Coordination of fluoro ligands toward sodium ions makes the difference: aqua sodium ions act as Brønsted acids in polymerization of vinyl ethers and styrenes.

In searching for aqua sodium species acting as Brønsted acids in catalysis, we explored the phenomenon that sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate dihydrate (NaBAr(F)4.2H2O) evidently provides one proton source to initiate the polymerization of vinyl ethers in anhydrous dichloromethane solutions. In addition, NaBAr(F)4 catalyzed efficiently in the polymerization of activated styrenes, such as p-methoxystyrene.