Exposing the intermolecular nature of the second relaxation pathway in a mononuclear cobalt(II) single-molecule magnet with positive anisotropy.

The investigation of a pentagonal bipyramidal Co(ii) complex with large positive anisotropy (D ≈ +30 cm(-1)) revealed field induced Single-Molecule Magnet behaviour with Ueff ≈ 50 K at 1.0 kOe. This compound belongs to a group of only a handful of complexes which exhibit this unique magnetic property while possessing easy-plane anisotropy. At high applied fields, a second relaxation process with an intermolecular nature has been exposed using magnetic dilution studies with varying percentages of Zn(ii) analogue. The disappearance of the second relaxation process at low frequency can be followed using magnetically diluted samples at 25%, 10% and 5% Co(ii) concentrations.