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

Abstract

[Bu₄N][Mo₂^vO₄(mnt)₂] (where mnt=1,2-dicyanoethylenedithiolate) (1), reacts with HX (X=SPh, Cl, Br) to form a series of complexes, [Bu₄N]₂[Mo₂^vO₃(mnt)₂(L)₂](L=SPh (2a), Cl (2b), Br (2c). In acidic-alcoholic medium 1 with thiophenol yields another series of compounds, [Bu₄N][Mo₂^vO₂(mnt) (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 [mo₂^vO₂(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[Mo₂^vO₂(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.