Structural studies of the hydrazine and ammine complexes of the dinuclear ruthenium polysulfide complexes

Article abstract of DOI:10.1021/ic9804115

The dinuclear ruthenium polysulfide complex, [Ru^II₂(μ-S_n(μ-S₂CNMe ₂)(S₂CNMe₂)(CO)₂(PPh ₃)₂] (1)·0.5CH₂Cl₂ (n = 5 or 6), was reacted with N-donor ligands, hydrazine, ammonia, and pyridine. The reaction of hydrazine with 1.2 equiv of 1·0.5CH₂Cl₂ affords the crystallographically characterized dinuclear Ru^II complex, {[Ru^II(S₂-CNMe₂)(CO)(PPh₃)] ₂(μ-S₄)(μ-N₂H₄} (2)·0.5CH₂Cl₂. The octahedrally coordinated Ru^II centers are doubly bridged by N₂H₄ and the S₄ chain. The S₄ chain is formed through a desulfurization reaction of the S_n (n = 5 or 6) ligand in 1. The reaction yield was improved in the presence of one equiv of PPh₃. The space group and the cell data for 2·0.5CH₂Cl₂ are as follows: triclinic, space group P1? (No. 2) with a = 20.003(3) A?, b = 14.155(2) A?, c = 10.061(2) A?, α = 110.70(1)°, β= 90.73(1)°, γ = 104.23(1)°, V = 2567.4(8) A?³, and Z = 2. The dinuclear ruthenium pentasulfide [Ru^II₂(μ-S₅)(μ-S₂CNMe ₂)(S₂CNMe₂)(CO)₂(PPh ₃)₂] (1p) and the hexasulfide [Ru^II₂(μ-S₆)(μ-S₂CNMe ₂)(S₂CNMe₂)(CO)₂(PPh ₃)₂] (1h) complexes in the crystals of 1·0.5CH₂Cl₂ were separated by partial recrystallization in benzene. The reaction between 1h and NH₃ forms the dinuclear Ru^II ammine complex, {[Ru^II(S₂-CNMe₂)(CO)(PPh₃)(NH ₃)]₂(μ-S₆)} (3)·0.5CH₂Cl₂ in which ammonia is terminally coordinated to the metal centers. Complex 3 crystallizes as the acetonitrile solvate in monoclinic space group C2/c(No. 15) with a = 30.481(7) A?, b = 12.455(2) A?, c = 15.463(3) A?, β= 113.90(2)°, V = 5367(1) A?³, and Z = 4. The reaction between 1p and excess amount of pyridine (py) yields {[Ru^II(S₂CNMe₂)(CO)(PPh₃)(py)] ₂(μ-S₅)} (4), of which structural information was obtained by ³¹P NMR and elemental analysis due to the poor crystal quality. Upon dissolution in CH₂Cl₂, both 3·0.5CH₂Cl₂ and 4 reinstate 1h and 1p, respectively, indicating that both complexes undergo intrinsically the same reaction. The N₂H₄ ligand in 2·0.5CH₂Cl₂ is chemically reduced and quantitatively measured 8.4 mol % of ammonia liberation.

Full text of DOI:10.1021/ic9804115

Inorg. Chem. 1999, 38, 109-114
109
Structural Studies of the Hydrazine and Ammine Complexes of the Dinuclear Ruthenium
Polysulfide Complexes
Takashi Furuhashi, Masaki Kawano, Yoshihiro Koide, Ryosuke Somazawa, and
Kazuko Matsumoto*
Department of Chemistry, Advanced Research Center for Science and Engineering, Waseda University,
Tokyo 169-8555, Japan
ReceiVed April 10, 1998
The dinuclear ruthenium polysulfide complex, [RuII (µ-Sn)(µ-S2CNMe2)(S2CNMe2)(CO)2(PPh3)2] (1)‚0.5CH2Cl2
2
(n ) 5 or 6), was reacted with N-donor ligands, hydrazine, ammonia, and pyridine. The reaction of hydrazine
with 1.2 equiv of 1‚0.5CH2Cl2 affords the crystallographically characterized dinuclear RuII complex, {[RuII(S2-
CNMe2)(CO)(PPh3)]2(µ-S4)(µ-N2H4} (2)‚0.5CH2Cl2. The octahedrally coordinated RuII centers are doubly bridged
by N2H4 and the S4 chain. The S4 chain is formed through a desulfurization reaction of the Sn (n ) 5 or 6) ligand
in 1. The reaction yield was improved in the presence of one equiv of PPh3. The space group and the cell data
for 2‚0.5CH2Cl2 are as follows: triclinic, space group P1h (No. 2) with a ) 20.003(3) Å, b ) 14.155(2) Å, c )
10.061(2) Å, R ) 110.70(1)°, â ) 90.73(1)°, γ ) 104.23(1)°, V ) 2567.4(8) Å3, and Z ) 2. The dinuclear
ruthenium pentasulfide [RuII (µ-S5)(µ-S2CNMe2)(S2CNMe2)(CO)2(PPh3)2] (1p) and the hexasulfide [RuII (µ-S6)(µ-
2
2
S2CNMe2)(S2CNMe2)(CO)2(PPh3)2] (1h) complexes in the crystals of 1‚0.5CH2Cl2 were separated by partial
recrystallization in benzene. The reaction between 1h and NH3 forms the dinuclear RuII ammine complex, {[RuII(S2-
CNMe2)(CO)(PPh3)(NH3)]2(µ-S6)} (3)‚0.5CH2Cl2, in which ammonia is terminally coordinated to the metal centers.
