Magnetic properties of hexanuclear manganese antiferromagnetic clusters {Mn6}

摘要

We report a study of magnetic properties of a series of hexanuclear manganese metallamacrocycles {Mn6}. The magnetic properties are characterized by antiferromagnetic (AFM) coupling constants J_1/k_B approx = - 4.0K, between the nearest neighbors, and J_2/k_B approx = -1.2 K, between the next-nearest neighbors. The temperature dependence of ~1H NMR linewidth is observed to be consistent with the AFM singlet ground state with a total spin S_T = 0. ~1H nuclear spin-lattice relaxation rate 1/T_1 shows a strong enhancement at low temperatures with a peak around T approx J_1, as commonly observed in AFM molecular rings and clusters.