Preparation of the hydrosulfido-bridged diruthenium complex [(η5-C5Me5)RuCl(μ-SH) 2Ru(η5-C5Me5)Cl] and its transformation into a cubane-type tetraruthenium sulfido cluster or triangular heterometallic RhRu2 sulfido cluster

Article abstract of DOI:10.1021/om960193s

The hydrosulfido-bridged diruthenium complex [Cp*RuCl(μ-SH)₂RuCp*Cl] (4; Cp* = η⁵-C₅Me₅) was obtained by the reaction of either [(Cp*Ru)₄(μ₃-Cl)₄] (1) or [Cp*RuCl(μ-Cl)₂-RuCp*Cl] with excess H₂S gas, while the reactions of 1 with thiols resulted in the formation of the thiolato-bridged diruthenium complexes [Cp*RuCl(μ-SR)₂RuCp*Cl] (R = Et (5a), C₆H₄-Me-p). When a solution of 4 in toluene was heated at reflux, the cubane-type tetraruthenium sulfido cluster [(Cp*Ru)₄(μ₃-S)₄]Cl₂ (6) was produced. On the other hand, treatment of 4 with 2 molar equiv of [RhCl(PPh₃)₃] in THF at room temperature afforded the triangular heterometallic sulfido cluster [(Cp*Ru)₂(μ₂-H)(μ₃-S) ₂RhCl₂(PPh₃)] (10). X-ray analyses have been undertaken to determine the detailed structures for 4, 5a, 6, and 10.

Full text of DOI:10.1021/om960193s

Organometallics 1996, 15, 3303-3309
3303
P r ep a r a tion of th e Hyd r osu lfid o-Br id ged Dir u th en iu m
Com p lex [(η5-C5Me5)Ru Cl(µ-SH)2Ru (η5-C5Me5)Cl] a n d Its
Tr a n sfor m a tion in to a Cu ba n e-Typ e Tetr a r u th en iu m
Su lfid o Clu ster or Tr ia n gu la r Heter om eta llic Rh Ru 2
Su lfid o Clu ster
Kohjiro Hashizume, Yasushi Mizobe, and Masanobu Hidai*
Department of Chemistry and Biotechnology, Graduate School of Engineering,
The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, J apan
Received March 13, 1996X
The hydrosulfido-bridged diruthenium complex [Cp*RuCl(µ-SH)2RuCp*Cl] (4; Cp* ) η5-
C5Me5) was obtained by the reaction of either [(Cp*Ru)4(µ3-Cl)4] (1) or [Cp*RuCl(µ-Cl)2-
RuCp*Cl] with excess H2S gas, while the reactions of 1 with thiols resulted in the formation
of the thiolato-bridged diruthenium complexes [Cp*RuCl(µ-SR)2RuCp*Cl] (R ) Et (5a ), C6H4-
Me-p). When a solution of 4 in toluene was heated at reflux, the cubane-type tetraruthenium
sulfido cluster [(Cp*Ru)4(µ3-S)4]Cl2 (6) was produced. On the other hand, treatment of 4
with 2 molar equiv of [RhCl(PPh3)3] in THF at room temperature afforded the triangular
heterometallic sulfido cluster [(Cp*Ru)2(µ2-H)(µ3-S)2RhCl2(PPh3)] (10). X-ray analyses have
been undertaken to determine the detailed structures for 4, 5a , 6, and 10.
In tr od u ction
sites of metalloproteins and heterogeneous hydrodes-
ulfurization catalysts,10 organic reactions and catalyses
using transition-metal-sulfur complexes have still been
poorly advanced.11 Another important feature of these
diruthenium complexes lies in their potential to serve
as starting compounds for the preparation of homo- and
heterometallic clusters with higher nuclearity. In this
context, we have already reported the reactions of
[Cp*Ru(µ-S2)(µ-SPri)2RuCp*], readily available from
[Cp*RuCl(µ-SPri)2RuCp*Cl], with [M(PPh3)4] (M ) Pt,
Pd), which lead to the formation of the heterometallic
sulfido clusters [(Cp*Ru)2(µ2-SPri)2(µ2-S)2Pt(PPh3)2] and
[(Cp*Ru)2(µ3-S)2Pd2(µ2-SPri)(SPri)(PPh3)].12
Extensive studies in this and other laboratories have
shown that the Ru(II) complex [(Cp*Ru)4(µ3-Cl)4] (1) and
the Ru(III) complex [Cp*RuCl(µ-Cl)2RuCp*Cl] (2; Cp*
) η5-C5Me5) are quite versatile precursors in the
preparation of polynuclear Ru-sulfur complexes con-
taining two or more Cp*Ru units. These include a series
of thiolato-bridged dinuclear complexes having a Ru-
(II)/Ru(II),1 Ru(II)/Ru(III),2 or Ru(III)/Ru(III) pair,1b,3
sulfido-capped triruthenium clusters,4 and a cubane-
type tetraruthenium sulfido cluster.5 This structural
diversity of the products arises from the nature of the
sulfur sources and reaction conditions as well as the
choice of the Ru precursor. Furthermore, intriguing
reactivities of diruthenium complexes such as [Cp*Ru-
(µ-SPri)2RuCp*], [Cp*Ru(µ-SPri)3RuCp*], and [Cp*RuCl-
(µ-SPri)2RuCp*][OTf] (OTf ) CF3SO3) toward terminal
alkynes,6 alkyl halides,1,7 and hydrazines8 have been
demonstrated. These substrates undergo unique trans-
formations at the diruthenium centers in these com-
plexes with retention of the bimetallic core,9 owing
apparently to the presence of the firmly bound thiolato
bridges. It might be emphasized that although the
chemistry of transition-metal-sulfur complexes is pro-
gressing rapidly because of their relevance to the active
In a previous paper dealing with a series of triruthe-
nium sulfido clusters derived from 1,4a we have briefly
shown that the reaction of 1 with (Me3Si)2S in the
presence of H2O affords a mixture of the fully character-
ized triangular cluster [(Cp*Ru)3(µ3-S)2(µ2-H)] (3) and
the diruthenium(III) complex [Cp*RuCl(µ-SH)2RuCp*Cl]
(4) determined by a preliminary X-ray diffraction study.