Complex 3 crystallizes as the acetonitrile solvate in monoclinic space group C2/c(No. 15) with a ) 30.481(7) Å,
b ) 12.455(2) Å, c ) 15.463(3) Å, â ) 113.90(2)°, V ) 5367(1) Å3, and Z ) 4. The reaction between 1p and
excess amount of pyridine (py) yields {[RuII(S2CNMe2)(CO)(PPh3)(py)]2(µ-S5)} (4), of which structural information
was obtained by 31P NMR and elemental analysis due to the poor crystal quality. Upon dissolution in CH2Cl2,
both 3‚0.5CH2Cl2 and 4 reinstate 1h and 1p, respectively, indicating that both complexes undergo intrinsically
the same reaction. The N2H4 ligand in 2‚0.5CH2Cl2 is chemically reduced and quantitatively measured 8.4 mol
% of ammonia liberation.
Introduction
chelation is known only for S7 .
2- 11 Some polysulfides participate
in both chelating and bridging two or more metals.2,12 In contrast
to these flourishing structural data, reported reactions of
polysulfides are limited. One typical reaction of higher polysul-
fides (so far known up to S92-) is desulfurization of one or more
sulfur atoms from a polysulfide chelate ring to a lower
polysulfide ring, by addition of sulfur-abstracting reagents such
as PR3.1 For example, [Pt(S5)3]2- is converted to [Pt(PPh3)2-
(S4)] and S2- by addition of PPh3.13 In some reactions, addition
of sulfur-abstracting reagent leads to dinucleation of a mono-
meric complex.14 Thus, the addition of PR3 to Cp2TiS5 gives
(Cp2Ti)2Sx (x ) 4, 6). To obtain a more general view on the
reactivity, several nucleophilic and electrophilic attack to
coordinated polysulfides were attempted. For example, perthio-
carbonate ligand is formed by the electrophilic attack of CS2
Although a number of transition metal complexes having
catenated polysufide ligands (Sn2-, n > 3) are known, most of
the studies are focused on the synthesis and structure determi-
nation, and little attention is paid on their reactivity.1,2 This is
probably due to the complicated chemical reactions of the ligand,
which generally allows so many variable coordination modes
to metals. Some examples of the coordination modes include
bidentate chelation by the two terminal sulfur atoms known for
S3 , , , , .
2- 1-3 S42- 2,4-6 S52- 5,7 S62- 2,8,9 and S92- 2,10 Novel tridentate
* Address correspondence to this author.
(1) Mu¨ller, A.; Dieman, E. In ComprehensiVe Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon:
Oxford, 1987; Vol. 2, p 541.
(2) Draganjac, M.; Rauchfuss, T. B. Angew. Chem., Int. Ed. Engl. 1985,
24, 742.
2-
on the coordinated S4 ligand in [SMo(S4)2]2-, yielding
[SMo(CS4)2]2- 15
. Similarly, in the reaction of ZnS4(PMDETA)
(3) Bird, P. H.; CcCall, J. M.; Shaver, A.; Siriwardane, U. Angew. Chem.
1982, 94, 375; Angew. Chem., Int. Ed. Engl. 1982, 24, 384.
(4) Draganjac, M.; Simhon, E.; Chan, L. T.; Kanatzidis, M.; Baenziger,
N. C.; Coucouvanis, D. Inorg. Chem. 1982, 21, 3321.
(5) Giolando, D. M.; Rauchfuss, T. B. Organometallics 1984, 3, 487.
(6) (a) Pafford, R. J.; Rauchfuss, T. B. Inorg. Chem. 1998, 37, 1974. (b)
Kim, K.-W.; Kanatzidis, M. G. J. Am. Chem. Soc. 1995, 117, 5606.
(7) Greaney, M. A.; Coyle, C. L.; Harmer, M. A.; Jordan, A.; Stiefel, E.
I. Inorg. Chem. 1989, 28, 912.
(8) Verma, A. K.; Rauchfuss, T. B.; Wilson, S. R. Inorg. Chem. 1995,
34, 3072.
(9) Tatsumi, K.; Inoue, Y.; Nakamura, A.; Cramer, R. E.; VanDoorne,
W.; Gilje, J. W. Angew. Chem., Int. Ed. Engl. 1990, 29, 422.
(PMDETA ) N,N,N′,N′,N′′-pentamethyldiethylenetriamine) with
(10) (a) Marbach, G.; Stra¨hle, J. Angew. Chem. 1984, 96, 229; Angew.
Chem., Int. Ed. Engl. 1984, 23, 246.
(11) Gotzig, J.; Rheingold, A. L.; Werner, H. Angew. Chem., Int. Ed. Engl.
1984, 23, 814.
(12) Ramli, E.; Rauchfuss, T. B.; Stern, C. L. J. Am. Chem. Soc. 1990,
112, 4043.
(13) Dudis, D.; Fackler, J. P., Jr. Inorg. Chem. 1982, 21, 3577.
