Geometrical control of the magnetic anisotropy in six coordinate cobalt complexes

Abstract

The geometry of cobalt(II) ions in the axially distorted octahedral cation in [Co(MeCN)₆](BF₄)₂ (1) was compared to the trigonal prismatic cation in [CoTp^py]PF₆ (2) which revealed significant differences in magnetic anisotropy. Combined experimental and ab initio CASSCF/NEVPT2 calculations support the observed zero field SMM behaviour for 2, with easy axis anisotropy, attributed to the rigidity of the trigonal prismatic ligand. Strong transverse anisotropy for 1 leads to significant quantum tunnelling processes.