A brief electrophile scoping study was performed using BEt3 and 1 as catalysts and this revealed the fluoroborates derived from these boranes to be poorer sources of fluoride relative to the Lewis base incorporated borate A. For example, no fluorination of octyl bromide or benzyl halides was observed even after prolonged periods refluxing with excess borane/CsF (Scheme 1). In contrast, using two eq. of A generated high yields of PhCH2F, 11a demonstrating the positive effect the B←SR2 dative bond has in enhancing fluoride transfer ability. Stronger electrophiles (than PhCH2Br) did undergo fluorination with CsF using 1 / BEt3 as catalysts. Reaction of β-bromo sulphide 8 with CsF with either BEt3 or 1 as catalyst in CHCl3 led to significant formation of stilbene (mixture of cis-trans isomers) with only traces of 9 formed. Serendipitously, we found that the outcome of this reaction is effected dramatically by solvent. Using DCM/n-hexane (6:1) as the reaction medium, stilbene formation was negligible (ca 3%) and 9 could be formed in moderate yield using BEt3 (Figure ). We attribute this disparity to the solvent effecting the equilibrium position between 8 and the thiiranium cation essential for fluorination. Reaction of Ph3CCl with CsF in CHCl3 catalysed by either BEt3 or 1 proceeded in moderate to good yield. Benzoyl chloride proved to be more challenging, with 1 as the catalyst fluorination proceeded to only ca. 5% conversion. However, using 10 mol% BEt3 benzoyl fluoride was formed in good yield.