Ligand field effect tuned magnetic behaviors of two chain compounds based on Mn^III₃O units: From slow magnetic relaxation to metamagnetism

Two chain compounds built with anti-anti acetate bridged Mn ^III₃O units, [Mn₃O(Clppz)₃(EtOH) ₄(OAc)]_n (1) and [Mn₃O(Clppz) ₃(EtOH)₂(OAc)]_n (2), were synthesized and characterized. The magnetic studies indicate that 1 is a single-chain magnet with two slow magnetization relaxation processes which has for the first time been found in this type of chain complex, while 2 shows a field-induced metamagnetic behavior. The quite different magnetic behaviors resulted from the different number of coordinated ethanol molecules on the Mn^III ₃O unit, four ethanol molecules for 1, and two ethanol molecules for 2. The best fittings to the experimental magnetic susceptibilities gave J ₁ = -2.72 cm^-1, J₂ = -4.34 cm^-1, zJ = 1.24 cm^-1 for 1 and J₁ = -5.91 cm^-1, J ₂ = -0.98 cm^-1, zJ = 1.71 for 2 above 30 K. The positive zJ values indicate the presence of weak ferromagnetic interactions between the trinuclear units via acetate bridges in 1 and 2.