(6) (a) Nishio, M.; Matsuzaka, H.; Mizobe, Y.; Hidai, M. Organome-
tallics 1996, 15, 965. (b) Matsuzaka, H.; Takagi, Y.; Ishii, Y.; Nishio,
M.; Hidai, M. Organometallics 1995, 14, 2153. (c) Nishio, M.; Mat-
suzaka, H.; Mizobe, Y.; Tanase, T.; Hidai, M. Organometallics 1994,
13, 4214. (d) Matsuzaka, H.; Takagai, Y.; Hidai, M. Organometallics
1994, 13, 13. (e) Matsuzaka, H.; Koizumi, H.; Takagi, Y.; Nishio, M.;
Hidai, M. J . Am. Chem. Soc. 1993, 115, 10396. (f) Matsuzaka, H.;
Hirayama, Y.; Nishio, M.; Mizobe, Y.; Hidai, M. Organometallics 1993,
12, 36. (g) Koelle, U.; Rietmann, Chr.; Tjoe, J .; Wagner, T.; Englert,
U. Organometallics 1995, 14, 703.
(7) Takahashi, A.; Mizobe, Y.; Hidai, M. Chem. Lett. 1994, 371.
(8) Kuwata, S.; Mizobe, Y.; Hidai, M. Inorg. Chem. 1994, 33, 3619.
(9) Hidai, M.; Mizobe, Y.; Matsuzaka, H. J . Organomet. Chem. 1994,
473, 1.
(10) For recent reviews, see: (a) Dance, I.; Fisher, K. Prog. Inorg.
Chem. 1994, 41, 637. (b) Saito, T. In Early Transition Metal Clusters
with π-Donor Ligands; Chisholm, M. H., Ed.; VCH: New York, 1995;
Chapter 3. (c) Shibahara, T. Coord. Chem. Rev. 1993, 123, 73. (d)
Krebs, B.; Henkel, G. Angew. Chem., Int. Ed. Engl. 1991, 30, 769. (e)
Holm, R. H.; Ciurli, S.; Weigel, J . A. Prog. Inorg. Chem. 1990, 38, 1.
(11) Rakowski, DuBois, M. Chem. Rev. 1989, 89, 1.
X Abstract published in Advance ACS Abstracts, J uly 1, 1996.
(1) (a) Takahashi, A.; Mizobe, Y.; Matsuzaka, H.; Dev, S.; Hidai, M.
J . Organomet. Chem. 1993, 456, 243. (b) Ho¨rnig, A.; Englert, U.;
Koelle, U. J . Organomet. Chem. 1994, 464, C25. (c) Ho¨rnig, A.;
Rietmann, Chr.; Englert, U.; Wagner, T.; Koelle, U. Chem. Ber. 1993,
126, 2609. (d) Koelle, U.; Rietmann, Chr.; Englert, U. J . Organomet.
Chem. 1992, 423, C20.
(2) Dev, S.; Mizobe, Y.; Hidai, M. Inorg. Chem. 1990, 29, 4797.
(3) (a) Dev, S.; Imagawa, K.; Mizobe, Y.; Cheng, G.; Wakatsuki, Y.;
Yamazaki, H.; Hidai, M. Organometallics 1989, 8, 1232. (b) Hidai,
M.; Imagawa, K.; Cheng, G.; Mizobe, Y.; Wakatsuki, Y.; Yamazaki, H.
Chem. Lett. 1986, 1299.
(4) (a) Hashizume, K.; Mizobe, Y.; Hidai, M. Organometallics 1995,
14, 5367. (b) Mizobe, Y.; Hashizume, K.; Murai, T.; Hidai, M. J . Chem.
Soc., Chem. Commun. 1994, 1051.
(5) Houser, E. J .; Dev, S.; Ogilvy, A. E.; Rauchfuss, T. B.; Wilson,
S. R. Organometallics 1993, 12, 4678.
(12) Kuwata, S.; Mizobe, Y.; Hidai, M. J . Am. Chem. Soc. 1993, 115,
8499.
S0276-7333(96)00193-8 CCC: $12.00 © 1996 American Chemical Society
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3304 Organometallics, Vol. 15, No. 15, 1996
Hashizume et al.
In this paper, we wish to report the details of the
preparation and structure of this new hydrosulfido-
bridged diruthenium complex 4 along with its reactions
to give a cubane-type tetraruthenium sulfido cluster
and a trimetallic RhRu2 sulfido cluster. The X-ray
structure of the thiolato-bridged diruthenium(III) com-
plex [Cp*RuCl(µ-SEt)2RuCp*Cl] (5a ) is also described
in relation to that of 4.
Resu lts a n d Discu ssion
P r ep a r a tion of [Cp *Ru Cl(µ-SH)2Ru Cp *Cl] (4).
Previously we have found that the reaction of 1 with
(Me3Si)2S in THF at room temperature gives a mixture
of the triruthenium sulfido clusters [(Cp*Ru)3(µ3-S)(µ3-
Cl)] and 3.4a To confirm whether the hydrido ligand in
3 comes from the adventitious moisture in THF, we
investigated the reaction of 1 with (Me3Si)2S in the
presence of either H2O or D2O. As expected, this led to
the formation of 3 or its deuterido analog, and [(Cp*Ru)3-
(µ3-S)(µ3-Cl)] was no longer observed in the reaction
mixture. However, from this reaction another com-
pound containing the Cp*Ru unit was also produced in
moderate yield, which was subsequently characterized
to be the hydrosulfido-bridged diruthenium complex 4
or its deuteriosulfido analog by the X-ray crystal-
lography of 4 (vide infra). Since 4 seems to be formed
by the reaction of 1 with H2S generated in situ from
(Me3Si)2S and H2O, the reaction of 1 with H2S gas has
been investigated.
When a suspension of 1 in THF was stirred for 15 h
under an H2S atmosphere at room temperature, both 3
and 4 were formed in an approximately 1:1 molar ratio.
