Valence-tautomeric adducts of Co(II) diketonates based on annelated di-o-quinones: Computer simulation

Abstract

The computer simulation (DFT B3LYP*/6-311++G(d,p)) is performed for the adducts of divalent cobalt diketonates with di-o-quinones in which the quinone rings are separated by the cycloalkane spacers. The isomers containing dianion–diradical forms of the redox-active ligand, the character of exchange between unpaired electrons of which depends on the spacer structure, correspond to the ground states of the considered compounds. Strong antiferromagnetic interactions (J > 400 cm^–1) are predicted for the most stable electromers of the adducts of Co(II) bis(chelates) with 9,10-dimethyl-9,10-ethanoanthracene-2,3,6,7(9H,10H)-tetraone, whereas a weak exchange favoring paramagnetism in a wide temperature range is expected for the ground states of the binuclear complexes with the isomeric 5,10-dimethyl-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-2,3,7,8-tetraone spacer. The electromers of the complex with the hexafluoroacetylacetone ligands are characterized by close values of the total energies, due to which the complex becomes a promising object for the development of spin qubits.