Shedding light on main group organometallic chemistry

点击翻译按钮获取中文摘要

The use of visible light as a clean, selective and yet powerful energy source has contributed to the development of synthetic methodologies otherwise inaccessible by means of thermal reactivity. Light irradiated on organometallic intermediates enables the generation of radical intermediates as well as reactivity modes that are unreachable in the ground state. This technology, however, is still dominated by transition metals (TM) and their ease to coordinate substrates and revolve between oxidation states. Yet, their rising cost, limited supply and carbon footprint (e.g., Rh: £48,200/mol, 0.001ppm, 35,100kg CO2/kg) urge chemists to focus on infusing these key properties to more abundant and benign elements beyond the d-block. Interestingly, scattered examples on the light sensitivity of organometallic main group (MG) compounds have been reported. Group 13 neighbours Indium (In; £0.07/mol, 0.052ppm, 102 kg CO2/kg) and Aluminium (Al; £0.07/mol, 84,149 ppm, 8.2kg CO2/kg) in low-valent states are known to oxidatively add to several bonds (H-H, H-Cl) under light irradiation, while organometallic group 15 compounds based on antimony (Sb; £1.5/mol, 0.2ppm, 13kg CO2/kg) exhibit photosensitisation, enhancing their reactivity towards small molecule activation and allowing homolytic cleavage of Sb-C bonds. These features are key to access reactive intermediates and radical species holding the potential to be applied to organic synthesis. Encouraged by these attributes, this interdisciplinary proposal will focus on the design of unique ambiphilic low-valent organometallic main group compounds and test their reactivity towards SMA, such as hydrogen, nitrogen and a variety of C-X bonds. We will focus on studying their key electronic properties (DFT in collaboration with Dr Rachel Crespo-Otero) and their reactivity towards SMA under light irradiation, with the aim of mimicking well-established visible-light-induced processes for TM. This project will pave the way towards catalytic light-assisted synthetic processes based on abundant p-block elements, thus tackling global challenges of social, academic, and industrial interest.