Utilization of CS2 as a source of C1 synthetic units for the preparation of bis(alkylthio)methanes and alkyl dithioformates

Article abstract of DOI:10.1021/ic048849u

Double insertion of CS₂ into two Ru-H bonds of [(dppm) ₂Ru(H)₂] (dppm = Ph₂PCH₂PPh ₂) affords the methanedithiolate complex [(dppm)₂Ru(η ²-S₂CH₂)]. The methanedithiolate moiety has been functionalized using 2 equiv of RX resulting in bis(alkylthio)methane derivatives [(dppm)₂Ru(RSCH₂SR)][X]₂. The bis(alkylthio)methane complex loses the bis(alkylthio)methane moiety under very mild conditions and in turn affords the [(dppm)₂RuX32] complex from which the starting dihydride [(dppm)₂Ru(H)₂] has been regenerated via reaction with KOH/EtOH. On the other hand, insertion of CS ₂ into one Ru-H bond of [(dppe)₂Ru(H)₂] (dppe = Ph₂PCH₂CH₂PPh₂) followed by functionalization using RX results in alkyl dithioformate complex trans-[(dppe)₂Ru(H)(SC(SR)H)][X]. In this case also, the alkyl dithioformate moiety gets eliminated under very mild conditions to afford the [(dppe)₂Ru(H)(X)] derivative from which the starting dihydride has been regenerated via reaction with NaBH₄. The reactions presented here constitute utilization of CS₂ as a C₁ synthetic source for the generation of useful organic compounds.

Full text of DOI:10.1021/ic048849u

Inorg. Chem. 2005, 44, 1118−1124
Utilization of CS2 as a Source of C1 Synthetic Units for the Preparation
of Bis(alkylthio)methanes and Alkyl Dithioformates
Thirumanavelan Gandhi and Balaji R. Jagirdar*
Department of Inorganic & Physical Chemistry, Indian Institute of Science,
Bangalore 560 012, India
Received August 21, 2004
Double insertion of CS2 into two Ru
−
H
bonds of [(dppm)2Ru(H)2] (dppm
) Ph2PCH2PPh2) affords the
methanedithiolate complex [(dppm)2Ru(
η
2-S2CH2)]. The methanedithiolate moiety has been functionalized using 2
equiv of RX resulting in bis(alkylthio)methane derivatives [(dppm)2Ru(RSCH2SR)][X]2. The bis(alkylthio)methane
complex loses the bis(alkylthio)methane moiety under very mild conditions and in turn affords the [(dppm)2RuX2]
complex from which the starting dihydride [(dppm)2Ru(H)2] has been regenerated via reaction with KOH/EtOH. On
the other hand, insertion of CS2 into one Ru−H bond of [(dppe)2Ru(H)2] (dppe ) Ph2PCH2CH2PPh2) followed by
functionalization using RX results in alkyl dithioformate complex trans-[(dppe)2Ru(H)(SC(SR)H)][X]. In this case
also, the alkyl dithioformate moiety gets eliminated under very mild conditions to afford the [(dppe)2Ru(H)(X)] derivative
from which the starting dihydride has been regenerated via reaction with NaBH4. The reactions presented here
constitute utilization of CS2 as a C1 synthetic source for the generation of useful organic compounds.
Introduction
complexes and demonstrate the utilization of CS2 as a C1
building block for the generation of bis(alkylthio)methanes
and alkyl dithioformates.
The insertion of heterocumulenes such as CO2, CS2, and
COS into metal-hydride and metal-carbon bonds of transi-
tion metal fragments is an important chemical reaction in
functionalizing these species. This area of research has been
receiving enormous interest due primarily to their potential
as C1 building blocks for the generation of useful organic
compounds.1
Experimental Section
General Procedures. All reactions were carried out under N2
at room temperature using standard Schlenk4 and inert-atmosphere
1
techniques unless otherwise specified. The H, 13C, 19F, and 31P
NMR spectral data were obtained using Avance Bruker 400 and
500 MHz instruments. The shift of the residual protons of the
deuterated solvent was used as an internal reference. The 19F NMR
spectra were recorded relative to CFCl3 and the 31P NMR spectra
with respect to 85% H3PO4 as external standards. Elemental
analyses were carried out at the RSIC, CDRI, Lucknow, India.
Bis(diphenylphosphino)methane (dppm),5 bis(diphenylphosphino)-
ethane (dppe),6 ROTf, TfO(CH2)nOTf (n ) 2-4),7 cis-/trans-
[(dppm)2Ru(H)2],8 cis-[(dppe)2Ru(H)2],9 [(dppm)2Ru(η2-S2CH2)],2
Recently, we reported our preliminary findings on the
insertion reactions of CO2 and CS2 into Ru-H bonds of
[(diphosphine)2Ru(H)2] (diphosphine ) Ph2PCH2PPh2 dppm,
Ph2PCH2CH2PPh2 dppe).2 We also communicated in another
preliminary report the functionalization of the inserted CS2
and its subsequent elimination as methyldithioformate from
the metal complex.3 In this paper, we present the complete
studies of the functionalization of CS2 and the subsequent
elimination of the organic fragment from certain ruthenium
(4) (a) Shriver, D. F.; Drezdon, M. A. The Manipulation of Air-SensitiVe
Compounds, 2nd ed.; Wiley: New York, 1986. (b) Herzog, S.;
Dehnert, J.; Luhder, K. In Technique of Inorganic Chemistry;
Johnassen, H. B., Ed.; Interscience: New York, 1969; Vol. VII.
(5) Hewertson, W.; Watson, H. R. J. Chem. Soc. 1962, 1490-1494.
(6) Chatt, J.; Hart, F. A. J. Chem. Soc. 1960, 1378-1389.
(7) Chapman, R. D.; Andreshak, J. L.; Herrlinger, S. P.; Shackelford, S.
A.; Hildreth, R. A.; Smith, J. P. J. Org. Chem. 1986, 51, 3792-3798.
(8) Hill, G. S.; Holah, D. G.; Hughes, A. N.; Prokopchuk, E. M. Inorg.
Chim. Acta 1998, 278, 226-228.
* Author to whom correspondence should be addressed. E-mail:
jagirdar@ipc.iisc.ernet.in.
(1) (a) Yin, X.; Moss, J. R. Coord. Chem. ReV. 1999, 181, 27-59. (b)
Leitner, W. Coord. Chem. ReV. 1996, 153, 257-284. (c) Pandey, K.
K. Coord. Chem. ReV. 1995, 140, 37-114. (d) Tanaka, K. AdV. Inorg.
Chem. 1995, 43, 409-435.
(2) Gandhi, T.; Nethaji, M.; Jagirdar, B. R. Inorg. Chem. 2003, 42, 667-
669.