Evolution of H2 gas accompanied by the formation of 4
from 1 and H2S has been confirmed by the GLC analysis
of the gaseous phase. Analytically pure 4 was isolated
in 31% yield as dark brown crystals from the reaction
mixture by fractional crystallization (eq 1). It has also
been found that 4 can be prepared from 2 instead of 1
in 43% yield by analogous treatment of 2 with H2S gas
(eq 2).
F igu r e 1. Molecular structure of 4 with atom-numbering
scheme.
Ta ble 1. Selected Bon d Dista n ces a n d An gles in 4
a n d 5a
Bond Distances (Å) in 4
Ru-Ru*
Ru-S
Ru-C
2.822(1)
2.310(1)
2.197(5)-2.231(5)
Ru-Cl
Ru-S*
S-H(16)
2.441(2)
2.319(2)
1.18
Bond Angles (deg) in 4
Ru*-Ru-Cl
Ru*-Ru-S*
Cl-Ru-S*
88.34(4)
52.28(4)
88.89(6)
75.14(5)
106.4
Ru*-Ru-S
Cl-Ru-S
52.58(4)
89.09(6)
104.86(5)
109.5
S-Ru-S*
Ru-S-Ru
Ru-S-H(16)
Ru*-S-H(16)
Bond Distances (Å) in 5a
Ru(1)-Ru(2) 2.850(2) Ru(1)-Cl(1) 2.424(4)
Ru(1)-S(1)
Ru(2)-Cl(2)
Ru(2)-S(2)
Ru(2)-C
2.306(4)
2.426(4)
2.305(4)
2.18(1)-2.27(2) S(1)-C(1)
1.84(1)
Ru(1)-S(2)
Ru(2)-S(1)
Ru(1)-C
2.324(4)
2.321(4)
2.21(1)-2.31(1)
1.79(1)
S(2)-C(3)
Bond Angles (deg) in 5a
Ru(2)-Ru(1)-Cl(1) 100.7(1) Ru(2)-Ru(1)-S(1)
52.2(1)
Ru(2)-Ru(1)-S(2)
Ru(1)-Ru(2)-S(1)
S(1)-Ru(1)-S(2)
Ru(1)-S(1)-Ru(2)
Ru(2)-S(1)-C(1)
Ru(1)-S(2)-C(3)
51.7(1) Ru(1)-Ru(2)-Cl(2) 100.6(1)
51.7(1) Ru(1)-Ru(2)-S(2)
103.2(2) S(1)-Ru(2)-S(2)
76.1(1) Ru(1)-S(1)-C(1)
113.0(5) Ru(1)-S(2)-Ru(2)
111.7(5) Ru(2)-S(2)-C(3)
52.3(1)
103.3(2)
115.8(5)
76.0(1)
114.9(5)
The molecule consists of a crystallographically im-
posed inversion center at the midpoint of the Ru-Ru
vector. The Ru-Ru distance of 2.822(1) Å suggests the
presence of a Ru-Ru single bond and is comparable to
those in the thiolato-bridged analogs [Cp*RuCl(µ-
SR)2RuCp*Cl] (R ) Et (5a ; see below), Pri 13) and the
related thiolato-bridged complexes [Cp*RuR(µ-SPri)2-
RuCp*R] (R ) CtCC6H4Me-p (Tol),6f CH2CH2Ph14) and
[Cp*RuBr(µ-SPri)2RuCp*(CH2CH2Ph)],1a which fall in
the range 2.80-2.86 Å. This bonding interaction be-
tween the two Ru atoms accounts well for the dimag-
netic nature of these complexes containing two Ru(III)
centers. The plane defined by two Ru and two Cl atoms
is almost perpendicular to the Ru2S2 plane, with a
dihedral angle of 89.88(7)°. The other metrical param-
eters associated with the Ru2S2Cl2 core are not unusual,
and the position of the SH proton was located unequivo-
cally in the final difference Fourier map. A significant
difference in the structure of 4 from those of the thiolato-
bridged complexes shown above is the mutually trans
Str u ctu r e of 4. The structure of 4 has been unam-
biguously determined by a single-crystal X-ray analysis.
The ORTEP drawing is shown in Figure 1, and the
pertinent bond distances and angles are listed in
Table 1.
(13) Matsuzaka, H.; Takagi, Y.; Hidai, M. Unpublished results.
(14) Takahashi, A.; Mizobe, Y.; Tanase, T.; Hidai, M. J . Organomet.
Chem. 1995, 496, 109.
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A New Hydrosulfido-Bridged Diruthenium Complex
Organometallics, Vol. 15, No. 15, 1996 3305
Sch em e 1
configuration of the two Cp* ligands and the anti
orientation of the two bridging SH ligands with respect
to the Ru2S2 plane. In contrast, the thiolato complexes
cited above generally contain mutually cis Cp* ligands
together with syn-axial thiolato ligands with respect to
the slightly puckered Ru2S2 ring.15
The IR spectrum of 4 shows a weak band at 2462 cm-1
characteristic of ν(SH), which shifts to 1792 cm-1 in the
deuterio analog prepared from the reaction of 1 with
(Me3Si)2S/D2O (see the Experimental Section). It is
noteworthy that the 1H NMR spectrum of 4 recorded
for a CDCl3 solution indicates the presence of two
isomers in about 1:1 ratio in the solution state. One
isomer exhibits one singlet Cp* resonance at 1.71 ppm
with 30H intensity, while the other isomer shows two
singlets at 1.68 and 1.74 ppm due to the Cp* ligand,
both with 15H intensities. The SH protons in these
isomers resonate at 5.11 and 5.13 ppm, each having 2H
1
intensity. These H NMR data may be interpreted in
terms of the syn-anti isomerization associated with the
bridging SH groups shown in eq 3. Such isomerization
involving the sulfur inversion occurs ubiquitously in
thiolato- or hydrosulfido-bridged complexes, which has
been well documented already.16 As for the related
diruthenium complex [Cp*Ru(µ-SH)2(µ-dppm)RuCp*]
(dppm ) Ph2PCH2PPh2) prepared from the reaction of
[Cp*Ru(µ-OMe)2(µ-dppm)RuCp*] with H2S, the presence
of the syn and anti isomers in a 4:1 ratio in solution
F igu r e 2. Molecular structure of 5a with atom-numbering
scheme.
the reaction of 1 with TolSSTol.15 It is to be noted that
the reaction of 2 with excess TolSH in CH2Cl2 results
in the formation of the triply bridged diruthenium(III)
complex [Cp*Ru(µ-STol)3RuCp*]Cl.3 Apart from the
arenethiolato complex 5b having the unexpected trans-
anti structure,15 it has been presumed that the diru-
thenium(III) complexes of this type containing two
alkanethiolato bridges generally consist of mutually cis
Cp* ligands and syn-axial thiolato groups (vide supra).
