Probing and predicting the interactions of frustrated Lewisp airs in silico

Main group frustrated Lewis pair (FLP) systems have shown promise in the area of sustainable transition metal-free catalysis and small molecule activation. FLP's react in a termolecular fashion with small molecules and the pre association of the Lewis acid and Lewis base to form an "encounter complex" is crucial to this reactivity. Experimental evidence for this "encounter complex" exists through methods such as NOESY NMR spectroscopy and neutron scattering. The Jupp group recently showed how this "encounter complex" can be probed through supramolecular methods to determine the association constant (Ka). The main technique to achieve this was UV-vis spectroscopy which relied entirely on the presence of a single electron charge transfer band that is present within the visible region of the electromagnetic spectrum. This charge transfer band however is only seen in species that are in the "active encounter complex" orientation, which is the orientation needed for small molecule activation and catalysis, with the lone pair on the Lewis base pointed directly at the unoccupied orbital on the Lewis acid. Many different orientations of the "encounter complex" of a given species are present in solution at any one time so the percentage of "encounter complexes" that match this "active" orientation is low. This percentage of "active encounter complexes" can vary drastically between different FLP systems and simple visual inspection of the structures does not provide any insight into the factors that affect the orientation of the Lewis acid and base pair. This project focuses on this fundamental problem within FLP design. Through the combined use of semiempirical quantum mechanical methods and density functional theorem calculations a data set on an extensive range of FLP systems will be produced. This data set will be used to train multiple machine learning models to identify trends between the different FLP systems that are indiscernible to the human eye in the hopes of producing a set of parameters/rules that define how a FLP will orient itself in solution. This will aid in future FLP design and help chemists to further advance the area of main group catalysis.