Molybdenum And Tungsten Complexes Synthesis And Properties

The design, synthesis and structural characterization of new hybrid materials, of which many applications can be predicted, through the self-assembly of organic and inorganic building blocks, is a highly visible research area. The construction of such organic-inorganic hybrid compounds has established new areas of research in the chemistry and is useful in order to obtain multifunctional materials which exhibit coexistence of solid-state magnetic, electric and optical properties.High-valent molybdenum and tungsten complexes with oxo legations have attracted considerable attention in the recent literature. Apart from their intrinsic interest, the chemistry of these complexes has been developed with a view to gaining a better understanding concerning their role in various industrial and biological processes. It is well documented that high-valent molybdenum and tungsten compounds can act as catalysts for olefin metathesis reactions and are also involved in various oxidation processes. Such compounds with dithiolene-type ligands are also related to a class of enzymes known as oxotransferases, which catalyze oxygen atom transfer to and from a substrate. While the relevant molybdenum chemistry is well developed and numerous oxomolybdenum complexes with a range of supporting ligands have been studied extensively, the chemistry of analogous tungsten complexes remains relatively little studied although substantial recent progress has been stimulated by the unique nature and properties of tungsten-containing enzymes.Here we select 2-methoxypyridine, 2, 3-dihydroxynaphthalene and DB18C6 as ligands, react with some inorganic compounds (WCl₆, Na₂WO₄·2H₂O and Na₂MoO₄·2H₂O) under the normal or thermal condition, get a series of novel compounds which characterized by X-ray crystal and some related spectra.1. Two novel cis-dioxotungsten (VI) complexes, WO₂(C₁₀H₆O₂)₂(C₅H₁₁N₂)₂C₃H₁₀N₂(1) and WO₂(C₆H₆NO)₂(2) 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. There are two six-member ring cations (C5H11N2) to compensate the negative charge of [W(VI)(OC₁₀H₆O)₂]^2- anion in complex1, the constituents of the six-member ring cations (C₅H₁₁N₂) are proved by the NMR spectra and single-crystal structure analysis. It is the first time to find that protonated 1,3-propanediamine and ethanenitrile can react into a six-member ring, and the potential mechanism has been put forward to interpret this phenomenon, while the complex2 is a neutral molecule, which is packed in crystal lattice via O…H—C hydrogen bonds and π-π interactions.2. A novel super-molecular complexes, [Na(DB18C6)(H₂O)]₄[S₂Mo₁₈O₆₂] is obtained by hydrothermal reaction and characterized by X-ray crystal, NMR, EPR and IR spectra. The title...