Interactions half-field transition

The ESR spectrum of the fully reduced anion, PV2 Wio04o (Figure 7), has the 15-hne pattern ((g) = 1.95, (a) = 53 G) expected for the interaction of the unpaired electrons with two vanadium nuclei. Observation of the half-field (Am, = 2) transition in the spectrum of the solid potassium salt confirms the triplet state of the species responsible for the spectrum in Figure 7. It seems very likely that those isomers (1,2 and 1,6 with V-O-V groups) which are responsible for the 15-line spectrum of the mixed valence complex would have antiferromagnetically coupled spins in the fully reduced anion. The remote isomers with vanadium atoms separated by O-W-0 (1,4 and 1,5) or O-W-O-W-O (1,11) sequences are therefore probably responsible for the triplet state ESR spectrum. Further ESR and magnetic susceptibihty measurements are planned on individual isomers. 

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