The versatile nature of [ClAu(L–L)AuCl] (L–L=bis(diphenylphosphino)methane (dppm) or -butane (dppb)) in reactions with [Rh 2Ru 4(CO) 16B] −: crystal structures of [{Rh 2Ru 4(CO) 16B} 2{μ-Au(dppb)Au}] and [RhRu 4(CO) 14B{Au(dppm)Au}

Abstract

The reaction of the octahedral borido cluster [Rh 2Ru 4(CO) 16B] − (which exists as trans and cis isomers with respect to the Rh sites) with [ClAu(dppb)AuCl] (dppb=bis(diphenylphosphino)butane) leads to the formation of separable isomers [{ cis-Rh 2Ru 4(CO) 16B} 2{μ-Au(dppb)Au}] and [{ trans-Rh 2Ru 4(CO) 16B} 2{μ-Au(dppb)Au}]. The cis-isomer converts rapidly to the trans-isomer. A similar reaction with [ClAu(dppm)AuCl] (dppm=bis(diphenylphosphino)methane) gives the linked dicluster [{Rh 2Ru 4(CO) 16B} 2{μ-Au(dppm)Au}], accompanied by the formation of [Rh 2Ru 4(CO) 15BAu(dppm)] and [RhRu 4(CO) 14BAu 2(dppm)], as well as the unstable [Rh 2Ru 4(CO) 16B{Au(dppm)AuCl}]. The crystal structures of [{ trans-Rh 2Ru 4(CO) 16B} 2{μ-Au(dppb)Au}] and [RhRu 4(CO) 14B{Au(dppm)Au}] have been determined; the former retains octahedral borido Rh 2Ru 4B units, while the latter is the consequence of cluster degradation and contains a square-based pyramidal RhRu 4B unit capped on the square-face by the two gold atoms (Au–Au=2.878(1) Å) of a {Au(dppm)Au} unit.