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SO₂ Solvation in the 1-Ethyl-3-Methylimidazolium Thiocyanate Ionic Liquid by Incorporation into the Extended Cation-Anion Network.

ABSTRACT: We have carried out an ab initio molecular dynamics study on the sulfur dioxide (SO₂) solvation in 1-ethyl-3-methylimidazolium thiocyanate for which we have observed that both cations and anions play an essential role in the solvation of SO₂. Whereas, the anions tend to form a thiocyanate- and much less often an isothiocyanate-SO₂ adduct, the cations create a "cage" around SO₂ with those groups of atoms that donate weak interactions like the alkyl hydrogen atoms as well as the heavy atoms of the [Formula: see text]-system. Despite these similarities between the solvation of SO₂ and CO₂ in ionic liquids, an essential difference was observed with respect to the acidic protons. Whereas CO₂ avoids accepting hydrogen bonds form the acidic hydrogen atoms of the cations, SO₂ can from O(SO₂)-H(cation) hydrogen bonds and thus together with the strong anion-adduct it actively integrates in the hydrogen bond network of this particular ionic liquid. The fact that SO₂ acts in this way was termed a linker effect by us, because the SO₂ can be situated between cation and anion operating as a linker between them. The particular contacts are the H(cation)[Formula: see text]O(SO₂) hydrogen bond and a S(anion)-S(SO₂) sulfur bridge. Clearly, this observation provides a possible explanation for the question of why the SO₂ solubility in these ionic liquids is so high.

SUBMITTER: Firaha DS

PROVIDER: S-EPMC4412831 | biostudies-literature |

REPOSITORIES: biostudies-literature

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