(3) Gandhi, T.; Nethaji, M.; Jagirdar, B. R. Inorg. Chem. 2003, 42, 4798-
(9) Nolan, S. P.; Belderrain, T. R.; Grubbs, R. H. Organometallics 1997,
16, 5569-5571.
4800.
1118 Inorganic Chemistry, Vol. 44, No. 4, 2005
10.1021/ic048849u CCC: $30.25
© 2005 American Chemical Society
Published on Web 01/25/2005

CS2 as a Source of C1 Synthetic Units
10.8 Hz), 5.76 (m, 2H, c). 13C NMR (CDCl3): δ 32.3 (s, a), 32.9
Table 1. Numbering Scheme for the Compounds
(s, b), 117.9 (s, c), 133.8 (s, d).
compd
no. for
compd
no. for
compd
no.
[(dppm)2M-
[(dppe)2M-
L
(η2-L)][X]2
(η2-L)][X]
MeSCH2SMe
L-1
L-2
L-3
L-4
L-5
1a
(PhCH2S)2CH2
(H2CdCHCH2S)2CH2
c-SCH2S(CH2)2
c-SCH2S(CH2)3
4a
5aa
5bb
Preparation of 1,3-Dithianes (L-4, L-5). These reactions were
performed in a manner similar to that described above except that
Br(CH2)2Br/Br(CH2)3Br were used. The cis-[(dppm)2RuBr2] and
SC(SH)H
L-6
L-7
L-8
L-9
L-10
6c
7d
SC(SH2CCHdCH2)H
SC(SH2CC6H5)H
SC(S(CH2)3OTf)H
SC(S(CH2)4OTf)H
1
the 1,3-dithianes were obtained in quantitative yields. H NMR
8d
9a
(CDCl3) spectral data for 1,3-dithiane c-SCH2S(CH2)2 (L-4): δ 3.88
(s, 2H, a), 3.17 (s, 4H, b). 13C NMR (CDCl3): δ 34.4 (s, b), 38.1
(s, a).13 1H NMR (CDCl3) spectral data for 1,3-dithiane c-SCH2S-
10a
a X ) OTf. b X ) Br. c X ) BF4. d X ) BPh4.
and trans-[(dppe)2Ru(H)(SC(S)H)]3 were prepared by literature
methods. The numbering scheme for the compounds reported in
this work is summarized in Table 1.
Preparation of Bis(methylthio)methane (L-1). To a CDCl3
solution (0.6 mL) of [(dppm)2Ru(η2-S2CH2)] (0.010 g, 0.010 mmol)
in a 5 mm NMR tube was added MeI (3 equiv, 4.8 µL, 0.030
mmol), and the mixture was shaken well. The color of the solution
changed from reddish brown to greenish-yellow within a few
minutes. After 1 day, a very clear greenish-yellow solution was
obtained that was identified as a mixture of cis-[(dppm)2RuI2] and
bis(methylthio)methane (MeSCH2SMe) (L-1) in quantitative yields.
1H NMR (CDCl3) spectral data for cis-[(dppm)2RuI2]: δ 4.94 (m,
2H, Ph2PCH2PPh2), 5.27 (m, 2H, Ph2PCH2PPh2), 6.49-8.25 (m,
40H, Ph2PCH2PPh2). 31P{1H} NMR (CDCl3): δ -8.3 (app t,
Ph2PCH2PPh2), -37.0 (app t, Ph2PCH2PPh2).10 1H NMR (CDCl3)
spectral data for L-1: δ 2.15 (s, 6H, MeSCH2SMe), 3.61 (s, 2H,
MeSCH2SMe). 13C{1H} NMR (CDCl3): δ 14.3 (s, MeSCH2SMe),
40.1 (s, MeSCH2SMe).11
(CH2)3 (L-5): δ 2.06 (m, 2H, c), 2.81 (t, 4H, b), 3.77 (s, 2H, a).
13C NMR (CDCl3): δ 26.6 (s, c), 29.9 (s, b), 31.9 (s, a).14
Preparation of [(dppm)2Ru(η2-S(CH3)CH2S(CH3))][OTf]2 (1).
A solution of [(dppm)2Ru(η2-S2CH2)] (0.050 g, 0.05 mmol) in
CH2Cl2 (5 mL) was treated with 2 equiv of MeOTf (12 µL, 0.10
mmol). An immediate color change from reddish brown to greenish-
yellow took place. The resulting solution was stirred for 1 h, and
then the volume was reduced to ca. 1 mL. The yellow product of
[(dppm)2Ru(η2-S(CH3)CH2S(CH3))][OTf]2 (1) was precipitated by
adding excess Et2O, and the precipitate was washed with more Et2O
Preparation of Bis(benzylthio)methane (L-2). This reaction
was carried out in a manner similar to that described above except
that PhCH2Br was used. The products of cis-[(dppm)2RuBr2] and
bis(benzylthio)methane [(PhCH2S)2CH2] (L-2) were obtained in
quantitative yields. 1H NMR (CDCl3) spectral data for cis-
[(dppm)2RuBr2]: δ 4.79 (m, 2H, Ph2PCH2PPh2), 5.09 (m, 2H,
Ph2PCH2PPh2), 6.46-8.25 (m, 40H, Ph2PCH2PPh2). 31P{1H} NMR
(CDCl3): δ -2.4 (app t, Ph2PCH2PPh2), -31.5 (app t, Ph2PCH2-
PPh2).10 1H NMR (CDCl3) spectral data for L-2: δ 3.36 (s, 2H,
[(PhCH2S)2CH2]), 3.82 (s, 4H, [(PhCH2S)2CH2]), 6.46-8.25 (m,
10H, [(PhCH2S)2CH2]). 13C{1H} NMR (CDCl3): δ 33.4 (s,
[(PhCH2S)2CH2]), 34.4 (s, [(PhCH2S)2CH2]), 126.5-140.5 (m,
[(PhCH2S)2CH2]).12
1
(3 × 5 mL) and dried in vacuo. Yield: 0.040 g (61%). H NMR
(CDCl3, 263 K) spectral data for 1: δ 1.05 (s, 6H, MeSCH2SMe),
3.58 (d, 2H, J(H,H) ) 8.8 Hz, MeSCH2SMe), 4.95 (br s, 2H,
Ph2PCH2PPh2), 5.30 (br s, 2H, Ph2PCH2PPh2), 6.34-8.46 (m, 40H,
Ph2PCH2PPh2). 31P{1H} NMR (CDCl3, 263 K), ABCD spin
system: δ -30.6 (d t, PA, J(PA,PB) ) 321.2 Hz, J(PA,Pav(C,D)) )
36.7 Hz), -20.3 (d t, PB, J(PB,PA) ) 321.2 Hz, J(PB,Pav(C,D)) )
25.2 Hz), -10.2 (m, PC, J(PC,Pav(A,B,D)) ) 20.6 Hz), -6.9 (m, PD,
J(PD,Pav(A,B,C)) ) 17.2 Hz). ES-MS: m/z ) 963 [M+ - (Me +
2OTf)], 929 [M+ - (Me + H2S + 2OTf)].
