Reactions of thallium(II) chloride complexes with iron(II) and iron(III)

Journal Article · Thu Nov 04 04:00:00 EST 1976 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100564a003· OSTI ID:7336594

Schwarz, H A; Dodson, R W

The reactions of thallium(II) with iron(II) and with iron(III) in hydrochloric--perchloric acid mixtures (1 M ionic strength, 21 to 45/sup 0/C) were studied by pulse radiolysis techniques. Second-order rate constants for Fe(II) + Tl(II) ..-->.. Fe(III) + Tl(I) and Fe(III) + Tl(II) ..-->.. Fe (II) + Tl(III) were determined as a function of chloride from 10/sup -4/ to 1 M. The oxidation of ferrous by thallium(II) chloride complexes goes in part via an innersphere mechanism with transfer of a chlorine atom and in part via electron transfer. Acid dependence is small. Rate constants of individual reactions in the two groups are given. The electron-transfer rate constants, after semiempirical correction for electrostatic work terms, show a satisfactory Marcus correlation with the corresponding equilibrium constants. The atom transfer reactions, when corrected for work terms, appear to have a common rate-limiting step, the replacement of water in the first coordination sphere of Fe/sup 2 +/. Detailed resolution of the reactions for the reduction of Fe(III) by Tl(II) is not possible. However, selective reaction with Fe(III) chloride complexes occurs, as shown by FeCl/sup 2 +/ disappearance, and the reactions may have atom transfer mechanisms. The results on the reduction of Fe(III) are reasonably well expressed by k/sub obsd/(M/sup -1/ s/sup -1/) = 5 x 10/sup 5//(H+) + 3.9 x 10/sup 8/f, where f is the fraction of Fe(III) complexed with chloride.

• Research Organization: Brookhaven National Lab., Upton, NY
• OSTI ID: 7336594
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 80:23; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COMPLEXES
ELEMENTS
ENERGY
HALIDES
HALOGEN COMPOUNDS
HYDROCHLORIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
IRON
KINETICS
METALS
OXIDATION
PERCHLORIC ACID
QUANTITY RATIO
REACTION KINETICS
REDUCTION
THALLIUM COMPLEXES
TRANSITION ELEMENTS