Synthesis and characterisation of two clusters [Ru8(µ-H)2(µ6-η2-CO)(CO)19(η6-C16H16)] and [Ru8(µ6-η2-CO)(µ4-η2-CO)(CO)18(η6-C16H16)] having an unusual metal geometry and considerable elongation of the µ6-C–O bond

Abstract

The [2.2]paracyclophane octanuclear clusters [Ru8(µ-H)2(µ6-η2-CO)(CO)19(η6-C16H16)]1 and [Ru8(µ6-η2-CO)(µ4-η2-CO)(CO)18(η6-C16H16)]2 have been isolated as by-products from the thermal reaction between [Ru3(CO)12] and [2.2]paracyclophane in heptane. Compounds 1 and 2 have been characterised in the solid-state by X-ray crystallography. Their metal cores are similar, consisting of square-based pyramidal units in which two edges have been bridged by two fused Ru atoms; this edge is also bridged by a Ru atom. In both 1 and 2 one of the carbon monoxide groups bonds to six of the Ru atoms via a µ6-η2 interaction resulting in considerable elongation of the C–O bond. Compounds 1 and 2 are possible intermediates in the carbide-generating reaction in which [Ru8(µ-H)4(CO)18(η6-C16H16)] undergoes quantitative conversion into [Ru6C(CO)14(µ3-η2:η2:η2-C16H16)] and [Ru3(CO)12].