Complexes with Platinum−Ruthenium Bonds:  Synthesis, Structure, and Fluxionality of Pt₃Ru Cluster Complexes

The reaction of [Pt₃(μ₃-CO)(μ-dppm)₃][PF₆]₂, 1, dppm = Ph₂PCH₂PPh₂, with [HRu(CO)₄]^- initially gives [Pt₃(μ-H)(μ-dppm)₃{Ru(CO)₄}]⁺, 2, which contains a PtRu(μ-H) unit. In solution, complex 2 rearranges to the cluster [Pt₃Ru(μ-H)(CO)₂(μ-CO)₂(μ-dppm)₃]⁺, 3, which has been characterized by X-ray structure determination to have a butterfly structure with ruthenium at a wingtip position and which contains a Pt₂(μ-H) unit. Both complexes 2 and 3 exhibit fluxionality, which is defined by low-temperature NMR studies.