Magneto-structural correlations in cobalt(II)-phenanthroline compounds with chloranilic acid.

The impact of subtle modification of the environment on magnetic properties, by exchanging only solvent molecules, was investigated using a novel series of cobalt(II) compounds as a case study. Three new cobalt(II) complexes with a phenanthroline ligand (phen) and chloranilic acid (CA) [Co(CA)(phen)2] (1) were synthesized: 1·MeOH, 1·EtOH, and 1·EtGly. Single-crystal and powder X-ray diffraction revealed that all structures are isostructural mononuclear complexes with a distorted octahedral cobalt environment. X-band ESR spectroscopy provided an effective spin of 1/2 with anisotropic geff-values for cobalt ions at low temperatures. ESR linewidth analysis, supported by DFT calculations, revealed negligible intermolecular interactions. Static magnetic properties were studied using the temperature and field dependence of magnetization. Comprehensive magnetic modeling of the experimental data provides deeper insight into the subtle influence of different crystal packing arising from solvent exchange on the magnetic properties of the complexes. Additionally, AC magnetic susceptibility studies at low temperatures revealed field-induced slow magnetization relaxation in these cobalt(II) compounds.