A new family of high-dimensional molecular magnets built from the manganese-azido system. Syntheses, structures, and magnetic characterization of two new ferro-antiferromagnetic two-dimensional complexes

Two new compounds in the series of general formula [Mn(L)(2)(N-3)(2)](n) in which L = 4-cyanopyridine (1) or 3-acetylpyridine (2) have been obtained and structurally and magnetically characterized. Both compounds crystallize in the monoclinic system, space group P2(1)/a, formula [C12H8MnN10] with a 13.286(4) Angstrom, b 8.340(3) Angstrom, c = 13.579(4) Angstrom, beta = 90.55(2)degrees 0, and Z = 4 for compound 1 and space group P2(1)/c, formula [C14H14MnN8O2] with a = 11.843(4) Angstrom, b = 9.550(3) Angstrom, c 14.998(5) Angstrom, beta = 105.99(3)degrees, and Z = 4 for compound 2. The two compounds show a similar arrangement of alternating end-to-end and end-on azido bridges between the manganese atoms, giving magnetically alternated ferro-antiferromagnetic two-dimensional compounds. The pyridyl ligands coordinated to the axial sites stick out above and below the 2-D sheets, and intersheet pi-pi interactions are formed between the pyridyl ligands, playing a role in the structural differences. The low-temperature magnetic properties of 1 and 2, together with those of the previously reported compounds with L = pyridine (3), 4-acetylpyridine (4), and ethyl isonicotinate (5), are reported. Magnetic ordering and spontaneous magnetization is achieved at T-C = 18, 16, 40, 28, and 16 K for 1-5, respectively.