Low Oxidation State Main-Group Diamides

Student thesis: Doctoral ThesisPhD

Abstract

Although small molecule activation was conventionally considered to be exclusive for transition-metal complexes, there have been significant developments in H2 activation and other molecular transformations mediated by low oxidation state p-block species in the past two decades. There have, however, been limited reports concerning the s-block counterparts in H2 activation and chemistry about low oxidation state aluminium anions.
Chapter 2 describes the synthesis of a low oxidation state magnesium diamide, which features sodium cations in its dimeric structure. Initial reactivity studies of the sodium magnesium complex demonstrate that the molecule exhibits a cooperative reactivity arising from the tetrameric unit. Addition of non-reducible Lewis bases to the molecule initiate an intramolecular reduction of Na+, while activation of H2, CO and various substrates has also been observed with this low oxidation state magnesium molecule.
Chapter 3 describes reactivity studies of a seven-membered cyclic diamidoalumanyl (anionic aluminium(I)) system, where the initial investigation disclosed that the potassium alumanyl exhibits Al(I)-centred characters. Heavier group 1 analogues of the potassium alumanyl have also been prepared, while an evaluation of their ability to conduct the C-H activation of benzene demonstrated that the identity of the counter cation influences the reactivity of this alumanyl system. An extensive studies of the potassium alumanyl in activation of organic substrates have also been performed, where particularly diverse reactivity was observed with a variety of ketone molecules. The potassium alumanyl also demonstrates a potent reducing ability towards p-block halides, indicating its potential utilisation as a homogeneous reductant.
Chapter 4 describes a series of group11-alumanyl species prepared by the salt metathesis process of a potassium alumanyl with ligand-supported coinage metal chlorides, demonstrating the application of the alumanyl in providing new aluminium-element bonds. The group 11-alumanyl complexes are evaluated with their reactivity towards heteroallenes, where copper, silver, and/or gold centred nucleophilicity was observed in some of the complexes, reflecting the influence of the co-ligand in this class of molecules.
Chapter 5 constitutes general synthetic notes and crystallographic data, while Chapter 6 describes some structures that demonstrate further applications and reactivity of some molecules contained within the thesis.
Date of Award13 Sept 2023
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorMichael Hill (Supervisor) & Michael Whittlesey (Supervisor)

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