Homogeneous hydrocarbon oxidation using nitrous oxide as a sustainable feedstock

Nitrous oxide (N2O) is a potent greenhouse gas, with a half-life of 114 years in the atmosphere and global warming potential 300 times greater than carbon dioxide, and the dominant ozone depleting substance emitted in the 21st century. As an abundant and sustainable resource, the use of N2O as an oxidant in chemical manufacture is an attractive prospect, liberating environmentally benign dinitrogen N2, but encumbered by the robust triatomic formulation of this gas. Whilst application of heterogenous catalysts under extreme conditions does permit reactions with N2O to be performed, such systems are energy intensive, unselective and ultimately not commercially viable.
This project will seek to establish the science underpinning the activation of N2O by homogeneous transition-metal complexes with the ultimate objective of translating these findings into impactful catalytic applications. Using group 9 and 10 metal complexes supported by robust mer-tridentate 'pincer' ligands, the formation and onward reactivity of intact M-N2O adducts will be leveraged to gain fundamental understanding of how N2O can be most effectively exploited in chemical synthesis, with the prospect for generating reactive terminal oxo/oxyl derivatives rigorously examined in particular. The resulting structure-property and structure-activity relationships generated from these studies will be harnessed to enable the rational design of new catalysts and achieve step-changes in performance for transformations employing N2O as a selective hydrocarbon oxidant. The upgrading of methane to methanol is one notable and industrially coveted transformation that will be targeted, with world demand for methanol approaching 100 million metric tons annually (MMSA data).

Building upon ongoing experimental work in the Chaplin group and drawing parallels with the chemistry of the early transition elements, this proposal will systematically investigate the activation of N2O using group 9 and 10 group metal pincer complexes, that is hypothesised to result in the formation of reactive terminal oxo/oxyl derivatives. Using a synergistic combination of experimental (with Chaplin) and computational (with Krämer) approaches, group 9 and 10 metal catalyst targets will be investigated to establish structure-property and structure-activity relationships underlying the coordination and activation of N2O. These findings will be harnessed to propel subsequent catalyst design, with the most promising leads rigorously examined experimentally.