Spectral and structural studies of some Group VIA dioxydihalides

Abstract

The infrared and mass spectra of MoO₂Cl₂, MoO₂Br₂, WO₂Cl₂, and WO₂Br₂ in the gas phase have been studied. The vapours contain mostly monomeric molecules but there is also a small amount of relatively unstable dimeric species present in each case. In inert solvents MoO₂Cl₂ and MoO₂Br₂ are dimeric and the infrared spectra are reported. In the solid state all four compounds are polymeric and the absence of the characteristic M = O infrared frequency suggests that only bridging oxygen atoms can be present. X-ray powder diffraction data suggest that the four compounds are isomorphous.