New Molybdaborane Clusters with a Bridged Phosphido Ligand

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

Chemistry of Molybdaboranes: Synthesis, Structures, and Characterization of a New Class of Open-Cage Dimolybdaheteroborane Clusters

Reaction of [Cp*MoCl(4)], 1 (Cp*= eta(5)-C(5)Me(5)), with [LiBH(4) center dot thf] in toluene at -70 degrees C, followed by pyrolysis with excess dichalcogenides RE-ER (R = Ph, CH(2)Ph, 2,6-((t)Bu)(2)-C(6)H(2)OH, (CH(3))(3)C=(t)Bu); E=S, Se) yielded a new class of hybrid clusters, 3-8: (3, [(Cp*Mo)(2)(mu-eta(1)-SPh)(2)(mu(3)-S)(H(2)BSPh)]; 4, [(CP*Mo)(2)B(5)H(8)(SPh)]; 5, [(CP*Mo)(2)B(6)H(8)(SePh)]; 6, [(CP*Mo)(2)B(2)S(2)H(2)(mu-eta(1)-S)]; 7, [(CP*Mo)(2)B(2)H(5)(BSR)(2)(mu-eta(1)-SR)], (R = 2,6-((t)Bu)(2)-C(6)H(2)OH); and 8, [(Cp*Mo)(2)B(2)H(5)(BSePh)(2)(mu-eta(1)-SePh)]. Compounds 3-8 have been isolated in modest yields as green or brown crystalline solids. In parallel with 3-8, [(CP*Mo)(2)B(5)H(9)] was isolated as a major product in all cases. The isolation and structural characterization of compounds 3 and 6-8 provided the first direct evidence of the existence of [(Cp*Mo)(2)B(4)H(8)], 2, an intermediate in the formation of [(Cp*Mo)(2)B(5)H(9)]. These new compounds have been characterized in solution by mass spectrometry, (1)H, (11)B, (13)C NMR, and IR spectroscopy, and elemental analysis. The structural types were unequivocally established by X-ray crystallographic analysis of compounds 3-8