Synthesis, characterization and X-ray crystal structures of two non-molecular coordination polymers of manganese(II) and copper(II) with N-(2-pyridylmethyl)-l-alanine and isothiocyanato ligands

The reduced Schiff base, N-(2-pyridylmethyl)-l-alanine (Pyala), has been prepared and used as a ligand for the synthesis of two new non-centrosymmetrical isothiocyanate mixed-ligand coordination polymers, [MnPyalaSCN]_n and [CuPyalaSCN]_n. Pyala and the metal complexes were characterized by physico-chemical and spectroscopic methods. The single-crystal X-ray structures of the complexes reveal both compounds to be non-molecular coordination polymers which crystallize in the orthorhombic system. The ligand acts as a bridge between two metal centres in both compounds, forming two six-membered rings around each Mn atom and two five-membered rings around each Cu centre. The 1D chains are assembled via N–H⋯O, N–H⋯S hydrogen bonds and S–S interactions building 3D helical supramolecular networks in both compounds. Packing of the polymers of both compounds along the b-axis gives chiral channels.