Ligands effects on the magnetic anisotropy of tetrahedral cobalt complexes

The effect of ligands with heavy donor atoms on the magnetic anisotropy of the pseudo-tetrahedral cobalt complexes, Co(quinoline)2I2 (1) and Co(EPh3)2I2 (2-3) (E = P, As) has been investigated. The axial zero-field splitting parameter D was found to vary from +9.2 cm(-1) in 1 to -36.9 cm(-1) in 2 and -74.7 cm(-1) in 3. Compounds 2 and 3 exhibit slow relaxation of the magnetization up to 4 K under an applied dc field, indicating SMM behavior.