Bis-o-semiquinonato cadmium(II) complexes with o-quinonato and N-heterocyclic carbene neutral ligands

Abstract

The reaction of cadmium amalgam with excess of 3,6-di-tert-butyl-o-quinone (3,6-Q) in THF afforded the new bis-o-semiquinonato cadmium(II) complex coordinated with one molecule of neutral o-quinone (3,6-SQ)2Cd(3,6-Q) (1) acting as a starting reagent to other bis-o-semiquinonato cadmium(II) complex with N-heterocyclic carbene (NHC)–(3,6-SQ)2Cd{C[N(Ar)(CH)]2} (Ar=2,6-dimethylphenyl) (2). Both complexes possess a singlet ground state with thermally accessible triplet state (the singlet-triplet gap is 8cm−1 for 1 and 132cm−1 for 2) as confirmed by magnetic data. The antiferromagnetic exchange SQ–SQ is observed for both complexes.