C-S bond cleavage in CpRu(PPh3)2SCH2CHdCH2 to give the trimer (CpRu)3(μ3-S)2(μ-SCH2CHdCH2)

Full text of DOI:10.1021/ic981433u

Inorg. Chem. 1999, 38, 5913-5915
5913
(PPh3)2SCH2CHdCH2, 1. When this complex was heated in
toluene, carbon-sulfur bond cleavage occurred to give (CpRu)3-
(µ3-S)2(µ-SCH2CHdCH2).
C-S Bond Cleavage in
CpRu(PPh3)2SCH2CHdCH2 To Give the Trimer
(CpRu)3(µ3-S)2(µ-SCH2CHdCH2)
Results
Alan Shaver,* Mohammad El-Khateeb, and
Anne-Marie Lebuis
When CpRu(PPh3)2Cl was briefly refluxed with excess
LiSCH2CHdCH2 in THF, the complex 1 was obtained in 81%
yield. When CO gas was bubbled through a THF solution of 1,
the complex CpRu(PPh3)(CO)SCH2CHdCH2, 2, was produced.
Compound 1 reacted easily with CS2 to give the thioxanthate
complex CpRu(PPh3)S2CSCH2CHdCH2, 3, in which a CS2
molecule has inserted into the Ru-S bond. These reactions are
analogous to those reported for the simple Ru-thiolate com-
plexes CpRu(PPh3)2SR.8a
Department of Chemistry, McGill University,
801 Sherbrooke Street West,
Montreal, Quebec, Canada H3A 2K6
ReceiVed December 15, 1998
Introduction
Cleavage of the carbon-sulfur bond is important in biological
systems1 and industrial applications.2 Particularly relevant is the
removal of sulfur from organosulfur compounds in crude oil
via hydrodesulfurization;3 the largest industrial application of
transition metal catalysis presently practiced.4
Complex 2 reacted with MeI in the presence of NH4PF6 to
give the salt [CpRu(PPh3)(CO)MeSCH2CHdCH2)]PF6, 4, in
Allylic carbon-sulfur bond cleavage reactions,5 and those
of allylic-oxygen and allylic-halogen bonds,6 are useful in
synthetic organic chemistry. An important example is the
synthesis of alkenes by the reaction of allylic sulfides with
Grignard reagents5 catalyzed by Ni, Pd, and Au(I) salts.7 The
π-allyl intermediate (µ-SPh)(µ-C3H7)[PCy3Pd]2 has been iso-
lated from the reaction of Pd(PCy3)2 with allylphenyl sulfide.5c
very good yield (81%). Compound 2 also reacted with HBF4
in THF at room temperature to give the thiol complex salt
[CpRu(PPh3)(CO)HSCH2CHdCH2)]BF4, 5. Thus the chemistry
of 2 is similar to that of the simple thiolato complexes, CpRu-
(PPh3)(CO)SR.9 The presence of two chiral centers in 4 and 5
should generate diastereomerism. The NMR spectrum of 4
revealed a broad single peak for the methyl group, and that of
5 gave only one multiplet for the SH proton due to phosphorus
proton coupling. This is consistent with relatively rapid inversion
at the sulfur atom.
The reactivity of the electron-rich ruthenium thiolates CpRu-
(PPh3)2SR8 prompted the preparation of the complex CpRu-
* To whom correspondence should be addressed.
(1) Ahn, Y.; Krzycki, J. A.; Floss, H. G. J. Am. Chem. Soc. 1991, 113,
4700.
(2) Reynolds, J. G. Chem. Ind. (London) 1991, 570.
Compound 1 underwent C-S bond cleavage in addition to
the loss of both PPh3 ligands in refluxing toluene to give the
trimer (CpRu)3(µ3-S)2(µ-SCH2CHdCH2), 6, in 42% yield.
(3) (a) Baranano, D.; Hartwing, J. F. J. Am. Chem. Soc. 1995, 117, 2937.
