Thermodynamic characteristics of the H-bonded complexes of anisidines with proton acceptors in solution

• Published in: Journal of molecular liquids 2004-04, Vol.111 (1), p.95-99
• Main Author: Morev, A.V
• Format: Article
• Language: English
• Subjects: Anisidines; Energetic characteristics of H-bonded complexes; Hydrogen bonding; Spectral characteristics of NH stretching bands
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2003.07.007

The influence of temperature on the spectral moments M (0), M (1) and effective half-width (2 M (2)) 1/2 of the absorption bands of the stretching vibrations of amino groups of ortho-, meta- and para-anisidines as well as their 1:1 complexes with dimethylformamide, dimethylsulfoxide and hexamethylphosphoramide in CCl 4 has been studied in the temperature range 285–330 K. The coefficients of linear Y=aT+ b regression of the spectral moments with temperature were determined. Enthalpy of the 1:1 complex formation (−Δ H 1) between anisidines with various proton acceptors in CCl 4 solutions was determined using the dependence of the equilibrium constants on temperature. Enthalpy of the 1:2 complex formation (−Δ H 2) was estimated on the basis on the ‘rule of intensity’: −Δ H=αΔ B 1/2 assuming that the α parameter does not depend on the composition of a complex. It was shown that −Δ H 1 is larger than −Δ H 2 recalculated for a single bond.