listed in Table 3.
The IR spectra of both compounds are similar to those of
[M{2-(Ph2P)C6H4S}2] described above, with additional medium-
intensity bands at 3100-2900 cm-1 corresponding to the methyl
group vibrations, and a strong-intensity band at 850 cm-1
The structure consists of discrete molecules with the zinc atom
located on a crystallographic 2-fold axis and coordinated to the
thiolate sulfur atoms and phosphorus atoms of two symmetry-
related ligand moieties. Thus both phosphinothiolate ligands
assume five-membered chelate ring geometries. The geometry
about the zinc atom is best described as distorted tetrahedral
[ZnP2S2], as a result of the small bite angle of the ligands, 87.60-
(3)°. The bond angles S-Zn-S# and S-Zn-P#, 122.82(5), and
119.12(3)°, also deviate from the theoretical 109°. The dihedral
angle between the P-Zn-S and P#-Zn-S# planes is 94.1°.
(19) Pauling, L. The Nature of the Chemical Bond; 3rd ed.; Cornell
University Press: Ithaca, New York, 1960; p 246.
(20) See, for example: (a) Gonzalez-Duarte, P.; Clegg, W.; Casals, I.; Sola,
J.; Ruis, J. J. Am. Chem. Soc. 1998, 120, 1260. (b) Vossmeyer, T.;
Reck, G.; Schulz, B.; Katsikas, L.; Weller, H. J. Am. Chem. Soc. 1995,
117, 12881. (c) Vossmeyer, T.; Reck, G.; Katsikas, L.; Houpt, E. T.
K.; Schulz, B.; Weller, H. Science 267, 1476 and references therein.
(21) Corao, E.; Baggio, S. Inorg. Chim. Acta 1969, 3, 617
(22) Griffith, E. A. H.; Charles, N. G.; Rodesiler, P.F.; Amma, E. L.
Polyhedron 1985, 4, 615.

3714 Inorganic Chemistry, Vol. 38, No. 16, 1999
Pe´rez-Lourido et al.
The Zn-S bond distance, 2.2791(9) Å, is comparable to those
of tetrahedral zinc thiolates with five-membered chelating rings,
such as in [Zn{SCH2CH2N(CH3)2}2], 2.266 Å (average value),23
or in other distorted tetrahedral thiolate zinc complexes.24 The
Zn-S(thiolate) distances are consistently shorter than Zn-
S(dithiocarbamate) distances in four-coordinate complexes.25
The Zn-P bond distance, 2.387(1) Å, is also similar to those
found in tetrahedral zinc complexes with tertiary phosphines
as ligands, 2.376(1) Å (average value) in [ZnCl2(PMe3)2]26 or
in the anion [ZnCl3PPh3]-, 2.392(1) Å.27
The phenyl rings of the ligand are essentially planar, the
maximum deviation being less than 0.02 Å. The P and the S
atoms are practically on the plane of the ring to which they are
bonded.
[M{2-(Ph2PO)-6-(Me3Si)C6H3S}2] Compounds. Compounds
with ligands 2-(Ph2PO)-6-(Me3Si)C6H3SH were obtained by
oxidation of zinc or cadmium in a cell containing 2-(diphe-
nylphosphinyl)-6-trimethylsilylbenzenethiol following the gen-
eral procedure described previously. In these cases at the end
of the electrolysis the clear solutions were filtered to remove
any particles of the metal. The [Zn{2-(Ph2PO)-6-(Me3Si)-
C6H3S}2] and [Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2] were obtained
as white crystalline solids by concentration of the solution in a
vacuum at room temperature. Crystals of [Cd{2-(Ph2PO)-6-
(Me3Si)C6H3S}2(CH3OH)] (3) suitable for X-ray studies were
obtained by crystallization of the initial compound from CHCl3/
CH3OH.
Both compounds show IR spectra similar to those of [M{2-
(Ph2P)-6-(Me3Si)C6H3S}2] described above, with an additional
strong-intensity band at 1130 cm-1 corresponding to the
vibration characteristic of the ν(P-O) group. The 31P NMR
spectra show a resonance at δ 45.1 and 40.7 ppm for the zinc
and cadmium compounds, respectively, downfield respect to
the same signal in the free ligand, δ 34.1 ppm.
