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Dinitrogen complexes of tungsten with bulky phosphine co-ligands. Preparation and crystal structures of [{W(N<sub>2</sub>)<sub>2</sub>(PEt<sub>2</sub>Ph)<sub>3</sub>}<sub>2</sub>(µ-N<sub>2</sub>)],trans-[W(N<sub>2</sub>)<sub>2</sub>(PEt<sub>2</sub>Ph)<sub>4</sub>]·C<sub>4</sub>H<sub>8</sub>O, and [W(η<sup>6</sup>-C<sub>6</sub>H<sub>5</sub>PPr<sup>n</sup><sub>2</sub>)(N<sub>2</sub>)(PPr<sup>n</sup><sub>2</sub>Ph)<sub>2</sub>] and their reactions to give hydrazine or ammonia
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1986
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Reaction SolutionsInorganic ChemistryChemical EngineeringBulky Phosphine Co-ligandsDinitrogen ComplexesEngineeringCoordination ComplexThf SolvateCrystal StructuresMolecular ComplexChemistryInorganic SynthesisInorganic Compound
Reduction of WCl6 or [WCl4(PR2Ph)2](R = Et or Prn) with Mg in the presence of PR2Ph under N2 in tetrahydrofuran (thf) gives a mixture of dinitrogen complexes: [{W(N2)2(PR2Ph)3}2(µ-N2)](1), trans-[W(N2)2(PR2Ph)4](2), and [W(η6-C6H5PR2)(N2)(PR2Ph)2](3) which can be observed in the 15N n.m.r. spectra of the reaction solutions and isolated in most cases in moderate yield. Compound (1a)(R = Et) is shown to be a dimer by X-ray analysis but the structure could be refined only with constraints on interatomic distances. Compounds (1) react with anhydrous HCl (thf, 20 °C) to give hydrazine (0.2 mol/W atom) and dinitrogen (2 mol/W atom). Compound (2a)(R = Et) crystallises as a thf solvate with W–N = 1.986(6) and 1.994(6), N–N = 1.146(7) and 1.139(7)Å. Complex (2a) gives ammonia (1.8 mol/W atom) and N2(1 mol/W atom) on treatment with H2SO4–MeOH. Compound (3b)(R = Prn) has W–N = 1.980(8) and N–N = 1.126(10)Å and loses N2 quantitatively on treatment with anhydrous HCl in thf.