Synthesis, structure and characterization of dimolybdaheteroboranes

摘要

Chalcogen-stabilized dimolybdaboranes 3-5 (3: [(Cp*MO) 2B_4H_5Se(Ph)], 4: [(Cp*MO) _2B_4H_3Se_2(SeCH_2Ph)] and 5: [(Cp*MO)_2B_3H_6(BSR)(μ- η1-SR)] (R = 2,6-(tBu)2-C_6H _2OH)) have been isolated from the mild pyrolysis of dichalcogenide ligands, RE-E'R (R = Ph: E = S, E' = Se; R = CH_2Ph, [2,6-(tBu) 2-C_6H_2OH]: E = E' = Se, S) and [(Cp*MO)_2B_4H_8], 2, an intermediate generated from the reaction of [Cp/MoCl4] (1) (Cp* = η5-C_5Me_5), with [LiBH_4.thf]. The geometry of [(Cp*MO)_2B_4H_5Se(Ph)] is similar to that of [(Cp*MO)_2B_5H_9], in which one BH_3 unit on the open face is replaced by a triple bridged selenium atom. All the compounds have been characterized in solution by ~1H, ~(11)B, ~(13)C NMR and IR spectroscopy and elemental analysis. The structural types were unequivocally established by X-ray crystallographic analysis of compounds 3-5.