New insights into the thermal stability of Mn-12 clusters: The case of complex [Mn12O12(O2CC CH)(16)(H2O)(4)]center dot 3H(2)O and its thermolysis derived [Mn-3(O2CC CH)(6)(H2O)(4)]center dot 2H(2)O complex.
Two novel Mn-12 derivatives [Mn12O12(O2CC CH)(16)(H2O)(4)]center dot 3H(2)O (1) and [Mn12O12(O2CC CC6H5)(16)(H2O)(4)]center dot 3H(2)O (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 degrees 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 [Mn-3(O2CC CH)(6)(H2O)(4)]center dot 2H(2)O (3), which corresponds to an extended sheet-like structure that crystallizes in the monoclinic space group P2(1)/n; a = 9.2800(2) angstrom, b = 9.4132(2) angstrom, c = 14.9675(3) angstrom, beta = 99.630(l)degrees, 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.