Allenyls and propargyls: versatile ligands in transition-metal chemistry

Mononuclear, binuclear, and trinuclear transition-metal allenyl and/or propargyl complexes are reviewed with respect to methods of synthesis, structure, and reaction chemistry. Structural relationships among the various types of complexes are presented and, to the extent possible, used to rationalize some patterns of reactivity. Recent developments in the field are accorded special emphasis.