Theoretical prediction on the insertion reactions of stannylenoid H2SnLiF with CH3X and SiH3X (X = F, Cl, Br)

Density functional theory was used to study the insertion reaction of stannylenoid H2SnLiF with CH3X, SiH3X (X = F, Cl, Br). Comparing the reaction barrier of H2SnLiF with CH3X, SiH3X, it can be found that the order of the difficulty of insertion reaction is F > Cl > Br. The insertion reaction potential barrier of SiH3X is lower than that of CH3X, which means that SiH3X is easier to react. According to the calculation results, the reaction law in THF solvent is consistent with that in vacuum, while in THF solvent, the barrier is lower and therefore more prone to reactions. This work provides theoretical support for the reaction properties of stannylenoids.

Cooperative effects between π-hole triel and π-hole chalcogen bonds

MP2/aug-cc-pVTZ calculations have been performed on π-hole triel- and chalcogen-bonded complexes involving a heteroaromatic compound. These complexes are very stable with large interaction energy up to −47 kcal mol⁻¹. The sp²-hybridized nitrogen atom engages in a stronger π-hole bond than the sp-hybridized species although the former has smaller negative electrostatic potential. The sp²-hybridized oxygen atom in 1,4-benzoquinone is a weaker electron donor in the π-hole bond than the sp²-hybridized nitrogen atom. The π-hole triel bond is stronger than the π-hole chalcogen bond. A clear structural deformation is found for the triel or chalcogen donor molecule in these π-hole-bonded complexes. The triel bond exhibits partially covalent interaction, whereas the chalcogen bond exhibits covalent interaction in the SO₃ complexes of pyrazine and pyridine derivatives with a sp²-hybridized nitrogen atom. Intermolecular charge transfer (>0.2e) occurs to a considerable extent in these complexes. In ternary complexes involving an aromatic compound, wherein a triel bond and a chalcogen bond coexist, both the interactions are weakened or strengthened when the central aromatic molecule acts as a double Lewis base or plays a dual role of both a base and an acid. Both electrostatic and charge transfer effects have important contributions toward changes in the strength of both interactions.

MP2/aug-cc-pVTZ calculations have been performed on π-hole triel- and chalcogen-bonded complexes involving a heteroaromatic compound. Both interactions exhibit cooperative/diminutive effect, depending on the role of the central heteroaromatic compound.