Tuning tetrel bonds via cation–π interactions: an <i>ab initio</i> study on concerted interaction in M<sup>+</sup>–C<sub>6</sub>H<sub>5</sub>XH<sub>3</sub>–NCY complexes (M = Li, Na, K; X = Si, Ge; Y = H, F, OH)

<div><p>ABSTRACT</p><p>In the present study, the M<sup>+</sup>–C<sub>6</sub>H<sub>5</sub>XH<sub>3</sub>–NCY (M = Li, Na, K; X = Si, Ge; Y = H, F, OH) complexes are investigated to find ways to enhance the X···N tetrel bond interactions. Cooperative effects are observed in complexes in which cation-π and tetrel bond interactions coexist. These effects are analysed in detail in terms of the energetic, geometric, charge-transfer and electron density properties of the complexes. The shortening of the tetrel bond distance in the ternary complexes is dependent on the strength of the cation-π interaction and it becomes larger in the order M = K < Na < Li. The cooperative energy ranges from −1.56 and −4.10 kcal/mol.</p></div>