Synthesis, structure and NMR of cis-dioxotungsten (VI) complexes with 2-methoxypyridine and 2,3-dihydroxynaphthalene bidentate ligands

Two novel cis-dioxotungsten (VI) complexes, [WO2(La)2](1) and [WO2(Lb)2R2Pr](2) [La=2-methoxypyridine, Lb=2,3-dihydroxynaphthalene, R=the six-member ring ion (C5H11N2), Pr=1,3-propanediamine] have been synthesized and characterized by X-ray crystallography, 1H, 13C NMR and IR spectra. It is found that the tungsten atom is coordinated in a pseudo-octahedral fashion by two cis–oxo functions. The complex 1 is a neutral molecule, which is packed in crystal lattice via O⋯H–C hydrogen bonds and π–π interactions while there are two six-member ring cations (C5H11N2) to compensate the negative charge of [W(VI)(OC10H6O)2]2− anion in complex 2. The new molecules of C5H11N2 are the by-products produced by the protonated 1,3-propanediamine and ethanenitrile.