Insertion reactions of (PPh3)2Pt(SR)2 with CS2, where R = H, CMe3, CHMe2, 4-C6H4Me; structure of (PPh3)Pt(SC6H4Me)(S2CS-4-C

Article abstract of DOI:10.1021/ic000825+

cis-(PPh₃)₂Pt(SH)₂ reacts with CS₂ to give 3, while (PPh₃)₂Pt(SR)₂ reacts to give the thiolatothioxanthato complexes 5.

Full text of DOI:10.1021/ic000825+

5288
Inorg. Chem. 2001, 40, 5288-5289
according to published procedures. CS2 (Aldrich) was used as received.
Nuclear magnetic resonance spectra were recorded under nitrogen on
a Varian XL-200 or JEOL-270 spectrometer. Chemical shifts are in
Insertion Reactions of (PPh3)2Pt(SR)2 with CS2,
where R ) H, CMe3, CHMe2, 4-C6H4Me;
Structure of (PPh3)Pt(SC6H4Me)(S2CS-4-C6H4Me)
1
ppm relative to TMS (for H) and H3PO4 (for 31P) at 0 ppm. Infrared
spectra were recorded on an Analect AQS-20 Fourier transform infrared
(FT-IR) spectrophotometer. Elemental analyses were performed by
Canadian Microanalytical Service Ltd., Delta, British Columbia. Melting
points were obtained on a Thomas Hoover Capillary melting point
apparatus and are uncorrected.
Alan Shaver,* Mohammad El-khateeb, and
Anne-Marie Lebuis
Department of Chemistry, McGill University,
801 Sherbrooke Street West, Montreal,
Quebec, Canada, H3A 2K6
(PPh3)2Pt(S2CS) (3). In a 100 mL Schlenk flask, carbon disulfide
(10.0 mL) was added to a solid sample of cis-(PPh3)2Pt(SH)2 (0.10 g,
0.13 mmol). The solution became yellow after stirring overnight. The
volatile compounds were removed under vacuum. Recrystallization of
the residue from methylene chloride/hexanes gave yellow crystals (0.09
ReceiVed July 24, 2000
1
Introduction
g, 85%). Mp: 265-267°. IR (KBr, cm-1): νCdS 1060(s). H NMR
(CDCl3): δ 7.20 (m, PPh3). 31P NMR (CDCl3): δ 18.3 (JPt-P ) 3146
Hz). Anal. Calcd for C37H30P2PtS3‚CH2Cl2: C, 50.00; H, 3.53; S, 10.54.
Found C, 49.81; H, 3.65; S, 10.02.
Recently we reported1 the reaction of 1 with SO2 to give 2
(Equation 1). Both complexes catalyze the industrially important
Claus reaction; they are the first homogeneous catalysts to do
so. The Claus reaction involves the reaction of SO2 with H2S
to give sulfur and water. Equation 1 is thought to be the first
step in the reaction.
(PPh3)Pt(SCHMe2)(S2CSCHMe2) (5a). In a 100 mL Schlenk flask,
carbon disulfide (10.0 mL) was added to a solid sample of cis-(PPh3)2-
Pt(SCHMe2)2 (0.050 g, 0.057 mmol). The solution became dark red
almost immediately, and the stirring was continued for 4 h. The volatile
compounds were removed under vacuum. Recrystallization of the
residue from hot hexanes gave purple crystals (0.031 g, 79%). Mp:
129-131°. IR (KBr, cm-1): νCS of CS3 985(s), νCS of SR 799(s), 925(m).
1H NMR (CDCl3): δ 1.32 (d, 6H, SCH(CH3)2), 1.42 (d, 6H, SCH-
(CH3)2), 2.99 (septet, 1H, SCH(CH3)2), 4.06 (septet, 1H, SCH(CH3)2),
7.28 (m, 9H, PPh3), 7.62 (m, 6H, PPh3). 31P NMR (CDCl3): δ 17.8
(JPt-P ) 3780 Hz). Anal. Calcd for C25H29PPtS4: C, 43.91; H, 4.27; S,
18.76. Found: C, 44.53; H, 4.33; S, 18.40.
Although SO2 readily inserts into M-C bonds,2 and there
are a few reports of SO2 insertion into M-N3 and M-O4 bonds,
there are no reports, to our knowledge, of SO2 insertion into
M-S bonds. Therefore, the reaction of 1 with SO2 is thought
to involve insertion into the S-H bond.1 On the other hand,
CS2 readily inserts into M-S bonds;5 however, its reactivity
with the MSH moiety has not been studied except for one
example.5a Therefore, we have conducted a study of the
reactivity of CS2 with cis-(PPh3)2Pt(SH)2, 1, and the thiolate
complexes (PPh3)2Pt(SR)2, 4a-c, the results of which are
reported below.
(PPh3)Pt(SCMe3)(S2CSCMe3) (5b). In a 100 mL Schlenk flask,
carbon disulfide (10.0 mL) was added to a solid sample of cis-(PPh3)2-
Pt(SCMe3)2 (0.050 g, 0.056 mmol). The solution became dark red
