Reaction of the Tetrahydroxoargentate(III) Ion with Thiosulfate

Document Type

Article

Date of Original Version

1-1-1985

Abstract

The reaction of Ag(OH)4- with thiosulfate ion (T), potentially an eight-electron reductant, was studied over the range 2.5 X 10–6 M ≤ [T] ≤ 0.2 M in 0.6 M NaOH. At lowest [T], reaction via the aquated silver(III) species, Ag(OH)3H2O, results in a monothiosulfato complex, Ag(OH)3S2O32-, which undergoes internal redox with a rate constant of 0.22 ± 0.03 s-1. The stability constant of the complex is about (1.4 ± 0.2) X 104 and an absorption maximum for the species occurs at 260 ± 5 nm. At [T] > 1.0 X 10-3M, Ag(III) is reduced by T without hydroxyl replacement. The rate law contains four terms with first- and second-order contributions predominating at high [T]: -d[Ag(III)]/dt ~ (D[T] + E[T]2)[Ag(III)]. At 25 °C and μ = 1.2 M, D - 158 ± 30 M-1s-1 and E = 768 ± 94 M-2s-1. The presence of a third-order term is attributed to the reaction of T with a five-coordinate Ag(III)-T species. The principal product at excess T is tetrathionate. © 1985, American Chemical Society. All rights reserved.

Publication Title, e.g., Journal

Inorganic Chemistry

Volume

24

Issue

5

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