There has been a significant amount of interest in recent years in the activation and functionalisation of small molecules and strong bonds by main-group-element compounds acting in similar ways to transition metals. In addition to fundamental interest and the development of novel reactivity, this has been driven, in part, by a desire to find more sustainable alternatives to the low-abundant, expensive and potentially toxic precious metals that are commonly used in homogeneous catalysis. A key foundation of this work is the concept of metallomimetic behaviour, where main-groupelement species can be prompted to display analogous reactivity to transition metals, e.g. through the formation of unusual bonding modes, oxidation states, coordination geometries and of course the huge efforts around frustrated Lewis pairs. Of all the transition-metal like reactivity, the ability to undergo reversible two-electron redox processes, such as oxidative addition (OA) and reductive elimination (RE), is at the core of many traditional homogeneous catalytic cycles. Similarly facile redox cycling in main-group elements is much rarer, although promoting OA and RE processes has been a highly active area of study in recent years. A key challenge with many main-group species is that there are often larger differences in stability between different oxidation states when compared to transition metals, which results in either rapid OA or RE, but then a much more challenging reverse process that renders catalysis difficult. However, amongst the main group elements the pnictogens stand out in this regard, often allowing access to stable species in different oxidation states, and as such they are ideal candidates for the development of metallomimetic reactivity and catalysis. A key design concept that has led to observations of redox-cycling within these systems is the use of ligands that geometrically constrain the pnictogen atoms, moving them away from their preferred pyramidal to more planar geometries, resulting in changes in orbital energies and reactivity. Pincer ligands are often used here to promote more planar geometries, ambiphilic behaviour and reactivity of the pnictogen, although metal-ligand cooperativity is also frequently observed in these systems. Scheme 1: Comparison of recent aromatic hydrodefluorination (HDF) reactions promoted or catalysed by main group compounds through redox-neutral (A) or redox-cycling (B) pathways and the present work (C).