Reactions of the Trinuclear Cluster (μ₂-H)Ru₃(CO)₉(μ₃,η²-SCNHPhNPh):  Synthesis and Molecular Structure of Ru₃(CO)₆(PPh₃)(μ₂,η²-C₆H₅)- (μ₂-PPh₂)(μ₃-S), a Complex Containing a Phenyl Ligand with a Rare σ,π-Coordination Mode

Abstract

Reactions of the previously isolated trinuclear cluster (μ2-H)Ru3(CO)9(μ3,η2-SCNHPhNPh) (1) with excess diphenylthiourea result in cluster fragmentation to produce the mononuclear complex Ru(CO)2(η2-SCNHPhNPh)2 (2) containing two bidentate diphenylthioureato ligands. Room-temperature reactions of 1 with 1 or 2 equiv of triphenylphosphine result in substitution of one or two carbonyl groups, respectively, to give the clusters (μ2-H)Ru3(CO)8(PPh3)(μ3,η2-SCNHPhNPh) (3) and (μ2-H)Ru3(CO)7(PPh3)2(μ3,η2-SCNHPhNPh) (4). An X-ray crystal structure analysis shows 3 to represent a monosubstituted derivative of 1 with the PPh3 ligand occupying an equatorial position on one of the two bridgehead ruthenium atoms; the crystal belongs to the triclinic space group P1̄; Z = 2, a = 10.014(2) Å, b = 14.449(4) Å, c = 14.573(4) Å, α = 100.38(2)°, β = 98.70(2)°, and γ = 107.20(2)°. Thermolysis of either 1 in the presence of 2 equiv of PPh3, or of 4 alone, gives the sulfur-capped, trinuclear cluster Ru3(CO)7(PPh3)(μ2,η2-C6H5)(μ2-PPh2)(μ3-S) (5). X-ray structural analysis of 5 shows a diphenylphosphido bridge and a phenyl bridge resulting from P−C bond activation of a PPh3 group and C−H activation of the aryl group; crystals of 5 are monoclinic, space group P21/n; Z = 4, a = 10.824(1) Å, b = 19.193(5) Å, c = 20.953(2) Å, and β = 97.44(1)°. Diphenylphosphinoethane (dppe) is found to replace two carbonyl ligands on two adjacent Ru atoms to give the cluster (μ2-H)Ru3(CO)7(Ph2PCH2CH2PPh2)- (μ3,η2-SCNHPhNPh) (6) whose X-ray structural analysis shows a dppe ligand bound cis to the μ2-S of the diphenylthioureato ligand and cis to the μ2-H ligand. Crystals of 6 are monoclinic, space group P21/n; Z = 4, a = 17.667(7) Å, b = 17.681(5) Å, c = 18.049(4) Å, and β = 108.06(2)°.