Syntheses, crystal structures, and DFT calculations of N'-(Pyridin-2-ylmethylene)nicotinohydrazide dihydrate and its copper complex

Abstract

A Schiff base ligand, N'-(pyridine-2-ylmethylene)nicotinohydrazide dihydrate (I) and its Cu complex, catena-Poly[N'-(picolinylpyridine-3-carbohydrazonate)copper(II) (II) have been synthesized and their structures have been determined by ¹H, ¹³C NMR and FT-IR spectroscopies, elemental analysis and single crystal X-ray diffraction technique. The SCXRD analysis conforms the I crystallized in a Triclinic crystal system, with a P−1 space group and lattice parameters are α = 87.910 (4)°, β = 76.629 (3)°, γ = 80.769 (3) °. II crystallized in an Orthorhombic crystal system, with a Pbca space group and lattice parameters, are a = 8.6502 (3) Å, b = 11.4314 (4) Å, and c = 25.4146 (6) Å, α, β, γ = 90°. When the FT-IR spectra of the functional groups of the two synthesized compounds were examined, it was determined that the vibrations of the N–N and pyridine C–N groups observed in the spectra of Compound I were not observed in the same region in the spectra of Compound II and that chemical shifts occurred, and these chemical shifts were attributed to the Cu–N bonds. The Hirshfeld surface analyses have confirmed the importance of H-atom contacts in establishing the packings. The large number of H–H, H–N/N–H, H–C/C–H, H–O/O–H, H–Cl/Cl–H and C–C interactions have been suggested that van der Waals interactions and hydrogen bonding play major roles in the crystal packings. In addition, geometric optimizations of both synthesized compounds were made and the electronic, nonlinear optical (NLO) property and vibration frequencies of the compounds in equilibrium were examined theoretically. The calculations of compound I were performed with both DFT/B3LYP and HF methods using the 6–311 +  + G(d,p) basis set but calculations on compound II are predicted at DFT/B3LYP level by using a mixed basis set of LANL2DZ (for Cu) and 6-311G (for other atoms). The dipole moment of compound I is calculated as 4.30 Debye at the DFT/B3LYP/6–311 +  + G(d,p)and 3.57 Debye HF/6–311 +  + G(d,p) level of theory, respectively.

Graphical abstract