An ab initio reinvestigation of the geometric and electronic structure of boron trioxide

Abstract In an attempt to resolve the controversy over the structure of the boron trioxide (B 2 O 3 ) molecule an ab initio molecular orbital study employing a minimal STO-3G basis set with complete geometry optimization is reported. Our results indicate that B 2 O 3 is a planar “w” shaped molecule with a rather small inversion barrier around the central atom and a quite important coupling between BOB and OBO angles. The computed bond distances are consistent with previous electron diffraction results, whereas the apex angle is in better agreement with the most recent IR study. The results obtained by the MNDO method are in good agreement with the ab initio ones. The electronic structure of B 2 O 3 is discussed by means of Walsh diagrams and Mulliken population analysis.