The FAB mass spectra of both compounds also show the
molecular ion at m/z 828 (6%), M ) Zn, and 875 (6%), M )
Cd. None of them show peaks of higher m/z than that of the
molecular ion. All of these results suggest that both compounds
have a monomeric structure. The monomeric structure of [Cd-
{2-(Ph2PO)-6-(Me3Si)C6H3S}2] may be compared with the
dimeric structure of [Cd2{2-(Ph2PO)C6H4S}4]. Once more, the
steric hindrance of the trimethylsilyl group prevents the forma-
tion of a dimer compound.
Crystal Structure of [Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2-
(CH3OH)] (3). The molecular structure of [Cd{2-(Ph2PO)-6-
(Me3Si)C6H3S}2(CH3OH)] is shown in Figure 3 together with
the atomic numbering scheme adopted. Final atomic coordinates
amd selected bond distances and angles are listed in Table 4.
The cadmium atom is coordinated to the thiolate sulfur and
oxygen atoms of two bidentate monanionic ligands and also
weakly coordinated to a molecule of methanol.
Figure 3. Molecular structure of [Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2(CH3-
OH)].
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
[Cd{2-(Ph2PO)-6-(Me3Si)C6H3S}2(CH3Oh)] (3)
Cd-O(1)
Cd-O(2)
Cd-S(2)
2.290(6)
2.374(6)
2.460(3)
2.474(3)
2.551(7)
1.504(6)
1.808(9)
1.765(10)
P(1)-C(36)
P(1)-C(26)
P(2)-O(2)
P(2)-C(66)
P(2)-C(56)
P(2)-C(46)
S(1)-C(11)
1.803(10)
1.800(10)
1.490(7)
1.809(10)
1.795(11)
1.816(10)
1.760(9)
Cd-S(1)
Cd-O(3)
P(1)-O(1)
P(1)-C(16)
S(2)-C(41)
O(1)-Cd-O(2)
O(1)-Cd-S(2)
O(2)-Cd-S(2)
O(1)-Cd-S(1)
O(2)-Cd-S(1)
86.5(2)
129.8(2)
84.8(2)
90.1(2)
100.0(2)
S(2)-Cd-S(1)
O(1)-Cd-O(3)
O(2)-Cd-O(3)
S(2)-Cd-O(3)
S(1)-Cd-O(3)
140.04(9)
81.3(2)
160.4(2)
91.3(2)
95.4(2)
atom as the apical atom. In this description, S(1) and S(2) are
0.53 and 0.65 Å above the best least-squares plane of S(1)-
S(2)O(2)O(3), and O(2) and O(3) are 0.53 and 0.65 Å below.
The cadmium atom is 0.24 Å out of this plane.
The two Cd-S bond distances in the complex are similar,
2.460(3) and 2.474(3) Å, and not very different from those
observed in 3. Similarly, the Cd-O bond distances correspond-
ing to oxygen atoms of the bidentate chelate ligands, 2.290(6)
and 2.374(6) Å, are in the range for the mentioned pentacoor-
dinated cadmium complexes. Nevertheless the bond distance
Cd-O(3), 2.551(7) Å, is considerably longer, but less than the
sum of the van der Waals radii for cadmium and oxygen, 3.10
Å, and indicative of the methanol being only weakly bonded to
the cadmium, with a bond order of ca. 0.4.
[M{PhP(C6H4S-2)2}] Complexes. Zinc and cadmium com-
pounds of the ligand PhP(C6H4SH-2)2 were prepared following
the standard procedure. White-yellow powdered insoluble solids
precipitated immediately at the anode of the cell. Analytical
data confirm the formation of [M{PhP(C6H4S-2)2}] compounds.
The lack of bands assignable to ν(S-H) is indicative of the
dianionic tridentate nature of the ligands in the complexes. The
high insolubility of both compounds in normal solvents suggests
that these complexes are either dimeric or polymeric species in
the solid state. The FAB spectrum of [Zn{PhP(C6H4S-2)2}]
shows, in addition to a signal at m/z 391 (37%) due to [Zn-
{PhP(C6H4S-2)2}]+, a signal at m/z 780 (4%) corresponding to
[Zn2{PhP(C6H4S-2)2}2]+ and another strong intensity peak at
m/z 456 (100%) due to [Zn2{PhP(C6H4S-2)2}]+, formed by loss
The environment around the cadmium atom may be described
as a [CdO3S2] distorted square pyramid, τ ) 0.34, with the O(1)
(23) Casals, C. I.; Gonzalez-Duarte, P.; Lo´pez, C.; Solans, X. Polyhedron
1990, 9, 763.
