Study of structural and temperature dependence on stability constants of certain charge transfer complexes in solution by ultrasonic method

Shubhajit Haldera, Pratibha S.

Abstract

The ultrasonic velocity (U), density (ρ) and coefficient of viscosity (η) of solutions containing equimolar concentration of two ketones (cyclohexanone and Ethyl methyl ketone) and Pyridine in n-hexane solvent have been measured at 293K, 298K and 303K. Acoustical parameters such as adiabatic compressibility (β), Intermolecular free length (Lf), internal pressure ( πi) and cohesive energy (CE) values are calculated from the experimental values of U, ρ and η. These investigations indicate the formation of weak charge transfer complexes between various ketones and pyridine in n-hexane solvent. Stability constant (K) values of the charge transfer complexes in solution have been evaluated using Marwein and Bhatt equation. The free energy of activation (ΔG#) for the formation of these complexes is also computed from K values. The free energy of formation (ΔG0 F) and viscous relaxation time () are found to be almost constant for these complexes indicating the formation of similar charge transfer complexes in these systems.