In the past 10 years, our research group have developed several new reactions that lead to the generation of well-defined four-coordinate aluminium fluoride complexes as products. More recently, we became interested in the use of these complexes as potential catalysts for the functionalisation of carbon-fluorine bonds. Here we show that molecular fluoride complexes of boron, aluminium and gallium are competent catalysts for the thiodefluorination and hydrodefluorination of electron-deficient arenes and alkenes. We report two defined approaches to catalysis, (i) an additive free reaction and (ii) a catalytic protocol that relies on the use of NaBAr F 4 (Ar F = 3,5-C6H3(CF3)2) as an additive. Experimental and computational data is provided to support the formation of nucleophilic four-coordinate complexes as key intermediates, and metal fluoride species as on-cycle species. Furthermore, we suggest that the additive plays a unique role in polarising and activating metal-fluorine intermediates through formation of weak M-F----Na interactions. Our findings complement existing uses of compounds based on main group elements such as tetrabutylammonium difluorophenylsilicate (TBAT), tetrabutylammonium fluoride (TBAF), or CsF as initiators for carbon-fluorine bond functionalisation.