Metal-framework degradation reactions of the mixed-metal cluster anions [M 3Ir(CO) 13] − (M=Ru, Os) with bis(diphenylphosphino)methane and with tricyclohexylphosphine: synthesis and structure of HRu 2Ir(CO) 5(dppm) 3, HRu 2Ir(CO) 6(PCy 3) 3, H 2Os 2Ir 2(CO) 10(PCy 3) 2 and H 3Os 3Ir(CO) 8(PCy 3) 3

Abstract

The mixed-metal cluster anions [M 3Ir(CO) 13] − (M=Ru, Os) react in methanol under metal-framework degradation with bis(diphenylphosphino)methane (dppm) or tricyclohexylphosphine (PCy 3) to give a series of neutral tri- and tetranuclear mixed-metal clusters. The reaction of [M 3Ir(CO) 13] − (M=Ru, Os) with dppm leads to the phosphine-substituted hydrido derivatives HRu 2Ir(CO) 5(dppm) 3 ( 1) and HOs 2Ir(CO) 5(dppm) 3 ( 2), respectively. The two 48e clusters show a triangular arrangement of the M 2Ir skeleton. The dppm ligands are coordinated in bridging positions over each metal–metal edge; the hydride is bonded terminally to the iridium atom. Cluster degradation is also observed by treating [Ru 3Ir(CO) 13] − with PCy 3 in methanol, giving the highly electron-deficient (44e) mixed-metal cluster HRu 2Ir(CO) 6(PCy 3) 3 ( 3). The reaction of the osmium homologue [Os 3Ir(CO) 13] − with PCy 3 under the same conditions leads to a mixture of the neutral tetranuclear clusters H 2Os 2Ir 2(CO) 10(PCy 3) 2 ( 4) and H 3Os 3Ir(CO) 8(PCy 3) 3 ( 5). Both clusters, 4 and 5 still have a tetrahedral metal core like the starting cluster anion but in 4 an osmium atom has been replaced by an iridium atom. The molecular structures of 1, 3, 4 and 5 were confirmed by single-crystal X-ray structure analyses.