(14) Giolando, D. M.; Rauchfuss, T. B.; Rheingold, A. L.; Wilson, S. R.
Organometallics 1987, 6, 667.
(15) Coucouvanis, D.; Draganjac, M. J. Am. Chem. Soc. 1982, 104, 6820.
10.1021/ic9804115 CCC: $18.00 © 1999 American Chemical Society
Published on Web 12/18/1998

110 Inorganic Chemistry, Vol. 38, No. 1, 1999
Furuhashi et al.
Scheme 1
Scheme 2
CS2, insertion of the carbon atom takes place and ZnS3CS-
(PMDETA) is obtained together with elemental sulfur.6a Most
widely reported reaction is the addition of acetylene and its
N-methylimidazole.8 This is not surprising, considering the
general stability of M-S(polysulfide) bonds. Previously, we
reported the synthesis of S52- and S62- coordinated diruthenium-
(II) complexes, [RuII2(µ-Sn)(µ-S2CNMe2)(S2CNMe2)(CO)2-
(PPh3)2] (1) (n ) 5 (78.5%); n ) 6 (21.5%)), and found that
these polysulfide ligands are less electron donating than S2-
and S22-, and are unstable to oxidation. In the present study,
substitution reactions of 1 with N2H4, NH3, and pyridine were
studied. The crystal structures of the resulting ammine complex,
2, and the hydrazine bridged complex, 3, were determined by
X-ray crystallography, and the pyridine complex by NMR and
elemental analysis. These amine complexes revert to the original
polysulfide-bridged complexes 1h and 1p, releasing the amine
ligands in the absence of excess amine ligands. These results
suggest the stability of polysulfide ligands relative to amine
ligands. For the hydrazine complex, reducibility of the coordi-
nated hydrazine to NH3 was also examined.
derivatives to the chelated polysulfide ligands to give dithiolene
ligands, RCSCSR′2- 1,16
For instance, the S5 ligand in Cp2-
.
2-
TiS5 reacts with (MeCOO)CC(COOMe) to give the dithiolene
complex Cp2Ti(MeCOO)CSCS(COOMe).17 Similar reaction is
also reported for Ru(bpy)2S5 (bpy ) 2,2′-bipyridine),7 and many
other polysulfide complexes.2,16 Comparison of the reactivities
of ZnS6(TMEDA) (TMEDA ) tetramethylethylenediamine) and
ZnS4(PMDETA) toward electrophilic alkyne C2(CO2Me)2 shows
that the shorter S42- ligand has more elevated nucleophilicity.6a,8
All these reactions suggest that Sn2- reacts with RCCR′ to give
dithiolene ligand, regardless of the sulfur number of the
polysulfide ring.
Another notable reaction of polysulfide ligand is the insertion
of R2C moiety into a polysulfide chelate ring. The insertion
takes place not to the metal-to-sulfur ligand bond, but to the
S-S bond in the middle of the polysulfide ligand. For instance,
a reaction of Cp2TiS5 with R2CBr2 or R2CO (R ) H or alkyl) in
the presence of (NH4)2S produces 1,4-Cp2TiS4CR2 and 1,3-Cp2-
TiS4CH2.5 The reaction is initiated by a sulfur atom abstraction
from the pentasulfide ring by (NH4)2S to give a bis(disulfide)
complex or a mono- and trisulfide complex as the intermediate.
In contrast to the above reactions, simple polysulfide dis-
placement reaction is known only for ZnS6(TMEDA) by
Results and Discussion
Synthesis. Previously, we reported that complex 1‚0.5CH2-
Cl2 contains 78.5% of 1p and 21.5% of 1h in the lattice. The
coordinates of the atoms are identical for the both complexes
except the polysulfide chain length.18,19 Despite this intermin-
gling, a reaction of 1‚0.5CH2Cl2 with 1.2 equiv of hydrazine
provided the tetrasulfide bridged RuIIRuII hydrazine complex,
(16) Coucouvanis, D. Polyhedron 1989, 8, 1716.
(17) Bollinger, C. M.; Rauchfuss, T. B. Inorg. Chem. 1982, 21, 3947.
