Heterospin complexes based on cobalt semiquinolate with nitroxides

Abstract

Heterospin complexes based on cobalt semiquinolate with stable nitroxides of composition [Co(SQ)2(NIT)2]·8CH2Cl2, [Co(SQ)2(NIT)2]·4MeCN, [Co(SQ)2(IN)2]·5Me2CO, [Co(SQ)2(IN)2]·4MeCN, and [Co(SQ)2(IN)2]·2CH2Cl2·C6H14, where SQ is 3,6-di-tert-butyl-o-benzosemiquinolate, NIT is 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, and IN is the imine analog of NIT, viz., 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-1-oxyl, were synthesized. The characteristic feature of these compounds is that they contain two different types of paramagnetic organic ligands. The X-ray diffraction study showed that the solid phases of the complexes have a molecular structure. According to the data from thermomagnetic analysis (2–350 K), all complexes exhibit effects of valence tautomerism at ∼20 °C. It was found that incorporated solvent molecules have an effect on the magnetic anomaly temperature.