However, full characterization of the complexes [Cp*RuX-
(µ-SR)2RuCp*X] (R ) alkyl, X ) halide) by X-ray
analysis has not yet been achieved. Now we have
succeeded in preparing single crystals of 5a , and
therefore, an X-ray diffraction study has been under-
taken.
The molecular structure of 5a depicted in Figure 2
clearly shows that 5a has mutually cis Cp* ligands and
syn-axial SEt groups, as expected. Selected bond dis-
tances and angles are listed in Table 1. The Ru-Ru
distance at 2.850(2) Å indicates the presence of a single
bond between these two atoms, and the Ru2S2 ring is
slightly puckered with a dihedral angle of 168.3(2)°
around the Ru-Ru bond. Metrical parameters with
respect to the Ru2S2Cl2 core in 5a are unexceptional, if
compared with those in the other well-defined Ru(III)/
Ru(III) complexes of this type.
1
has been suggested from the H NMR criteria.17 Ap-
pearance of the SH resonances for 4 at unusually low
field should be noteworthy, since the SH proton in
transition-metal hydrosulfido complexes generally reso-
nates in a much higher region, viz. a few ppm higher
than TMS.18
P r ep a r a tion of [Cp *Ru Cl(µ-SR)2Ru Cp *Cl] (5)
a n d X-r a y Str u ctu r e of 5a (R ) Et). Treatment of 1
with excess EtSH in place of H2S for 15 h in THF at 50
°C resulted in the formation of the Ru(III)/Ru(III)
complex [Cp*RuCl(µ-SEt)2RuCp*Cl] (5a ), which was
isolated as red-purple crystals in 51% yield. The
reaction of 1 with TolSH in THF proceeded at room
temperature, and the corresponding STol complex
[Cp*RuCl(µ-STol)2RuCp*Cl] (5b) was obtained as green
crystals in 51% yield (Scheme 1). Complex 5a was
isolated previously from the reaction of 2 with Me3-
SiSEt,3,19 whereas 5b was found to be available from
(15) The X-ray analysis of [Cp*RuCl(µ-STol)2RuCp*Cl] (5b) has
revealed quite recently that this complex has an unexpected trans-
anti structure: Matsuzaka, H.; Ogino, T.; Hidai, M. Unpublished
results.
(16) See, for example: Abel, E. W.; Bhargava, S. K.; Orrell, K. G.
Prog. Inorg. Chem. 1984, 32, 1.
(17) Koelle, U.; Ho¨rnig, A.; Englert, U. J . Organomet. Chem. 1992,
438, 309.
(18) An SH resonance at exceptionally low field was previously
observed for, e.g. [(η5-MeC5H4)2Ti(SH)2] (3.1 ppm): Ruffing, C. J .;
Rauchfuss, T. B. Organometallics 1985, 4, 524.
Con ver sion of Dir u th en iu m Com p lex 4 in to th e
Cu ba n e-Typ e Tetr a r u th en iu m Clu ster [(Cp *Ru )4-
(µ3-S)4]Cl2 (6). When a solution of 4 in toluene was
heated under reflux conditions for 7 h, the cubane-type
tetraruthenium sulfido cluster 6 precipitated as a black
solid. Concurrent formation of H2 gas has been con-
firmed by the GLC study. After recrystallization from
MeCN/ether, 6‚MeCN has been isolated as dark brown
(19) We have recently found that the mixture from the reaction of
2 with EtSH also contains 5a together with uncharacterizable byprod-
uct(s), which is in contrast to our previous result that 5a was not
available from the reaction of 2 with EtSH.3
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3306 Organometallics, Vol. 15, No. 15, 1996
Hashizume et al.
F igu r e 4. Bonding schemes in the [(Cp′Ru)4(µ3-S)4]2+
cubane clusters: (a) 7-9; (b) 6 in the solid state; (c) 6 in
the solution state at -40 and -90 °C.
Ta ble 2. Selected In ter a tom ic Dista n ces a n d
An gles in 6‚MeCN
Interatomic Distances (Å)
Ru(1)-Ru(2) 2.858(1)
Ru(1)-S(1)
Ru(1)-S(3)
Ru(2)-S(2)
Ru(3)-S(1)
Ru(3)-S(4)
Ru(4)-S(3)
Ru(1)-C
2.269(2)
2.329(3)
2.265(3)
2.303(2)
2.358(3)
2.293(3)
2.333(3)
2.232(8)-2.287(9) Ru(2)-C
2.193(8)-2.28(1) Ru(4)-C
Ru(3)-C
Ru(1)‚‚‚Ru(4) 3.47
Ru(2)‚‚‚Ru(4) 3.25
Ru(2)‚‚‚Ru(3) 3.46
Ru(3)‚‚‚Ru(4) 3.22
F igu r e 3. Structure of the cation in 6‚MeCN with atom-
numbering scheme.
