Charge transfer complexes of aryl diphenylmethyl sulphides with iodine and with tetracyanoethylene

Abstract

Charge transfer complexes of iodine (σ acceptor) and tetracyanoethylene (π acceptor) with aryl diphenylmethyl sulphides, X¹C₆H₄(X²C₆H₄)CH·S·C₆H₄Y, have been studied in cyclohexane and carbon tetrachloride at 25°. The effect of substituents X and Y on the charge transfer constant, K_ct, is notably different. Y Substituents modify this constant much more than do X substituents. The presence in the donor molecule of two electron-donating sites could produce the formation of multiple equilibria. If the sulphide is regarded as a combination of diphenylmethyl and thiyl radicals, spectral and equilibrium data show that iodine interacts exclusively with the thiyl protion. On the other hand, tetracyanoethylene interacts competitively with both halves of diphenylmethyl phenyl sulphide to give two isomeric, stable 1:1 charge transfer complexes. The absence of multiple equilibria involving the formation of 2:1 and 1:2 stable complexes is discussed.