Low-coordinate E1 ligand complexes of Group 15 elements—A developing area

A survey of transition–metal complexes with substituent-free Group 15 E1 ligands of coordination numbers 1 and 2 is presented. Such ligands exhibit interesting bonding properties and diverse reactivity patterns including cycloadditions, redox, and single-atom transfer. The various modes of coordination and relevant aspects to each regarding synthesis, bonding, and reactivity are summarized.