Preparation of [(dppm)2Ru(η2-c-SCH2S(CH2)2)][OTf]2 (4). A
solution of [(dppm)2Ru(η2-S2CH2)] (0.050 g, 0.05 mmol) in CH2Cl2
(5 mL) was treated with 2 equiv of TfO(CH2)2OTf (0.034 g, 0.10
mmol) in benzene. An immediate color change from reddish brown
to greenish-yellow was noted. The resulting solution was stirred
for 1 h, and then the volume was reduced to ca. 1 mL. The yellow
product of [(dppm)2Ru(η2-c-SCH2S(CH2)2)][OTf]2 (4) was precipi-
tated by adding excess Et2O, and the precipitate was washed with
more Et2O (3 × 5 mL) and dried in vacuo. Yield: 0.035 g (52%).
1H NMR (CDCl3, 233 K) spectral data for 4: δ 1.03 (s, 4H, SCH2S-
Preparation of Bis(allylthio)methane (L-3). This reaction was
also carried out in a manner similar to that described above except
that H2CdCHCH2Br was used. The products consisting of cis-
[(dppm)2RuBr2] and bis(allylthio)methane [(H2CdCHCH2S)2CH2]
(L-3) were obtained in quantitative yields. 1H NMR (CDCl3)
spectral data for L-3: δ 3.25 (d, 4H, b, J(b,c) ) 6.8 Hz), 3.57 (s,
2H, a), 5.11 (d, 2H, e, J(e,c) ) 6.0 Hz), 5.15 (d, 2H, d, J(d,c) )
(10) The NMR data matched with the data reported in the literature:
Bickley, J. F.; La Pense´e, A. A.; Higgins, S. J.; Stuart, C. A. J. Chem.
Soc., Dalton Trans. 2003, 4663-4668.
(11) The NMR data matched with the data reported in the literature: (a)
Fisher, C. L.; Kahn, S. D.; Hehre, W. J.; Caserio, M. C. J. Am. Chem.
Soc. 1989, 111, 7379-7387. (b) Atkins, R. C.; Lentz, C. M. J. Org.
Chem. 1978, 43, 773-775.
(13) The NMR data matched with the data reported in the literature:
Batyrbaev, N. A.; Zorin, V. V.; Zlot-skii, S. S.; Rakhmankulov, D. L.
Zh. Org. Khim. 1981, 17, 1934-1937.
(14) The NMR data matched with the data reported in the literature: Wan,
Y.; Kurchan, A. N.; Barnhurst, L. A.; Kutateladze, A. G. Org. Lett.
2000, 2, 1133-1135.
(12) The NMR data matched with the data reported in the literature: Kuhn,
N.; Schumann, H. J. Organomet. Chem. 1986, 315, 93-103.
Inorganic Chemistry, Vol. 44, No. 4, 2005 1119

Gandhi and Jagirdar
(CH2)2), 3.55 (d, 2H, J(H,H) ) 8.8 Hz, MeSCH2SMe), 4.67 (br,
2H, Ph2PCH2PPh2), 5.01 (br m, 2H, Ph2PCH2PPh2), 6.23-8.51 (m,
40H, Ph2PCH2PPh2). 31P{1H} NMR (CDCl3, 233 K): δ -13.6 (app
t, Ph2PCH2PPh2, J(P,P) ) 36.7 Hz), -7.3 (app t, Ph2PCH2PPh2).
ES-MS: m/z ) 1125 [M+ - OTf].
CH2)H), 6.55-7.63 (m, 40H, Ph2PCH2CH2PPh2), 6.55-7.63 (m,
20H, BPh4), 7.98 (s, 1H, SC(SH2CCHdCH2)H). 13C{1H} NMR
(CDCl3): δ 33.3 (qnt, Ph2PCH2CH2PPh2), 37.2 (s, SC(SH2CCHd
CH2)H), 120.2 (s, SC(SH2CCHdCH2)H), 121.7-136.3 (m, Ph2PCH2-
CH2PPh2), 130.4 (s, SC(SH2CCHdCH2)H), 164.3 (q, BPh4), 213.7
(s, SC(SH2CCHdCH2)H). 31P{1H} NMR (CDCl3): δ 63.4 (s,
Ph2PCH2CH2PPh2).
Preparation of [(dppm)2Ru(η2-c-SCH2S(CH2)3)][OTf]2 (5a).
A solution of [(dppm)2Ru(η2-S2CH2)] (0.050 g, 0.05 mmol) in
CH2Cl2 (5 mL) was treated with 2 equiv of TfO(CH2)3OTf (0.035
g, 0.10 mmol) in benzene. An immediate color change from reddish
brown to greenish-yellow was observed. The resulting solution was
stirred for 1 h, and then the volume was reduced to ca. 1 mL. The
yellow product of [(dppm)2Ru(η2-c-SCH2S(CH2)3)][OTf]2 (5a) was
precipitated by adding excess Et2O, and the precipitate was washed
with more Et2O (3 × 5 mL) and dried in vacuo. Yield: 0.042 g
(63%). 1H NMR (CDCl3, 263 K) spectral data for 5a: δ 1.35 (qnt,
2H, SCH2S(CH2CH2CH2)), 2.84 (d m, 4H, SCH2S(CH2CH2CH2)),
3.54 (d, 2H, J(H,H) ) 8.8 Hz, MeSCH2SMe), 4.92 (br s, 2H,
Ph2PCH2PPh2), 5.32 (br s, 2H, Ph2PCH2PPh2), 6.34-8.45 (m, 40H,
Ph2PCH2PPh2). 31P{1H} NMR (CDCl3, 263 K), ABCD spin
system: δ -30.4 (d t, PA, J(PA,PB) ) 321.2 Hz, J(PA,Pav(C,D)) )
36.7 Hz), -20.6 (d t, PB, J(PB,PA) ) 321.2 Hz, J(PB,Pav(C,D)) )
25.2 Hz), -10.5 (m, PC, J(PC,Pav(A,B,D)) ) 17.2 Hz), -7.2 (m, PD,
J(PD,Pav(A,B,C)) ) 19.3 Hz). ES-MS: m/z ) 963 [M+ - (C2H4 +
2OTf)], 929 [M+ - (C2H4 + H2S + 2OTf)].
Preparation of trans-[(dppe)2Ru(H)(SC(SH2CC6H5)H)][BPh4]
(8). This compound was prepared in a manner similar to that of
the allyl dithioformate analogue described above except that benzyl
bromide was used. Yield: 73%. Anal. Calcd for C84H77BP4RuS2‚
THF: C, 72.46; H, 5.87. Found: C, 72.70; H, 5.59 (the presence
of a molecule of THF was confirmed using 1H NMR spectroscopy).
