The ground-state properties of the group III trihalides

Abstract

The electronic structures of the monomeric trihalides of boron, aluminium, and gallium are calculated by the SCMO method. The ground-state electron distribution and the vertical reorganisation energies of the molecules are obtained, the latter quantities being, for boron and aluminium, in fair agreement with previous work. The expected decrease in π-energy on passing from the boron and aluminium to the gallium compounds does not occur and, in fact, boron tri-iodide possesses the lowest π-stabilising energy. It is further concluded that neither the electron density on the central atom nor the M–X bond order can be related to the electron-acceptor strength of a particular molecule.