almost immediately, and the stirring was continued for 4 h. The volatile
compounds were removed under vacuum. Recrystallization of the crude
residue from hot hexanes gave purple crystals (0.031 g, 78%). Mp:
160-162°. IR (KBr, cm-1): νCS
) 988(m), νCS
) 768(s),
of CS3
of SR
1
922(m). H NMR (CDCl3): δ 1.35 (s, 9H, SC(CH3)3), 1.61 (s, 9H,
SC(CH3)3), 7.37 (m, 9H, PPh3), 7.67 (m, 6H, PPh3). 31P NMR
(CDCl3): δ 17.1 (JPt-P ) 3780 Hz). Anal. Calcd for C27H33PPtS4: C,
45.56; H, 4.67; S, 18.02. Found C, 45.50; H, 4.86; S, 15.93.
Experimental Section
(PPh3)Pt(S-4-C6H4Me)(S2CS-4-C6H4Me) (5c). In a 100 mL Schlenk
flask, carbon disulfide (10.0 mL) was added to a solid sample of trans-
(PPh3)2Pt(S-4-C6H4Me)2 (0.05 g, 0.052 mmol). The solution became
dark red after it was stirred overnight. The volatile compounds were
removed under vacuum. Recrystallization of the residue from methylene
All experiments were performed under nitrogen using vacuum lines
and Schlenk techniques. Complexes 17 and 4a-c8 were prepared
* To whom correspondence should be addressed.
(1) Shaver, A.; El-khateeb, M.; Lebuis, A.-M. Angew. Chem., Int. Ed.
Engl. 1996, 35, 2362.
(2) (a) Bennett, M. A.; Bruce, M. I.; Matheson, T. W. ComprehensiVe
Organometallic Chemistry; Wilkinson, G., ed.; Pergamon Press:
Toronto, 1982; Vol. 4, p 778. b) Kubas, G. J.; Ryan, R. R. Polyhedron
1986, 5, 473. c) Schenk, W. A. Angew. Chem., Int. Ed. Engl. 1987,
26, 98. d) Kubas, G. J. Inorg. Chem. 1979, 18, 182. e) Wojcicki, A.
AdV. Organomet. Chem. 1974, 12, 31. f) Jacobson, S. E.; Wojcicki,
A. J. Am. Chem. Soc. 1973, 95, 6921.
chloride/hexanes gave red crystals (0.035 g, 86%). Mp: 196-198°.
1
IR (KBr, cm-1): νCS
980 (s), νCS
805(s), 943(s). H NMR
of CS3
of SR
(CDCl3): δ 2.24 (s, 3H, SC6H4CH3), 2.34 (s, 3H SC6H4CH3), 6.88 (d,
2H, SC6H4CH3), 7.12 (d, 2H, SC6H4CH3), 7.25 (d, 2H, SC6H4Me), 7.29
(d, 2H, SC6H4Me), 7.45 (m, 9H, PPh3), 7.60 (m, 6H, PPh3). 31P NMR
(CDCl3): δ 16.8 (JPt-P ) 3730 Hz). Anal. Calcd for C33H29PPtS4: C,
50.82; H, 3.75; S, 16.45. Found: C, 49.77; H, 3.55; S, 15.08.
(3) Wernschuh, E.; Zimmering, R. Z. Chem. 1988, 190.
(4) (a) Michelin, R. A.; Napoli, M.; Ros, R. J. Organomet. Chem. 1979,
175, 239. b) Green, L. M.; Meek, D. W. Organometallics 1989, 8,
659. c) Randall, S. L.; Miller, C. A.; Janik, T. S.; Churchill, M. K.;
Atwood, J. D. Organometallics 1994, 13, 141.
(5) (a) Shaver, A.; Plouffe, P.-Y.; Bird, P.; Livingstone, E. Inorg. Chem.
1990, 29, 1826. b) Shaver, A.; Lum, B. S.; Bird, P.; Arnold, K. Inorg.
Chem. 1989, 28, 1900. c) Coucouvanis, D. Prog. Inorg. Chem. 1979,
26, 301. d) Burns, P. P.; McCullough, F. P.; McAuliffe, C. A. AdV.
Inorg. Chem. Radiochem. 1980, 23, 211. e) Sato, F.; Fida, K.; Sato,
M. J. Organomet. Chem. 1972, 39, 197. f) Avdeef, A.; Facklev, J. P.
J. Coord. Chem. 1975, 4, 211.
X-ray Structure Determination for 5c (Table 1).
Data for a red crystal of dimensions 0.48 × 0.35 × 0.17 mm was
measured on a Rigaku AFC6S diffractometer using ω/2θ scan mode
and Cu KR radiation. In all, 9408 reflections were measured of which
4731 were used for structure solution and refinement. The structure
was solved by the Patterson method (SHELXS-96)9 and refined on F2
using SHELXL-96.9 All non-hydrogen atoms are isotropic and were
introduced in calculated positions. The structure was checked for missed
symmetry and solvent voids using PLATONS.10
(6) Hunt, C. T.; Matson, G. B.; Balch, A. L. Inorg. Chem. 1981, 20, 2270.
(7) Shaver, A.; Lai, R. D.; Bird, P.; Wickramasinghe, W. Can. J. Chem.
1985, 63, 2555.
(9) Sheldrick, G. M. SHELXS-96; University of Gottingen: Germany,
1996.
(8) Lai, R. D.; Shaver, A.; Inorg. Chem. 1981, 20, 477.
(10) Spek, A. L. Acta Cryst. 1990, A46, C34.
10.1021/ic000825+ CCC: $20.00 © 2001 American Chemical Society
Published on Web 08/23/2001

