Accurate mapping of chemical reaction mechanisms is of crucial importance towards understanding reaction rate, efficiency, and selectivity. Quantum chemistry is highly effective for these investigations due to its ability to produce detailed elementary step mechanisms from first principles. This process, however, requires extensive human effort and chemical intuition to elucidate these mechanisms, making standard methods impractical for the study of complete chemical reaction spaces. In many cases, investigations focus on only the most promising chemical pathways and neglect new, unknown pathways of chemical importance. To ensure that the most chemically relevant paths are sampled, automated reaction path finding (ARF) methods can be used to broaden the scope of searchable chemical space. Our ARF methods make use of connectivity rules to define generic chemical reactions which are generally applicable to main group elements. Until recently, these methods were not available for transition metals due to the complex variety of coordination geometries that are possible. By developing a systematic set of rules pertaining to transition metals, ARF can now be used to systematically identify many chemical reactions that are vital to catalysis. Our recent development also extended the methodology to bimolecular reactions, where initial alignment of reactant species is important. These methods utilize the single-ended growing string method for reaction path and transition state searches, giving rise to an automated procedure for mapping chemical reaction pathways in transition metal catalyzed reactions. The ARF method has been applied to methane C-H activation by cisplatin, where we have been able to locate previously reported as well as unknown reaction pathways. This presentation will provide full details on these new developments in ARF and their application to C-H functionalization catalysis.

Reaction exploration for transition metal-catalyzed C-H activation

251st National Meeting (2016)

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