Abstract:
Electron transfer reaction of iron(III)-1,10-phananthroline by L-cysteine has been studied spectrophotometrically over the range 1.1 <= pH <= 2.26,25 <= t <= 40 degrees C, 0.1 <= I <= 0.2,4.5 <= 10(5) [Fe-III]T <= 6.5, 1.5 <= 10(3) [phen](T) <= 6.0 and 3.0 <= 10(3) [H(3)A(+)]<= 7.0 mol dm(-3). The, products of the reaction are Fell and cystine. The Delta H* and Delta S* values for the electron transfer reaction are (4.5 +/- 1) kJ/mol and (-149 +/- 3) JK(-1) mol(-1). The electron transfer reaction between the oxidant [Fe(phen)(2)(OH2)(2)](3+) and the zwitterionic form of the amino acid follows the rate law : k(obs) = K2K3 [Sub](T) [Hphen] (k(1) + k(2)K(1)[H+]/([H+] + K-1 [H+](2) + K2K3 [Hphen](e) + K1K2K3 [H+] [Hphen]).