Notes
Inorganic Chemistry, Vol. 40, No. 20, 2001 5289
Table 1. Crystallographic Data for 5c
The spectroscopic properties and elemental analyses of 5a-c
suggested that only one CS2 molecule had been incorporated
while one PPh3 ligand had been lost. This was confirmed by
the X-ray structure determination of 5c shown in Figure 1.
Complexes 1 and 4a did not react with CO2 or COS at room
temperature in THF or CH2Cl2.
The reactivity of CS2 with 1 is similar to that of SO21 in that
only one molecule of each is incorporated, leading to elimination
of H2S and H2O to give 3 and 2, respectively. In the case of
CS2, the probable intermediate contains the PtSC(S)SH moiety,
which reacts internally with the other SH ligand. Similar
intermediates were proposed5a in the sequential reaction of CS2
with two molecules of CpRu(PPh3)2SH to give Cp2Ru2(PPh3)3-
CS3, which contains a bridging CS3 ligand. The chemistry of
CS2 with 1 is similar to the Claus chemistry observed between
1 and SO2. Complex 3 has also been prepared6 via Equation 4.
empirical formula C33H29S4PPt
a 10.2050(10) Å
b 11.206(2) Å
FW 779.86
space group triclinic P1
T 20 °C
c 15.235(2) Å
λ 1.54056
R 93.14(2)°
d
calc 1.636 g/cm-3
â 92.54(2)°
µ 11.388 mm-1
γ 114.14(1)°
trans range 0.02-0.14
V 1583.2(4) Å3
Z 2
R1 (I > 2σI, all) 0.0390/0.0411a
ωR2 (I > 2σI, all) 0.1073/0.1101b
reflns measured 9408
unique refln (Rint) 4731 (0.053)
a R1 ) ∑|Fo| - |Fc|/∑|Fo|. b ωR2 ) [∑ω(Fo2 - Fc2)2/∑(ω (Fo )2)]1/2
.
2
Complexes 4a-c, which do not contain the reactive Pt-SH
moiety, react with CS2 probably via an intermediate containing
a monodentate thioxanthato ligand which becomes bidentate via
loss of a PPh3 ligand. The reactions between 4a-c and CS2
were monitored by NMR spectroscopy. The rates of reaction
with complexes containing electron releasing groups (CHMe2,
CMe3) were much faster than that containing 4-C6H4Me. There
was no evidence of any intermediates. The rate increases with
increasing CS2 concentrations, decreases in the presence of
added PPh3, and is invariant in the presence of CO. These
observations are very similar to those5 made for the reactions
of CS2 with CpRu(PPh3)2SR and CpW(CO)2(PPh3)SR. These
latter reactions are thought to proceed via loss of PPh3 and
precoordination of CS2 to the metal atoms followed by elec-
trophilic attack by the CS2 ligand on the sulfur atom of the
thiolato ligand. The reactions of 4 with CS2 are also consistent
with precoordination of CS2.
Figure 1. ORTEP drawing of (PPh3)Pt(SCS2-4-C6H4Me)(S-4-C6H4-
Me) (5c). Selected bond lengths (Å) and angles (deg): Pt-P, 2.246-
(2); Pt-S(1), 2.382(2); Pt-S(2), 2.326(2); Pt-S(4), 2.293(2); P-Pt-
S(1), 172.26(6); P-Pt-S(2), 98.72(6); P-Pt-S(4), 91.03(7); S(4)-
Pt-S(2), 169.73(7); S(4)-Pt-S(1), 96.48; S(2)Pt-S(1), 73.68(6).
Results and Discussion
Complex 1 reacted with CS2 to give (PPh3)2Pt(S2CS), 3, in
85% yield with evolution of H2S (Equation 2).
The yellow, air stable complex was identified by its spectro-
scopic properties6 and elemental analysis. The thiolato com-
plexes 4a-c also reacted with CS2 to give the thiolato-
thioxanthato complexes (PPh3)Pt(SR)(S2CSR) 5a-c in 78% to
86% yield (Equation 3).
Acknowledgment. We thank the Natural Science and
Engineering Research Council of Canada and the Quebec
Department of Education for financial support. We thank McGill
University for Fellowship support of M.E.
Supporting Information Available: X-ray crystallographic file,
in CIF format, for the structure determination of 5c. This material is
available free of charge via the Internet at http://pubs.acs.org.
IC000825+