A new Zn(II) complex of N'-(1-(thiophen-2-yl)ethylidene)isonicotinohydrazide: synthesis, spectral characterization, X-ray structure

Abstract

The hydrazone ligand E-N'-(1-(thiophen-2-yl)ethylidene)isonicotinohydrazide (HL) was synthesized by a one-step condensation reaction and characterized by elemental analysis, infrared spectroscopy, and 1H and 13C NMR spectroscopies. The Zn(II) complex derived from ligand (HL) was synthesized and characterized by elemental analysis, conductivity measurements in DMF solutions, FT-IR and electronic spectroscopies, and single-crystal X‑ray diffraction. Elemental analysis showed that the Zn(II) complex is composed of a single metal, organic ligand, and chloride ions in a 1:1:2 molar ratio. This Zn(II) complex is a neutral electrolyte in solution in DMF. The mononuclear complex 1 crystallizes in the triclinic space group Pī with the following unit cell parameters: a = 5.831 (3) Å, b = 9.337 (4) Å, c = 13.738 (4) Å, V = 731.6 (5) Å3, Z = 2. The asymmetric unit of complex 1 contains one Zn(II) ion, one ligand molecule, and two coordinated chloride ions. In this complex, the ligand exists in its overall neutral bidentate form. The hydrazine group is deprotonated while the pyridine nitrogen atom is protonated. The ligand is coordinated to the Zn(II) through the carbonyl oxygen and the azomethine nitrogen. The metal cation is also coordinated with two chloride ions, resulting in a tetra-coordinated Zn(II). The environment around the cation Zn(II) is best described as a tetrahedral geometry. Numerous hydrogen bonds and an intramolecular chalcogen bond consolidate the structure into a three-dimensional network.