Formation of metallaboratranes:: The missing link.: The first iridaboratranes, [IrH(CO)(PPh3){κ3-B,S,S′-B(mt)2R}](Ir→B) (mt = methimazolyl, R = mt, H)

The reaction of Vaska's complex with 1 equiv of Na[HB(mt)(3)] or Na[H2B(mt)(2)] (mt = methimazolyl) affords the iridaboratranes [IrH(CO)(PPh3){kappa(3)-B,S,S'-B(mt(2))R}](Ir-I -> B) (R = mt, H), the first examples of metallaboratranes in which the transannular metal -> boron bond is supported by only two methimazolyl buttresses.