Anion⋅⋅⋅Si Interactions in an Inverse Sandwich Complex: A Computational Study

Combination of an electron‐rich molecule (e.g. chloride anion or nitrile group) with a chlorinated cyclohexasilane ring produces a supramolecular inverse sandwich complex formed by two guests (Cl^? or R?C≡N) strongly bonded to both faces of a planar host (Si₆ ring). In‐depth theoretical studies were carried out to investigate the nature of the bonding interactions that generate such a stable complex. Second‐order Møller–Plesset perturbation theory (MP2) calculations confirmed that the presence of the Cl substituents is fundamental to the stability of the supramolecular assemblies. The density functional theory (DFT) functional wB97XD gave an estimation of the contribution of dispersion interactions to the binding energy. These interactions become more important as the Cl atoms of the rings are systematically replaced by methyl groups or hydrogen atoms. Analysis of the topology of the electron density and the reduced density gradient gave insight into the binding of the studied supramolecular assemblies.