Interatomic Angles (deg)
S(1)-Ru(1)-S(2)
S(2)-Ru(1)-S(4)
S(1)-Ru(2)-S(4)
S(1)-Ru(3)-S(3)
S(3)-Ru(3)-S(4)
S(2)-Ru(4)-S(4)
Ru(1)-S(1)-Ru(2)
Ru(2)-S(1)-Ru(3)
Ru(1)-S(2)-Ru(4)
Ru(1)-S(3)-Ru(3)
Ru(3)-S(3)-Ru(4)
Ru(2)-S(4)-Ru(4)
101.31(9)
78.08(9)
79.59(9)
102.71(9)
89.50(10)
89.72(9)
77.40(7)
97.50(9)
96.96(9)
76.78(8)
89.9(1)
S(1)-Ru(1)-S(3)
S(1)-Ru(2)-S(2)
S(2)-Ru(2)-S(4)
S(1)-Ru(3)-S(4)
S(2)-Ru(4)-S(3)
S(3)-Ru(4)-S(4)
Ru(1)-S(1)-Ru(3)
Ru(1)-S(2)-Ru(2)
Ru(2)-S(2)-Ru(4)
Ru(1)-S(3)-Ru(4)
Ru(2)-S(4)-Ru(3)
Ru(3)-S(4)-Ru(4)
101.57(9)
102.43(9)
88.82(9)
79.05(9)
79.48(9)
91.04(10)
77.09(7)
76.84(8)
90.67(9)
97.27(10)
95.12(10)
88.22(9)
single crystals in 35% yield (eq 4),whose structure has
89.88(10)
been established by the X-ray diffraction. The structure
of the cation in 6 is shown in Figure 3, while the selected
interatomic distances and angles are summarized in
Table 2.
taining the three relatively short Ru-Ru edges along
with the three much longer Ru-Ru edges. The former,
at ca. 2.8 Å, is diagnostic of a bonding contact, while
the latter, at ca. 3.5 Å or more, is indicative of the
absence of any bonding interaction (Figure 4a). The
presence of three metal-metal bonds in these clusters
corresponds well to the structure expected for an
electron count of 66 from a simple EAN rule count. In
contrast, as illustrated in Figure 4b, the Ru4 tetrahedron
in 6 consists of only two bonding Ru-Ru contacts (Ru-
(1)-Ru(2), 2.858(1) Å; Ru(1)-Ru(3), 2.849(1) Å). As for
the remaining four Ru-Ru edges, two are apparently
nonbonding Ru‚‚‚Ru contacts (Ru(2)‚‚‚Ru(3), 3.46 Å; Ru-
(1)‚‚‚Ru(4), 3.47 Å) and the other two are significantly
shorter than these two (Ru(2)‚‚‚Ru(4), 3.25 Å; Ru(3)‚‚‚
Ru(4), 3.22 Å).
The chemistry of metal-sulfur cubane clusters is
currently the subject of intense study, and a significant
number of homo- and heterometallic clusters of this type
are known.20 For ruthenium, clusters of the type
[(Cp′Ru)4(µ3-S)4]n+ (Cp′ ) η5-C5RxH5-x, n ) 0, 2) have
already been prepared, and their structures have been
determined in detail by Rauchfuss and his co-workers.
Thus, the clusters [{(η5-C5H4R)Ru}4(µ3-S)4] (R ) Me,21
SiMe321a) have been synthesized by condensation of the
monoruthenium complexes [(η5-C5H4R)Ru(PPh3)2(SH)],
while [(Cp*Ru)4(µ3-S)4]5 has been obtained by treatment
of 1 with NaSH. Cationic cubane clusters analogous to
5
6 have also been isolated: [(Cp*Ru)4(µ3-S)4][PF6]2 and
Mobility of the metal-metal bonds in the mixed-
valence cubane-type clusters has recently been demon-
[{(η5-C5H4R)Ru}4(µ3-S)4]2+ (7, R ) Me;21a,22 8, R )
SiMe321a) by oxidation of the corresponding neutral
clusters and [(CpRu)2(Cp*Ru)2(µ3-S)4]2+ (9)23 from the
reaction of [(Cp*Ru)2S4] with 2 molar equiv of [CpRu-
(MeCN)3]+. Reduction of 9 afforded another well-
defined neutral cluster, [(CpRu)2(Cp*Ru)2(µ3-S)4].23
For the cationic cubane clusters, X-ray structures are
available for 7-9. These 66-electron clusters are all
isostructural with respect to the Ru4 tetrahedron con-
strated well for the formal RuIII2RuIV clusters 7,21a,22
2
8,21a and 923 as well as the IrIII2IrIV cluster [(Cp*Ir)4-
2
(µ3-S)4]2+ 24
.
Also for 6, with a formal RuIII2RuIV core,
2
the 1H NMR spectrum in CDCl3 recorded at room
temperature exhibits one sharp singlet at 1.88 ppm due
to the Cp* ligands, indicating that all Cp*Ru sites are
equivalent under these conditions. This indicates that
rapid migration of the metal-metal bonds in 6 is
occurring in solution. When the temperature was
lowered, this sharp singlet separated into two broad
singlets. Thus, the spectra recorded at -40 and -55
°C in CDCl3 and at -90 °C in CD2Cl2 all showed two
(20) Harris, S. Polyhedron 1989, 8, 2843.
(21) (a) Houser, E. J .; Rauchfuss, T. B.; Wilson, S. R. Inorg. Chem.
1993, 32, 4069. (b) Amarasekera, J .; Rauchfuss, T. B.; Wilson, S. R.
J . Chem. Soc., Chem. Commun. 1989, 14.
(22) Houser, E. J .; Amarasekera, J .; Rauchfuss, T. B.; Wilson, S. R.
J . Am. Chem. Soc. 1991, 113, 7440.
(23) Feng, Q.; Rauchfuss, T. B.; Wilson, S. R. J . Am. Chem. Soc.
1995, 117, 4702.
(24) Venturelli, A.; Rauchfuss, T. B. J . Am. Chem. Soc. 1994, 116,
4824.
