Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.640912
Title: Organouranium complexes for the insertion and reduction of small molecules
Author: Higgins, Jessica Anne
ISNI:       0000 0004 5349 3144
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 2014
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Abstract:
This thesis explores the behaviour of U(III) and U(IV) organometallic complexes towards small molecules, with respect to both their reductive activity and insertion chemistry. A range of mixed-sandwich U(IV) organyl complexes of the form U(η-C8H6{1,4-SiiPr3}2)(η-C5Me5)(R) (= U(COTTIPS2Cp*(R), where R = CH3, CH2Ph, CH2TMS, CH{TMS}2) have been synthesised and the products of their reactions with CO2, CO, and H2 (κ2-carboxylates, η2-acyls, and a monomeric terminal hydride) have been characterised – all of which are formed under mild conditions (< 1 atm of gas, sub-ambient temperature). The hydride also inserts CO2 to yield a formate, U(COTTIPS2)Cp*(κ2-O2CH), which is the first example of its kind, and inserts CO to form cis-enediolate, {U(COTTIPS2)Cp*}2(μ-κ1:κ1-OCH=CHO). A rare primary amido, U(COTTIPS2)Cp*(NH2), and its CO2 insertion product, U(COTTIPS2)Cp*(κ2-O2CNH2), have also been characterised. The latter is the first crystallographically characterised U(IV) primary carbamate. Deprotonation of the parent amido yield an anionic U(IV) terminal primary imido, [U(COTTIPS2)Cp*(NH)][K(18-crown-6)]. U(III) and U(IV) complexes containing a dianionic diamidoamine ligand, [N{SiMe3}(CH2CH2N{SiMe3})2]2- (= N'N'2) have been synthesised. It has been found that the migration of a SiMe3 group along the ligand backbone occurs spontaneously when bound to uranium. Reduction of the U(IV) compound U(N'N'2)Cp*Cl with KC8 yields either the U(III) product, U(N'N'2)Cp*, or bridging arene products, {U(N'N'2)}2(μ-η6:η6-C6H5R) (where R = H, Me), depending on the reaction stoichiometry. Further reactivity of these diamidoamine complexes with small molecules is also discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.640912  DOI: Not available
Keywords: QD0241 Organic chemistry
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