Inducing ring distortions in unsubstituted metallophthalocyanines using axial N-heterocyclic carbenes.

A series of metallophthalocyanine (PcM) complexes with axial N-heterocyclic carbene ligands (NHC; 1,3-diisopropylimidazol-2-ylidene (DIP) and 1,3-dimethylbenzimidazol-2-ylidene (DMB)) were prepared and structurally characterized. PcCo(DIP), PcZn(DIP), and PcZn(DMB) are five-coordinate complexes with mild dome-type Pc-ring distortions, while PcFe(DIP) is six-coordinate and has a very large ruffle-type ring-distortion with respect to typical PcM(L) systems. The distortion is induced by the highly steric axial DIP ligands.