(24) (a) Castro, J.; Romero, J.; Garc´ıa-Va´zquez, J. A.; Dura´n, M. L.;
Castin˜eiras, A.; Sousa, A.; Fenton, D. E. J. Chem. Soc., Dalton Trans.
1990, 3255. (b) Swenson, D.; Baezinger, N. C.; Coucouvanis, D. J.
Am. Chem. Soc. 1978, 100, 1933. (c) Ueyama, N.; Sugawara, T.;
Sasaki, K.; Nakamura, A.; Yamoshita, S.; Watatsuki, Y.; Yamazaki,
H.; Yasuoka, N. Inorg. Chem 1988, 27, 741.
(25) See, for example: (a) Malik, M. A.; O’Brien, P.; Motevalli, M. Acta
Crystallogr. 1996, C52, 1931. (b) Hursthouse, M. B.; Malik, M. A.;
Motevalli, M.; O’Brien, P. Organometallics 1991, 10, 730.
(26) Cotton, F. A.; Schmid, G. Polyhedron 1996, 15, 4053.
(27) Cotton, F. A.; Duraj, S. A.; Roth, W. J.; Schmulbach, C. D. Inorg.
Chem. 1985, 24, 525.

Zn and Cd Compounds with Arenephosphinothiol Ligands
Inorganic Chemistry, Vol. 38, No. 16, 1999 3715
Table 5. Selected Bond Lengths (Å) and Angles (deg) for
[Zn{PhPO(C6H4S-2)2}(bipy)] (4)
Zn-O
2.093(3)
2.184(4)
2.398(2)
1.357(6)
1.340(6)
1.771(5)
Zn-N(1)
Zn-S(2)
2.108(4)
2.314(1)
1.509(3)
1.347(6)
1.342(7)
1.769(5)
Zn-N(2)
Zn-S(1)
P-O
N(1)-C(35)
N(1)-C(31)
S(1)-C(11)
N(2)-C(45)
N(2)-C(41)
S(2)-C(21)
O-Zn-N(1)
O-Zn-N(2)
N(1)-Zn-N(2)
O-Zn-S(2)
90.29(14)
164.58(14)
76.0(2)
92.11(10)
122.67(11)
N(2)-Zn-S(2)
O-Zn-S(1)
N(1)-Zn-S(1)
N(2)-Zn-S(1)
S(2)-Zn-S(1)
101.21(12)
92.98(10)
120.43(11)
88.00(13)
116.62(5)
N(1)-Zn-S(2)
molecule in the equatorial plane of the molecule. The zinc atom
is nearly on the equatorial plane, with a deviation of 0.07 Å
out of the least-squares plane. Equatorial bond angles, in the
range 116.62(5)-122.67(11)°, are close to the idealized 120°,
but angular deviation is observed along the axial direction of
the trigonal bipyramid with an O-Zn-N(2) angle of 164.58-
(14)°, significantly distorted from the theoretical 180°. The small
bite of the bipyridine ligand, N(1)-Zn-N(2) bond angle of
76.0(2)°, is the principal source of distortion. This value is
similar to those found in other pentacoordinated zinc complexes
containing 2,2′-bipyridine as chelating ligand.28
The bond distances around the zinc atom are similar to those
reported for other pentacoordinated complexes containing the
same donor atoms. Thus, the Zn-S bond distances, 2.356(2) Å
(average value), although longer than those of [Zn{SCH2CH2N-
(CH3)2}2],23 are of the same order as the value of 2.334(4) Å
found for Zn-S in the pentacoordinated mixed-ligand compound
[(2,2′-bipyridine){2-(2-mercaptophenyl)iminophenoxy}]zinc-
(II).28 In addition, the values of 2.146(4) and 2.093 Å for the
Zn-N and Zn-O bond distances, respectively, are similar to
those found in the above-mentioned complex, and in other
pentacoordinate complexes of Zn with Schiff bases containing
N and O as donor atoms.29
Figure 4. Molecular structure of [Zn{PhPO(C6H4S-2)2}(bipy)].
of one ligand from the dimer species. For the Cd{PhP(C6H4S-
2)2}] complex, the FAB spectrum shows a peak at m/z 438 (4%),
corresponding to [Cd{PhP(C6Y4S-2)2}]+, and additional peaks
at m/z 547 (7%), corresponding to [Cd2{PhPH(C6H4S-2)2}]+.
