Mining the air for amines

Dinitrogen is plentiful and the source of ammonia (used in fertilizers on mega-tonne scales) and organoamines (for speciality, fine, and pharmaceutical chemicals) via Haber Bosch industrial processes, but ironically it is one of the most challenging bonds to activate and thus incorporate into added-value molecules in a sustainable way. Fortunately, however, various transition metals are quite effective at binding and activating dinitrogen, so the challenge for us is to harness that and develop it to include functionalization. Producing ammonia is still fundamentally interesting from a mechanistic perspective, but a major step-change will be to activate dinitrogen and incorporate it directly into organic molecules containing NR3 and R2N-NR2 units, that have extensive added-value, thus by-passing the need for several post-ammonia reaction steps. Elucidating the mechanism of these transformations is also critical to achieve, because this thermodynamic and kinetic information at a fundamental level is badly needed to feedback into designing new dinitrogen to organoamine catalytic cycles.
After decades of research, there are still only 7 metals from the entire Periodic Table that in molecular species can catalytically reduce and fix dinitrogen into ammonia and 5 were added in the past 4 years: Ti, V, Mo, Fe, Ru, Os, Co. Ti is our work introduced only recently (Scheme 1 left, Angew. Chem. Int. Ed., 2018, 57, 6314-6318), which is appealing as Ti is 9th in crustal abundance and 2nd only to Fe for metals that can activate dinitrogen. Now we have established that a molecular Ti-Tren complex can catalytically fix dinitrogen to ammonia, and also shown that FLPs can split dihydrogen and introduce those H-atoms to produce ammonia (Scheme 1 right, Angew. Chem. Int. Ed., 2019, 58, 6674-6677). We seek to develop this science.
Our aim is to make major advances in our understanding of dinitrogen reduction chemistry and its fixation by way of functionalization into ammonia and organoamines directly. We seek to achieve this aim by securing the following objectives: extend this catalysis to Zr and Hf; develop this to include direct formation of NR3 and R2N-NR2 compounds via C-N bond formation reactions without having to go via ammonia; unravel the reaction mechanisms to feedback, via structure-reactivity correlations, to reaction optimisation and generation of new catalytic cycles; develop the FLP aspect to deliver catalytic ammonia synthesis using dihydrogen.
This project will thus involve: significant synthetic studies; catalysis; mechanistic analysis; computational modelling.
The project is firmly rooted in chemocatalysis. It seeks to exploit the inorganic and N2 reduction expertise of STL with the amine synthesis and mechanistic expertise of DW to derive new chemical reactivity and atom-efficient routes to amines which could have biological relevance. It is therefore by definition a problem-solving, inter-disciplinary integrated catalysis project that seeks to make transformative step-changes in our understanding of catalysis that links to real-world challenges involving ammonia and organoamine syntheses. At this point in time with two preliminary papers published, this project is very much as TRL0, but we believe this project will be the perfect vehicle to develop the science and links to industry, via iCAT andthe UK Catalysis Hub, in order to make the fundamental-applied transition and raise the TRL rating of this research to exploitable outcomes.

iCAT will work with industry partners to create an holistic approach to the training of students in biocatalysis, chemocatalysis, and their process integration. Traditional graduate training typically focuses on one aspect of catalysis and this approach can severely restrict innovation and impact. Advances in technology and fundamental reaction discovery are rendering this silo-approach obsolete, and a new training modality is needed to produce the next generation of chemists and engineers who can operate across a far broader chemical continuum. iCAT will meet this challenge with a state-of-the-art CDT, equipping the next generation of scientists and engineers with the skills needed to develop future catalytic processes and create the functional molecules of tomorrow.

The UK has one of the world's top-performing chemical industries, achieving outstanding levels of growth, exports, productivity and international investment. The UK's chemical industry is a significant provider of jobs and creator of wealth, with a turnover in excess of £50 billion and a contribution of over £15 Billion of value to the UK economy [2015 figures]. iCAT will deliver highly skilled people to lead this industry across its various sectors, achieving impact through the following actions:

1. Equip the next generation of science and engineering leaders with the interdisciplinary skills and knowledge needed to work across the bio and chemo catalytic remit and build the functional molecules we need to structure society.

2. Provide a highly skilled workforce and research base, skilled in the latest methodologies, strategies and techniques of catalysis and engineering that is crucial for the UK's Chemical Industry.

3. Build the critical mass necessary to support effective cohort-based training in a world-class research environment.

4. Develop and disseminate new catalytic technologies and processes that will be taken up by industrial and academic teams around the world.

5. Encourage Industry to promote research challenges within the CDT that are of core relevance to their business.

6. Provide cohesion in the integration of biocatalysis, engineering and chemocatalysis to create a more unified voice for strategic dialogue with industry, funders and policy makers, and more generally outreach and public engagement.

7. Draw-in and bring together Industrial partners to facilitate future Industrial collaborations.

8. Benefit Industrial scientists through interactions with the CDT (e.g. training and supervisory experience, exposure to cutting-edge synthesis and catalysis etc).

9. Link with other activities in the landscape: bringing unique expertise in catalysis to, for example, externally-funded University-led initiatives, EPRSC Grand Challenge Networks, and the National Catalysis Hub.