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A New Hydrosulfido-Bridged Diruthenium Complex
Organometallics, Vol. 15, No. 15, 1996 3307
broad signals at 1.75 and 1.90 ppm with almost the
same intensities. This finding is not consistent with a
solid structure having three types of Cp*Ru units
(Figure 4b) and probably suggests that cluster 6 has the
structure shown in Figure 4c, containing only one
relatively rigid Ru-Ru bond as a transient, at least in
this temperature region, although the details are still
uncertain. This difference in the structure of the Ru4
core observed for 6 from the other cationic Ru4S4
cubanes presumably arises from the steric repulsion
between the four Cp* ligands in 6, which may be
significantly greater than that in 7 and 8, containing
the monosubstituted cyclopentadienyl ligands exclu-
sively, and in 9, having two nonsubstituted Cp ligands
and two Cp* ligands. It should be noted that the
repulsive interactions between the Cp* ligands have
previously been invoked to account for the Ru-Ru
bonding distances observed in the selenide cubane
cluster [(Cp*Ru)4(µ3-Se)4] being longer than those in the
telluride cluster [{(MeC5H4)Ru}4(µ3-Te)4], despite the fact
that the Ru-Se distances are shorter than the Ru-Te
distances by ca. 8%, owing to the chalcogen sizes.5
P r ep a r a tion a n d X-r a y Str u ctu r e of th e Tr ia n -
gu la r Rh Ru 2 Su lfid o Clu ster [(Cp *Ru )2(µ2-H)(µ3-
S)2Rh Cl2(P P h 3)] (10). Oxidative addition of an S-H
bond to a low-valent transition-metal center is one of
the general methods of preparing thiolato or hydrosul-
fido complexes. Reactions of certain low-valent noble-
metal complexes with 4 containing bridging SH groups
have therefore been investigated to synthesize new
mixed-metal sulfido clusters. Now we have found that
the reaction of 2 molar equiv of [RhCl(PPh3)3] (11) with
4 readily affords a triangular RhRu2 cluster with two
capped sulfido ligands, 10, in moderate yield (eq 5),whose
F igu r e 5. Molecular structure of 10 with atom-numbering
scheme. The solvating THF molecule is omitted for clarity.
Ta ble 3. Selected Bon d Dista n ces a n d
An gles in 10
Bond Distances (Å)
Rh-Ru(1)
Rh-Cl(1)
Rh-S(1)
Rh-P
2.790(3)
2.435(6)
2.301(6)
2.320(7)
Rh-Ru(2)
Rh-Cl(2)
Rh-S(2)
2.756(3)
2.420(6)
2.256(6)
Ru(1)-Ru(2) 2.707(3)
Ru(1)-S(1) 2.276(7)
Ru(1)-S(2)
Ru(2)-S(2)
2.259(6)
2.279(6)
2.15(2)-2.26(3)
Ru(2)-S(1) 2.291(6)
Ru(1)-C
2.17(3)-2.24(3) Ru(2)-C
Bond Angles (deg)
Ru(1)-Rh-Ru(2)
Cl(1)-Rh-S(1)
Cl(1)-Rh-P
58.43(7)
92.8(2)
91.4(2)
133.8(2)
91.4(2)
85.6(2)
60.15(7)
51.8(2)
53.7(2)
61.42(6)
52.2(1)
53.1(2)
Cl(1)-Rh-Cl(2)
95.9(2)
129.9(2)
91.7(2)
88.1(2)
175.8(2)
Cl(1)-Rh-S(2)
Cl(2)-Rh-S(1)
Cl(2)-Rh-P
S(1)-Rh-P
Cl(2)-Rh-S(2)
S(1)-Rh-S(2)
S(2)-Rh-P
Rh-Ru(1)-Ru(2)
Rh-Ru(1)-S(2)
Ru(2)-Ru(1)-S(2)
Rh-Ru(2)-Ru(1)
Rh-Ru(2)-S(2)
Ru(1)-Ru(2)-S(2)
Rh-Ru(1)-S(1)
Ru(2)-Ru(1)-S(1)
S(1)-Ru(1)-S(2)
Rh-Ru(2)-S(1)
Ru(1)-Ru(2)-S(1)
S(1)-Ru(2)-S(2)
52.8(2)
53.9(2)
92.0(2)
53.3(2)
53.4(2)
53.1(2)
Rh atom is trigonal bipyramidal with the P and S(1)
atoms in two apical positions. The Rh-Cl, Rh-S, and
Rh-P bond distances are all unexceptional. Two Cp*
ligands bind to two Ru atoms, where both Cp* planes
are almost perpendicular to the RhRu2 plane. In
addition to the triruthenium cluster 3, the closo tr-
irhodium cluster with two µ3-sulfido ligands [(Cp*Rh)3-
(µ3-S)2]2+ has been reported recently.26 However, to our
knowledge, the RhRu2(µ3-S)2 core observed for 10 is
unprecedented.
structure has been verified by an X-ray diffraction study
using a single crystal of 10‚THF. From the reaction of
a stoichiometric amount of 11 with 4, a mixture of
several products, including 10, was obtained; however,
isolation of 10 from this mixture in a pure form was
unsucessful. Oxidative addition of H2S to 11 has
previously been demonstrated to give the dirhodium
complex [RhCl(H)(µ-SH)(PPh3)2]2.25
1
In the H NMR spectrum of 10, the resonance due to
An ORTEP drawing of 10 is shown in Figure 5, and
selected bond distances and angles are collected in Table
3. Cluster 10 has a triangular RhRu2 core, for which
two Rh-Ru distances at 2.790(3) and 2.756(3) Å as well
as the Ru-Ru distance at 2.707(3) Å are all consistent
with the metal-metal bond order of unity. This core
structure is diagnostic of the diamagnetic nature of 10,
containing one Rh(III) and two Ru(III) centers. The
RhRu2 plane is capped from both sides by the µ3-sulfido
ligands almost symmetrically, but the M-S bond lengths
are all somewhat shorter for S(2) than for S(1). Ne-
glecting the two Rh-Ru bonds, the geometry around the
the Cp* methyl protons appeared as one singlet, indi-
cating the equivalent nature of the two Cp* ligands.
This is in accordance with the solid-state structure
having a mirror plane that bisects the Ru-Ru bond. The
1H NMR spectrum has also demonstrated the presence
of one hydrido ligand in 10. Although the position of
the hydrido ligand could not be located by X-ray crystal-
lography, the singlet nature of the hydrido resonance
as well as the equivalence of the two Cp*Ru units
(26) Nishioka, T.; Isobe, K. Chem. Lett. 1994, 1661. The related Rh-
(III) cluster [Rh3(µ3-S)2(µ2-S)(µ2-Cl)2(PEt3)6]+ is also known, which
contains a Rh3(µ3-S)2 core without direct Rh-Rh interactions.27
(27) Cecconi, F.; Ghilardi, C. A.; Midollini, S.; Orlandini, A.; Vacca,
A.; Ramirez, J . A. Inorg. Chim. Acta 1989, 155, 5.
