Synthesis of a Heterometallic Trinuclear Cluster of Ruthenium and Platinum with a Linear Alignment

A heterobimetallic trinuclear complex of Ru and Pt in a linear alignment, {Cp*Ru(H)(2)}(2)(Pt)(mu-(PBu2)-Bu-t)(2)(mu-H)(2) (2; Cp* = eta(5)-Csrvres), was synthesized via P-C bond scission upon the photolysis of Cp*Ru(mu-H)(4)RuCp* (1) in the presence of Pt((PBu3)-Bu-t)(2). Complex 2 was alternatively synthesized by the reaction of 1 with Pt((PBu2H)-Bu-t)(3), together with the formation of a triangular Ru2Pt complex, (Cp*Ru)(2){Pt ((PBu2H)-Bu-t)} (mu-(PBu2)-Bu-t) (mu-H)(3)(H)(2) (4). X-ray diffraction experiments showed that the structure of 2 could be regarded as a dimer of [Cp*RuH3(P*Bu-2)](-) fragments linked by a Pt2+ ion. In contrast to the relevant monometallic trihydrido complex of ruthenium, Cp*RuH3((PR3)-R-t), terminal hydrides of 2 were readily substituted by CO and ethylene, leading to the formation of {Cp*Ru(L)}(2)(Pt)(mu-(PBu2)-Bu-t)(2)(mu-H)(2) (5; L = CO, 6; L = C2H4). Such high reactivity could be attributed to the facile formation of a coordinatively unsaturated intermediate owing to stabilization by bulky gamma-PtBu2 moieties as well as electronic influence of the central Pt atom. In fact, terminal hydrides of 2 were readily removed upon evacuation, leading to the formation of tetra- and dihydrido complexes (Cp*Ru){Cp*Ru(H)(2)}Pt(mu-PtBu2)(2)(mu-H)(2) (3) and (Cp*Ru)2Pt(mu-PtBu2)(2)(mu-H), (8), consecutively. Upon hydrogenation, 3 and 8 were smoothly transformed into 2. In contrast with the reactions of 2 with 2e donors, substitution at the Pt atom occurred in reactions with Ph2SiH2 and Et2SiH2, resulting in itsilylene and ti-sily1 complexes {Cp*Ru(H)}{Cp*Ru(PtBu2H)}Pt(pt-PtBu2)(gamma-SiPh2)(mu-H)(2) (9) and {Cp*Ru(H)2}{Cp*Ru(mu Bu2H)}Pt(gamma-PtBu2)(mu-e-SiE(t)2)(gamma-H)(2) (10), respectively. In these reactions, the ii-phosphido ligand bridging the Ru and Pt atoms was transformed into a terminal phosphine ligand at the peripheral Ru atom, alongside the formation of y-silylene and itsilyl ligands via reductive P H bond formation.