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Gas‐Phase Acidities of Nine Sulfur Oxoacids of Composition [H 2 ,S,O n ] ( n = 1–4)
Author(s) -
Otto André H.,
Steudel Ralf
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(200004)2000:4<617::aid-ejic617>3.0.co;2-z
Subject(s) - chemistry , deprotonation , sulfur , sulfuric acid , nitric acid , iodide , hydrogen iodide , inorganic chemistry , medicinal chemistry , proton , hydrogen , molecule , organic chemistry , ion , physics , quantum mechanics
The gas‐phase acidities of the most stable conformations of nine sulfur oxo acids were determined by ab initio MO calculations at the CBS‐Q, G2(MP2), and G2 levels of theory. The most accurate G2 results are as follows (Δ G ° 298 of the deprotonation reaction in kJ mol –1 ): H–S–O– H 1468, H –S–O–H 1449, (HO) 2 S 1426, H –S(=O)OH 1406, H 2 S/O 1394, H–S(=O)O H 1361, (HO) 2 S/O 1324, H 2 S(=O) 2 1321, H 2 O→S 1294, H –S(=O) 2 OH 1287, H–S(=O) 2 O H 1279, (HO) 2 S(=O) 2 1268. These values are in excellent agreement with the few experimental data that can be considered reliable. For molecules of analogous structure, the acidity increases with increasing oxidation number of the sulfur atom. While sulfenic acid, HSO H , is as weak an acid as HOCl, sulfurous acid, (HO) 2 SO, is as strong a proton donor as nitric acid, HNO 3 , and sulfonic acid, H S(O) 2 OH, is even stronger than hydrogen iodide, HI, surpassed only by sulfuric acid, H 2 SO 4 . These results are of relevance to phenomena such as acid rain and aerosol formation in the earth′s atmosphere.