1H NMR (CDCl3) spectral data for trans-[(dppe)2Ru(H)(SC(SH2-
CC6H5)H)][BPh4] (8): δ -12.64 (qnt, 1H, Ru-H, J(H,Pcis) ) 18.6
Hz), 2.21 (br s, 4H, Ph2PCH2CH2PPh2), 2.65 (br s, 4H, Ph2PCH2CH2-
PPh2), 3.98 (s, 2H, SC(SH2CC6H5)H), 6.52-7.40 (m, 40H, Ph2PCH2-
CH2PPh2), 8.01 (s, 1H, SC(SH2CC6H5)H). 13C{1H} NMR (CDCl3):
δ 33.0 (qnt, Ph2PCH2CH2PPh2), 38.9 (s, SC(SH2CC6H5)H), 121.6-
136.3 (m, Ph2PCH2CH2PPh2), 164.3 (q, BPh4), 211.6 (s, SC(SH2-
CC6H5)H). 31P{1H} NMR (CDCl3): δ 63.4 (s, Ph2PCH2CH2PPh2).
Reaction of trans-[(dppe)2Ru(H)(SC(SH2CCHdCH2)H)][BPh4]
(7) with CH3CN. A CH2Cl2 solution (10 mL) of trans-[(dppe)2Ru-
(H)(SC(SH2CCHdCH2)H)][BPh4] (7) (0.500 g, 0.370 mmol) was
treated with 5 equiv of CH3CN (98 µL, 1.850 mmol), and the
resulting solution was stirred for 15 min. During this time, the color
of the solution turned from orange to yellow. Then the solution
was subjected to vacuum distillation and the free allyldithioformate
(L-7) was fractionally collected in a liquid-N2 trap and character-
ized. 1H NMR (CDCl3) spectral data for L-7: δ 3.99 (m, 2H,
SC(SH2CCHdCH2)H), 5.23 and 5.35 (two d, 2H, SC(SH2CCHd
CH2)H), 5.85 (m, 1H, SC(SH2CCHdCH2)H), 11.25 (s, 1H, SC(SH2-
CCHdCH2)H). 13C{1H} NMR (CDCl3): δ 35.1 (s, SC(SH2CCHd
CH2)H), 120.0 (s, SC(SH2CCHdCH2)H), 130.8 (s, SC(SH2CCHd
CH2)H), 217.2 (s, SC(SH2CCHdCH2)H).15 IR (CH2Cl2; cm-1):
1108 (ν(CdS)). Electronic spectrum: 307 nm.
In another experiment, the crude product from the reaction of
[(dppm)2Ru(η2-S2CH2)] and Br(CH2)3Br consisting of a mixture
of [(dppm)2Ru(η2-c-SCH2S(CH2)3)][Br]2 (5b) and cis-[(dppm)2RuBr2]
was analyzed by mass spectroscopy. ES-MS: m/z ) 1071 [M+
-
Br], 963 [M+ - (C2H4 + 2Br)], 929 [M+ - (C2H4 + H2S + 2Br)].
Preparation of trans-[(dppe)2Ru(H)(SC(SH)H)][BF4] (6). To
a CDCl3 solution (0.6 mL) of trans-[(dppe)2Ru(H)(SC(S)H)] (0.015
g, 0.015 mmol) in a 5 mm NMR tube was added HBF4‚Et2O (1
equiv, 2 µL, 0.015 mmol), and the solution was shaken well. The
color of the reaction mixture turned from yellow to red immediately.
Attempts to isolate the product trans-[(dppe)2Ru(H)(SC(SH)H)]-
[BF4] (6) resulted in its decomposition; therefore, it was character-
ized using NMR spectroscopy only. 1H NMR (CDCl3) spectral data
for 6: δ -12.25 (qnt, 1H, Ru-H, J(H,Pcis) ) 18.6 Hz), 2.31 (br s,
4H, Ph2PCH2CH2PPh2), 2.81 (br s, 4H, Ph2PCH2CH2PPh2), 5.78
(d, 1H, SC(SH)H, 3J(H,H) ) 13.7 Hz), 6.52-7.42 (m, 40H,
In another experiment, after the addition of CH3CN and stirring
for 15 min, the volume of the solution was reduced and the product
of trans-[(dppe)2Ru(H)(CH3CN)][BPh4] was precipitated by the
addition of excess Et2O. It was dried in vacuo. Yield: 0.400 g
1
3
(85%). H NMR (CDCl3) spectral data for trans-[(dppe)2Ru(H)-
Ph2PCH2CH2PPh2), 7.69 (d, 1H, SC(SH)H, J(H,H) ) 13.7 Hz).
13C{1H} NMR (CDCl3): δ 33.1 (qnt, Ph2PCH2CH2PPh2), 125.3-
137.9 (m, Ph2PCH2CH2PPh2), 210.7 (s, SC(SH)H). 31P{1H} NMR
(CDCl3): δ 63.4 (s, Ph2PCH2CH2PPh2).
(CH3CN)][BPh4]: δ -15.98 (qnt, 1H, Ru-H, J(H,Ptrans) ) 18.6
Hz), 0.96 (s, 3H, CH3CN), 2.00 (m, 4H, Ph2PCH2CH2PPh2), 2.41
(m, 4H, Ph2PCH2CH2PPh2), 6.56-7.44 (m, 40H, Ph2PCH2-
CH2PPh2), 6.56-7.44 (m, 20H, BPh4). 31P{1H} NMR (CDCl3):
65.1. 13C{1H} NMR (CDCl3): δ 2.7 (s, CH3CN), 31.6 (qnt,
Ph2PCH2CH2PPh2), 121.7-136.3 (m, Ph2PCH2CH2PPh2), 164.2 (q,
BPh4), 123.1 (s, CH3CN).
Reaction of trans-[(dppe)2Ru(H)(SC(SH2CC6H5)H)][BPh4] (8)
with CH3CN. This reaction was carried out in a manner similar to
that described in the case of allyl dithioformate hydride complex.
The product of benzyl dithioformate (L-8) was fractionally distilled
and characterized. 1H NMR (CDCl3) spectral data for L-8: δ 4.56
(s, 2H, SC(SH2CC6H5)H), 6.52-7.40 (m, 5H, SC(SH2CC6H5)H),
11.28 (s, 1H, SC(SH2CC6H5)H). 13C{1H} NMR (CDCl3): δ 36.8
(s, SC(SH2CC6H5)H), 121.6-136.3 (s, SC(SH2CC6H5)H), 217.0 (s,
SC(SH2CC6H5)H).16
Preparation of trans-[(dppe)2Ru(H)(SC(SH2CCHdCH2)H)]-
[BPh4] (7). A THF solution (10 mL) of NaBPh4 (0.140 g, 0.40
mmol) and allyl bromide (30 µL, 0.40 mmol) was added to a THF
solution (10 mL) of trans-[(dppe)2Ru(H)(SC(S)H)] (0.200 g, 0.200
mmol). An immediate color change from yellow to orange was
noted. The reaction mixture was stirred for 10 min, and then the
volatiles were removed under vacuo. The resulting orange solid
was redissolved in 10 mL of CH2Cl2, the solution was filtered, and
the volume of the filtrate was reduced to ca. 2 mL. The product of
trans-[(dppe)2Ru(H)(SC(SH2CCHdCH2)H)][BPh4] (7) was pre-
cipitated by adding excess Et2O and dried in vacuo. Yield: 0.210
g (79%). Anal. Calcd for C80H75BP4RuS2‚THF: C, 71.57; H, 5.93.
