Family of Quasi-Isotropic Mn^II and Mn₂^II Complexes Exhibiting Slow Relaxation of the Magnetization

Abstract

Slow relaxation of magnetization has been studied for a family of mononuclear Mn II complexes and one ferromagnetic dinuclear system, all of them presenting very weak anisotropy. Complexes with formula [{NiL1Mn- 5) are derived from compartmental Schiff bases, in which the Ni II environment is square planar and thus diamagnetic. All of the systems have been structurally and magnetically characterized. Zero field splitting (D) values for the Mn II cations have been obtained from EPR spectroscopy and NEVPT2 calculations. The slow relaxation of the magnetization for 1−5 has been studied by means of ac magnetometry and rationalized on the basis of their low, but not zero, anisotropy, providing the first example of a polynuclear Mn II complex, with S = 5 ground state, exhibiting slow relaxation.