(b) Jones, W. D.; Chin, R. M. J. Am. Chem. Soc. 1992, 114, 9851. (c)
Wong, K.; Yuan, T.; Wang, M. C.; Tung, H.; Luh, T. J. Am. Chem.
Soc. 1994, 116, 8920. (d) Garcia, J. J.; Mann, B. E.; Adams, H.; Bailey,
N. A.; Maitlis, P. M. J. Am. Chem. Soc. 1995, 117, 2179.
(4) Angelici, R. J. Acc. Chem. Res. 1988, 21, 387.
(5) (a) Gendreau, Y.; Normant, J. F.; Villieras, J. J. Organomet. Chem.
1977, 142, 1. (b) Anderson, R. J.; Henrich, C. A.; Siddall, J. B. J.
Am. Chem. Soc. 1970, 92, 259. (c) Yamamoto, T.; Akimoto, M.;
Yamamoto, A. Chem. Lett. 1983, 1725. (d) Osakada, K.; Chiba, T.;
Nakamura, Y.; Yamamoto, T.; Yamamoto, A. J. Chem. Soc., Chem.
Commun. 1986, 1589.
(6) (a) Tsuji, J.; Minami, I.; Shimizu, I. Tetrahedron Lett. 1983, 24, 1793.
(b) Shimizu, I.; Minami, I.; Tsuji, J. Tetrahedron Lett. 1983, 24, 1797.
(c) Matsushita, H.; Negishi, E. J. Org. Chem. 1982, 47, 4161. (d)
Trost, B. M.; Keinan, E. Tetrahedron Lett. 1980, 21, 2595. (e) Stille,
J. K.; Goldschlx, J. Tetrahedron Lett. 1980, 21, 2599.
Complex 6 is air stable and soluble in THF, benzene, and ether.
Its H NMR spectrum showed two peaks in the Cp region in
1
(7) (a) Osakada, K.; Ozawa, Y.; Yamamoto, A. J. Organomet. Chem. 1990,
399, 341. (b) Auburn, P. R.; Whelan, J.; Bosnich, B. J. Chem. Soc.,
Chem. Commun. 1986, 146. (c) Goux, C.; Lhoste, P.; Sinou, D.
Tetrahedron 1994, 50, 10321. (d) Miyauchi, Y.; Watanbe, S.;
Kuniyasu, H.; Kurosawa, H. Organometallics 1995, 14, 5450.
(8) (a) Shaver, A.; Plouffe, P.-Y.; Bird, P.; Livingstone, E. Inorg. Chem.
1990, 29, 1826. (b) Shaver, A.; Plouffe, P.-Y.; Liles, D.; Singleton,
E. Inorg. Chem. 1992, 31, 997. (c) Sato, T.; Nishio, M.; Ishii, Y.;
Yamazaki, H.; Hidai, M. Organomet. Chem. 1998, 569, 99.
the ratio of 2:1. The crystal structure of 6 is presented in Figure
1. The two sulfur atoms triply bridge the ruthenium atoms and
the one thiolato group bridges two of the ruthenium atoms. The
Ru-Ru bond lengths of 2.800(1) and 2.780(2) Å are longer
than the corresponding average length in the trimer8b (CpRu-
(9) Schenk, W. A.; Stur, T. Z. Naturforsch. 1990, 45b, 1495.
10.1021/ic981433u CCC: $18.00 © 1999 American Chemical Society
Published on Web 11/19/1999

5914 Inorganic Chemistry, Vol. 38, No. 25, 1999
Notes
Experimental Section
All experiments were performed under nitrogen using vacuum lines
and Schlenk techniques.8a,b The complex CpRu(PPh3)2Cl was prepared
according to the published procedure.15 Allyl mercaptan (Aldrich) was
distilled before use. Nuclear magnetic resonance spectra were recorded
under nitrogen on a Varian XL-200 spectrometer. Chemical shifts are
in ppm relative to TMS at 0 ppm. Infrared spectra were recorded on
an Analect AQS-20 Fourier transform infrared (FT-IR) spectropho-
tometer. Elemental analyses were performed by Canadian Microana-
lytical Service Ltd., Delta, British Columbia, Canada. Melting points
were obtained on a Thomas-Hoover capillary melting point apparatus
and are uncorrected.
