Spectrophotometric and Conductometric Studies of Charge Transfer Interaction of 2‐(1H)‐Pyridinethione with π‐Acceptors

Abstract

Kinetic studies on the formation of charge transfer complexes of 2-(1H)-pyridinethione with p-acceptors p-chloranil and p-bromanil in dipolar aprotic solvent N,N-dimethylformamide have been carried out spectrophotometrically at various temperatures. The reaction follows an overall third order rate equation, through first order with respect to p-acceptors and second order with respect to the 2-(1H)-pyridinethione. The rates were found to increase with increasing temperature. Activation parameters, DH ¹ and DS ¹ have been calculated for the charge transfer complexes. The structure of the products was confirmed by their elemental analysis, IR, 1 H NMR and mass spectrometry. Conductometric method has been used to investigate the electron donor-acceptor complex formation. The stoichiometries of these complexes have been established and their conductance (s P-) and molar conductivity (sM-) values are reported.

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“…Accordingly, the molecular size increases and consequently decrease in conductivity is observed [29] . Since, the σp values depend mainly on the solvent polarity and the donor (or acceptor) concentration, thus if the solvent polarity and the donor concentration are kept constant, thus σp values should reflect the electron affinity of the acceptors.…”

“…Spectral characteristic and stability constant of the formed C T complexes are examined [18][19][20][21][22][23][24][25][26]. The importance of conductometric studies of electron donor acceptor [ EDA ] complexes is increasing rapidly on account of their use as semi conductors [27][28][29][30].Many authors discussed the charge transfer complexes it was considered to be of interest to investigate the formation of charge transfer (CT) complexes of pyridine (D) as electron donor with π-acceptor [31][32][33][34]. Accordingly, it was considered to be interest to investigate the formation of CT complexes of 4-amino pyridine (L1) , 2-amino 5-chloro pyridine (L2) and 2,6 diamino pyridine (L3), as electron donor with the aromatic -acceptors, maleic anhydride,-nitroso--naphthol ,pchloroaniline ,picric acid ,anthraquinone and p-bromoaniline..…”