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Can Conventional Bases and Unsaturated Hydrocarbons Be Converted into Gas‐Phase Superacids That Are Stronger than Most of the Known Oxyacids? The Role of Beryllium Bonds
Author(s) -
Yáñez Manuel,
Mó Otilia,
Alkorta Ibon,
Elguero José
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201300808
Subject(s) - chemistry , medicinal chemistry , deprotonation , inorganic chemistry , pyridine , base (topology) , protonation , formamide , sulfuric acid , organic chemistry , ion , mathematical analysis , mathematics
The association of BeX 2 (X: H, F, Cl) derivatives with azoles leads to a dramatic increase of their intrinsic acidity. Hence, whereas 1 H ‐tetrazole can be considered as a typical N base in the gas phase, the complex 1 H ‐tetrazole–BeCl 2 is predicted to be, through the use of high‐level G4 ab initio calculations, a nitrogen acid stronger than perchloric acid. This acidity enhancement is due to a more favorable stabilization of the deprotonated species after the beryllium bond is formed, because the deprotonated anion is a much better electron donor than the neutral species. Consequently, this is a general phenomenon that should be observed for any Lewis base, including those in which the basic site is a hydroxy group, an amino group, a carbonyl group, an aromatic N atom, a second‐row atom, or the π system of unsaturated hydrocarbons. The consequence is that typical bases like aniline or formamide lead to BeX 2 complexes that are stronger acids than phosphoric or chloric acids. Similarly, water, methanol, and SH 2 become stronger acids than sulfuric acid, pyridine becomes a C acid almost as strong as acetic acid, and unsaturated hydrocarbons such as ethylene and acetylene become acids as strong as nitric and sulfuric acids, respectively.