Quantum chemical calculations and experimental investigations on 2-aminobenzoic acid-cyclodiphosph(V)azane derivative and its homo-binuclear Cu(II) complex

• Published in: Journal of molecular structure 2012-03, Vol.1011, p.50-58
• Main Authors: El-Gogary, Tarek M., Alaghaz, Abdel-Nasser M.A., Ammar, Reda A.A.
• Format: Article
• Language: English
• Subjects: B3LYP; copper; Cu(II) complex; Cyclodiphosph(V)azane ligand; Electronic spectra; isomers; nitrogen; pyridines; Quantum chemical calculations; spectroscopy; TD-DFT; thermogravimetry; UV–VIS spectra
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2011.12.009

► Novel cyclodiphosph(V)azane ligand and its Cu(II) complex were synthesized and characterized. ► Analytical results have justified the [Cu2L(H2O)2]·2.5H2O composition. ► Structure and spectra for the ligand and its Cu complex were computed at the B3LYP/6-31G(d). ► Six tautomers and geometrical isomers of the ligand were optimized at the ab initio level. ► Computed TD-DFT UV–VIS spectra show good agreement with measured electronic spectra. A novel 2-aminobenzoic acid-cyclodiphosph(V)azane ligand H4L and its homo-binuclear Cu(II) complex of the type [Cu2L(H2O)2].2.5 H2O in which L is 1,3-di(-o-pyridyl)-2,4-(dioxo)-2′,4′-bis-(2-iminobenzoic acid) cyclodiphosph(V)azane, were synthesized and characterized by different physical techniques. Infrared spectra of the complex indicate deprotonation and coordination of the imine NH and carboxyl COOH groups. It also confirms that nitrogen atom of the pyridine ring contribute to the complexation. Electronic spectra and magnetic susceptibility measurements reveal square-planar geometry for the Cu(II) complex. The elemental analyses and thermogravimetric results have justified the [Cu2L(H2O)2]·2.5H2O composition of the complex. Quantum chemical calculations were utilized to explore the electronic structure and stability of the H4L as well as the binuclear Cu(II) complex. Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of H4L and its binuclear Cu(II) complex. Different tautomers and geometrical isomers of the ligand were optimized at the ab initio DFT level. Simulated IR frequencies were scaled and compared with that experimentally measured. TD-DFT method was used to compute the UV–VIS spectra which show good agreement with measured electronic spectra.