Synthesis, crystallographic and spectroscopic characterization, and theoretical elucidation of an elusive aminyl radical containing a CuII–aminyl-iminosemiquinone complex

Abstract

An elusive aminyl radical and an iminosemiquinone radical-coordinated square pyramidal Cu(II) complex (1) have been isolated by the reaction between the noninnocent ligand H₄L_Py^(AP) and Cu(ClO₄)₂·6H₂O in the presence of Et₃N and air as the sole oxidant. The geometry and electronic structure of the complex were concluded by X-ray crystallography, magnetic and EPR measurements, and density functional theory (DFT) calculations. This work reports the first crystallographic example of the two different types of radicals co-existing in a stable complex.