CpRu(PPh3)2SCH2CHdCH2, 1. A three-neck round-bottom flask
equipped with a reflux condenser was charged with THF (100.0 mL)
and cooled to -78 °C in an ethanol/dry ice bath. Methyllithium (2.05
mL, 1.4 M in ether, 2.87 mmol) was added followed by allyl mercaptan
(0.23 mL, 2.87 mmol). The cooling bath was removed, and the solution
was warmed to 0 °C. The flask was immersed in a water bath at 40 °C
for 15 min. The complex CpRu(PPh3)2Cl (1.00 g, 1.44 mmol) was
added, and the resulting slurry was refluxed for 30 min. The volume
of the mixture was concentrated under vacuum to about 50 mL, and
ethanol (100.0 mL) was added. Further concentration to about 30 mL,
followed by standing, gave the product as an orange solid which was
collected by decanting the mother liquor. The solid was washed with
ethanol and hexanes several times and dried in vacuo overnight (0.90
g, 81%). Mp: 128-130 °C. 1H NMR (C6D6): 3.06 (d, 2H, CH2CHd
CH2, J(H-H) ) 7.0 Hz), 4.38 (s, 5H, Cp), 5.02 (dd, 1H, CH2CHd
CH2, 1J(H-H) ) 2.4 Hz, 3J(H-H) ) 9.8 Hz), 5.28 (dd, 1H, CH2CHd
CH2, 1J(H-H) ) 2.4 Hz, 3J(H-H) ) 16.9 Hz), 6.80 (m, 1H,
CH2CHdCH2), 7.30 (m, 18H, PPh3), 7.40 (m, 12H, PPh3). Anal. Calcd
for C44H40P2RuS: C, 69.17; H, 5.28; S, 4.20. Found: C, 69.32; H,
5.21; S, 4.36.
Figure 1. ORTEP drawing (40% probability level) of (CpRu)3(µ3-
S)2(µ-SCH2CHdCH2), 6. Selected bond lengths (Å) and angles (deg):
Ru(1)-S(1), 2.366(3); Ru(1)-S(2), 2.339(3); Ru(1)-S(3), 2.404(3);
Ru(2)-S(1), 2.361(3); Ru(2)-S(2), 2.351(3); Ru(2)-S(3), 2.389(3);
Ru(3)-S(1), 2.231(3); Ru(3)-S(2), 2.220(3); Ru(1)-Ru(3), 2.800(1);
Ru(2)-Ru(3), 2.780(1); Ru(3)-S(1)-Ru(2), 74.47(8); Ru(3)-S(1)-
Ru(1), 74.99(8); Ru(2)-S(1)-Ru(1), 85.65(9); Ru(3)-S(2)-Ru(1),
75.74(9); Ru(3)-S(2)-Ru(2) 74.87(9); Ru(1)-S(2)-Ru(2), 86.49(9);
Ru(2)-S(3)-Ru(1), 84.20(8); Ru(1)-Ru(3)-Ru(2), 70.30(3).
µ2-SC3H7)3 (average 2.715 Å) and similar to those observed in
(CpRu)3(µ-Cl)(µ3-S) (average 2.770 Å).10 The Ru-S(allyl) bond
lengths of 2.403(4) and 2.388(3) Å are longer than those in
(CpRu-µ2SC3H7)3 (average 2.296 Å). The Ru-S (triply bridged)
bond lengths (average 2.353 Å) are longer than the correspond-
ing lengths in (CpRu)3(µ3-Cl)(µ3-S) (average 2.292 Å).
