Metal Complex Chromophores Based on -Iminobenzoquinonato Derivatives of Cobalt(iii), Copper(ii) and Nickel(ii): Molecular Structure, Electronic Absorption Spectra and Thermal Properties

A series of the 3-row transition metal complexes was synthesized on the base of -aminophenol АРН augmented by azo-fragment: bis--iminobenzosemiquinonate derivatives (imSQ)Ni (1), (imSQ)Cu (2), as well as mixed-ligand compound (imSQ)(AP)Co (3) (where imSQ and AP are radical anion and dianion redox-forms of ligand АРН, correspondingly). The molecular structure of ligand АРН and complexes 1·CH, 2·CH and 3·CH was determined using x-ray diffraction analysis (CIF files CCDC Nos 2444549-2444553, correspondingly). The planar coordination environment of metal center caused the mutual planar displacement of frontier orbitals HOMO and LUMO, that is why low-energy charge transfer ligand-to-ligand is implemented in compounds 1-3, corresponding the light absorption in the IR-region. Obtained metal complexes are characterized by rich set of redox states, predominantly provided by redox-active nature of ligands. The compounds of nickel(II) 1 and cobalt(III) 3 are volatile and distinguished by high thermostability and completeness transfer into the vapor phase, that is the favourable factor for the design of optoelectronic devices based on them using the vacuum deposition method.