Reactions of µ-hydroxo-dicobalt complexes. Part IV. The kinetics of the reduction of the µ-amido-µ-hydroxo-bis[tetra-amminecobalt(III)] complex with vanadium(II) and chromium(II) in aqueous perchlorate solution
- 1 January 1970
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 1991-1994
- https://doi.org/10.1039/j19700001991
Abstract
The reductions of the µ-amido-µ-hydroxo-complex (I)(referred to as dimer), with V2+ and Cr2+(M2+ ions) have been studied in aqueous perchloric acid media, ionic strength µ= 2·0M(LiClO4), over the [H+] range 0·20–1·75M, and at 35–50 °C. Rate laws are of the form d(In)[dimer]/dt=a+b[H+]+c[M2+]+d[H+][M2+]. In this equation a corresponds to the replacement of a co-ordinated ammonia molecule by a water molecule, and b is a [graphic omitted] composite rate constant for the formation of the single-bridged µ-amido-bisaquo-complex. These terms are identical for both systems. The constant c is for the direct attack of the dimer by M2+, and d is a composite rate constant for the reaction of M2+ with a protonated from of the dimer. At 35°a= 0·46 × 10–4sec.–1, b= 1·63 × 10–4 l. mole–1 sec.–1, c= 3·11 × 10–3 l. mole–1 sec.–1 for the reaction with V2+(no contribution with Cr2+), and d= 1·73 × 10–3 l.2 mole–2 sec.–1(V2+) and 1·12 × 10–3 l.2 mole–2 sec.–1(Cr2+). Activation parameters for each of the paths have been determined.Keywords
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