Formation and hydrogen release of hydrazine bisborane: transfer vs. attachment of a borane

The reactivity of hydrazine in the presence of diborane has been investigated using ab initio quantum chemical computations (MP2 and CCSD(T) methods with the aug-cc-pVTZ basis set). Portions of the relevant potential energy surface were constructed to probe the formation mechanism of the hydrazine diborane (BH(3)BH(3)NH(2)NH(2)) and hydrazine bisborane (BH(3)NH(2)NH(2)BH(3)). The differences between both adducts are established. The release of hydrogen molecules from hydrazine bisborane adducts has also been characterized. Our results suggest that the BH(3)NH(2)NH(2)BH(3) adduct, which has been prepared experimentally, is formed from the starting reactants hydrazine + diborane. The observed adduct is produced by a transfer of a BH(3) group from BH(3)BH(3)NH(2)NH(2) rather than by the direct attachment of a separate BH(3) group, generated by predissociation of diborane, to BH(3)NH(2)NH(2).