Reactions of bis(mesitylimido)bis(arylthiolato)chromium(VI) compounds

The chromium(VI) imidothiolato complex, Cr(Nmes)2(Smes)2 (1), mes = 2,4,6-Me3C6H2, reacts with 2,6-xylylisocyanide (xylNC) to form the five-coordinate chromium(IV) complex Cr(Nmes)(Smes)2(xylNC)2(2). A similar interaction of Cr(Nmes)2 (SC6H2-2,4,6-Pi3)2 gives only the disulfide adduct Cr(Nmes)2(SC6H2-2,4,6-Pri3)2 · (2,4,6-Pri3C6H2S)2(3). Interaction of 1 and PMePh2 gives Cr4(Nmes)2(μ-Nmes)4(Smes)2(O)2(μ-O)2(4), where the oxygen atoms arise from adventious oxygen during work up. The X-ray crystal structures of 2–4 have been determined. In 2 the CrIV centre has trigonal bipyramidal geometry with axial isocyanides. The CrVI centre in 3 is tetrahedral and 4 is a centro-symmetric tetramer in which the outer CrV centres are tetrahedral and the inner CrIV centres are square-pyramidal