STRUCTURAL AND STEREODYNAMIC STUDIES ON MOLECULAR EARLY TRANSITION-METAL DERIVATIVES .5. NMR-STUDY OF ISOLATED TUNGSTEN DIOXOFLUORIDE ADDUCTS OF TYPE WO2F3L-

The title compounds (L = phosphine oxide, pyridine N-oxides)have been isolated and characterized, and their ClCH2CN so1utions studied by variabletemperature 1H, 19F and 31PNMR. A detailedinvestigation on Et4N[WO2F3(OPMe3)] showsthat the F atom trans to an oxo ligand, as well as the OPMe3 ligand trans to the other oxo ligand in thecis-dioxostructure A, are rapidly dissociated on the NMRtimescale, while the apical F atoms trans to each otherare not, which illustrates the trans-labilizing effect ofthe oxo ligands. Upon ageing new species are formed in the solutions, including WO2F2[OPMe32,[WO2F3(CICH2CN)],WO2F2(ClCH2CN)2, F- and OPMe3 An equilibrium situation is reached after 4 days' heating at 80°C. The neutral WO2F2(OPMe3)2is then largely predominant. Material balance calculationsindicate that polynuclear species are also likely to be present. © 1979.