Slow magnetic relaxation in two octahedral cobalt(II) complexes with positive axial anisotropy

摘要

Two mononuclear Co(II) complexes [Co(L)(4)(NO3)(2)] (L= 3-phenylpyrazole for 1 and 4-methylpyridine for 2) featuring distorted octahedral geometry were prepared and structurally characterized by X-ray crystallographic analyses. Direct-current magnetic and high-frequency/field electron paramagnetic resonance measurements reveal that both complexes have the large and positive D values with the nonnegligible transverse anisotropy (E). Slow magnetic relaxation effects were observed under the applied direct-current field in 1 and 2 by dynamic alternative-current magnetic susceptibility measurements, which provide two interesting examples of six-coordinate Co(II)-based single ion magnets constructed by nitrate groups and nitrogen heterocyclic compounds in mono-dentate coordination modes. (C) 2018 Elsevier B.V. All rights reserved.