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.

A two dimensional GdIII coordination polymer based on isonicotinic acid N‐oxide with large magnetocaloric effect

“…Each Gd III ion is nine coordinated and has a distorted monocapped square antiprism geometry, which is completed by nine oxygen atoms (O1, O2, O3, O4, O4B, O6, O6A, O7 and O8) from five INNO − and two HCOO − ligands (Figure1a). The bond lengths of Gd−O bonds fall in the range of 2.320(3)–2.778(4) Å, which are consistent with the reported Gd III compounds [18,25–29] …”

Characterization, theoretical investigation, and biological applications of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes of a triazene ligand containing a benzothiazole ring

“…The angles around Co(II) range from 74.59 to 104.81 and from 158.06 to 183.12 , which are in agreement with the distorted octahedral geometry of Co(II) complex. [34] T A B L E 3 Geometric bond lengths and bond angles for metal complexes…”

Field-Induced Slow Magnetic Relaxation of a Six-Coordinate Mononuclear Manganese(II) and Cobalt(II) Oxamate Complexes

“…Using this approach, we obtained g = 2.50 and D = +71.35 cm −1 . 22,23 Because D > 0, the m s = ± 1 / 2 doublet is below the m s = ± 3 / 2 doublet and 2D represents the energy separation between the ± 1 / 2 and ± 3 / 2 doublets arising from second-order SOC of the quartet ground state of the axially distorted octahedral Co 2+ . The magnetization isotherm for 2 at 2.5 K (Figure S6b) shows M sat = 2.19 Nβ at 60 kOe, close to the expected value for the effective spin (S eff = 1 / 2 ) approach (2.20 Nβ).…”