Reactions of tungsten(VI) and molybdenum(V) chlorides,and tungsten(VI) and molybdenum(VI) oxychlorides,with azoxybenzene

Reactions of W^VI and Mo^V chlorides with azoxybenzene yield ionic species of W^VI and Mo^VI oxychlorides in which the cation is a protonated azobenzene. The reaction between MoCl₅ or MoOCl₄ and azoxybenzene gives, after extraction with methylene chloride—ethanol mixture, the complex [trans-MoOCl₄(OC₂H₅)]^? [C₁₂H₁₀N₂H]⁺. In contrast, WOCl₄ reacts with azoxybenzene to give a stable non-ionic adduct in which the organic moiety is coordinated through its oxygen atom trans to the WO bond. Several complexes of substituted azoxybenzene having similar structures are described.