Electronic Structure, Spectra, and Magnetic Properties of Oxycations. V. The Electronic Spectra of Some Vanadyl Complexes

The observation of four low-intensity absorption bands below 20 000 cm—1 for the C2v molecule vanadyl bisacetylacetonate is verified and four such bands are reported for C4v vanadyl species. The likelihood of these four bands representing the whole of the d—d series and the plausibility of understanding the splitting of the crystal field levels in the C4v molecules in terms of a spin—orbit coupling mechanism is discussed. The time course of the oxidation V(iv) to V(v) has been followed spectrally; the results identify the d—d series of transitions and suggest that the ∼25 000 cm—1 transition is charge transfer in nature. The paper should be regarded as a critique of two alternative energy-level schemes of the vanadyl ion, that scheme which is proposed herein being heavily favored by the arguments presented.