Interactions between solvent molecules and the reduced or unreduced forms of silico-molybdic acid studied by ESR and NMR spectroscopies and molecularmodelling

H-4[SiMo12O40] can take part in redox reactions as well as electrophilic tr ansformations. The reduction of Mo(VI) to Mo(V) in various solvents was fol lowed by ESR spectroscopy. The spectra show significant rhombic splitting, which can be correlated with the dielectric constants of the solvents. Coor dination of solvents distorts the symmetry of MoO6 octahedra. Based on the degree of splitting it is suggested that the strength of coordination decre ases in the sequence: acetone > ethanol > 1,4-butanediol > acetonitrile > D MSO. The comparison of Mo-95 NMR chemical shift data obtained in Various so lvents and the results of modelling solvent-solute interactions indicated, however, that dimethyl sulfoxide (DMSO) interacts most strongly with the Mo sites of unreduced acid. (C) 2000 Elsevier Science S.A. All rights reserve d.