A spectrophotometric and thermodynamic study of the charge-transfer complexes of N-aryl-N'-isopropyloxycarbonylsulfamides with DDQ and TCNE.

Abstract Molecular charge-transfer complexes of three N-aryl-N′-isopropyloxycarbonylsulfamides derivatives with π-acceptors tetracyanoethylene (TCNE), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), were studied by using zero and second order derivative UV spectrophotometry in different solvents at four different temperatures within the range of 20–35 °C. The stoichiometries of the complexes were found to be 1:1 ratio between donors and acceptors using Job’s method. The data were analyzed in terms of their stability constant ( K ), molar extinction coefficient ( e CT ), thermodynamic standard reaction quantities (Δ G °, Δ H °, Δ S °), oscillator strength ( f ), transition dipole moment ( μ EN ) and ionization potential ( I D ). The results show that the stability constant ( K ) for the complexes was found to be dependant upon the nature of electron acceptor, electron donor, and polarity of used solvents.