Mechanistic Studies of Transition-Metal Mediated Catalysis

Our research focusses on understanding mechanisms and structure/activity relationships in chemical reactions mediated by transition metals. Our work is primarily experimental, but insight from high-quality calculations supports and tests our hypotheses. Studies are conducted to check proposed mechanisms by modelling intermediates and transition states on the reaction pathway using Gaussian09, Gaussian16, and ORCA. Structure/activity relationships are probed by understanding how the energies of intermediates and transition states change as structure changes.

Ongoing projects include:

Studies of nickel-catalysed cross-coupling reactions to identify ‘privileged’ substrates that react in preference to others. Experimental work identified several classes of substrate that undergo reaction anomalously quickly, or in preference to other substrates.^{1, 2} Computational studies allowed us to identify why this selectivity is observed, and to triage new reactions to understand the most reactive site, decreasing experimental workload.
Studies of the nickel-catalysed reactions of ‘difficult’ substrates, such as alkyl halides, which present considerable additional mechanistic complexity.³
A detailed examination of the effects of new ligands in nickel catalysis, with Dr Marcus Drover (University of Windsor).
Studies of side-reactions and off-cycle species that can inhibit nickel catalysis.
Studies of the activation mechanisms of organometallic catalysts. We must strike a balance between stability, so that we can store the catalysts under ambient conditions before use, but later unleash high reactivity in chemical reactions.
Studies of reactions that utilise very strong bonds, such as C-O and C-F bonds in aryl substrates. These are known to work experimentally, but require very harsh and inefficient conditions. We are using calculations to explore the mechanisms of these reactions, and design new catalysts.
Studies of C-H activation selectivity, in collaboration with Dr David Lindsay and Professor Billy Kerr. While this uses H/D exchange as a model reaction, we anticipate that the results can be extrapolated to a range of chemical reactions.
Develop an understanding of some interesting side-reactions in C-H borylation reactions, in collaboration with Dr Bob Edkins. This will improve our knowledge of these valuable reactions.

Calculations add an important extra dimension to our research, and one that often leads to a more well-rounded, solid, and complete study. We seek not only to understand experimental observations, but to be able to calibrate our calculations so that we can confidently predict selectivity and reactivity in new scenarios. As such, the use of theoretical calculations can help us publish our (predominantly experimental) work in more impactful journals that cater to a broader audience.

A. K. Cooper, P. M. Burton and D. J. Nelson, Synthesis, 2020, 52, 565-573.
A. K. Cooper, D. K. Leonard, S. Bajo, P. M. Burton and D. J. Nelson, Chem. Sci., 2020, 11, 1905-1911.
M. E. Greaves, T. O. Ronson, G. C. Lloyd-Jones, F. Maseras, S. Sproules and D. J. Nelson, ACS Catal., 2020, DOI: 10.1021/acscatal.0c02514, 10717-10725.

For more information about the project contact Dr David Nelson (david.nelson@strath.ac.uk), Strathclyde Chancellor’s Fellow at the Department of Pure and Applied Chemistry at the University of Strathclyde.
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