A ‘passe-partout’ for the stabilization of highly polar unsupported M–M′ bonds (M = Ti, Zr, Hf; M′= Fe, Ru) and α-addition of the metal nucleophile–electrophile pairs to an isocyanide

The coordination of a novel type of tripodal amido ligand provides the key to the synthesis of stable M–M′(M = Ti, Zr, Hf; M′= Fe, Ru) heterobimetallic complexes, [MeSi{SiMe2N(C6H4Me-4)}3M–M′(η5-C5H5)(CO)2] 4–9, with unsupported metal–metal bonds and thus enables systematic studies of these complexes; the crystal structures of the Ti–Fe (4) and Zr–Fe (6) complexes are reported, the latter being the first X-ray structure of a compound containing a Zr–Fe bond; reaction of the M–M′ complexes with methyl isocyanide leads to the immediate insertion into the metal–metal bond, a reaction which is analogous to α-additions to isocyanides.