(18) Uemura, H.; Kawano, M.; Watanabe, T.; Matsumoto, T.; Matsumoto,
K. Inorg. Chem. 1992, 31, 5137.

Dinuclear Ru Polysulfide Complexes
Inorganic Chemistry, Vol. 38, No. 1, 1999 111
Table 1. Selected Bond Distances (Å) and Angles (deg) for
a,b
2‚0.5CH2Cl2
Bond Distances
Ru(1)-S(1)
Ru(1)-S(6)
Ru(1)-N(3)
Ru(2)-S(4)
Ru(2)-S(8)
Ru(2)-N(4)
S(1)-S(2)
2.389(3)
2.414(3)
2.222(8)
2.407(3)
2.428(3)
2.228(8)
2.058(4)
2.069(4)
1.726(10)
1.71(1)
Ru(1)-S(5)
Ru(1)-P(1)
Ru(1)-C(1)
Ru(2)-S(7)
Ru(2)-P(2)
Ru(2)-C(2)
S(2)-S(3)
S(5)-C(3)
S(7)-C(4)
P(1)-C(9)
P(1)-C(21)
P(2)-C(33)
O(1)-C(1)
N(3)-N(4)
2.437(3)
2.322(2)
1.79(1)
2.453(3)
2.341(3)
1.82(1)
2.066(4)
1.70(1)
1.74(1)
1.852(9)
1.836(10)
1.85(1)
1.19(1)
1.48(1)
S(3)-S(4)
S(6)-C(3)
S(8)-C(4)
P(1)-C(15)
P(2)-C(27)
P(2)-C(39)
O(2)-C(2)
1.833(10)
1.855(10)
1.851(10)
1.16(1)
Bond Angles
S(1)-Ru(1)-S(5)
S(1)-Ru(1)-P(1)
S(1)-Ru(1)-C(1)
S(5)-Ru(1)-P(1)
S(5)-Ru(1)-C(1)
S(6)-Ru(1)-N(3)
P(1)-Ru(1)-N(3)
N(3)-Ru(1)-C(1)
S(4)-Ru(2)-S(8)
S(4)-Ru(2)-N(4)
S(7)-Ru(2)-S(8)
S(7)-Ru(2)-N(4)
S(8)-Ru(2)-P(2)
S(8)-Ru(2)-C(2)
P(2)-Ru(2)-C(2)
96.43(9)
97.42(9)
90.4(3)
166.02(9)
90.4(3)
S(1)-Ru(1)-S(6)
S(1)-Ru(1)-N(3)
S(5)-Ru(1)-S(6)
S(5)-Ru(1)-N(3)
S(6)-Ru(1)-P(1)
S(6)-Ru(1)-C(1)
P(1)-Ru(1)-C(1)
S(4)-Ru(2)-S(7)
S(4)-Ru(2)-P(2)
S(4)-Ru(2)-C(2)
S(7)-Ru(2)-P(2)
S(7)-Ru(2)-C(2)
S(8)-Ru(2)-N(4)
P(2)-Ru(2)-N(4)
N(4)-Ru(2)-C(2)
166.11(9)
87.0(2)
72.36(9)
84.3(2)
93.66(8)
97.7(3)
91.4(3)
96.19(9)
88.11(9)
92.5(3)
175.16(10)
84.7(3)
Figure 1. ORTEP diagram of {[Ru(S2CNMe2)(CO)(PPh3)]2(µ-S4)(µ-
N2H4} (2)‚0.5CH2Cl2 showing 50% probability thermal ellipsoids for
all nonhydrogen atoms.
{[RuII(S2CNMe2)(CO)(PPh3)]2(µ-S4)(µ-N2H4)} (2)‚0.5CH2Cl2
(Scheme 1), as a unique product.
83.8(2)
94.5(2)
173.8(4)
167.40(9)
88.0(2)
72.13(9)
89.8(2)
103.76(9)
91.1(3)
93.0(3)
We have successfully separated 1p from 1h by partial
recrystallization in benzene (see Experimental Section). Com-
plex 1h was then reacted with large excess of NH3. The reaction
produced the dinuclear ruthenium ammine complex, {[RuII(S2-
CNMe2)(CO)(PPh3)(NH3)]2(µ-S6)} (3)‚0.5CH2Cl2 (Scheme 2),
with an excellent yield, and the orange X-ray quality crystals
were grown by layer diffusion of ether into a CH2Cl2 solution.
The reaction of 1p with pyridine yielded yellow crystals of
{[RuII(S2CNMe2)(CO)(PPh3)(py)]2(µ-S5)} (4) (py ) pyridine).
The crystals of 4 were too fragile and were not suitable for
X-ray diffraction, whereas the 31P NMR and elemental analysis
elucidated that the structure is akin to that of 3‚0.5CH2Cl2. This
structure was further supported by the fact that dissolution of
the crystals of 3‚0.5CH2Cl2 and 4 in CH2Cl2 readily reverted
to 1h and 1p, respectively (Scheme 2).
X-ray Crystal Structures. Complex 2‚0.5CH2Cl2 crystallizes
with one molecule of CH2Cl2 in the lattice. However, refinement
of the CH2Cl2 molecule was impossible due to disorder in the
position of C. Consequently, the Max Shift/Error value was
limited to 4.03. The ORTEP diagram is shown in Figure 1 and
the selected bond distances and angles are listed in Table 1.
The distorted octahedral coordination geometry around each
ruthenium atom is completed by a bidentate dithiocarbamate, a
terminal carbonyl, a triphenylphosphine, a bridging tetrasulfide,
and a bridging N2H4. Each dithiocarbamate plane is perpen-
dicular to the Ru-N bond. The µ-N2H4 group positions trans
to the terminal CO groups, and separates the two RuII centers
by 5.22 Å through the zigzag RuIINNRuII core with dihedral
angle of 143.4(4)°. The observed geometry of the trans-RuII-
NNRuII core is similar to that in [W(NPh)Me3]2(µ-η1,η1-NH2-
NH2)(µ-η2,η2-NHNH),20a and several other complexes,20b while
we previously prepared the µ-N2H4 bridged RuIIRuIII mixed
valence complexes, which possess the cis-RuIIINNRuII core.21,22
The N-N distance in the bridging hydrazine (1.48(1) Å) is
slightly longer than the value in analogous µ-N2H4, µ-S2 bridged
87.2(2)
92.6(2)
174.5(4)
Torsion Angles
65.5(2) Ru(2)-S(4)-S(3)-S(2) -114.8(1)
68.4(2)
Ru(1)-S(1)-S(2)-S(3)
Ru(1)-N(3)-N(4)-Ru(2) 143.4(4) S(1)-S(2)-S(3)-S(4)
a See Figure 1 for the atom-labeling scheme. b Numbers in paren-
theses are estimated standard deviations for the last significant digit.
