Mononuclear High‐spin Octahedral Cobalt(II) Complex with Positive Axial Magnetic Anisotropy: Synthesis, Crystal Structure, and DFT Studies

Abstract

This article outlines the magnetic features of a new six–coordinate high‐spin cobalt(II) complex cis‐[CoII(tmphen)2(NCS)2] (1) achieved via the reactions of cobalt(II) thiocyanate with 3,4,7,8‐tetramethyl‐1,10‐phenanthroline. The complex 1 was thoroughly characterized by different analytical and spectroscopic techniques and further confirmed by single X‐ray crystal diffraction pattern. Complex 1 is a neutral molecule and adopt highly distorted six‐coordinate CoN6 octahedral coordination sphere surrounded by two thiocyanate N atoms in cis locations and the equatorial plane is occupied by two imine N atoms from the two tmphen ligand while the remaining two imine N atoms reside in the axial positions. Magnetic susceptibility data of complex 1 revealed that the χΜT values decrease significantly to a value of 1.49 cm3·K·mol–1 at 2.0 K on decreasing temperatures below 100 K, mainly ascribed to the significant spin–orbit coupling (SOC) of six‐coordinate CoII ions. Furthermore, a field‐dependence measurement was performed at 2 K, which shows a positive curvature up to 27 kOe, while it becomes linear up to 2.01 NμB, which authenticated the fact that only the lowest Kramers doublet of ground state is appreciably populated.