Distortional isomerism in oxomolybdenum systems: The evidence re-evaluated

Abstract

Two blue forms of the oxomolybdenum complex [Mo(O)Cl₂(PMe₂Ph)₃] exist, and not one blue and one green or even only one blue form! The molecules of the two blue forms can be characterized and are deformation isomers in which the phosphane ligands are clearly differently oriented, and the Mo–O bonds have different lengths, which lead to stretching frequencies differing by about 12 cm⁻¹ in the IR spectra of the solids. The lack of change in the IR spectrum for the isomer absorbing at ṽ = 943 cm⁻¹ on cocrystallization with [MoCl₃(PMe₂Ph)₃] suggests that a crystal packing effect cannot explain the presence of two forms.