Complexes with Platinum−Ruthenium Bonds:  Synthesis, Structure, and Fluxionality of Pt<sub>3</sub>Ru Cluster Complexes

The reaction of [Pt<sub>3</sub>(μ<sub>3</sub>-CO)(μ-dppm)<sub>3</sub>][PF<sub>6</sub>]<sub>2</sub>, <b>1</b>, dppm = Ph<sub>2</sub>PCH<sub>2</sub>PPh<sub>2</sub>, with [HRu(CO)<sub>4</sub>]<sup>-</sup> initially gives [Pt<sub>3</sub>(μ-H)(μ-dppm)<sub>3</sub>{Ru(CO)<sub>4</sub>}]<sup>+</sup>, <b>2</b>, which contains a PtRu(μ-H) unit. In solution, complex <b>2</b> rearranges to the cluster [Pt<sub>3</sub>Ru(μ-H)(CO)<sub>2</sub>(μ-CO)<sub>2</sub>(μ-dppm)<sub>3</sub>]<sup>+</sup>, <b>3</b>, which has been characterized by X-ray structure determination to have a butterfly structure with ruthenium at a wingtip position and which contains a Pt<sub>2</sub>(μ-H) unit. Both complexes <b>2</b> and <b>3</b> exhibit fluxionality, which is defined by low-temperature NMR studies.