Synthesis, crystal structure and magnetic properties of a two-dimensional lamellar coordination polymer manganese(II) pyrazinecarboxylate

The two-dimensional (2D) lamellar coordination polymer [Mn(pzc)₂]_n (pzc = pyrazinecarboxylate) was prepared and its structure determined by X-ray diffraction. Each Mn^II ion lies in a distorted octahedron coordination sphere, and the pzc ligand adopts two types of bridging mode. As a result, there are two different distances between adjacent Mn¹¹ atoms: one being 3.50(6) Å via μ₂-O forming a dimer of Mn^II, and the other 5.65(4) Å through the syn-anti carboxy oxygen atoms. The latter links the dimer to form an extended 2D lamellar structure. All Mn^II ions in each layer are nearly coplanar. The adjacent sheets are significantly associated via hydrogen bonding and the shortest interlayer Mn⋯Mn separation is 9.4 Å. The e.s.r. spectrum shows a broad isotropic band centered at g = 2.019. Temperature-dependent magnetic susceptibility measurements (2.0-300 K) reveal the presence of an antiferromagnetic interaction in the coordination polymer.