Hydroxycoumarine Azodye, Thermal Stability, Harmonic Vibrational Spectra, Conductance, and pH Measurements

• Published in: Journal of chemical and engineering data 2010-01, Vol.55 (1), p.267-272
• Main Authors: El-Dossoki, F. I, Shoair, A. F, Hosny, N. M
• Format: Article
• Language: English
• Subjects: Chemistry; Coordination compounds; Exact sciences and technology; Inorganic chemistry and origins of life; Preparations and properties
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je900323u

Two metal complexes resulting from reaction of hydroxycoumarine azodye with Zn(II) and Cd(II) have been synthesized and characterized using elemental analyses, thermal analyses (TGA and DTG), IR, and conductance measurements. The results show that the ligand coordinates to Zn(II) and Cd(II) as a neutral bidentate through the carbonyl oxygen and the azo nitrogen. Semiempirical calculations using PM3 and ZINDO/1 have been employed to study the harmonic vibrational spectra of the ligand and its metal complexes with the purpose to assist in the experimental assignments of the bands. The thermodynamic parameters E, ΔH, ΔG, and ΔS have been calculated from the thermal analysis curves (TGA and DTG) using the Coats−Redfern, Horowitz−Metzger, and Freeman−Carroll methods. The dissociation constant of the ligand has been determined pH-metrically in 0.1 mol·dm−3 KCl at 298.15 K. Conductometric titrations showed that all the investigated metal ions have 1:1 and 1:2 (M:L) stoichiometric ratios.