The Raman spectra of the vanadium oxytrihalides in the vapour, dissolved, and solid states, and of the mixed oxytrihalides

Abstract

The Raman spectra of vanadium oxytrichloride and vanadium oxytribromide have been recorded as solid films at ca. 77 K. Evidence is presented for the formation of only one solid phase by the former (a phase which is not isomorphous with that of phosphorus oxytrichloride) but of two or three phases by vanadium oxytribromide. Values for the fundamentals of these molecules in cyclohexane solutions are also given. The vapour spectrum of vanadium oxytrifluoride has been obtained, and the values for the fundamentals and the band contours are compared with the correspondingly determined i.r. values and band contours. The vapour spectrum of vanadium oxytrichloride has likewise been recorded, and the contradiction between the i.r. and Raman assignments for the lowestlying fundamental (125 cm^–1) has been resolved in favour of its assignment to an e mode. Vanadium oxytribromide is not sufficiently stable in the vapour phase to allow its Raman spectrum to be determined. Liquid mixtures of vanadium oxytrichloride and vanadium oxytribromide are found to contain approximately statistical proportions of the mixed halogeno-species VOCl₂Br and VOClBr₂. Assignments for the fundamentals of these mixed species are also presented. One fundamental of the molecule VOCl₂F has also been located.