Synthesis, structural characterization and magnetic properties of 2-pyrazinecarboxylate manganese compounds [Mn(pyz)2(H2O)4] and [MnCl(pyz)(H2O)]n (pyz=2-pyrazinecarboxylate)

Two pyz complexes [Mn(pyz)2(H2O)4] (1) and [MnCl(pyz)(H2O)]n (2) have been synthesized and structurally characterized. Complex 1 contains an eight-coordinate Mn(II) ion with square anti-prismatic geometry. The extensive intermolecular hydrogen-bonding interactions of Ocarboxyl⋯HOaqua correlate the complex molecules, forming 2D polymeric layer structure. The structure of complex 2 contains 1D Mn/pyz chains, which link to each other by double μ2-Cl bridges to form 2D layer with Mn⋯Mn distance of 3.664 Å. Hydrogen-bonding interactions of Ocarboxyl⋯HOaqua are found between the layers to correlate the 2D layers to form a 3D framework. In addition, the variable temperature magnetic susceptibilities of complex 2 were measured and weak ferromagnetic exchange interactions between the neighboring magnetic species were found with J=0.42 cm−1.