New insights into the thermal stability of Mn12 clusters: The case of complex [Mn12O12(O2CCCH)16(H2O)4]·3H2O and its thermolysis derived [Mn3(O2CCCH)6(H2O)4]·2H2O complex

Abstract

Two novel Mn₁₂ derivatives [Mn₁₂O₁₂(O₂CCCH)₁₆(H₂O)₄]·3H₂O (1) and [Mn₁₂O₁₂(O₂CCCC₆H₅)₁₆(H₂O)₄]·3H₂O (2) have been prepared and characterized. Magnetic measurements confirm that both function as single-molecule magnets (SMM), showing frequency-dependent out-of-phase AC susceptibility signals and magnetization hysteresis curves. Thermal stability studies of both complexes were first conducted in the solid state. While complex 1 undergoes a sudden exothermal decomposition at T_onset = 118 °C, complex 2 exhibits a higher stability. Thermolysis reaction of 1 was hence assessed in solution to yield dark red crystals of a two-dimensional Mn^II-based co-ordination polymer [Mn₃(O₂CCCH)₆(H₂O)₄]·2H₂O (3), which corresponds to an extended sheet-like structure that crystallizes in the monoclinic space group P2₁/n; a = 9.2800(2) Å, b = 9.4132(2) Å, c = 14.9675(3) Å, β = 99.630(1)°, and Z = 2. Finally, the magnetic properties of complex 3 have been studied on an oriented single crystal over two different orientations of the reciprocal vector versus the external field.