Found: C, 71.83; H, 5.65 (the presence of a molecule of THF was
confirmed using 1H NMR spectroscopy). 1H NMR (CDCl3) spectral
data for 7: δ -12.65 (qnt, 1H, Ru-H, J(H,Pcis) ) 18.6 Hz), 2.23
(br s, 4H, Ph2PCH2CH2PPh2), 2.69 (br s, 4H, Ph2PCH2CH2PPh2),
3.28 (d, 2H, SC(SH2CCHdCH2)H, J(H,H) ) 6.8 Hz), 5.00 (d, 1H,
SC(SH2CCHdCH2)H, J(H,H) ) 16.6 Hz), 5.08 (d, 1H, SC(SH2-
CCHdCH2)H, J(H,H) ) 16.6 Hz), 5.41 (m, 1H, SC(SH2CCHd
Preparation of trans-[(dppe)2Ru(H)(SC(S(CH2)3OTf)H)][OTf]
(9). A solution of trans-[(dppe)2Ru(H)(SC(S)H)] (0.100 g, 0.10
(15) Allyl dithioformate has not been reported in the literature.
(16) The NMR data matched with the data reported in the literature:
Sanchez, S.; Bateson, J. H.; O’Hanlon, P. J.; Gallagher, T. Org. Lett.
2004, 6, 2781-2783.
1120 Inorganic Chemistry, Vol. 44, No. 4, 2005

CS2 as a Source of C1 Synthetic Units
Scheme 1
mmol) in CH2Cl2 (5 mL) was treated with 5 equiv of TfO(CH2)3-
OTf (0.170 g, 0.5 mmol) in benzene. An immediate color change
from yellow to red took place. The resulting solution was stirred
for 10 min, and then the volume was reduced to ca. 1 mL. The
product of trans-[(dppe)2Ru(H)(SC(S(CH2)3OTf)H)][OTf] (9) was
precipitated by adding excess Et2O, and the precipitate was washed
with more Et2O (3 × 5 mL) and dried in vacuo. Yield: 0.09 g,
67%. Anal. Calcd for C58H56F6O6P4RuS4: C, 52.88; H, 4.28.
1
Found: C, 52.21; H, 4.94. H NMR (CDCl3) spectral data for 9:
δ -12.63 (qnt, 1H, Ru-H, J(H,Ptrans) ) 18.6 Hz), 2.30 (br s, 4H,
Ph2PCH2CH2PPh2), 2.85 (br s, 4H, Ph2PCH2CH2PPh2), 3.19 (t, 2H,
SC(SCH2CH2CH2OTf)H), 3.55 (t, 2H, SC(SCH2CH2CH2OTf)H),
2.14 (qnt, 2H, SC(SCH2CH2CH2OTf)H), 7.89 (s, 1H, SC(SCH2-
CH2CH2OTf)H), 6.61-7.37 (m, 40H, Ph2PCH2CH2PPh2). 13C{1H}
NMR (CDCl3): δ 30.2 (s, SC(SCH2CH2CH2OTf)H), 32.6 (s,
SC(SCH2CH2CH2OTf)H), 32.1 (s, SC(SCH2CH2CH2OTf)H), 33.4
(qnt, Ph2PCH2CH2PPh2), 127.9-132.8 (m, Ph2PCH2CH2PPh2),
212.7 (s, SC(SCH2CH2CH2OTf)H), 133.2 (qnt, SC(SCH2CH2-
CH2OTf)H), 135.7 (qnt, [OTf]). 31P{1H} NMR (CDCl3): δ 63.9
(s, Ph2PCH2CH2PPh2). 19F{1H} NMR (CDCl3): δ -72.7 (s, 3F,
SC(SCH2CH2CH2OTf)H), -72.8 (s, 3F, free [OTf]- (counterion)).
excess CS2 was used, the methanedithiolate complex was
isolated as a major product in good yield (Scheme 1).2
The methanedithiolate complex provides an opportunity
for functionalizing the inserted CS2 due to the virtue of the
accessibility of the lone pairs on both the sulfur atoms. We
reacted the methanedithiolate moiety with electrophilic
reagents such as RX (R ) Me, X ) I; R ) H2CdCHCH2,
X ) Br; R ) C6H5CH2, X ) Br) and XRX (R )
(-CH2-)2, X ) Br; R ) (-CH2-)3, X ) Br) and monitored
the reactions using NMR spectroscopy. The added electro-
phile (RX) attacks both the sulfur atoms resulting in a bis-
(alkylthio)methane derivative [(dppm)2Ru(η2-S(R)CH2S(R)]-
[X]2 that we have not been able to isolate; we, however,
have observed this species using NMR spectroscopy. Over
a period of time at room temperature, the bis(alkylthio)-
methane, RSCH2SR (R ) Me (L-1), C6H5CH2 (L-2), H2Cd
CHCH2 (L-3)), gets eliminated and the halide counterions
bind to the metal center giving cis-[(dppm)2RuX2]. Both the
species were obtained in quantitative yields. In the reaction
of the [(dppm)2Ru(η2-S2CH2)] with alkyl dihalides (XRX),
derivatives with 1,3-dithianes bound to the metal center of
the type [(dppm)2Ru(η2-c-SCH2S(CH2)n)][X]2 (n ) 2, 3) were
observed spectroscopically. The 1,3-dithiane moieties (L-4,
L-5) get eliminated from the metal complex over a period
of time leaving behind the cis-[(dppm)2RuX2] complex. In
these cases also, both 1,3-dithiane and the ruthenium halide
complex were obtained in quantitative yields. These reactions
have been summarized in Scheme 2.
