About the Project
Whilst the rational synthesis of p-block element-element bonds is the ambit of organic chemistry, the extension of this approach to inorganic molecules is far less extensive. This is despite the increasing importance of polymers, materials and molecules containing inorganic p-block moieties. For example, BN fragments can act as CC isosteres and confer interesting materials, catalytic and photophysical properties to molecules containing them.
Although their application to the synthesis of BN containing compounds has been limited, iminoboranes (RBNR’, containing a BN triple bond) have been synthetic targets, spurred on by interest in main group multiple bonds. Synthetic routes to these compounds are simplified by the ready accessibility of higher coordinate B-N bonded precursors. Thus, elimination of small molecules (i.e. Me3SiX (X = F, Cl, Br), HBr) from aminoborane starting materials has yielded a range of stable, isolable iminoboranes. These reactions rely on sterically demanding substituents, or harsh reaction conditions. This limits their application beyond isolation of these interesting BN moieties.
This project will validate rational approaches to installing BN fragments in molecules and to generating BN containing materials. Aminoboranes bearing suitable substituents are synthons for lower coordinate BN moieties. The ability to generate iminoboranes bound to small substituents in solution would greatly enhance the range of reactions in which these species could be applied. Currently, this approach is hampered by the harsh conditions required to unmask such species (i.e. vacuum pyrolysis at 400-600°C), or complexities in accessing stable, isolable starting materials bearing small substituents (i.e. the propensity of H-N-B-X fragments to spontaneously lose HX when steric protection is absent). Thus, this project will focus on catalytic and stoichiometric reagents which allow the unmasking of unbulky iminoboranes in solution, and the onward reactivity of such transient species in the formation of new and interesting BN containing molecules.
Synthetic applications of masked main group multiple bonds are of increasing interest, and phosphaborenes (RBPR’), the heavier congeners of iminoboranes have been generated from diphosphadiboretanes. This approach is unsuitable for iminoborane generation due to the high stability of the analogous diazadiboretidines. Instead, unmasking the desired iminoborane fragments from other molecular precursors under mild conditions, will be attempted using deprotection strategies inspired by organic synthesis.
With such a methodology in hand, extension of this work to other unsaturated moieties would be highly attractive, these include BP, BO and BC unsaturated fragments. Furthermore, the ability to apply this approach to the generation of BN derived materials would be a key focus. Attempts to generate boron nitride aerogels; to inkjet print boron nitride and to generate precisely doped boron nitride via chemical vapour deposition should all be accessible through suitable precursors.
Applicants should possess a background in chemistry and a keen interest in inorganic synthesis. You will join a small but dynamic group with a highly motivated supervisor and receive extensive training in the synthesis and analysis of reactive main group species.
Informal enquiries should be directed to Dr David Liptrot ([Email Address Removed]).
Formal applications should be made via the University of Bath’s online application form for a PhD in Chemistry:
https://www.bath.ac.uk/samis/urd/sits.urd/run/siw_ipp_lgn.login?process=siw_ipp_app&code1=RDUCH-FP01&code2=0012
More information about applying for a PhD at Bath may be found here:
http://www.bath.ac.uk/guides/how-to-apply-for-doctoral-study/
Anticipated start date: 1 October 2018