Chloro and azido bonded manganese complexes: synthesis, structural, and magnetic studies

Two manganese complexes, [Mn2(tptz)2Cl4] · CH3CN (1) and [Mn(tptz(ac)(N3)(H2O)] · H2O (2) (where tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, ac = acetate anion), were synthesized and characterized by elemental analyses, infrared spectra, and UV-Vis absorption spectral analyses. The structures of both the complexes were determined by single crystal X-ray diffraction analysis. Complex 1 is binuclear with chloro-bridged manganese ions at the Mn-Mn separation of 3.777(27) Å. Each manganese center in 1 is six coordinate with three nitrogens from a tridentate tptz, three chlorides (one terminal and two bridging), adopting a centrosymmetric distorted octahedral geometry. Various hydrogen bonds form 2-D spiral structures in 1 with Mn-Mn separation of 7.421(2) Å along a-axis and 9.121(2) Å along b-axis. Complex 2 is seven coordinate with pentagonal bipyramidal geometry. The metal center coordinates to three nitrogens from tptz, two oxygens from acetate, one nitrogen from azide, and one oxygen from water. It has a 1-D layered structure, where three independent molecules are linked by uncoordinated water present in the lattice. Magnetic susceptibility in the temperature range 5-300 K for 1 shows the presence of antiferromagnetic interaction between the local high-spin manganese(II) ions with J = -0.17 cm-1.