The addition of 2,2′-bipyridine and 1,10-phenanthroline into
the cell as coligands affords the synthesis of the mixed-ligand
compounds [M{PhP(C6H4S-2)2}L′] (M ) Zn, Cd; L′ ) bipy,
phen), as yellow-white crystalline solids moderately soluble in
the reaction medium and also soluble in a range of other organic
solvents. The IR spectra of the complexes confirm the presence
1
of both coordinated ligands. H NMR spectra show signals in
the range δ 9.2-7.7 ppm corresponding to bipyridine or
phenanthroline and a multiplet at δ 7.6-6.5 ppm, due to the
aromatic protons of the arenephoshinothiol ligand. The FAB
mass spectra of the zinc and cadmium mixed-ligand complexes
with bipyridine show in both cases the molecular ion, at m/z
545 (65%) and 595 (2%), respectively, and also peaks at m/z
389 (30%) and 438 (4%) due to [M{PhP(C6H4S-2)2}]+, formed
by loss of the bipyridine ligand from both complexes. The FAB
mass spectra of the mixed-ligand compounds with phenanthro-
line show the molecular ion, at m/z 569 (100%), M ) Zn, and
616 (5%), M ) Cd.
Crystals of [Zn{PhPO(C6H4S-2)2}(bipy)]‚CHCl3 suitable for
X-ray studies were obtained by crystallization of [Zn{PhP-
(C6H4S-2)2}bipy] from CHCl3/CH3OH. Once more, the presence
of a phosphinyl group in the resulting compound shows the
extreme sensitivity to oxidation of the phosphorus atom in this
type of ligand.
The bipyridine ligand is essentially planar, with no atom
deviating from thr least-squares plane by more than 0.02 Å.
Bond lengths and angles within the ligand are similar to those
found in other bipyridine.30, 31
Acknowledgment. We thank the Xunta de Galicia (Spain)
(Xuga 20910B93 and Xuga 20316B96) for financial support
and the Department of Energy Office of Health and Environ-
mental Research (DE-FG02-99ER62791 to J.Z.).
Supporting Information Available: X-ray crystallographic files,
in CIF format, for the structures of 1-4. This material is available
free of charge via the Internet at http://pubs.acs.org.
IC981405B
Crystal Structure of [Zn{PhPO(C6H4S-2)2}bipy] (4). The
structure of [Zn{PhPO(C6H4S-2)2}(bipy)] is shown in Figure
4. Positional parameters and selected bond lengths and angles
are given in Table 5. The complex consists of monomer units
in which a pentacoordinated [ZnON2S2] zinc atom is bound to
two sulfur atoms and one oxygen atom of a tridentate ligand
and also to two nitrogen atoms of a bidentate chelating
bipyridine molecule. The environment of the zinc atom can be
described a distorted trigonal bipyramidal, τ ) 0.7, with both
sulfur atoms and one of the nitrogen atoms of the bipyridine
(28) Labisbal, E.; Garc´ıa-Vazquez, J. A.; Gomez, C.; Macias, A.; Romero,
J.; Sousa, A.; Englert, U.; Fenton, D. E. Inorg. Chim. Acta 1993, 203,
67.
(29) (a) Lindoy, L. F.; Busch, D. H.; Goedken, V. J. Chem. Soc., Chem.
Commun. 1972, 683. (b) Hall, D.; Moore, F. H. Proc. Chem. Soc.
1960, 256. (c) Orioli, P. L.; di Vaira, M.; Sacconi, L. Inorg. Chem.
1966, 5, 400.
(30) Sanmartin, J.; Bermejo, M. R.; Romero, J.; Garc´ıa-Va´zquez, J. A.;
Sousa, A.; Castin˜eiras, A.; Hiller, W.; Stra¨hle, J. Z. Naturforsch. 1993,
48b, 431.
(31) Castro, R.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa, A.; McAuliffe,
C. A.; Pritchard, R. Polyhedron 1993, 12, 2241.