Synthesis, crystal structure, Hirshfeld surface analysis, and characterization of a new 1-D dicyanamide-bridged, polymeric Mn(III) complex

A 1-D dicyanamide (DCA)-bridged, polymeric manganese(III) Schiff base complex, \({[\text{Mn}{L}_{2}({\mu }_{\text{1,5}}-\text{dca})] }_{n}\)(1), where HL is 5-methoxy-2-[(E)-{[2-(thiophen-2-yl)ethyl]imino}methyl]phenol, a bidentate Schiff base prepared from the condensation reaction of 2-hydroxy-4-methoxybenzaldehyde and 2-thiopheneethylamine, has been synthesized by stirring Mn(ClO₄)₂·6H₂O, Schiff base (HL), and sodium dicyanamide (1:2:1 M ratio) in acetonitrile medium. The complex was characterized by FTIR, UV–Vis absorption spectra, TGA analysis, and single-crystal X-ray diffraction studies. According to X-ray diffraction study, the compound crystallizes in a monoclinic system with space group P2₁/n. The manganese atom of the complex is in octahedral coordination with two imine nitrogen atoms (N1, N1ⁱ) and two phenoxy oxygen atoms (O1, O1ⁱ) of two molecules of Schiff base ligand, which defines the equatorial plane around Mn(III), and the axial sites are occupied by two nitrogen atoms (N2, N2ⁱ) of DCA. The Hirshfeld surface (HS) analysis was also performed by means of the crystallographic data to inspect the nature and quantitative influence of all possible non-covalent intermolecular contacts inside the crystal lattice. The direct optical band gap energy has been calculated using the Tauc plot.