(25) Mueting, A. M.; Boyle, P.; Pignolet, L. H. Inorg. Chem. 1984,
23, 44.
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3308 Organometallics, Vol. 15, No. 15, 1996
Ta ble 4. X-r a y Cr ysta llogr a p h ic Da ta for 4, 5a , 6‚MeCN, a n d 10‚THF
Hashizume et al.
4
5a
6‚MeCN
10‚THF
(a) Crystal Data
C24H40Cl2S2Ru2
665.8
formula
fw
C20H32Cl2S2Ru2
609.6
C42H63NCl2S4Ru4
1185.4
C42H54OCl2PS2RhRu2
1045.9
cryst syst
space group
cryst color
cryst dimens, mm
a, Å
monoclinic
P21/a (No. 14)
dark brown
0.2 × 0.3 × 0.4
9.466(1)
13.985(1)
9.589(1)
90.00
116.33(1)
90.00
1137.8(3)
2
triclinic
monoclinic
P21/n (No. 14)
dark brown
0.3 × 0.3 × 0.5
12.146(2)
26.166(6)
14.840(2)
90.00
monoclinic
P21/c (No. 14)
dark brown
0.15 × 0.15 × 0.25
18.910(4)
10.860(5)
21.775(3)
90.00
97.86(1)
90.00
4429(2)
4
P1h (No. 2)
dark brown
0.1 × 0.3 × 0.9
11.192(4)
15.448(4)
8.707(3)
106.32(3)
112.88(3)
80.84(3)
1328.9(9)
2
b, Å
c, Å
R, deg
â, deg
101.41(1)
90.00
4623(1)
γ, deg
V, Å3
Z
D
4
calc, g cm-3
1.779
1.664
1.703
1.568
F(000), e
612
17.49
676
15.05
2384
16.08
2180
13.22
µ(Mo KR), cm-1
(b) Data Collection
Rigaku AFC7R
graphite
diffractometer
monochromator
radiation (λ, Å)
temp
Mo KR (0.7107)
room temp
ω-2θ
scan type
scan rate, deg min-1
2θmax, deg
16.0
55.0
+h,+k,(l
2720
55.0
+h,(k,(l
6112
55.0
50.0
rflns measd
no. of unique rflns
transmissn factors
+h,+k,(l
10 888
+h,+k,(l
6846
0.790-1.00
0.555-1.00
0.832-1.00
0.801-1.00
(c) Solution and Refinements
no. of data used (I > 3.0σ(I))
no. of variables
2252
118
3610
271
5584
478
2912
460
R
Rw
0.029
0.042
0.92
0.068
0.058
2.1
0.060
0.035
2.0
0.067
0.062
1.4
max residual, e Å-3
and 3 as the major products in a ca. 1:1 molar ratio. The
residue was extracted with THF (20 mL), and the extract was
concentrated. Addition of hexane (10 mL) yielded 4 as dark
brown crystals (38 mg, 31%). 1H NMR (CDCl3): δ 1.68 (s, 15H,
Cp*), 1.71 (s, 30H, Cp*), 1.74 (s, 15H, Cp*), 5.11 (s, 2H, SH),
5.13 (s, 2H, SH). IR (KBr): ν(SH) 2462 cm-1 (w). Anal. Calcd
for C20H32S2Ru2: C, 39.40; H, 5.29. Found: C, 39.04; H, 5.23.
(b) After H2S gas was bubbled through a suspension of 2
(434 mg, 0.706 mmol) in THF (30 mL) for 5 min, the mixture
was stirred for 15 h at room temperature under H2S. The
mixture was dried in vacuo, and the residue was extracted
with benzene (50 mL). Addition of hexane (30 mL) to the
concentrated extract afforded 4 as dark brown crystals (186
mg, 43%).
suggests that the hydrido ligand bridges the Ru-Ru
bond. The chemical shift observed for this hydride is
comparable to that in the sulfido-capped triruthenium
cluster 34a (10, δ -22.2; 3, δ -22.3), although the Ru-
Ru bond supported by the hydride bridge in 10 (2.707-
(3) Å) is considerably shorter than that in 3 (2.851(3)
Å).
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All manipulations were carried
out under an atmosphere of nitrogen by the use of Schlenk
techniques. Solvents were dried by common procedures and
degassed before use. IR and 1H NMR spectra were recorded
on Shimadzu FTIR-8100M and J EOL EX-270 spectrometers,
respectively. Evolution of H2 gas has been verified by GLC
analysis using a Shimadzu GC-8A gas chromatograph equipped
with a Molecular Sieve 13X column. Elemental analyses were
done with a Perkin-Elmer 2400II CHN analyzer. Complexes
1,28 2,29 and 1130 were prepared according to the literature
methods, while organic and inorganic reagents were used as
received. The yields of the compounds below have been
calculated by (mol of Ru in the product)/(mol of Ru charged).
P r ep a r a tion of [Cp *Ru Cl(µ-SH)2Ru Cp *Cl] (4). (a) Hy-
drogen sulfide gas was passed through a suspension of 1 (110
mg, 0.101 mmol) in THF (10 mL) for 5 min, and the mixture
was continuously stirred for 15 h at room temperature under
H2S. The GLC analysis of the gaseous phase revealed the
evolution of H2 gas during the reaction. From the resulting
mixture all the volatile materials were removed in vacuo. The
1H NMR spectrum of the residue revealed the presence of 4
P r ep a r a tion of th e Deu ter io An a log of 4. To a suspen-
sion of 1 (98.3 mg, 0.0905 mmol) in THF (10 mL) was added
D2O (4.8 µL, 0.24 mmol) and (Me3Si)2S (51 µL, 0.24 mmol),
and the mixture was stirred for 15 h at room temperature.
