Family of Quasi-Isotropic Mn and Mn Complexes Exhibiting Slow Relaxation of the Magnetization.

Slow relaxation of magnetization has been studied for a family of mononuclear Mn complexes and one ferromagnetic dinuclear system, all of them presenting very weak anisotropy. Complexes with formula {NiL1Mn(HO)(MeOH)}{NiL1} (), Mn{NiL1} (), Mn{NiL2} (RR-L2, RR, SS-L2, SS), Mn{NiL3} (RR-L3, RR, SS-L3, SS) and (μ-N)[NiMn(L1)(N)] () are derived from compartmental Schiff bases, in which the Ni environment is square planar and thus diamagnetic. All of the systems have been structurally and magnetically characterized. Zero field splitting () values for the Mn cations have been obtained from EPR spectroscopy and NEVPT2 calculations. The slow relaxation of the magnetization for - 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 complex, with = 5 ground state, exhibiting slow relaxation.