Phosphorus, Arsenic, Antimony, and Bismuth Multiply Bonded Systems with Low Coordination Number — Their Role as Complex Ligands

Abstract Multiply bonded systems with low coordination number (one to three) involving phosphorus and its homologues, whether isolable or generated in situ at a metal complex, are versatile ligands that can function as two‐, four‐, six‐ or eight‐electron donors to transition metal fragments and that may be coordinated in η 1 (terminal), η 2 (side‐on), edge‐ or face‐bridging modes. The (p‐p)π bonding system of the ligand is thereby rendered capable of addition and intra‐ or intermolecular cycloaddition reactions. Some of the polycyclic species thus generated represent novel, polydentate ligands.