Carbene complexes of titanium group metals — formation and reactivity

The principles in the formation of carbene complexes of titanium group metals are summarized. Characteristic examples of isolated as well as carbene complexes as intermediates are given. Selected structures and reactivity patterns are discussed. Starting from the Tebbe-type chemistry, new aspects of carbene complexes with only one or without cyclopentadienyl ligands are illustrated. In that direction, the formation of carbene complexes with N and O-donor ligands is described. Applications in co-ordination chemistry, organic syntheses and material sciences are summarized.