Ab initio MO studies on the isomers of Si₂BH₃

Abstract

Ab initio molecular orbital calculations at the QCISD(T)/6-31 G* level on the isomers of Si₂BH₃ indicate the global minimum to be a hydrogen-bridged structure with 2π electron delocalization and planar tetra coordination around boron. Disilaborirene, analogous to borirene, lies slightly higher in energy than the global minimum. In contrast to borylethyne, disilaborylethyne was found to be a higher-order stationary point. Cyclic delocalization and divalency on silicon tend to stabilize the isomers, while multiple bonding involving silicon is not favoured. Isomers predicted using the diagonal relationship between boron and silicon retain similar relative energies.