Periodic Reporting for period 3 - HurdlingOxoWall (Late First-Row Transition Metal-Oxo Complexes for C–H Bond Activation)
Reporting period: 2019-03-01 to 2020-08-31
This will be accomplished using a family of novel low coordinate ligands that will support LM=O’s. Due to their expected potent reactivity we will prepare LM=O’s under unique oxidatively robust, low-temperature conditions to ensure their stabilisation. The poorly understood factors (thermodynamics, metal, d-electron count) that control the reactivity of M=O’s will be thoroughly investigated. Based on these investigations LM=O reactivity will be manipulated and optimised. We expect LM=O’s will be significantly more reactive than any early transition metal-oxo’s (EM=O’s), because they will display a greater thermodynamic driving force for C–H activation. It is thus expected that LM=O’s will be capable of the activation of the strongest of C–H bonds (i.e. CH4). Driven by the knowledge acquired from these investigations, we will design and prepare the next generation of molecular oxidation catalysts - a family of late first-row transition metal compounds capable of catalysing hydrocarbon functionalisation under ambient conditions.
The first important discovery made was the identification of a facile means to tune the reactivity of high-valent oxidants (putative reactive species in oxidation catalysis) by simple anion exchange (changing the groups that interact with the metal). The second critical breakthrough in the project was the identification of the first example of a high-valent metal-halide complex (nickel chloride) capable of performing hydrogen atom transfer oxidation (again, a process often implicated in oxidation catalysis). Both breakthroughs have opened new avenues for late transition metal oxidation catalysis and the field of oxidation catalysis as a whole. The latter, halide-based oxidation, could open up the field of oxidation catalysis to oxo-free catalysis in the future.
Hydrogen atom transfer by a high-valent nickel-chloride complex
Prasenjit Mondal, Paolo Pirovano, Ankita Das, Erik R. Farquhar, Aidan R. McDonald*, J. Am. Chem. Soc. 2018, 140, 1834–1841. https://pubs.acs.org/doi/10.1021/acs.chemmater.8b01454
Modulation of nickel pyridinedicarboxamidate complexes to explore the properties of high-valent oxidants
Paolo Pirovano, Brendan Twamley, Aidan R. McDonald*, Chem. Eur. J. 2018, 24, 5238-5245. http://dx.doi.org/10.1002/chem.201705203
Indirect evidence for a NiIII-oxyl oxidant in the reaction of a NiII complex with peracid
Paolo Pirovano, Abigail R. Berry, Marcel Swart, Aidan R. McDonald*, Dalton Trans. 2018, 47, 246-250. http://pubs.rsc.org/en/Content/ArticleLanding/2018/DT/C7DT03316H
Synthetic High-Valent M–O–X Oxidants
Paolo Pirovano, Aidan R. McDonald*, Eur. J. Inorg. Chem. 2018, 547–560. https://doi.org/10.1002/ejic.201701072
Tuning the reactivity of terminal nickel(III)-oxygen adducts for C–H bond activation
Paolo Pirovano, Erik R. Farquhar, Marcel Swart, Aidan R. McDonald*, J. Am. Chem. Soc. 2016, 138, 14362–14370. http://pubs.acs.org/doi/abs/10.1021/jacs.6b08406
Synthesis and Characterisation of a Mesocyclic Tripodal Triamine Ligand
Andrew D. Ure, Isabel Abánades Lázaro, Michelle Cotter, Aidan R. McDonald*, Org. Biomol. Chem. 2016, 14, 483-494. http://pubs.rsc.org/en/content/articlelanding/2015/ob/c5ob01556a#!divAbstract"
The expected results until the end of the project are the same as initially proposed, but including a closer focus on high-valent metal-halides in oxidation catalysis, based on our important discovery in that area.