The resulting mixture was evaporated to dryness in vacuo, and
the residue was extracted with THF (20 mL). Addition of
hexane to the concentrated filtrate gave the product as dark
1
brown crystals (45.1 mg, 41%). IR and H NMR spectra have
shown that the product contains the SD and SH groups in an
approximately 1:1 ratio. IR (KBr): ν(SH) 2462 (w); ν(SD) 1792
cm-1 (w). 1H NMR (CDCl3): δ 1.68 (s, 15H, Cp*), 1.71 (s, 30H,
Cp*), 1.74 (s, 15H, Cp*), 5.11 (s, 1H, SH), 5.13 (s, 1H, SH).
P r ep a r a tion of [Cp *Ru Cl(µ-SEt)2Ru Cp *Cl] (5a ). To a
suspension of 1 (127 mg, 0.117 mmol) in THF (5 mL) was
added EtSH (150 µL, 2.88 mmol), and the mixture was stirred
at 50 °C for 15 h. The resultant red-purple suspension was
filtered and hexane (10 mL) was added to the filtrate, giving
5a as red-purple crystals (79 mg, 51%). The product was
characterized by comparing its 1H NMR spectrum with that
of the authentic compound.3a
(28) Fagan, P. J .; Ward, M. D ; Calabrese, J . C. J . Am. Chem. Soc.
1989, 111, 1698.
(29) Oshima, N.; Suzuki, H.; Moro-oka, Y. Chem. Lett. 1984, 1161.
(30) Osborn, J . A.; Wilkinson, G. Inorg. Synth. 1967, 10, 67.
P r ep a r a tion of [Cp *Ru Cl(µ-STol)2Ru Cp *Cl] (5b).
A
suspension containing 1 (121 mg, 0.111 mmol) and TolSH (55
+
+

A New Hydrosulfido-Bridged Diruthenium Complex
Organometallics, Vol. 15, No. 15, 1996 3309
mg, 0.44 mmol) in THF (7 mL) was stirred for 15 h at room
temperature. The green suspension obtained was filtered off,
and the remaining green solid was crystallized from CH2Cl2/
hexane (3 mL/10 mL); yield 81 mg (51%). The 1H NMR
spectrum was identical with that of the authentic compound,
which was fully characterized by an X-ray diffraction study.15
P r ep a r a tion of [(Cp *Ru )4(µ3-S)4]Cl2‚MeCN (6‚MeCN).
A yellow-brown solution of 4 (66 mg, 0.11 mmol) in toluene
(20 mL) was heated at reflux for 7 h. The black solid that
deposited was filtered off and recrystallized from MeCN/ether
(5 mL/10 mL), affording 6‚MeCN as dark brown crystals (22
mg, 35%). 1H NMR (CDCl3, room temperature): δ 1.88 (s,
60H, Cp*); see also the test. Anal. Calcd for C42H63NS4Cl2-
Ru4: C, 42.56; H, 5.36; N, 1.18. Found: C, 42.90; H, 5.50; N,
0.80.
reflections were monitored every 150 reflections during data
collection, which revealed no significant decay for all crystals.
Intensity data were corrected for Lorentz and polarization
effects and for absorption (ψ scans). Details of crystal and data
collection parameters are summarized in Table 4.
Structure solution and refinements were carried out by
using the teXsan program package.31
The positions of the non-
hydrogen atoms were determined by Patterson methods and
subsequent Fourier syntheses (DIRDIF PATTY),32 which were
refined anisotropically by full-matrix least-squares techniques.
The hydrogen atom of the SH group in 4 was found in the final
difference Fourier map, while all other hydrogen atoms were
placed at calculated positions, except for those in the solvating
THF for 10‚THF, which were included in the final stages of
refinements with fixed parameters.
P r ep a r a tion of [(Cp *Ru )2(µ2-H)(µ3-S)2Rh Cl2(P P h 3)]‚-
THF (10‚THF ). A solution containing 4 (22 mg, 0.036 mmol)
and 11 (67 mg, 0.072 mmol) in THF (15 mL) was stirred at
room temperature for 15 h, and the resultant red solution was
filtered. Addition of hexane (10 mL) to the concentrated
filtrate afforded 10‚THF as dark brown crystals (29 mg, 76%).
1H NMR (C6D6): δ 1.62 (s, 30H, Cp*), 6.5-7.5 (m, 15H, PPh),
1.45 and 3.60 (m, 4H each, THF), -22.2 (s, 1H, RuHRu). Anal.
Calcd for C42H54OS2Cl2Ru2Rh: C, 48.23; H, 5.20. Found: C,
48.23; H, 5.24. The presence of both Ru and Rh in 10 has
been confirmed by electron-probe microanalysis (EPMA) using
a Kevex µX 7000 energy dispersive type X-ray analyzer.
X-r a y Diffr a ction Stu d ies. Single crystals of 4, 5a , 6‚-
MeCN, and 10‚THF prepared as described above were sealed
in glass capillaries under N2 and transferred to a Rigaku
AFC7R diffractometer equipped with a graphite-monochro-
matized Mo KR source. Diffraction studies were carried out
at room temperature. Orientation matrices and unit cell
parameters were determined by least-squares treatment of 25
reflections with 35 < 2θ < 40°. The intensities of 3 check
Ack n ow led gm en t. Financial support by the Min-
istry of Education, Science, and Culture of J apan is
appreciated.
Su p p or tin g In for m a tion Ava ila ble: Tables containing
atom coordinates, anisotropic temperature factors of non-
hydrogen atoms, and extensive bond distances and angles and
figures giving the full views, including hydrogen atoms, for 4,
5a , 6‚MeCN, and 10‚THF (30 pages). Ordering information
is given on any current masthead page.
OM960193S
(31) teXsan: Crystal Structure Analysis Package, Molecular Struc-
ture Corp. (1985 and 1992).
(32) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bos-
man, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla,
C. The DIRDIF Program System; Technical Report of the Crystal-
lography Laboratory; University of Nijmegen, Nijmegen, The Nether-
lands, 1992.
+
+