Phosphoraneiminato complexes of transition metals

A review on syntheses, chemical reactions, structure and bonding of phorpho raneiminato complexes of transition metals (TM) is given. The ligand group [NPR3](-), not known as a discrete ion, is isoelectronic with, amongst othe rs, [OSiMe3](-), and is capable of a versatile coordination chemistry. Apar t from terminal functions [M] = N-PR3 with a close to linear M-N-P axis (A) and bent axis [GRAPHICS] (B), complexes with mu(2)-N-bridges forming symmetrical (D) or unsymmetrica l (C) four-membered M2N2 rings are as well known as those of the mu(3)-N-ty pe (E) leading to heterocubane M4N4 structures. The coordination type prefe rred is primarily dependent on the oxidation state (OS) of the TM, but also on the ligand sphere of the TM and on the steric and electronic properties of the substituents at phosphorus (R = organic group, NR;, halogen). Types A and B are predominantly realized in complexes of metals in high OS. Elec tron-rich metals prefer type E, and in mediate OS bonding modes C and D pre vail. (C) 1999 Elsevier Science S.A. All rights reserved.