Borane and beryllium derivatives of sulfuric and phosphoric acids: Strong inorganic acids

Abstract

A new class of strong inorganic acids is designed using substitution of the hydrogen atoms of H2SO4 and H3PO4 by BX2 and BeX moieties (X: H, F, Cl, CN, CF3). The acidities of these compounds are assessed by B3LYP/6-311++G(d,p) method in gas phase. These boron and beryllium derivatives are stronger acids than their parents H2SO4 and H3PO4. The acidity of these compounds is attributed to the strong interaction of the oxo group with the Be and B atoms after deprotonation. The electron withdrawing groups enhance the acidity so that a superacid, (B(CF3))2HPO4, with ΔHacid value of 255.5 kcal mol−1 was obtained. In the neutral compounds, Be atom interacts with two oxygen atoms simultaneously to form a four-membered ring while the acyclic isomers of boron derivatives are more stable. However, in the negatively charged conjugated bases, both B and Be atoms interact with two oxygen atoms to form cyclic structures.