CpRu(PPh3)(CO)SCH2CHdCH2, 2. In a 100-mL Schlenk flask,
1 (0.50 g, 0.65 mmol), was dissolved in THF (50.0 mL). CO gas was
bubbled through the solution for 1 h, and the resulting yellow mixture
was stirred under CO atmosphere for 5 h. The solution was reduced in
volume to 2.0 mL and chromatographed on alumina (20 mm × 30
cm). Elution with hexanes removed PPh3. Elution with THF in hexanes
(1:2) gave a yellow fraction which was collected and stripped to
dryness. The resulting yellow solid was recrystallized from THF/
hexanes to give yellow crystals (0.30 g, 87%). Mp: 149-150 °C. IR
Discussion
The reactions of 1 are similar to those reported for other
ruthenium thiolates of the type CpRu(PPh3)2SR, including the
tendency to lose both phosphine ligands8b,c to give trimers of
the type (CpRu-µ2-SR)3. However the presence of the allyl
residue in 1 activates C-S bond cleavage.9c The fate of the C3
fragment was not determined. It may have dimerized to give
hexadienes (C6H10) which are volatile and may have been lost
during the reflux or the removal of the solvent. Warming 1 in
toluene-d8 in a NMR tube gave a NMR spectrum which
contained several peaks in the ranges 2.5-3.0, 4.0-5.2, and
5.5-6.1 ppm consistent with the presences of hexadienes.
A possible reaction sequence might involve loss of PPh3 and
C-S bond cleavage to give a coordinatively unsaturated
ruthenium sulfide species, CpRu(PPh3)(dS), which could ag-
gregate to give 6. Similar species have been reported11 such as
Cp*2Ta(CH2R)(dS)12 and Cp*2Zr(py)(dS).13 The formation of
the dimer Cp*Ir(PMe3)(µ2-S)IrCp*, which is postulated to
involve aggregation of the species Cp*Ir(PMe3)(dS)14 obtained
via dehalogenation of Cp*Ir(PMe3)(SH)Cl, is particularly
relevant to the results reported here.
1
(KBr disk): νCO ) 1908 (s), 1921 (sh) cm-1. H NMR (C6D6): 3.24
(d, 2H, CH2CHdCH2, J(H-H) ) 7.7 Hz), 4.70 (s, 5H, Cp), 5.00
(dd, 1H, CH2CHdCH2, 1J(H-H) ) 2.3 Hz, 3J(H-H) ) 9.8 Hz), 5.21
(dd, 1H, CH2CHdCH2, 1J(H-H) ) 2.3 Hz, 3J(H-H) ) 16.9 Hz), 6.21
(m, 1H, CH2CHdCH2), 7.09 (m, 9H, PPh3), 7.69 (m, 6H, PPh3).
Anal. Calcd for C27H25OP2RuS: C, 61.22; H, 4.76. Found: C, 60.20;
H, 4.76.
CpRu(PPh3)S2CSCH2CHdCH2, 3. A solution of 1 (0.50 g, 0.65
mmol) in toluene (100.0 mL) was treated with CS2 (40.0 mL) and stirred
for 30 min. The solvent was removed under vacuum, the remaining
solid was dissolved in THF (3.0 mL), and the solution was chromato-
graphed on alumina (20 mm × 30 cm). Elution with hexanes removed
PPh3. Elution with THF in hexanes (1:2) gave a brown fraction which
was collected and stripped to dryness. The resulting brown solid was
recrystallized from THF/hexanes to give dark red crystals (0.34 g, 90%).
Mp: 132-133 °C. IR (KBr disk): νCS of CS3 ) 991 (s) cm-1, νCS of SR
1
) 692 (s) cm-1. H NMR (C6D6): 3.43 (d, 2H, CH2CHdCH2, J(H-
H) ) 7.0 Hz), 4.29 (s, 5H, Cp), 4.86 (dd, 1H, CH2CHdCH2, 1J(H-H)
) 2.2 Hz, 3J(H-H) ) 9.9 Hz), 4.94 (dd, 1H, CH2CHdCH2, 1J(H-H)
) 2.2 Hz, 3J(H-H) ) 15.9 Hz), 5.61 (m, 1H, CH2CHdCH2, 7.03 (m,
9H, PPh3), 7.60 (m, 6H, PPh3). Anal. Calcd for C27H25PRuS3: C, 56.12;
H, 4.36. Found: C, 56.53; H, 4.56.
