Coordination Compound of Copper(II) with an Isonicotinohydrazide Derivative

The {[CuCl(L)]·DMF}_n complex compound is prepared by the interaction of (E)-N′-(pyridin-2-ylmethylene)isonicotinohydrazide (L) with CuCl₂·2H₂O in ethanol. The obtained compound is characterized by elemental analysis and IR spectroscopy; its crystal structure is determined by XRD. The compound has a polymeric structure and is composed of {CuCl(L)} fragments connected into zigzag chains due to the coordination of the pyridine nitrogen of the L ligand of one fragment to the copper atom of the neighboring fragment. The copper ion has a distorted square-pyramidal coordination environment (∠NCuO = 155.71° and ∠NCuCl = 101.16°). The unit cell containing four {[Cu(L)Cl]·DMF} fragments is calculated within the quantum chemical approach of the density functional theory. The electronic structure is analyzed; the band structure and density of states diagrams are constructed. It is shown that the electronic structure has no band gap: the Fermi level virtually coincides with the highest occupied crystal orbital (HOCO) and is equal to –5.733 eV. The HOCO and the lowest unoccupied crystal orbital (LUCO) have similar compositions, but the contribution of p orbitals of the organic ligand is higher for the LUCO. The electron density Laplacian values at the critical points of Cu–N, Cu–Cl, and Cu–O bonds indicate that these bonds belong to the intermediate type with a predominant contribution of ionic bonding.