Alkaline Element Derivatives of Group 13-Centred Nucleophiles

Abstract

Whilst Group 13 elements are renowned for their electrophilic nature, the potential for their wider applicability continues to emerge through extensive investigations into the inversion of this inherent reactivity. The work presented in this thesis describes the synthesis and utilisation of formally low oxidation state group 13 complexes and contributes to the understanding of the contemporary field of anionic group 13-centred nucleophiles.

Chapter 2 explores the reaction between a β-diketiminato magnesium diboranate species and a variety of organic nitriles. The diboranate anion was observed to act as a surrogate source of nucleophilic boron towards the electrophilic sp-hybridised nitrile carbon centres, as evidenced by B-C bond formation. This resulted in the successful preparation of a series of complexes that have been fully characterised by solution- and solid-state analytical methods.

Chapter 3 describes the insertion chemistry of a neutral diborane into the Ca-C bonds of a dimeric calcium n-alkyl, yielding the first isolated calcium diboranate system. Subsequent treatment with organic nitriles indicated a preference for the coordination of the selected nitriles to the calcium centre, in contrast to the insertion of an isonitrile into the B-B bond of the diboranate. These observations are further explored through a Density Functional Theory (DFT) study which complements the experimental findings. This chapter concludes with the isolation of a family of non-β-diketiminato-based alkaline earth triboranates, which represent the first examples of calcium and strontium bis-triboranate species.

Chapter 4 demonstrates the diverse chemistry attainable with anionic aluminium(I) compounds. The activation of C≡N and C≡C triple bonds in organic nitriles and alkynes, respectively, was reported through the use of a diamido alumanyl species, to yield several oxidative addition products including aluminium κ2-nitrile, metalla-diazabutadiene and [2+1] cycloaddition complexes. The metalation of the acetylenic protons of terminal alkynes further reinforced the propensity of these anionic low oxidation state aluminium(I) systems to act as potent reducing agents.

Date of Award	14 Sept 2022
Original language	English
Awarding Institution	University of Bath
Supervisor	Michael Hill (Supervisor) & David Liptrot (Supervisor)