(10) Hashizume, K.; Mizobe, Y.; Hidai, M. Organometallics 1995, 14, 5367.
(11) Firth, A. V.; Witt, E.; Stephan, D. W. Organometallics 1998, 17, 3716
and references therein.
(12) Nelson, J. E.; Parkin, G.; Bercaw, J. E. Organometallics 1992, 11,
2181.
(13) (a) Carney, M. J.; Walsh, P. J.; Bergman, R. G. J. Am. Chem. Soc.
1990, 112, 6426. (b) Carney, M. J.; Walsh, P. J.; Hollander, F. J.;
Bergman, R. G. Organometallics 1992, 11, 761.
[CpRu(PPh3)(CO)CH3SCH2CHdCH2)]PF6, 4. In a 100-mL Schlenk
flask, 2 (0.20 g, 0.38 mmol) was dissolved in THF (10.0 mL). Methyl
iodide (0.056 g, 0.40 mmol) was added followed by ammonium
hexafluorophosphate (0.065 g, 0.40 mmol). The reaction mixture was
(15) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg. Synth.
1982, 21, 78.
(14) Dobbs, D. A.; Bergman, R. G. Inorg. Chem. 1994, 33, 5329.

Notes
Inorganic Chemistry, Vol. 38, No. 25, 1999 5915
Table 1. Crystallographic Data for
stirred for 3 h. A yellow precipitate was formed during that time which
was collected by the removal of the mother liquor with a syringe. The
precipitate was washed with hexanes (3 × 5.0 mL) and recrystallized
from methylene chloride/hexanes to give yellow crystals (0.19 g, 73%).
(CpRu)3(µ3-S)2(µ-SCH2CHdCH2)
chem formula: C18H20S3Ru3
fw ) 635.75
Z ) 4
dcalc ) 2.199 g cm-3
Mp: 181-183 °C. IR (KBr disk): νCO ) 1991 (s) cm-1. H NMR
1
space group: P21/c (No. 14)
a ) 12.358(2) Å
λ ) 1.541 78 Å
µ(Cu KR) ) 223.57 cm-1
T ) 20 °C
(acetone-d6): 2.36 (s, 3H, CH3), 3.50 (m, 2H, CH2CHdCH2), 5.29 (m,
1H, CH2CHdCH2), 5.36 (m, 1H, CH2CHdCH2), 5.56 (s, 5H, Cp), 5.70
(m, 1H, CH2CHdCH2, 7.44 (m, 9H, PPh3), 7.63 (m, 6H, PPh3). Anal.
Calcd for C28H28F6OP2RuS: C, 48.76; H, 4.09. Found: C, 48.01; H,
4.16.
b ) 10.876(2) Å
c ) 15.817(2) Å
R1a ) 0.058, 0.086 (I > 2σ(I), all)
ωR2b ) 0.168, 0.184 (I > 2σ(I), all)
â ) 116.36(1)°
V ) 1920.3(5) Å
2
2
a R1 ) ∑|Fo| - |Fc|/∑|Fo|. b ωR2 ) [∑ω(Fo - Fc2)2/∑ω (Fo )2]1/2
.
