The first bimetallic metallaboratrane:: [Rh2{B(mt)3}2{k2-S,S′-HB(mt)3]Cl and its synthesis from the fluxional rhodaboratrane salt [Rh{B(mt)3}(η4-C8H12)]Cl, (Rh→B, mt = methimazolyl)

The prolonged reaction of [Rh{B(mt)(3)}(eta 4C8H12)]Cl, prepared from [Rh(eta(4)-C8H12)Cl](2) and 2 equiv of Na(HB(mt)(3)], with a further excess of Na[HB(mt)(3)] leads to formation of the first binuclear metallaboratrane salt, [Rh-2[B(mt)(3)](2){kappa(2)-S,S'-HB(mt)(3)})Cl. This compound, which is also observed as a decomposition product of rhodium tris(methimazolyl)borane complexes, affords the first evidence for bridging of transition metals by the methimazolyl sulfur donors.