dc.contributor.author |
Shooter, David |
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dc.date.accessioned |
2021-08-26T06:17:09Z |
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dc.date.available |
2021-08-26T06:17:09Z |
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dc.date.issued |
1969 |
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dc.identifier.uri |
https://hdl.handle.net/2292/56263 |
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dc.description |
Full text is available to authenticated members of The University of Auckland only. |
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dc.description.abstract |
The catalysed and uncatalysed racemisation of the trisoxalato-chromium(lll) anion has been studied in the presence and absence of various electrolytes, ;'i+'b emphasis on the catalysed racemisation. The interpretation of the observed catalytic effects of the metal ions Cu2+ and Ni2+, has been attempted in terms of both ionic strength and ion association, with the result that "metalation"of the CrOXg33- anion has been postulated to account for the rate accelerating effects of these metal ions. Formation and specific rate constants of the various species existing in solutions of the metal ions and the trisoxalatochromium(lll) anion have been obtained by curve fitting.
The existence of an uncatalysed rate has been established and tentatively ascribed to solvent action. Large tetraalkyl ammonium ions were found to produce a decelerating effect on the uncatalysed rate, this has been discussed in terms of ion-pair formation with the associated exclusion of solvent water molecules. It has also been deduced that the blocking of two coordination 2+ 2+ positions on the Cu ion by ethylenediamine, prevents the Cu2+ ion from being an effective catalyst of the racemisation of the trisoxalatochromium(lll) anion, indicating that three vacant co-ordination sites on the Cu2+ ion are necessary for it to ion-pair with the trisoxalatochromium(lll) anion. This, coupled with the belief that coordination of two metal ions to the trisoxalato-chromium(lll) anion results in a much faster racemisation than only one, has led to the conclusion that the racemisation takes place either by an intramolecular non-dissociative twist mechanism, or a one-ended-dissociation mechanism involving only a small degree of bond stretching. Weak absorption bands in the visible spectrum of the tris-oxalatochromium(lll) anion in aqueous solution have been carefully measured, and interpreted in terms of vibronic coupling. Chapter 9, (an addendum to Chapter 4), describes additional curve fitting, designed to improve the calculated fit to the dependence of the observed rate of racemisation of the trisoxalato chromium(lll) anion on copper and nickel perchlorate concentration. An attempt has also been made to predict the dependence of the observed rate of racemisation on the concentration of the tris-oxalatochromium(lll) anion in the presence of 0.010M copper sulphate. A number of other results of relevance to the main theme of this work have also been included. |
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dc.publisher |
ResearchSpace@Auckland |
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dc.relation.isreferencedby |
UoA9921589314002091 |
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dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
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dc.rights |
Restricted Item. Full text is available to authenticated members of The University of Auckland only. |
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dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
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dc.title |
Salt effects in the racemisation of the trisoxalatochromium (III) anion. |
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dc.type |
Thesis |
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thesis.degree.discipline |
Chemistry |
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thesis.degree.grantor |
The University of Auckland |
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thesis.degree.name |
PhD |
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dc.rights.holder |
Copyright: The author |
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dc.identifier.wikidata |
Q112836488 |
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