Bis-o -Benzosemiquinonato Cobalt(II) and Nickel(II) Complexes with Neutral N-Heterocyclic Carbene Ligand: Synthesis, Structure and Magnetic Properties

Abstract

N,N′‐bis(2,6‐dimethylphenyl)imidazol‐2‐ylidene (Me2PhIm) interacts easily with cobalt(III) and nickel(II) o‐benzosemiquinonato complexes, (3,6‐SQ)3Co and (3,6‐SQ)2Ni, as a neutral donor ligand giving mixed‐ligand NHC bis‐o‐benzosemiquinonato cobalt(II) and nickel(II) complexes ‐ (3,6‐SQ)2Co(Me2PhIm) (1) and (3,6‐SQ)2Ni(Me2PhIm) (2) (3,6‐SQ is radical‐anion 3,6‐di‐tert‐butyl‐o‐benzosemiquinolate). Cobalt complex 1 has a square‐pyramidal geometry in crystal with NHC ligand in the apical site in accordance with single‐crystal X‐ray analysis. Accordingly to magnetic measurements, the strong antiferromagnetic exchange interaction between spins of o‐benzosemiquinonato ligands was observed for these complexes.