Anionic ligands palladacycles

Ligands with a carbon anion directly bonded to a metal ion are more common than perhaps supposed. The family of ligands (82) (Figure 14) invariably act as a tridentate N2C donor ligand to Pt, via deprotonation of the carbon marked in the figure. The C-deprotonated N2C pincer ligand (83) forms a totally flat palladacycle with sp hybridization of C and both N donors. A diimine tridentate (84) with the carbanion as a terminal rather than central donor of the N2C ligand has... 

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