Combination of low-temperature photolysis and ESR spectroscopy as a method for investigating nonparamagnetic complexes

The possibility of the use of ESR for investigating coordination compounds formed by ions of transition metals having no d electrons has been demonstrated on the basis of an analysis of the data obtained on the low-temperature photolysis of labile complexes of titanium(IV), vanadium(V), and molybdenum(VI). Under the proposed procedure, the d complex is converted into a d¹ complex by means of photochemical reduction under conditions which are favorable to the maintenance of the coordination sphere unchanged, its ESR spectrum is recorded, and the parameters obtained are used to characterize the composition, structure, symmetry, and degree of aggregation of the original compound in the solution. The use of this procedure is restricted to the investigation of systems in which photochemical redox conversions are realized according to an outer-sphere mechanism; however, it may also be useful in the interpretation of the results of the photolysis of compounds which undergo inner-sphere conversions.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 197–203, March–April, 1989.