A theoretical investigation on the cooperativity effect, reduced density gradient, stability and aromaticity in the benzonitrile∙∙∙H₂O complex with Na⁺ or Cl^–

Abstract

The cooperativity effect between the H-bonding and Na⁺∙∙∙<span style="mso-fareast-font-family:AdvOT863180fb" lang="EN-GB">σ/π or Cl^–∙∙∙H–O/C interactions, the reduced density gradient (RDG) and the aromaticity <span style="mso-bidi-font-weight:bold" lang="EN-GB">evaluated by nucleus-independent chemical shift inNa⁺/Cl^–∙∙∙benzonitrile∙∙∙H₂O complex are investigated by using the B3LYP and MP2(full) methods with the 6-311++G(2d,p) basis set. The results show that the influence of the Na⁺∙∙∙<span style="mso-fareast-font-family:AdvOT863180fb" lang="EN-GB">σ/π or Cl^–∙∙∙H–O/C interaction on H-bond is more pronounced than that of the latter on the former. Most of the ternary complexes with Na⁺ exhibit the <span style="mso-bidi-font-weight:bold" lang="EN-GB">cooperativity effects while most of the Cl^– systems show anti-<span style="mso-bidi-font-weight:bold" lang="EN-GB">cooperativities. The <span style="mso-bidi-font-weight:bold">cooperativity effect is observed in the complex in which Na⁺ or Cl^– point towards either benzonitrile or H₂O, while the anti-<span style="mso-bidi-font-weight:bold">cooperativity effect is seen in the system where the ion points simultaneously to benzonitrile and H₂O. The anti-cooperative structures are more stable than the cooperative structures. The cooperativity effect has a notable influence on the aromaticity and π→π* conjugative effect. The analyses of RDG and AIM (atoms in molecules) confirm the existence of cooperativity.

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