title: Single-site N-N bond cleavage by Mo(IV): possible mechanisms of hydrazido(1-) to nitrido conversion.
abstract: Mo(NMe(2))(4) and the tridentate, dipyrrolyl ligand H(2)dpma(mes) were found to form 5-coordinate Mo(NMe(2))(2)(dpma(mes)) (1), which exhibits spin-crossover behaviour in solution. The complex is a ground state singlet with a barrier of 1150 cm(-1) for production of the triplet in d(8)-toluene. The complex reacts with 1,1-disubstituted hydrazines or O-benzylhydroxylamine to produce nitrido MoN(NMe(2))(dpma(mes)). The mechanism of the 1,1-dimethylhydrazine reaction with 1 was examined along with the mechanism of substitution of NMe(2) with H(2)NNMe(2) in a diamagnetic zirconium analogue. The proposed mechanism involves production of a hydrazido(1-) intermediate, Mo(NMe(2))(NHNMe(2))(dpma(mes)), which undergoes an α,β-proton shift and N-N bond cleavage with metal oxidation to form the nitrido. The rate law for the reaction was found to be -d[1]/dt = k(obs)[1][hydrazine] by initial rate experiments and examination of the full reaction profile. This conversion from hydrazido(1-) to nitrido is somewhat analogous to the proposed mechanism for O-O bond cleavage in some peroxidases.
authors.affiliation: Michigan State University, Department of Chemistry, 578 S. Shaw Ln, East Lansing, MI 48824, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: DiFranco
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Staples
authors.forename: Aaron L
authors.initials: AL
authors.lastname: Odom
mesh_terms: D006834:Hydrazines / Q000737:chemistry*; D008982:Molybdenum / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D006834:Hydrazines; D009942:Organometallic Compounds; D000644:Quaternary Ammonium Compounds; D008982:Molybdenum; D009584:Nitrogen