Synthesis, Characterization and Crystal Structure of Caffeine Complex of Mn(II) p-Hydroxybenzoate

A new manganese(II) complex containing p-hydroxybenzoate and caffeine ligands, namely [Mn(OH-C6H4COO)2(H2O)4].2(C8H10N4O2).8H2O has been prepared. The synthesized complex has been characterized by elemental analyses, FT-IR spectroscopy, X-ray crystallography, and molar conductance measurements. The thermal properties of the complex were analyzed by TGA/DTA. The complex crystallizes in the monoclinic space group P21/c having cell dimensions a=11.1311(2), b=14.3579(3), c=13.5383(3) Å, β=101.879(2)º, V=2117.34(8) Å3, Z=2. In the mononuclear complex, Mn atom is coordinated by two p-hydroxybenzoate anions and four water molecules. Moreover, the asymmetric unit of the complex also contains four uncoordinated water molecules and one caffeine ligand. Crystal structure of the complex has 3D supramolecular networks formed via O-HOH···Ocaf, O-Hw···Ow, O-Hw···Ncaf, O-Hw···Ocaf, and O-Hw···Ocar hydrogen bonds.