Static and Dynamic Magnetic Properties of a Co(II)‐Complex with N ₂ O ₂ Donor Set – A Theoretical and Experimental Study

Abstract A representative Co(II) based single ion magnet (SIM) with N 2 O 2 donor set and distorted pseudo‐tetrahedral geometry has been synthesized and characterized to study the atomic and electronic structure. DC magnetometry results have been evaluated by means of a phenomenological Hamiltonian approach regarding zero field splitting (ZFS) parameters and compared with results from ab‐initio multi‐reference CASSCF (complete active space self‐consistent field) calculations and qualitative ligand field theory (AILFT). Profound investigation of spin‐lattice relaxation with the variation of temperature (from 1.8 to about 8 K) and magnetic field (at 14 different fields from zero up to 1 T) have been performed based on AC magnetometry. Under an applied dc magnetic field, spin‐lattice relaxation occurs via a direct process with T 2 temperature dependence due to limited heat transfer at very low temperature and above 5 K relaxation by an Orbach process with an energy barrier of ≈80 K dominates.