New Molybdaborane Clusters with a Bridged Phosphido Ligand

Abstract

Treatment of [Cp*MoCl(4)], 1 (Cp* = eta(5)-C(5)Me(5)), with [LiBH(4)center dot thf] in toluene at -40 degrees C, followed by thermolysis with [(thf)Li{CH(PPh(2)-BH(3))(2)}] results in the formation of a new class of phosphido bridged molybdaborane [(Cp*Mo)(2)B(4)H(7) (mu-PPh(2))], 2 which has been characterized crystallographically. In addition, the above reaction also produces known [(Cp*Mo)(2)B(5)H(9)], 3 and an unusual molybdaborane [(Cp*Mo)(2)B(5)H(8)(O(i)Pr)], 4 ((i)Pr = -CH(CH(3))(2)). All the new compounds have been characterized in solution by (1)H, (11)B, (13)C, (31)P NMR spectroscopy and the structural types were unambiguously established by X-ray crystallographic analysis of compounds 2 and 4.