Reaction of 1-Ga-NaBAr F 4 with Et3SiH was calculated to occur through TS-1 (DG ‡ 298K = 28.8 kcal mol -1 ) leading to direct formation of 6-Ga-NaBAr F 4. In the absence of the promoter, 1-Ga was calculated to react with Et3SiH by a higher barrier through TS-1' (DG ‡ 298K = 30.5 kcal mol -1 ) to form 6-Ga. The lower energy of TS-1 relative to TS-1' is explained through Na + playing a role in charge stabilization during the polarisation and breaking of the Ga---F bond. Experimentally it was found that 7-Ga is an effective nucleophile for the hydrodefuorination of pentafluoropyridine at 100 ºC, and that 10 mol% 7-Ga + NaBAr F 4 can be used as a pre-catalyst for the hydrodefluorination of the same substrate with Et3SiH at 160 ºC (Figure ).