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

The reaction of [Pt33-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.