Mudanças conformacionais no ácido carbônico induzidas por fluoreto

Abstract

Anion receptors are useful e.g. as catalysts in transfer phase processes. Carbonic acid is an interesting model to evaluate the role of hydrogen bonds in the formation of complexes with anions. Fluoride is an anion that participates as proton acceptor in hydrogen bonding and is magnetically active in NMR spectroscopy. Theoretical calculation at the B3LYP/6-31g(d,p) level showed that fluoride induces a conformation in carbonic acid that maximizes the formation of F...HO hydrogen bond; this conformation is not the preferential one for the free carbonic acid. The establishment of hydrogen bond in the carbonic acid:fluoride complex was 1h confirmed using natural bond orbital analysis, while the high calculated value for the J coupling constant in F,H the complex indicates that this parameter can experimentally probe the formation of supramolecular systems in similar complexes.