Phosphinidine ligands

The robust Cp Ir(NHC) moiety (NHC = l,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) has also been used to stabilize [Cp (NHC)Ir=PMes] complex 552 which contains an unusually stable phosphinidine ligand (Scheme 11) ... 

Primary phosphanes, like primary amines, possess two hydrogen atoms and thus can be doubly deprotonated. A doubly deprotonated primary phosphane is known as a phosphinidine. It can realize a variety of different bonding modes with metals (see Fig. 7.18). It can form two covalent bonds and one donor bond. It can act as a two electron or a four electron donor ligand, either as a terminal or a bridging ligand. 

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