Poly(azolyl) chelate chemistry 14.[1] κ2-S,S′ vs κ3-H,S,S′- H2B(mt)2 (mt=methimazolyl)borate coordination in the complex [W(CO){H2B(mt)2}2]

The reactions of [M(triple bond; length of mdashCC6H2Me3-2,4,6)X(CO)2(L)2] (M = Mo, W; X = Cl, Br; L = pyridine, 3,5-dimethylpyrazole) with Na[H2B(mt)2] (mt = methimazolyl) are metal dependent, providing either the alkylidyne complex [Mo(triple bond; length of mdashCC6H2Me3-2,4, 6)(CO)2{κ3-H,S,S′-H2B(mt)2}] or the bis(chelate) complex [W(CO){κ2-S,S′-H2B(mt)2}{κ3-H,S,S′-H2B(mt)2}], the latter featuring both bi and tridentate coordination modes for the H2B(mt)2 ligand.