Structures of alatetraborane(10) and gallatetraalane(10) isomers

Abstract

Tetraborane(10) is well known and 2-gallatetraborane(10) has been synthesized. Other isomers of both systems along with gallaborane(10), digallatetraborane(10) and tri-gallatetraborane(10) have been studied using ab initio quantum chemical methods. This study extends this theoretical work to tetraborane(10) with aluminium substitution of boron and tetraalane(10) with gallium substitution of aluminium. The structures of the aluminium substituted tetraborane(10) structures are very similar to the gallium substituted tetraborane(10) structures. The heavier aluminium atom prefers the ‘wing-tip’ position in the arachno structures. However, the stabilization of the aluminium substituted bis(diboranyl) structures when the aluminium is in the central position is less marked than for the gallium substituted bis(diboranyl) structures. In the gallium substituted tetraalanes, somewhat surprisingly the heavier gallium atom prefers the central positions in both the arachno and the bis(diboranyl) structures.

Acknowledgement

We thank Gretel Parker for some earlier Hartree–Fock calculations on some of the structures studied here.

Harmonic frequencies at B3LYP/6-311G^†(2d, p) level of theory are available from the first author. (E-mail address of first author: [email protected]).