SYNTHESIS, PROPERTIES AND CRYSTAL-STRUCTURES OF [MO-VL(O)I2]PF6, [MO-IVL(O)I2], [MO-VL(O)(OME)2]PF6, [MO-IVLO2(OME)]BPH4 AND [MO2L2O3(MU-O)I][BPH4]2 (L = 1,4,7-TRIMETHYL-1,4,7-TRIAZACYCLONONANE)

A series of mononuclear oxomolybdenum-(IV), -(V) and -(VI) complexes has been prepared from the precursor complex [Mo(V)L(O)I2]PF6 2 where L = 1,4,7-trimethyl-1,4,7-triazacyclononane. Compound 2 is reduced by NEt3 in MeCN yielding [Mo(IV)L(O)I2] 3. The iodide ligands in 2 may be substituted by alkoxy ligands generating paramagnetic mononuclear complexes [Mo(V)L(O)(OMe)I]PF6 4 and [Mo(V)L(O)(OMe)2]PF6 5. The latter is oxidized by H2O2 to [Mo(VI)LO2(OMe)]BPh4 6. Complex 2 was found to form the dinuclear diamagnetic species [Mo(V)2L2O2(mu-O)I2][PF6]2 7 which generates the asymmetric, diamagnetic mixed-valence complex [I(O)LMo(IV)(mu-O)Mo(VI)LO2]BPh4 8 in the presence of NaOH. Complex 8 undergoes a reversible one-electron-transfer oxidation and paramagnetic [I(O)LMo(V)(mu-O)Mo(VI)LO2][BPh4]2 9 has been isolated. The electrochemical, magnetic, and electronic structural as well as infrared and ESR spectral properties of the new complexes have been investigated. The structures of 2, 3, 5, 6 and 9 have been determined by X-ray crystallography.