RuIIRuIII dinuclear complex, {[RuCl(TMP)2]2(µ-Cl)(µ-N2H4)-
(µ-S2)} (5) (TMP ) trimethyl phosphite),24 and is comparable
to the value in free N2H4 (1.47 Å).23 The Ru-N distances
(2.222(8) and 2.228(8) Å) are slightly longer than those in 5
(2.170(7) Å and 2.172(7) Å). The RuII-S (tetrasulfide) distances
(2.389(3) Å and 2.407(3) Å) are longer than the RuII/III-S
distance in 5 (2.281 Å (av)), and the RuIII-S (disulfide) distance,
which usually is in the range 2.19-2.22 Å.24 The observed
oxidation state dependence of the Ru-S distance is a conse-
quence of the difference in the ionic radii of RuII and RuIII, and
also in the π-acceptor ability of ruthenium that decreases in
order of RuIII > RuIII/II > RuII. As anticipated, the tetrasulfide
chain is severely puckered (the Ru(1)-S(1)-S(2)-S(3), Ru-
(2)-S(4)-S(3)-S(2), and the S(1)-S(2)-S(3)-S(4) torsion
angles are 65.5(2), -114.8(1), and 68.4(2)°, respectively) in
order to pack in the void created by the two RuII centers and
the µ-N2H4 ligand. The average S-S single bond distance (2.064
Å) is a typical value found in polysulfide chains.25
Complex 3‚0.5CH2Cl2 also crystallizes with one molecule of
CH2Cl2 per two complex molecules in the lattice. The structure
(21) Kawano, M.; Hoshino, C.; Matsumoto, K. Inorg. Chem. 1992, 31,
5158.
(22) Matsumoto, K.; Uemura, H.; Kawano, M. Chem. Lett. 1994, 1215.
(23) Cotton, F. A.; Wilkinson, G. AdVanced Inorganic Chemistry, 5th ed.;
Wiley: New York, 1988; p 316.
(24) (a) Matsumoto, K.; Uemura, H.; Kawano, M. Inorg. Chem. 1995, 34,
658. (b) Matsumoto, K.; Matsumoto, T.; Kawano, M.; Ohnuki, H.;
Shichi, Y.; Nishide, T.; Sato, T. J. Am. Chem. Soc. 1996, 118, 3597.
(25) (a) Steudel, R. Angew. Chem., Int. Ed. Engl. 1975, 14, 655. (b) Maheu,
L. J.; Pignolet, L. H. J. Am. Chem. Soc. 1980, 102, 6348. (c) Mu¨ller,
A.; Eltzner, W.; Bo¨gge, H.; Krickemeyer, E. Angew. Chem., Int. Ed.
Engl. 1983, 22, 884.
(19) A few examples of penta- and hexasulfide ring coexistence are
reported: (a) Coucouvanis, K.; Baenziger, N. C.; Simon, E. D.;
Stremple, P.; Swenson, D.; Kastikas, A.; Simopoulos, A.; Petrouleas,
V.; Papaefthymiou, V. J. Am. Chem. Soc. 1980, 102, 1730. (b)
Coucouvanis, D.; Patil, P. R.; Kanatzidis, M. G.; Detering, B.;
Baenziger, N. C. Inorg. Chem. 1985, 24, 24.
(20) (a) Blum, L.; Williams, I. D.; Schrock, R. R. J. Am. Chem. Soc. 1984,
106, 8316 (b) Heaton, B. T.; Jacob, C.; Page, P. Coord. Chem. ReV.
1996, 154, 193.

112 Inorganic Chemistry, Vol. 38, No. 1, 1999
Furuhashi et al.
Table 2. Selected Bond Distances (Å) and Angles (deg) for
a
3‚0.5CH2Cl2
Bond Distances
Ru(1)-S(1)
Ru(1)-S(5)
Ru(1)-N(1)
S(4)-C(2)
S(1)-S(2)
P(1)-C(5)
P(1)-C(17)
2.382(5)
Ru(1)-S(4)
Ru(1)-P(1)
Ru(1)-C(1)
S(5)-C(2)
S(2)-S(3)
2.435(6)
2.314(6)
1.81(2)
1.74(3)
2.05(1)
1.82(2)
2.439(6)
2.21(2)
1.72(3)
2.043(9)
1.84(2)
1.83(2)
P(1)-C(11)
Bond Angles
S(1)-Ru(1)-S(4)
S(1)-Ru(1)-P(1)
S(1)-Ru(1)-C(1)
S(4)-Ru(1)-P(1)
S(4)-Ru(1)-C(1)
S(5)-Ru(1)-N(1)
P(1)-Ru(1)-N(1)
N(1)-Ru(1)-C(1)
168.0(2)
90.5(2)
94.3(7)
99.4(2)
92.0(7)
85.9(5)
92.8(5)
174.0(8)
S(1)-Ru(1)-S(5)
S(1)-Ru(1)-N(1)
S(4)-Ru(1)-S(5)
S(4)-Ru(1)-N(1)
S(5)-Ru(1)-P(1)
S(5)-Ru(1)-C(1)
P(1)-Ru(1)-C(1)
97.8(2)
87.0(5)
72.2(2)
85.8(5)
171.5(2)
88.1(7)
93.1(7)
Figure 2. ORTEP diagram of {[Ru(S2CNMe2)(CO)(PPh3)(NH3)]2(µ-
S6)} (3)‚0.5CH2Cl2 showing 50% probability thermal ellipsoids for all
nonhydrogen atoms.
