Synthesis, structure and reactions of a series of 1,2-dicyanoethylenedithiolate coordinated dimeric Mo(V) complexes

[Bu4N]2[Mo2VO4(mnt)2] (where mnt = 1,2-dicyanoethylenedithiolate) (1), reacts with HX (X = SPh, Cl, Br) to form a series of complexes, [Bu4N]2[Mo2VO3(mnt)2(L)2](L=SPh(2a),Cl(2b),Br(2c)). In acidic–alcoholic medium 1 with thiophenol yields another series of compounds, [Bu4N][Mo2VO2(mnt)2(μ-SPh)2(μ-OY)](Y=Me(3a),Et(3b),iPr(3c)). Under similar conditions tertiary-butanol does not coordinate where a complex can only be isolated in the presence of bromide as [Bu4N]2[Mo2VO2(mnt)2(μ-O)(μ-SPh)(μ-Br)](4). The use of excess of methanesulfonic acid in the presence of HSPh or HSEt facilitates methanesulfonate coordination in complexes, [Bu4N]2[Mo2VO2(mnt)2(μ-O)(μ-SZ)(μ-CH3SO3)](Z=Ph(5),Et(6)). All these complexes are structurally characterized by single crystal X-ray study. These complexes show pH dependent hydrolytic reaction leading to quantitative reversal to the starting complex, 1. Complexes 2a–c respond to hydrolysis in CH2Cl2 with the intermediate formation of EPR active molybdenum(V) species.

Synthesis, structure and reactions of a series of 1,2-dicyanoethylenedithiolate coordinated dimeric Mo(V) complexes in relevance to the chemistry of Mo(V)-dithiolate coordinated Mo-cofactor in molybdenum enzymes are described.Figure optionsDownload as PowerPoint slide