Field-Induced Slow Magnetic Relaxation in a Mononuclear Manganese(II) Complex.

A mononuclear manganese(II) complex, [Mn(4-bzpy)4Cl2] (4-bzpy = 4-benzylpyridine), exhibits a slow magnetic relaxation with three relaxation modes that is supported by the external magnetic field. The low-frequency mode shows an exceptionally slow relaxation time: τ = 798 ms at T = 1.9 K and BDC = 0.35 T. The high-frequency domain exhibits unusual acceleration of the relaxation time upon cooling below 3.5 K.