title: Oxidation of 1-Methyl-1-phenylhydrazine with Oxidovanadium(V)-Salan Complexes: Insight into the Pathway to the Formation of Hydrazine by Vanadium Nitrogenase.
abstract: A series of oxidovanadium(V) complexes [VO(L-κ4O,N,N,O)(OR)] (1a, R = Et, L = L1; 1b, R = Me, L = L1; 2, R = Me, L = L2; 3, R = Me, L = L3) were synthesized by the σ-bond metathesis reaction between [VO(OR)3] and the linear diaminebis(phenol) derivatives H2L (salans) containing different para-substituents on the phenoxo group [CMe3CH2CMe2, L1; Me, L2; Cl, L3]. As shown by X-ray crystallography complexes 1a, 1b, and 2 exhibit cis-α geometry, do have a stereogenic vanadium center, and exist as a racemic mixture of the Δ cis-α and Λ cis-α enantiomers. In solution, as demonstrated by1H and51V NMR investigations, the structures of complexes 1-3 are consistent with their solid state. The reactions of 1b, 2, and 3 with NH2NMePh in n-hexane afforded the oxidovanadium(IV) [VO(L-κ4O,N,N,O)] (4, L1; 5, L2; 6, L3) and 1,4-dimethyl-1,4-diphenyl-2-tetrazene (Me2Ph2N4) (7) as the main products together with a small amount of hydrazido(2-) vanadium(V) [V(L3-κ4O,N,N,O)(NNMePh)(OMe)] (8). Proposed reaction course for the oxidation of NH2NMePh by 1b-3 is discussed. Compounds 4-8 were characterized by chemical and physical techniques including the X-ray crystallography for 4, 7, and 8. The solid-state (powder) electron paramagnetic resonance spectra and magnetic features strongly indicate that complexes 4-6 are formed as a mixture of a mononuclear (S = 1/2) and a dinuclear (S = 1) species.
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14, F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kober
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14, F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Zofia
authors.initials: Z
authors.lastname: Janas
authors.affiliation: Faculty of Chemistry, University of Wrocław , 14, F. Joliot-Curie, 50-383 Wrocław, Poland.
authors.forename: Julia
authors.initials: J
authors.lastname: Jezierska
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006834:Hydrazines / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009591:Nitrogenase / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010659:Phenylhydrazines / Q000737:chemistry*; D014639:Vanadium / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D056831:Coordination Complexes; D006834:Hydrazines; D010659:Phenylhydrazines; D014639:Vanadium; C030299:phenylhydrazine; C013243:salicylaldehyde; C029424:hydrazine; D009591:Nitrogenase