Neutral tricoordinated beryllium(0) compounds--isostructural to BH(3) but isoelectronic to NH(3)

The electronic structure and reactivity of neutral tricoordinated Be(0) compounds BeL(3), L = CO (1), NHC (2) and PMe(3) (3) are explored by quantum mechanical calculations. These BeL(3) complexes are found to be planar or nearly planar like electron deficient BH3 but isoelectronic with NH3 and possess three L→Be donor-acceptor bonds. The Be atom can be considered as sp(2)-hybridized with a lone pair in the highly diffused 2p(z)-orbital in contrast to the sp(3) hybridization in isoelectronic NH(3). Even though the lone pair on Be is stabilized through π-back donation or hyperconjugative interaction with the ligands, yet it is highly reactive towards Lewis acids such as H(+), BH(3) and W(CO)(5). The calculated gas phase protonation energies reveal that the NHC complex 2 and the trimethylphosphine complex 3 are 'super basic' in nature. Promising ligand property of BeL(3) has also been noted with BH(3) and transition metal fragment W(CO)(5). Besides, the reactivity of 2 and 3 is found to be more as compared to 1.