Preparation of trans-[(dppe)2Ru(H)(SC(S(CH2)4OTf)H)][OTf]
(10). A solution of trans-[(dppe)2Ru(H)(SC(S)H)] (0.100 g, 0.10
mmol) in CH2Cl2 (5 mL) was reacted with 5 equiv of TfO(CH2)4-
OTf (0.180 g, 0.5 mmol) in benzene. The solution color turned
from yellow to red immediately. It was stirred for 10 min, and
then the volume was reduced to ca. 1 mL. The product of trans-
[(dppe)2Ru(H)(SC(S(CH2)4OTf)H)][OTf] (10) was precipitated by
adding excess Et2O, and the precipitate was washed with more Et2O
(3 × 5 mL) and dried in vacuo. Yield: 0.085 g, 62%. Anal. Calcd
for C59H58F6O6P4RuS4: C, 53.22; H, 4.39. Found: C, 52.49; H,
1
4.19. H NMR (CDCl3) spectral data for 10: δ -12.71 (qnt, 1H,
Ru-H, J(H,Ptrans) ) 18.6 Hz), 2.30 (br s, 4H, Ph2PCH2CH2PPh2),
2.83 (br s, 4H, Ph2PCH2CH2PPh2), 2.96 (t, 2H, SC(SCH2CH2
CH2CH2OTf)H), 3.52 (t, 2H, SC(SCH2CH2CH2CH2OTf)H), 1.74
(qnt, 2H, SC(SCH2 CH2CH2CH2OTf)H), 1.97 (qnt, 2H, SC(SCH2-
CH2CH2CH2OTf)H), 7.96 (s, 1H, SC(SCH2CH2CH2OTf)H), 6.61-
7.37 (m, 40H, Ph2PCH2CH2PPh2). 13C{1H} NMR (CDCl3): δ 25.9
(s, SC(SCH2CH2CH2CH2OTf)H), 31.5 (s, SC(SCH2CH2CH2CH2-
OTf)H), 33.3 (qnt, Ph2PCH2CH2PPh2), 127.9-132.8 (m, Ph2PCH2-
CH2PPh2), 213.4 (s, SC(SCH2CH2CH2CH2OTf)H), 133.3 (qnt,
SC(SCH2CH2CH2OTf)H), 135.7 (qnt, [OTf]). 31P{1H} NMR
(CDCl3): δ 63.91 (s, Ph2PCH2CH2PPh2). 19F{1H} NMR (CDCl3):
δ -72.7 (s, 3F, SC(SCH2CH2CH2OTf)H), -72.8 (s, 3F, free [OTf]-
(counterion)).
To our knowledge, transition metal complexes bearing
bis(alkylthio)methane or 1,3-dithiane as ligands are un-
precedented. Our attempts to isolate the [(dppm)2Ru(η2-S(R)-
CH2S(R))][X]2 or the [(dppm)2Ru(η2-c-SCH2S(CH2)n)][X]2
(n ) 2, 3) complexes afforded only the dihalide cis-
[(dppm)2RuX2] suggesting that these neutral sulfur ligands
are extremely loosely bound to the metal center and are quite
labile. We also attempted to employ a slightly different
strategy by using a sterically congested and noncoordinating
counterion such as OTf to prevent the elimination of the
sulfur ligand and the subsequent binding of the counterion
to the metal center. Our attempts were successful in the
isolation of [(dppm)2Ru(η2-S(CH3)CH2S(CH3))][OTf]2 (1)
and [(dppm)2Ru(η2-c-SCH2S(CH2)n)][OTf]2 (n ) 2 (4), 3 (5))
derivatives; however, the purification procedures to obtain
samples pure enough for elemental analyses resulted in
certain decomposed material. Nevertheless, the crude prod-
Results and Discussion
Preparation of Bis(alkylthio)methanes and 1,3-Dithianes.
Solutions of cis-/trans-[(dppm)2Ru(H)2] in C6D6/toluene react
with CO2 (1 atm) and CS2 (1 or 2 equiv) to give the insertion
products trans-[(dppm)2Ru(H)(OC(O)H)] and a mixture of
cis- and trans-[(dppm)2Ru(H)(SC(S)H)], respectively. At-
tempts to hydrogenate the hydride formate derivative only
resulted in the recovery of the starting dihydride complex
via the deinsertion of CO2. On the other hand, when the
mixture of cis- and trans-[(dppm)2Ru(H)(SC(S)H)] was
allowed to crystallize, a new species was formed that was
identified by NMR spectroscopy and X-ray crystallography
as [(dppm)2Ru(η2-S2CH2)]. This species is a result of a
unique double insertion of CS2 into two Ru-H bonds. When
Inorganic Chemistry, Vol. 44, No. 4, 2005 1121

Gandhi and Jagirdar
Scheme 2
expected to release the free methane dithiol, it being a weakly
binding ligand. This further results in other side reactions in
addition to generating certain decomposed material. The
NMR spectra of the reaction mixture indicated complex
mixtures of products thus precluding the specific character-
ization of the dithiol complex.
Caserio and co-workers11a prepared bis(methylthio)-
methane (L-1) earlier in high yield in quite a laborious
process using MeSH as one of the starting materials.
Tanikaga et al.17 obtained bis(methylthio)methane in moder-
ate yields starting from Me2S. Although bis(allylthio)methane
(L-3) has been reported in the literature, there exists no
characterization data.18 By using the pathway shown in
Scheme 2, we have been able to isolate bis(allylthio)methane
and characterize it. The NMR spectral assignments were
made on the basis of a 1H-1H COSY experiment. Kuhn and
Schumann12 reported the preparation of bis(benzylthio)-
methane using thiol as one of the starting materials; in
addition, they also made an iron derivative using this species.
The 1,3-dithiane c-SCH2S(CH2)2- (L-4) has been prepared
in a low yield via condensation of paraform (or paraldehyde)
with 1,2-ethanedithiol.13 On the other hand, Kutateladze and
co-workers reported a one-pot synthesis of 1,3-dithiane
c-SCH2S(CH2)3- (L-5) in 83% yield using CS2 and NaBH4.14
Our routes to obtain the bis(alkylthio)methanes and the 1,3-
dithianes are quite facile, and in all the cases, the yields were
quantitative. In these respects, the pathways presented here
are better than those available in the literature.
Open-chain bis(alkylthio)methanes, which are also known
as 1,3-dithioacetals, especially bis(methylthio)methane, are
used in the synthesis of carbocycles19 and certain hetero-
cycles.20 Unlike cyclic dithioacetals which have steric
constraints, bis(methylthio)methane is sterically unbiased and
is also used extensively in carbohydrate chemistry.21 Bis-
(benzylthio)methane and bis(allylthio)methane are used as
a ligand22 and in the synthesis of allylsilanes,23 respectively.
Bis(alkylthio)methanes also have a special place in organic
synthesis; they are used as reagents for C-C bond formation
and carbonyl addition reactions.24 In addition, the 1,3-dithiane
(c-SCH2S(CH2)3-), a six-membered cyclic dithioacetal, is
used extensively as a good nucleophile25 and an efficient
ucts could be characterized by both NMR (at low temper-
atures) and mass spectroscopy. We found that some of the
NMR resonances of these products at room temperature were
broadened, whereas at low temperatures they resolve and
the spectral assignments could be made without any ambigu-
ity. We are currently investigating the origin of the broaden-
ing of the NMR signals. The NMR resonances not belonging
to those of the products in the crude materials could not be
assigned. The NMR spectral features of the isolated
[(dppm)2Ru(η2-S(CH3)CH2S(CH3))]2+ (cation of 1) and
[(dppm)2Ru(η2-c-SCH2S(CH2)n)][X]2 (n ) 2 (4), 3 (5))
complexes matched those of the in-situ generated bis-
(alkylthio)methane and 1,3-dithiane complexes.