a See Figure 2 for the atom-labeling scheme.
improved yield from 39% to ca. 70%. It is not clear, however,
if both 1p and 1h have been converted to 2‚0.5CH2Cl2 or 1p
has reacted exclusively with N2H4.
Resemblance of the coordination geometry of 3‚0.5CH2Cl2
with that of 2‚0.5CH2Cl2 implies that the reaction between 1h
and NH3 proceeds analogously.
is depicted in Figure 2, and the selected bond distances and
angles are listed in Table 2.
Unlike 2‚0.5CH2Cl2, however, a true crystallographic C2 axis
relates the two halves of 3‚0.5CH2Cl2. The two RuII centers
are bridged by the µ-S6 ligand, which separates the metal centers
by 7.68 Å. A distorted octahedron of each RuII center is
completed by a bidentate dithiocarbamate, a terminal carbonyl,
a terminal ammine, and a triphenylphosphine. The NH3 group
and the CO group are trans to each other that corresponds to
the relation of µ-N2H4 to the CO group in 2‚0.5CH2Cl2. The
plane of a dithiocarbamate is perpendicular to the Ru-N bond.
Unlike 2‚0.5CH2Cl2, the polysulfide ligand remains intact
throughout the reaction because, without any other bridging
ligand, the S62- chain can rearrange freely between the two RuII
centers, and thus amasses no internal strain that induces
desulfurization reaction. The RuII-S (hexasulfide) distances of
2.382(5) Å is comparable to those in 2‚0.5CH2Cl2, and thus
the value is considered insensitive to presence or absence of
the µ-N2H4 ligand.
An Attempted Reduction of the Bridging N2H4 to Am-
monia. We attempted to reduce the N2H4 ligand in 2‚0.5CH2-
Cl2 to NH3 in CH2Cl2 according to a literature method using 8
equiv of sodium amalgam as a reductant and 4 equiv of 2,6-
lutidine hydrochloride as a proton source.27 Liberated ammonia
was trapped as NH4Cl, which was subjected to quantitative
measurement by the indophenol method.28 The detected amount
was only 8.4 mol % of NH4+, implying intrinsic difficulty in
reduction of the coordinated N2H4. Reliability of the test was
confirmed by applying the procedure to a CH2Cl2 solution of
3‚0.5CH2Cl2, which possesses NH3 as a ligand, to detect nearly
+
stoichiometric amount of NH4 (97 mol %).
Conclusion
Reaction Mechanism. Extended Hu¨ckel calculations of 1
show that the LUMO consists of virtually degenerate ruthenium
orbitals, which will receive nucleophilic attack of the N2H4
ligand. Upon completion of the N2H4 coordination, PPh3
dissociation is likely to occur as a minor path, although such a
product was not isolated (route A in Scheme 3).
We discussed reactions of the dinuclear ruthenium polysul-
fides with the N-donor ligands. Hydrazine links the two RuII
centers and forms the RuNNRu core that restricts relative
positions of the two RuII centers in 2‚0.5CH2Cl2. In the course
of 2‚0.5CH2Cl2 formation, the polysulfide chain in 1 is converted
from penta- to tetrasulfide, which then fits between the two RuII
centers. On the contrary, no desulfurization reaction occurs in
preparations of 3‚0.5CH2Cl2 and 4, where the polysulfide is the
only bridging ligand. The reactions in Scheme 2 are significant
in that these are the second example that polysulfide undergoes
substitution by amine ligand. Since the polysulfides participate
both in chelating and bridging in 1h and 1p, the coordination
of these polysulfides to the Ru atoms would be weaker than
they would be if they are only chelating to the Ru atom.
Nevertheless, these substitution reactions are noteworthy and
give information about the relative coordination stability
between polysulfide and amine ligands. Since 3 and 4 revert to
1h and 1p, respectively, in the absence of excess amine, these
two ligands seem to have comparable coordination stability. It
As a major path, the other end of the N2H4 coordinates on
the other RuII atom concomitantly with cleavage of the Ru(1)-
S(3) and Ru(2)-S(9) bonds (route B in Scheme 3). Significant
strain is imposed on the polysulfide chain as a consequence of
the four-center six-electron Ru-N-N-Ru bond formation. The
free PPh3 will serve in a desulfurization reaction26 that will
alleviate the strain, yielding 2‚0.5CH2Cl2. Desulfurization by
PPh3 was confirmed experimentally as follows. In the course
of the reaction, the reaction solution changed its color from
orange to yellow, and immediate addition of excess ether
resulted in precipitation of the intermediate species whose 31P
NMR spectrum agrees with neither 1‚0.5CH2Cl2 nor 2‚0.5CH2-
Cl2. A crystallization attempt of the intermediate gave a mixture
of 1‚0.5CH2Cl2 and metallic ruthenium in addition to SPPh3 in
the supernatant. The desulfurization reaction of PPh3 was
bolstered by the fact that the presence of 1 equiv of PPh3
(27) (a) Vale, M. G.; Schrock, R. R. Inorg. Chem. 1993, 32, 2767. (b)
Vale, M. G.; Schrock, R. R. Organometallics 1993, 12, 1140.
