Fe5Mo Cluster with Iron-Carbide and Molybdenum-Carbide Bonding Motifs: Structure and Selective Alkyne Reductions.

Herein we report the synthesis, X-ray structure, and characterization of the title pentairon (molybdo)carbido cluster. The reaction of the pentairon (μ5-carbido) dianion [Fe5(μ6-C)(μ2-CO)2(CO)12]2- (1) with [Mo(CO)3(chpt)] (chpt = cycloheptatriene) forms the heterohexanuclear cluster [K(benzo-18-crown-6)]2[Fe5Mo(μ6-C)(μ2-CO)3(CO)14] (2). The dianion exhibits a Fe5Mo(μ6-C) core structure supported by three bridging (νCO = 1788 cm-1) and terminal (νCO = 1943 cm-1) CO ligands. Cluster 2 provides the selective reduction of diphenylacetylene to cis-diphenylethylene via a spectroscopically observed cluster-hydride intermediate (1H NMR: δ -26).