Potentiometric and Thermodynamic Studies of Some Azosulfoxine Derivatives and Their Metal Complexes
Pages 191-196
A.A.El-Bindary, A.Z. El-Sonbati, M.A. Diab and A.M. Barakat

DOI: http://dx.doi.org/10.6000/1929-5030.2013.02.03.4

Published: 31 August 2013

Abstract: The proton-ligand dissociation constants of some azosulfoxine derivatives and metal-ligand stability constants of their complexes with the metal ions (Mn²⁺, Co²⁺, Ni²⁺ and Cu²⁺) have been determined potentiometrically in 0.1 MKCl and 50 % (by volume) DMF–water mixture at (298, 308 and 318) K. The stability constants of the formed complexes increases in the order Mn²⁺, Co²⁺, Ni²⁺ and Cu²⁺. The effect of temperature was studied and the corresponding thermodynamic parameters (∆G, ∆H and ∆S) were derived and discussed. The dissociation process is non-spontaneous, endothermic and entropically unfavourable. The formation of the metal complexes has been found to be spontaneous, endothermic and entropically favourable.

Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane
Pages 197-204
R. Kumar, B.S. Santhi, Vijayakanth and V. Kannappan

DOI: http://dx.doi.org/10.6000/1929-5030.2013.02.03.5

Published: 31 August 2013

Abstract: Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular properties.