Metal Ion Catalysis of Substitution and Rearrangement Reactions of Some Complex Oxalates of Chromium(III)
Increasing the pH was found to have an accelerating affect on the aquation of the trisoxalatochromium(III) ion at constant copper ion concentration. This has been discussed, using ion association, in terms of catalysis of the aquation reaction by hydrolysis products of the copper(II) ion, in particular the CuOH+ ion. The catalysed and uncatalysed isomeristion of the bisoxalatochromium(III) ion has been investigated in the presence and absence of various electrolytes and the kinetic data has been rationalized in terms of an ion association model.
It has also been proposed, from comparisons of studies on the copper(II) ion catalyes aquation and racemisation of the trisoxalatochromium(III) ion, that a copper(II) ion associates with the CrOX33- ion through three carboxyl oxygen atoms, one from each oxalate group to form a monometallated species. Further comparison of these studies has led us to postulate, in the aquation, that a second copper(II) ion, proposed to associate with the monometallated species, associates with two carbonyl oxygen atoms of one of the oxalate groups of the CrOX33- ion. This, and the comparison of the specific rates of aquation of the monometallated and bimetallated species, led us to the conclusion that aquation occurs by a rapid one ended dissociation of an oxalate ligand followed by a rate determining loss of the oxalate group.
A number of other results of relevance to the substitution and rearrangement reactions of chromium(III)-oxalate complexes, have also been included.
Advisor:Prof. A.L. Odell
School Location:New Zealand
Source Type:Master's Thesis
Keywords:fields of research 250000 chemical sciences
Date of Publication:01/01/1971