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

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 (εCT), thermodynamic standard reaction quantities (ΔG°, ΔH°, ΔS°), oscillator strength (f), transition dipole moment (μEN) and ionization potential (ID).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.

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► We examine the interaction between N-aryl-N′-isopropyloxycarbonylsulfamides and DDQ or TCNE.
► Zero and second order derivative UV spectrophotometry were used.
► Spectroscopic and thermodynamic properties were determined.
► Complexes properties were influenced by acceptor–donor nature and medium polarity.