Synthesis, structure and characterization of dimolybdaheteroboranes

Abstract: Chalcogen-stabilized dimolybdaboranes 3–5 (3: [(Cp∗Mo)2B4H5Se(Ph)], 4: [(Cp∗Mo)2B4H3Se2(SeCH2Ph)] and 5: [(Cp∗Mo)2B3H6(BSR)(μ-η1-SR)] (R=2,6-( t Bu)2-C6H2OH)) have been isolated from the mild pyrolysis of dichalcogenide ligands, RE-E‘R (R=Ph: E=S, E‘=Se; R=CH2Ph, [2,6-( t Bu)2-C6H2OH]: E=E‘=Se, S) and [(Cp∗Mo)2B4H8], 2, an intermediate generated from the reaction of [Cp∗MoCl4] (1) (Cp∗ =η5-C5Me5), with [LiBH4.thf]. The geometry of [(Cp∗Mo)2B4H5Se(Ph)] is similar to that of [(Cp∗Mo)2B5H9], in which one BH3 unit on the open face is replaced by a triple bridged selenium atom. All the compounds have been characterized in solution by 1H, 11B, 13C NMR and IR spectroscopy and elemental analysis. The structural types were unequivocally established by X-ray crystallographic analysis of compounds 3–5. [Copyright &y& Elsevier]