[MoO(NNPh₂)(acac)₂], a precursor of novel binuclear hydrazido(2-)molybdenum(VI) complexes containing bridging alkoxo ligands: [{MoO(NNPh₂)(acac)(μ-OR)}₂]. Syntheses, characterization, reactivity and electrochemical studies. Crystal structure of [{MoO (NNPh₂) (acac) (μ-OEt)}₂]

1,1-Diphenylhydrazine reacts with [MoO₂(acac)₂] in methanol to yield either the mononuclear complex [MoO(NNPh₂)(acac)₂] (I) or the binuclear complex [{MoO(NNPh₂)(acac)(μ-OMe)}₂] (II) depending on the temperature. In refluxing ROH, complex I transforms into [{MoO(NNPh₂)(acac)(μ-OR)}]. (R=Me: II; R=Et: III; R=n-Pr: IV.) The crystal structure of III is reported. Crystals are triclinic, space group P1, with unit cell dimensions a=9.211(1), b=10.375(2), c=12.107(3) Å, α=72.98(2), β=64.55(1), γ=70.10(1)° and Z=1. The structure was solved using 5034 unique observed reflections; the refinement of 304 variables gave R and R_w values of 0.024 and 0.026, respectively. The lattice is made of discrete centrosymmetrical dinuclear molecules. The geometry of the hydrazido(2-) ligand (MoN = 1.784(1), NN = 1.298(2) Å, MoNN = 169.5(1)°) indicates extensive delocalization through the MoNN unit. II, III and IV are representative members of a new family of dinuclear complexes which display the [(Ph₂NN)OMo(μ-OR)₂MoO(NNPh₂)]²⁺ core.