Synthesis, Characterization and Electronic Structures of Rh and Co analogs of Decaborane-14

We report the synthesis, isolation and structural characterization of several crystalline, moderately air stable nido-metallaboranes which represent novel metal rich open cage systems. The reaction of [Cp*CoCl]2, (Cp* = η 5-C5Me5), with [LiBH4·thf] in toluene at −78 °C, followed by thermolysis with [BH3·thf] in boiling toluene yielded clusters, [(Cp*Co)3B6H8O] (1) and [(Cp*Co)2B8H11Me] (2). Under the similar reaction condition, [Cp*RhCl2]2 yielded [(Cp*Rh)3B7H11] (3) and [(Cp*Rh)2B8H12] (4). All the new compounds, 1–4 have been characterized by elemental analysis, IR, 1H, 11B, 13C NMR spectroscopy, and the geometric structures were unequivocally established by X-ray diffraction analysis of compound 1–4. Quantum chemical calculation by using density functional theory method is implemented on model compounds 1′–4′ (1′–4′ are the Cp analogs of 1–4 respectively, Cp = C5H5) and yields geometries in agreement with the X-ray detaermined geometries. Large HOMO–LUMO gaps are in tally with the higher stabilities of 1′ and 3′.