Coordination chemistry of tris(azolyl)phosphines

An overview is given of the chemistry of tris(azolyl)phosphines with focus on their preparation and application in coordination- and organometallic chemistry and catalysis. These systems share with the more abundant tris(pyrazolyl)borates and -methanes the ability to function as tridentate nitrogen ligands with hemilabile character, but the additional phosphine donor site grants them bifunctional potential. Applications of tris(azolyl)phosphine complexes range from enzyme models and medicinal leads to catalysts for organic transformations and polymerization reactions, which demonstrate their versatility.