Halogen atom effect on the magnetic anisotropy of pseudotetrahedral Co(II) complexes with a quinoline ligand

Field-induced slow relaxation of magnetization in the S = 3/2 octahedral complexes trans-[Co{(OPPh2)(EPPh2)N}2(dmf)2], E = S, Se: effects of Co–Se vs. Co–S coordination

“…70,71 In the above context, the coordination of heavier halogeno ligands to Ni(II) 72 or Cr(II) 73 has been shown to confer increased axial anisotropies. Similar effects, on the magnitude of the axial anisotropy due to the coordination of heavier halides, have also been established in tetrahedral [74][75][76][77][78][79][80] Co(II) complexes, in some instances imposing a concomitant change in the sign of D as well. 76,77 On the other hand, contrary to the above observations, lower axial anisotropy due to the coordination of heavier halides has been observed in squarepyramidal 81,82 and pentagonal bipyramidal 83 Co(II) complexes.…”

Tuning electronic structure through halide modulation of mesoionic carbene cobalt complexes

“…The two components contributing to ZFS are the minor direct spin-spin interactions and the dominant second-order spin-orbit coupling (SOC) introduced by mixing of ground and excited states. 37 Computational 31,38 and experimental [39][40][41][42][43] works have shown how anisotropy can be influenced via heavy atom coordination with further corroboration for ligand influence on ZFS in tetrahedral Co halide complexes emerging over the past five years. 14,[40][41][42][43][44][45] Complexes 1-3 show a clear trend in their |D| values consistent with the expected electronic-structure effect.…”

“…37 Computational 31,38 and experimental [39][40][41][42][43] works have shown how anisotropy can be influenced via heavy atom coordination with further corroboration for ligand influence on ZFS in tetrahedral Co halide complexes emerging over the past five years. 14,[40][41][42][43][44][45] Complexes 1-3 show a clear trend in their |D| values consistent with the expected electronic-structure effect. Specifically, we can attribute this trend to three effects: (1) Ligand-field strength correlates inversely with halide size, bringing the Co excited-states lower in energy for larger halides (Figure 4).…”

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

“…Among numerous 3d metal complexes showing SIM behavior, those based on high-spin Co­(II) complexes with quasi-octahedral coordination of the Co ion are especially interesting because unlike conventional SMMs and SIMs they often exhibit slow magnetic relaxation for both easy-plane and easy-axis types of magnetic anisotropy. ,− This atypical behavior was shown to be a result of the Kramers character of the Co­(II) ion …”