title: The Strongest Acid: Protonation of Carbon Dioxide.
abstract: The strongest carborane acid, H(CHB11F11), protonates CO2 while traditional mixed Lewis/Brønsted superacids do not. The product is deduced from IR spectroscopy and calculation to be the proton disolvate, H(CO2)2(+). The carborane acid H(CHB11F11) is therefore the strongest known acid. The failure of traditional mixed superacids to protonate weak bases such as CO2 can be traced to a competition between the proton and the Lewis acid for the added base. The high protic acidity promised by large absolute values of the Hammett acidity function (H0) is not realized in practice because the basicity of an added base is suppressed by Lewis acid/base adduct formation.
authors.affiliation: Center for s and p Block Chemistry, Department of Chemistry, University of California, Riverside, CA, 92521, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Cummings
authors.affiliation: School of Natural Sciences, University of California, Merced, Merced, CA, 95348, USA.
authors.forename: Hrant P
authors.initials: HP
authors.lastname: Hratchian
authors.affiliation: Center for s and p Block Chemistry, Department of Chemistry, University of California, Riverside, CA, 92521, USA. chris.reed@ucr.edu.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Reed
keywords: Brønsted; acids; carbon dioxide; carboranes; protonation