Synthesis, properties and crystal structures of [MoVL(O)l2]PF6′[MoIVL(O)l2], [MoVL(O)(OMe)2]PF6′[MoVILO2(OMe)]BPh4 and [Mo2L2O3(µ-O)l][BPh4]2(L = 1,4,7-trimethyl-1,4,7-triazacyclononane)

Abstract

A series of mononuclear oxomolybdenum-(IV), -(V) and -(VI) complexes has been prepared from the precursor complex [Mo^VL(O)l₂]PF₆2 where L = 1,4,7-triazacyclononane. Compound 2 is reduced by NEt₃ in MeCN yielding [Mo^IVl(o)l₂]3. The iodide ligands in 2 may be substituted by alkoxy ligands generating paramagnetic mononuclear complexes [Mo^VL(O)(OMe)l]PF₆4 and [Mo^VL(O)-(OMe)₂]PF₆5. The latter is oxidized by H₂O₂to [Mo^VILO₂(OMe)]BPh₄6. Complex 2 was found to form the dinuclear diamagnetic species [Mo^V₂L₂O₂(µ-O)l₂][PF₆]₂7 which generates the asymmetric, diamagnetic mixed-valence complex [l(O)LMo^IV(µ-O)Mo^VILO₂]BPh₄8 in the presence of NaOH. Complex 8 undergoes a reversible one-electron-transfer oxidation and paramagnetic [l(O)LMo^V(µ-O)Mo^VILO₂]-[BPh₄]₂9 has been isolated. The electrochemical, magnetic, and eletcronic structural as well as infrared and ESR spectral properties of new complexes have been investigated. The structures of 2, 3, 5, 6 and 9 have been determined by X-ray crystallography.