Adducts of cobalt(II) bis(salicylaldiminates) and redox-active Phenoxazin-1-one: Synthesis, structure, and magnetic properties

Adducts of cobalt(II) bis(salicylaldiminates) and 2,4,6,8-tetra-tert- butylphenoxazin-1-one were synthesized and their molecular and crystal structures were determined. According to the ESR and magnetochemical data, the metal atom is in the low-spin trivalent state (CoIII) due to the intramolecular electron transfer to the redox-active ligand. In the solid state, the mixed- ligand complexes are stable in air for several months, but in solution at elevated temperatures they dissociate to the starting components. Such a behavior detected by the temperature depen- dence of the effective magnetic moment is explained by the quantum chemical DFT calcula- Tions of the energy barriers of possible valence tautomeric dynamics, whose values were found to be higher than the enthalpy of dissociation. © 2013 Springer Science+Business Media, Inc.