FLP Zintl Clusters for Small Molecule Activation and Catalysis

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Catalytic carbon-carbon bond formation reactions are ubiquitous in synthetic chemistry, widely employed by academic researchers and within the manufacturing sector, with direct applications in the pharmaceutical and polymer industries. The importance of this transformation is reflected by the sheer number of Nobel prizes awarded in the arena (Grignard; Diels, Alder; Wittig; Ziegler, Natta; Grubbs, Schrock, Chauvin; Heck, Negishi, Suzuki). Current technologies to affect this transformation employ expensive precious metals (such as palladium) that can act as electron reservoirs due to the availability of multiple stable oxidation states. However, the high operational costs associated with their use has ignited the study of alternative catalysts based on main-group elements. The most successful examples of main-group catalysts are frustrated Lewis pairs (FLPs), systems that feature both an electron poor and electron rich site. In this research programme, FLP systems with Zintl cluster (polyanionic cluster of the p-block) as the electron-rich component will be employed in small molecule activation and subsequent carbon-carbon bond formation chemistry. Given its nefarious environmental impact, activation and linking carbon dioxide molecules together is the high-profile target for this work. Unlike other FLP systems, the cluster component can be understood as an electron reservoir with access to multiple oxidation states. Additionally, these clusters are capable of multi-site activation, bringing multiple carbon dioxide molecules in the right configuration to undergo further carbon-carbon bond formation chemistry. Zintl clusters are particularly attractive candidates for this chemistry as they are molecular analogues of larger solid-state systems (and can thus act as models for heterogenous catalysts). Findings from this work are important as they build the groundwork to replace catalysts based on precious metals with earth-abundant alternatives (i.e. Pd: $44.29(USD)/g; P: $0.04(USD)/g), making a key process that is globally implemented more sustainable. Further, developing systems that catalytically mine the air for fuel (by recycling the green house gas carbon dioxide to afford hydrocarbons) contributes to global efforts towards Clean Growth and addressing humanity's greatest challenge - climate change.