Fluoride counterions boost gold(i) catalysis: case studies for hydrodefluorination and CO2 hydrosilylation

We reported herein a novel gold(i) bifluoride complex, LAuHF2, supported by a sterically bulky ligand (L, (t)BuXantphos), that displays exceptional reactivity toward hydrodefluorination (HDF) and hydrosilylation of CO2 in the presence of hydrosilanes. Compared to the LAuCl counterpart, the LAuHF2 complex exhibited an over 27-fold increase in turnover frequency in HDF and a 16-times higher turnover number in the hydrosilylation of CO2. Subsequent experimental and computational studies revealed the counterion effect of non-coordinated fluoride on silane activation, which is critical to synergistically generating an active gold hydride intermediate capable of triggering a sequence of events in the catalytic cycle. This work highlights the prominent counterion effect on gold catalysis and provides new insights into the design of metal catalysts for the synergistic activation of small molecules.