(28) (a) Japanese Industrial Standard: Testing Method for CorrosiVity of
Industrial Water; JIS K 0101 36.2; Japanese Standards Association:
Tokyo, Japan. (b) Chaney, A. L.; Marbach, E. P. Clin. Chem. 1962,
8, 130.
(26) (a) Bolinger C. M.; Hoots, J. E.; Rauchfuss, T. B. Organometallics
1982, 1, 223. (b) Bolinger, C. M.; Rauchfuss, T. B.; Wilson, S. R. J.
Am. Chem. Soc. 1981, 103, 5620.

Dinuclear Ru Polysulfide Complexes
Inorganic Chemistry, Vol. 38, No. 1, 1999 113
Scheme 3
Cl2 and 3‚0.5CH2Cl2. All non-hydrogen atoms were refined anisotro-
pically, except the low-occupancy chlorine atoms and the phenyl
carbons in 3‚0.5CH2Cl2, which were refined isotropically. Relevant
crystallographic information is summarized in Table 3.
is rather surprising that amine ligands, which are usually stable,
can be removed so easily in these reactions, and this suggests
strong chelating tendency of the polysulfides as well as strong
bridging tendency of the dithiocarbamate ligand.
Chemical Reduction of 2‚0.5CH2Cl2. A reductant was prepared
by adding 8 equiv of 2,6-lutidine hydrochloride and 4 equiv of sodium
amalgam in an appropriate flask under argon atmosphere. To this flask,
a CH2Cl2 solution (10 mL) of the ruthenium complex (30 mg) was
added via syringe and stirred at 0 °C. After 24 h, the solvent and
volatiles were removed under vacuum. The residue was dissolved in
water (50 mL) and stirred for 2 h before filtration. The filtrate was
brought up to 100 mL with distilled water, and a portion (10 mL) was
used for quantitative detection by the indophenol method.28 First, a
sodium phenoxide aqueous solution was prepared by dissolving phenol
(25 g, 0.27 mol) in 55 mL of a NaOH/H2O (20 wt %), and brought up
to 200 mL with distilled water. A 0.2% EDTA/H2O (5 mL) and a
sodium phenoxide/H2O (10 mL) were added to the filtrate under
vigorous agitation. Following addition of a NaClO aqueous solution
(5 mL, 1% effective Cl concentration), the solution mixture was brought
up to 50 mL with distilled water, and allowed to stand at 25 °C for 40
Although chemical reduction of the µ-N2H4 to NH4+ was not
efficient enough for any practical use, electrochemical reduction
of the dinuclear ruthenium complexes are planned as an
alternative method and will be reported in future.
Experimental Section
General Methods. All synthetic procedures were performed under
purified nitrogen using standard Schlenk techniques or in a nitrogen
atmosphere glovebox unless otherwise mentioned. Solvents were
distilled and degassed prior to use. Solution NMR spectra were obtained
on a JEOL EX-270WB spectrometer using CD2Cl2. 31P NMR chemical
shifts were recorded in reference to P(OMe)3/(CD3)2CO external
standard (140 ppm). UV-vis spectra were recorded on a Shimadzu
UV-3101PC using a quartz cuvette with 1.0 cm optical path. [RuII
-
2
(µ-Sn)(µ-S2CNMe2)(S2CNMe2)(CO)2(PPh3)2] (1)‚0.5CH2Cl2 (Figure 3)
was prepared as previously reported.2 Molecular orbital calculations
were performed within the extended Hu¨ckel formalism with use of the
weighted Hij formula using CaChe system.
Crystallographic Studies. Crystals were covered with epoxy-resin
and adhered to a glass tip and mounted on a goniometer of a Rigaku
AFC-7R four-circle automated diffractometer using graphite-mono-
chromated Mo KR radiation (0.710 69 Å). Data collection and cell
determinations were performed in a manner previously described by
using the θ-2θ scan technique.18 Absorption correction was made based
on azimuthal scans of several reflections. The data were corrected for
Lorentz and polarization effects. Pertinent details are given in Table 1.
The structures were solved by a direct method and the model was
refined using full-matrix least-squares techniques. One molecule of CH2-
Cl2 was found per complex molecule in the crystal lattice of 2‚0.5CH2-
Figure 3. Bond distances (Å) in the diruthenium core of 1‚0.5CH2-
Cl2 (represented by the S5 isomer).

114 Inorganic Chemistry, Vol. 38, No. 1, 1999
Table 3. Crystal Data for 2‚0.5CH2Cl2 and 3‚0.5CH2Cl2
Furuhashi et al.
