Structural Studies of the Hydrazine and Ammine Complexes of the Dinuclear Ruthenium Polysulfide Complexes

The dinuclear ruthenium polysulfide complex, [RuII2(μ-Sn)(μ-S2CNMe2)(S2CNMe2)(CO)2(PPh3)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 RuII complex, {[RuII(S2CNMe2)(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 P1̄ (No. 2) with a = 20.003(3) Å, b = 14.155(2) Å, c =
10.061(2) Å, α = 110.70(1)°, β = 90.73(1)°, γ = 104.23(1)°, V = 2567.4(8) Å3, and Z = 2. The dinuclear
ruthenium pentasulfide [RuII2(μ-S5)(μ-S2CNMe2)(S2CNMe2)(CO)2(PPh3)2] (1p) and the hexasulfide [RuII2(μ-S6)(μ-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(S2CNMe2)(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, β = 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.