Shand, Mark Alexander (1987) Excited state processes of complexes of W(V) and U(VI) by laser photolysis and ESR spectroscopy. PhD thesis, University of Warwick.

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Abstract

This thesis deals with the reactions of two high-valent metal complexes.
[UO2]2+ and [W(CN)8]3- in their excited states in which their one-electron
reduction potentials are increased greatly, i.e. sufficiently
for them to remove an electron from water.
The studies with uranyl ion cover the following, (i) the ground state
interaction with some simple amino acids, (ii) the excited-state
interaction with a variety of amino acids including some containing
sulphur, which gave results of particular interest and, in following up
the latter, (iii) the excited state interaction with some simple
organosulphur compounds. These three inter-related topics form Chapters
8, 9 and 10 of this thesis. In more detail, in Chapter 8 we
characterise optically, three new complexes of 1:4 stoichiometry between
[UO2]2+ and glycine and α- and β-alanine in acidic aqueous solution.
The x-ray crystal structure of the glycine complex confirms it as
tetrakis (glycine) dioxouranium (VI) nitrate.
Chapter 9 covers the kinetics of luminescence quenching of
*[U02]2+
by
amino acids (indicating the level of reactivity) and the quant yields
of [U(IV)] which indicate the degree of charge separation from the
initial radical-pair configuration, while cryogenic ESR data reveal the
nature of the primary ligand-derived radical. Interestingly we find
that while much the greatest kinetic reactivity towards *[UO2]2+
is
shown by the sulphur-containing amino acids, these show very low yields
for [U(IV)] production. This pattern is repeated in our study of the
photo-oxidation of dialkyl sulphides by excited uranyl ion, in which we
believe to have demonstrated that a. recent report of high quantum yields
in this system and published in Inorganic Chemistry is erroneous.

Our brief study of the aqueous [W(CN)8]3- system confirms the quantum
yields for [W(CN)8]4- of Samotus et al., as opposed to the earlier data
of Balzani and Carassiti and characterises, using ESR, IR and UV-vis
spectroscopy, new W(V)-cyanide
4 complexes obtained during irradiation
into the C-T bands of [W(CN)8]4-
and [W(CN)8]3- in aqueous solution.
Three publications have resulted hitherto from the above work in the
following journals:
Chapter 8: J. Chem. Soc., Dalton Trans., 1985, 517.
Chapter 9:, Inorgý Chim. Acta, 1986, 114, 215.
Chapter 10: Inorg. Chem., 1986, 21, 3840.
The results from the final chapter together with data from the
photoreduction of [W(CN)8]3-
81 with many organic systems obtained by Dr.
D. Rehorek during his visit to the Department, have been compiled and
submitted for publication to the Journal of the Chemistry Society,
Dalton Transactions (paper 6/2444).

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Excited state chemistry
Official Date:	January 1987
Dates:	Date Event January 1987 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Kemp, T. J. (Terence James), 1938-
Sponsors:	University of Warwick
Extent:	[7], ii, 128 leaves
Language:	eng

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