Quantum chemical modeling of valence tautomeric adducts of CoII bischelates with pyrene-4,5-diimines

Abstract

Quantum chemical study of mixed-ligand (1: 1) adducts of tetracoordinated cobalt complexes (diketonates, bis-aminovinylketonates, and bis-salicylaldiminates) with pyrene-4,5-diimines using density functional theory (DFT B3LYP*/6-311++G(d,p)) revealed compounds possessing valence tautomeric properties. The mechanisms of intramolecular electron transfer accompanied by changing magnetic properties of the complexes under consideration were studied. It was shown that the variation of substituents at the nitrogen atoms of the diimine ligand and the donor groups in the cobalt bischelate, as well as the annulation of five- and six-membered rings to the azomethine fragment exerts a considerable influence on the stability of the formed adducts and the energy difference between their low- and high-spin isomers.