C44.5ClH47N4O2P2Ru2S8: C, 43.60; H, 3.86; N, 4.57. Found: C, 43.71;
H, 4.01; N, 4.27. 31P NMR (ppm): 49.4.
2‚0.5CH2Cl2
3‚0.5CH2Cl2
Separation of 1p from 1h. The pentasulfide and the hexasulfide
complexes were separated by partial recrystallization as follows. The
complex 1‚0.5CH2Cl2 was redissolved in the minimum amount of
benzene at ambient temperature and then recrystallized at -40 °C to
obtain orange crystals of 1p. The supernatant was collected and the
volume was reduced to a half by evaporation. The resulting solution
was stored at -40 °C to yield crystals of 1h.
Synthesis of {[Ru(S2CNMe2)(CO)(PPh3)(NH3)]2(µ-S6)} (3)‚
0.5CH2Cl2. A CH2Cl2 solution (10 mL) of [Ru2(µ-S6)(µ-S2CNMe2)(S2-
CNMe2)(CO)2(PPh3)2] (50 mg, 0.04 mmol) was stirred vigorously in
the presence of NH3/H2O (28%, 2 mL) for 12 h at ambient temperature.
The yellow solution was layered with ether and allowed to equilibrate
at 5 °C. The resulting orange crystals of 3‚0.5CH2Cl2 were rinsed with
ether. Yield: 49 mg, 90%. Anal. Calcd for C44.5ClH49N4O2P2Ru2S10:
C, 41.37; H, 3.82; N, 4.34. Found: C, 41.50; H, 3.83; N, 4.36. 31P
NMR (ppm): 51.8.
Synthesis of {[Ru(µ-S2CNMe2)(CO)(PPh3)(py)]2(µ-S5)} (4). To a
CH2Cl2 solution (10 mL) of [Ru2(µ-S5)(µ-S2CNMe2)(S2CNMe2)(CO)2-
(PPh3)2] (1p) (50 mg, 0.04 mmol) was added pyridine (0.2 mL, 2.5
mmol) at ambient temperature. The solution was then stored at 5 °C to
yield yellow plate-shaped crystals of 4. Yield: 57 mg, 93%. Anal. Calcd
(with a molecule of pyridine per complex molecule) for C59H57N5O2P2-
Ru2S9: C, 49.88; H, 4.04; N, 4.98. Found: C, 49.58; H, 4.03; N, 5.27.
31P NMR (ppm): 43.35.
formula
fw
cryst syst
space group
a, Å
C44.5H47O2N4Ru2S8P2Cl C44.5H49O2N4Ru2S10P2Cl
1225.91
triclinic
P1h (No. 2)
20.003(3)
14.155(2)
10.061(2)
110.70(1)
90.73(1)
104.23(1)
2567.4(8)
2
1292.04
monoclinic
C2/c (No. 15)
30.481(7)
12.455(2)
15.463(3)
90
113.90(2)
90
5367(1)
4
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
d
calcd, g cm-3
1.586
1.599
abs coeff (µ), cm-1 10.69
11.02
radiation (λ), Å
Mo KR 0.710 69
Mo KR 0.710 69
Ra
0.055
0.075
1.14
0.072
b
Rw
0.097
1.13
GOFc
T (deg)
20.0
20.0
a R ) Σ(|Fo| - |Fc|)/Σ|Fo|. b Rw ) [Σw(|Fo| - |Fc|)2/Σw|Fo| ]1/2, w
2
) 1/σ(Fo)2. c GOF ) [Σw(|Fo| - |Fc|)2/Σ(Nreflcns - Nparams)]1/2
.
min. The resulting blue solution was subjected to measure its absorbance
at 630 nm. The amount of NH4 was determined by using a working
curve obtained by plotting the measured absorbance of standard NH4-
Cl solutions as a function of the NH4 concentration.
+
+
Acknowledgment. We are grateful for the financial support
of this work by CREST (Core Research for Evolutional Science
and Technology) of the Japan Science and Technology Corpora-
tion (JST).
Synthesis of {[Ru(S2CNMe2)(CO)(PPh3)]2(µ-S4)(µ-N2H4)} (2)‚
0.5CH2Cl2. To a CH2Cl2 solution (10 mL) of [Ru2(µ-Sn)(µ-S2-
CNMe2)(S2CNMe2)(CO)2(PPh3)2] (1)‚0.5CH2Cl2 (50 mg, ca. 0.04 mol)
was added 1.2 equiv of anhydrous hydrazine (1.6 mL) and 1.2 equiv
of PPh3 (13 mg) in this order at ambient temperature. The resulting
orange solution was stirred for 2 h until the solution turned yellow.
The solution was then allowed to stand at -40 °C for 2 days. The
volume of the resulting solution was reduced to a third by evaporation
prior to ether layer addition. After two weeks at 5 °C, yellow crystals
of 2‚0.5CH2Cl2 were obtained. Yield: 20 mg, 39%. Anal. Calcd for
Supporting Information Available: X-ray crystallographic files,
in CIF format, for 2‚0.5CH2Cl2 and 3‚0.5CH2Cl2 are available on the
Internet only. Access information is given on any current masthead
page.
IC9804115