Research

Andy worked with Prof Doug Stephan in Toronto as a postdoctoral fellow, and since that time he has been intrigued with the conceptual simplicity and endless possibilities of frustrated Lewis pairs (FLPs). FLPs are combinations of Lewis acids and bases that are precluded from forming a Lewis adduct, and are capable of reactivity that has typically been the domain of transition metals, including small-molecule activation and catalysis. We have been particularly interested in exploring the interactions of FLPs with light.

Typically, FLP reactions occur on addition of the substrate, but we designed the first (and so far, only) example of an FLP that is initiated by light to promote the activation of alkynes (J. Am. Chem. Soc. 2018, 140, 8119), which permitted enhanced temporal control over reactivity. Furthermore, the reaction could also be initiated by mild heating to give a different isomer. Ultimately, this is a "switch on" FLP system where the stereochemistry of the product can be controlled depending on whether light or heat is used as the stimulus.

We have a long-standing interest in the synthesis and properties of phosphorus-containing analogues of common organic molecules, which started during Andy's PhD with Prof Jose Goicoechea. We have worked on the synthesis and reactivity of the PCO– anion (Angew. Chem. Int. Ed. 2013, 52, 10064); the discovery of phosphinecarboxamide (J. Am. Chem. Soc. 2013, 135, 19131); and the first synthesis of P,P-dimethylformylphosphine (J. Am. Chem. Soc. 2018, 140, 12751). These molecues are P-containing analogues of the cyanate anion, urea, and the ubiquitous solvent DMF, respectively (see figure below). Far from being solely academic curiosities, these new functional groups serve as ligands (Chem. Sci. 2015, 6, 6379; Chem. Commun. 2014, 50, 12281; Eur. J. Inorg. Chem. 2016, 5, 639), catalysts (Chem. Sci. 2015, 6, 4017), and air-stable substitutes for pyrophoric and toxic phosphine (PH3) gas in the synthesis of zinc phosphide thin films via chemical vapour deposition (Dalton Trans. 2018, 47, 9221). We are continuing to explore new P-containing architectures and their applications.

The alarming trend in rising atmospheric CO2 levels since the industrial revoution necessitates urgent action and a variety of strategies and technologies. One approach is the capture and utilisation of carbon dioxide as a sustainable C1 feedstock for useful chemicals. We have shown that CO2 can be converted into useful urea derivatives using silylamines and an indium catalyst (Angew. Chem. Int. Ed. 2017, 56, 14277). The process was subsequently improved to remove the need for the indium catalyst, and the scope extended to incorporate 13C-labelled, chiral or macrocyclic derivatives of urea (Angew. Chem. Int. Ed. 2019, 58, 5707). Finally, FLP hydrogenation catalysis reactions of CO2 in the presence of silylhalides were developed to selectively reduce CO2 to silylacetal, methoxysilane, methyliodide and methane derivatives under mild conditions, where the judicious choice of silylhalide and solvent could control the selectivity (Angew. Chem. Int. Ed. 2021, 60, 25771).