The unique feature of the reaction sequence presented in
Scheme 2 is that it affords an opportunity to recycle
the starting ruthenium dihydride cis-/trans-[(dppm)2Ru(H)2]
from the dihalide complex cis-[(dppm)2RuX2]. When cis-
[(dppm)2RuX2] was reacted with KOH/EtOH, cis-/trans-
[(dppm)2Ru(H)2] was obtained in a yield of 48% (eq 1).8
(17) Tanikaga, R.; Hiraki, Y.; Ono, N.; Kaji, A. Chem. Commun. 1980,
41-42.
(18) Mart´ın, G.; Mart´ınez, H.; Ortega, H.; Salazar, J. Phosphorus Sulfur
1985, 22, 153-159. The bis(allylthio)methane was obtained via some
thermal rearrangement process unexpectedly during the distillation of
crude (allylthio)(ethylthio)methane.
(19) Trost, B. M.; Dumas, J.; Villa, M. J. Am. Chem. Soc. 1992, 114, 9836-
9845.
(20) Trost, B. M.; Nu¨bling, C. Carbohydr. Res. 1990, 202, 1-12.
(21) (a) Fukase, H.; Horii, S. J. Org. Chem. 1992, 57, 3642-3650. (b)
Labe´gue´re, F.; Lavergne, J. P.; Martinez, J. Tetrahedron Lett. 2002,
43, 7271-7272.
(22) Kuhn, N.; Schumann, H. J. Organomet. Chem. 1986, 315, 93-103.
(23) (a) Fugami, K.; Oshima, K.; Utimoto, K.; Nozaki, H. Tetrahedron
Lett. 1986, 27, 2161-2164. (b) Fugami, K.; Hibino, J.; Nakatsukasa,
S.; Matsubara, S.; Oshima, K.; Utimoto, K.; Nozaki, H. Tetrahedron
1988, 44, 4277-4292.
(24) (a) Corey, E. J.; Seebach, D. Angew. Chem., Int. Ed. Engl. 1965, 4,
1075-1077. (b) Seebach, D.; Jones, N. R.; Corey, E. J. J. Org. Chem.
1968, 33, 300-305. (c) Corey, E. J.; Erickson, B. W. J. Org. Chem.
1971, 36, 3553-3560.
(25) Smith, A. B.; Pitram, S. M.; Gaunt, M. J.; Kozmin, S. A. J. Am. Chem.
Soc. 2002, 124, 14516-14517.
We attempted to generate a methanedithiol complex
[(dppm)2Ru(η2-S(H)CH2S(H))][BF4]2 by reacting [(dppm)2Ru-
(η2-S2CH2)] with 2 equiv of HBF4‚Et2O. An instantaneous
reaction was apparent; however, NMR spectroscopy of the
products did not reveal the presence of a dithiol species. We
speculate that the dithiol complex, if at all formed, could be
1122 Inorganic Chemistry, Vol. 44, No. 4, 2005

CS2 as a Source of C1 Synthetic Units
Michael donor.26 On the other hand, its five-membered
counterpart (c-SCH2S(CH2)2-) has found fewer occurrences
in organic synthesis; this compound also undergoes nucleo-
philic addition27 and radical addition to alkenes.28
site of protonation was the dithioformate to afford the
methane dithiolate derivative. The lone pairs of electrons on
the sulfur atoms were unaffected in the protonation reaction.
Preparation and Characterization of the Dithioformic
Acid Complex of Ruthenium. The addition of CS2 to the
sterically impeding cis-[(dppe)2Ru(H)2] in toluene solution
resulted in a quantitative yield of the dithioformate derivative
trans-[(dppe)2Ru(H)(SC(S)H)]. This compound under ther-
mal conditions in toluene gave the double-inserted methane
dithiolate complex [(dppe)2Ru(η2-S2CH2)] as in the dppm
analogue.2 This reaction was not found to be as clean as in
the case of the dppm complex, perhaps due to the sterically
encumbered diphosphine ligand leading to certain unidenti-
fied decomposed material in addition to the methanedithiolate
complex.
Preparation of Alkyl Dithioformates. The dithioformate
moiety of trans-[(dppe)2Ru(H)(SC(S)H)] can be function-
alized using various electrophilic reagents such as RX (R )
Me, X ) OTf; R ) H2CdCHCH2, X ) BPh4; R ) C6H5CH2,
X ) BPh4) affording the corresponding alkyl dithioformate
derivatives (eq 3). The methyldithioformate complex trans-
[(dppe)2Ru(H)(SC(SMe)H)][OTf] has been crystallographi-
cally characterized,3 whereas the others were characterized
by NMR spectroscopy.
Dithioformic acid (L-6), an unstable molecule and a
potential interstellar species, has been studied extensively
by theoretical methods29 and microwave30 and IR spectros-
copy.31 Addition of 2 equiv of HBF4‚Et2O to a chloroform
solution of trans-[(dppe)2Ru(H)(SC(S)H)] resulted in an
instantaneous reaction to afford an unprecedented example
of a dithioformic acid complex of a transition metal, trans-
[(dppe)2Ru(H)(SC(H)SH)][BF4] (6) (eq 2). Our attempts to
isolate this derivative in the solid state only gave certain
decomposed material as evidenced by NMR spectroscopy.
The dithioformic acid complex was found to be stable in
solution for extended periods of time (2-3 days) without
undergoing any decomposition. The complex 6 shows a
quintet at δ -12.23 for the hydride and two broad singlets
at δ 5.78 and 7.69, respectively, one each for the SH and
We found that the alkyl dithioformate complexes trans-
[(dppe)2Ru(H)(SC(SR)H)][X] can be isolated in the solid
state and can be characterized provided the counterions are
bulky and noncoordinating type, e.g., OTf and BPh4. The
free alkyl dithioformates can be released from the respective
complexes via substitution of the alkyl dithioformate by (a)
H2 or (b) CH3CN. In the substitution with H2 the free alkyl
dithioformates were obtained only in small quantities whereas,
with CH3CN, the free esters were obtained in quantitative
yields. In both of these pathways, the resulting hydride
complexes, trans-[(dppe)2Ru(H)(η2-H2)]+ and trans-[(dppe)2-
Ru(H)(CH3CN)]+, are dead ends from where the starting
ruthenium dihydride complex cis-[(dppe)2Ru(H)2] cannot be
recovered.
Thus, using the above protocol, we were able to isolate
the free esters, methyl dithioformate, allyl dithioformate (L-
7), and benzyl dithioformate (L-8), and characterize them
spectroscopically. Gallagher et al.16 synthesized benzyl
dithioformate by direct thionation of the corresponding
thioformate (PhCH2SC(O)H)33 using Lawesson’s reagent.