[CpRu(PPh3)(CO)HSCH2CHdCH2)]BF4, 5. In a 100-mL Schlenk
flask, 2 (0.20 g, 0.38 mmol) was dissolved in THF (10.0 mL) and
HBF4‚Et2O (0.069 mL, 0.40 mmol) was added. The reaction mixture
was stirred for 30 min. The solution was reduced in volume to 3.0
mL, and 10.0 mL of diethyl ether was added. A yellow precipitate
was formed, which was collected by the removal of the mother liquor
with a syringe. The precipitate was washed with hexanes (3 × 5.0 mL)
and recrystallized from methylene chloride/hexanes to give yellow
crystals (0.19 g, 81%). Mp: 162-164 °C. IR (KBr disk): νCO ) 1991
(s), 1979 (m) cm-1, νSH ) 2508 (w) cm-1. 1H NMR (acetone-d6): 3.40
(tt, 3H, CH2CHdCH2, SH, J(H-H) ) 2.3 Hz, J(P-H) ) 6.6 Hz),
5.25 (dd, 1H, CH2CHdCH2, 1J(H-H) ) 1.8 Hz, 3J(H-H) ) 8.8 Hz),
5.35 (dd, 1H, CH2CHdCH2, 1J(H-H) ) 1.8 Hz, 3J(H-H) ) 15.6 Hz),
5.50 (s, 5H, Cp), 5.80 (m, 1H, CH2CHdCH2), 7.42 (m, 9H, PPh3),
7.56 (m, 6H, PPh3). Anal. Calcd for C27H26BF4OPRuS: C, 52.52; H,
4.24. Found: C, 52.30; H, 4.35.
X-ray Structure Determination for 6 (Table 1). A dark plate
crystal (0.100 × 0.010 × 0.500 mm) was mounted on glass fiber. Cell
dimensions were obtained from 20 reflections with 2θ in the range
95.0-100.0°. Intensity measurements were made using a Rigaku
AFC6S diffractometer with graphite-monochromated Cu KR radiation.
A total of 3910 reflections were collected (h,k,(l) using the ω/2θ scan
technique to a maximum 2θ value of 140°; of these 3507 were unique
(merging R ) 5.0%, decay ) 1.7%). The data were processed and
corrected for absorption (ψ scans, transmission range 0.161-1.000)
using the Texsan system of crystallographic computer programs. The
structure was solved by the Patterson methods and refined on F2 using
Shelx196. The Cp ring on Ru(2) was found to be disordered over two
orientations of related occupancy 0.55 and 0.45. The non-hydrogen
atoms were refined anisotropically except for those in the disordered
Cp ring. All hydrogen atoms were added in calculated positions. These
atoms were kept isotropic. The structure was checked for missed
symmetry and solvent-containing areas using Platon. Details of the
programs used are given in the Supporting Information.
(CpRu)3(µ3-S)2(µ-SCH2CHdCH2), 6. A solution of 1 (0.50 g, 0.65
mmol) in toluene (50.0 mL) was prepared in a Schlenk flask fitted
with a reflux condensor. The solution was refluxed for 3 h and was
allowed to cool. The solution was reduced in volume to about 3 mL
and was chromatographed on alumina (20 mm × 30 cm). Elution with
hexanes removed PPh3. Elution with THF in hexanes (1:4) gave a brown
fraction which was collected and stripped to dryness. Recrystallization
from benzene/hexanes gave brown crystals (0.058 g, 42%). Mp: 177-
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.-K.
1
179 °C. H NMR (C6D6): 2.79 (d, 2H, CH2CHdCH2, J(H-H) ) 7.3
Hz), 4.46 (s, 10H, Cp), 4.78 (s, 5H, Cp), 4.95 (dd, 1H, CH2CHdCH2,
1J(H-H) ) 1.9 Hz, 3J(H-H) ) 9.9 Hz), 5.01 (dd, 1H, CH2CHdCH2,
1J(H-H) ) 1.9 Hz, 3J(H-H) ) 17.1 Hz), 5.93 (m, 1H, CH2CHdCH2).
Anal. Calcd for (C18H20Ru3S3): C, 33.99; H, 3.17; S, 15.12. Found:
C, 34.51; H, 3.28; S, 14.52.
Supporting Information Available: : An X-ray crystallographic
file in CIF format for complex 6. This material is available free of
charge via the Internet at http://pubs.acs.org.
IC981433U