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)­(μ-P^tBu₂)₂(μ-H)₂ (<b>2</b>; Cp* = η⁵-C₅Me₅), was synthesized via P–C bond scission upon the photolysis of Cp*Ru­(μ-H)₄RuCp* (<b>1</b>) in the presence of Pt­(P^tBu₃)₂. Complex <b>2</b> was alternatively synthesized by the reaction of <b>1</b> with Pt­(P^tBu₂H)₃, together with the formation of a triangular Ru₂Pt complex, (Cp*Ru)₂{Pt­(P^tBu₂H)}­(μ-P^tBu₂)­(μ-H)₃(H)₂ (<b>4</b>). X-ray diffraction experiments showed that the structure of <b>2</b> could be regarded as a dimer of [Cp*RuH₃(P^tBu₂)]⁻ fragments linked by a Pt²⁺ ion. In contrast to the relevant monometallic trihydrido complex of ruthenium, Cp*RuH₃(P^tR₃), terminal hydrides of <b>2</b> were readily substituted by CO and ethylene, leading to the formation of {Cp*Ru­(L)}₂(Pt)­(μ-P^tBu₂)₂(μ-H)₂ (<b>5</b>; L = CO, <b>6</b>; L = C₂H₄). Such high reactivity could be attributed to the facile formation of a coordinatively unsaturated intermediate owing to stabilization by bulky μ-P^tBu₂ moieties as well as electronic influence of the central Pt atom. In fact, terminal hydrides of <b>2</b> were readily removed upon evacuation, leading to the formation of tetra- and dihydrido complexes (Cp*Ru)­{Cp*Ru­(H)₂}­Pt­(μ-P^tBu₂)₂(μ-H)₂ (<b>3</b>) and (Cp*Ru)₂­Pt­(μ-P^tBu₂)₂(μ-H)₂ (<b>8</b>), consecutively. Upon hydrogenation, <b>3</b> and <b>8</b> were smoothly transformed into <b>2</b>. In contrast with the reactions of <b>2</b> with 2<i>e</i> donors, substitution at the Pt atom occurred in reactions with Ph₂SiH₂ and Et₂SiH₂, resulting in μ-silylene and μ-silyl complexes {Cp*Ru­(H)}­{Cp*Ru­(P^tBu₂H)}­Pt­(μ-P^tBu₂)­(μ-SiPh₂)­(μ-H)₂ (<b>9</b>) and {Cp*Ru­(H)₂}­{Cp*Ru­(P^tBu₂H)}­Pt­(μ-P^tBu₂)­(μ-η²-SiEt₂)­(μ-H)₂ (<b>10</b>), respectively. In these reactions, the μ-phosphido ligand bridging the Ru and Pt atoms was transformed into a terminal phosphine ligand at the peripheral Ru atom, alongside the formation of μ-silylene and μ-silyl ligands via reductive P–H bond formation