Both methyl and benzyl dithioformates are potential 1,3-
dipolarophiles and have been utilized to synthesize C(2)-
unsubstituted penems from â-lactam-based oxazolidinones.
We employed a slightly different strategy for the recovery
of the starting ruthenium dihydride complex. When trans-
[(dppe)2Ru(H)(SC(S)H)] was reacted with the simple alkyl
halides (MeI, H2CdCHCH2Br, or C6H5CH2Br), the free alkyl
1
SCH fragments of the dithioformic acid in the H NMR
spectrum. The two broad singlets for the dithioformic acid
3
resolve into doublets at low temperatures with J(H,H) )
13.7 Hz. The 31P{1H} NMR spectrum shows only one singlet
at δ 63.4 indicating that all the four P atoms are equivalent.
It is interesting to compare the reactivity of trans-[(dppe)2Ru-
(H)(SC(S)H)] and a somewhat analogous osmium derivative
[(PiPr3)2Os(H)(CO)(η2-S2CH)]32 with HBF4‚Et2O. In the case
of the osmium complex, protonation in CD2Cl2 gave the
corresponding dihydrogen complex, and in Et2O solvent, the
(26) Amat, M.; Pe´rez, M.; Llor, N.; Bosch, J. Org. Lett. 2002, 4, 2787-
2790.
(27) Aggarwal, V. K.; Gu¨ltekin, Z.; Grainger, R. S.; Adams, H.; Spargo,
P. L. J. Chem. Soc., Perkin Trans. 1 1998, 17, 2771-2782.
(28) Batyarbaev, N. A.; Zorin, V. V.; Zolt-Skii, S. S.; Rakhmankulov, D.
L. Zh. Org. Khim. 1981, 17, 1934-1937.
(29) (a) Nguyen, M. T.; Nguyen, T. L.; Le, H. T. J. Phys. Chem. A 1999,
103, 5758-5765. (b) Huang, J.-H.; Han, K.-L.; Zhu, R.-S.; He, G.-
Z.; Lou, N.-Q. J. Phys. Chem. A 1998, 102, 2044-2049. (c) Smeyers,
Y. G.; Villa, M.; Ca´rdenas-Jiro´n, G. I.; Toro-Labbe´, A. J. Mol. Struct.
(THEOCHEM) 1998, 426, 155-163. (d) Jemmis, E. D.; Giju, K. T.;
Leszczynski, J. J. Phys. Chem. A 1997, 101, 7389-7395. (e) Xie, X.;
Tao, Y.; Cao, H.; Duang, W. Chem. Phys. 1996, 213, 133-137. (f)
Remko, M.; Liedl, K. R.; Rode, B. M. Chem. Phys. Lett. 1996, 263,
379-384.
(30) (a) Bak, B.; Nielson, O. J.; Svanholt, H. J. Mol. Spectrosc. 1978, 69,
401-408. (b) Bak, B.; Nielson, O. J.; Svanholt, H.; Christiansen, J. J.
J. Mol. Spectrosc. 1979, 75, 134-143.
(31) Ioannoni, F.; Moule, D. C.; Goddard, J. D.; Clouthier, D. J. J. Mol.
Spectrosc. 1989, 197, 159-170 and references therein.
(32) Albe´niz, M. J.; Buil, M. L.; Esteruelas, M. A.; Lo´pez, A. M.; Oro, L.
A.; Zeier, B. Organometallics 1994, 13, 3746-3748.
(33) Bax, P. C.; Holsboer, D. H.; van der Veek, A. P. M. Recl. TraV. Chim.
Pays-Bas 1971, 90, 562-567.
Inorganic Chemistry, Vol. 44, No. 4, 2005 1123

Gandhi and Jagirdar
Scheme 3
Scheme 4
compounds. Thus, the strategy of employing bulky, non-
coordinating counterions proved successful in isolating these
novel species in the solid state (Scheme 4).
dithioformate and trans-[(dppe)2Ru(H)X] (X ) I or Br) were
obtained in a very facile reaction via the intermediacy of
trans-[(dppe)2Ru(H)(SC(SR)H)][X] that was observed NMR
spectroscopically (Scheme 3). The starting cis-[(dppe)2Ru-
(H)2] was recovered via reaction of trans-[(dppe)2Ru(H)X]
with NaBH4 in a THF-methanol solution. Thus, by employ-
ing a good coordinating ligand as the counterion in the
hydride alkyl dithioformate complex, it is possible to obtain
a precursor from which the ruthenium dihydride complex
cis-[(dppe)2Ru(H)2] could be recovered.
Conclusions
In conclusion, CS2 has been inserted into M-H bonds of
ruthenium dihydride complexes to obtain either methane-
dithiolate or dithioformate derivatives. The methanedithiolate
moiety can be functionalized using various electrophiles, and
the corresponding organic compounds, e.g., bis(alkylthio)-
methanes or 1,3-dithianes, could be obtained in quantitative
yield. On the other hand, the dithioformate species can also
be functionalized using various electrophiles and the corre-
sponding organic moieties were obtained in quantitative
yields. In both of these pathways, the starting ruthenium
dihydride complexes have been regenerated thus making the
processes attractive. Thus, CS2 has been used as a source of
the C1 synthetic unit for the generation of useful organic
compounds.
Reaction of Hydride Dithioformate Complex with
XRX. In an attempt to prepare bimetallic complexes using
a linker, e.g., [(dppe)2Ru(H)(SCH(S)(CH2)n(S)HCS)(H)Ru-
(dppe)2]2+, we examined the reactivity of the dithioformate
complex with alkaneditriflates. Solutions of trans-[(dppe)2Ru-
(H)(SC(S)H)] in CH2Cl2 react with 5 equiv of propanedi-
triflate OTf-(CH2)3-OTf or butaneditriflate OTf-(CH2)4-
OTf to afford the respective ruthenium derivatives trans-
[(dppe)2Ru(H)(SC(S(CH2)3OTf)H)][OTf] (9) and trans-
[(dppe)2Ru(H)(SC(S(CH2)4OTf)H)][OTf] (10). No bimetallic
complexes were obtained. In addition, the isolated products
were accompanied by a few other unidentifiable species and
purification proved to be difficult. When the same reactions
were carried out using the respective halides, the derivatized
species were observed as intermediates; however, the isola-
tion of the products was accompanied by a few other
Acknowledgment. We gratefully acknowledge the De-
partment of Science & Technology of India for the financial
support and also for funding the procurement of a 400 MHz
NMR spectrometer under the “FIST” program.
Supporting Information Available: NMR stack plots of the
reactions. This material is available free of charge via the Internet
at http://pubs.acs.org.
IC048849U
1124 Inorganic Chemistry, Vol. 44, No. 4, 2005