Role of the cation formal charge in cation–π interaction. A survey involving the [2.2.2]paracyclophane host from relativistic DFT calculations

Abstract

Of charge and cations. Isoelectronic cation–π complexes unravel the nature of variation of the interaction.

On the cation–π capabilities of small all sp2‐carbon host structures. Evaluation of [6.8]3cyclacene from relativistic DFT calculations

“…For a cation with electronic configuration 5s 0 5p 0 , the charge donation was found to be more effective in η 2 :η 2 :η 2 ‐[2.2.2]pCp → 5s 0 scheme, which has the interaction happening in a similar way to our η 1 :η 1 :η 1 cases in 1, and the η 1 :η 1 in 2. On the other hand, the scheme η 6 :η 6 :η 6 ‐[2.2.2]pCp → 5p 0 was found as more effective in cations with 5s 2 5p 0 electronic configuration …”

“…The optimized geometries reveal that the isoelectronic cations with the available 5 second‐shell, namely, Ag + and Cd 2+ , adopt exclusively a η 1 :η 1 :η 1 coordination mode with 1 , where the cation–π interaction is observed toward one face of the nanobelt. In contrast, Sn 2+ with an empty 5p‐shell assumes only a η 6 :η 6 :η 6 coordination mode ( 1 ‐6Sn 2+ ), which is located at the center of the nanobelt, owing to the more effective [6.8] 3 cyclacene → Sn 2+ bonding in such disposition . On the other hand, its isoelectronic In + cation converges into both coordination modes η 1 :η 1 :η 1 ( 1 ‐1In + ) and η 6 :η 6 :η 6 ( 1 ‐6In + ).…”

“…In this respect, Ag(I) and Sn(II) serve as prototypical cations, providing available s‐ and p‐type orbitals for π‐backbone →M charge transfer, were employed as guest. In addition, Cd(II) and In(I) serve as isolectronic cations in order to further evaluate the role of the formal cation charge on the cation–π formation . All calculations were performed by using relativistic density functional methods, and the nature of the host–guest interaction was analyzed via energy decomposition analyses (EDA‐NOCV), Natural Bond Orbital (NBO) analysis and noncovalent index (NCI) …”

Advances in bonding and properties of inorganic systems from relativistic calculations in Latin America

“…Reproduced from Ref. with permission from the Centre National de la Recherche Scientifique (CNRS) and The Royal Society of Chemistry…”

Helicenes as Molecular Tweezers in the Formation of Cation−π Complexes. Bonding and Circular Dichroism Properties from Relativistic DFT Calculations

“…In addition to silver, Sn(II) is another representative ion in the formation of cation−π complexes, as seen from the chemistry of [2.2.2]paracyclophane ([2.2.2]pCp) acting as suitable polyaromatic receptor for metal cations involving three aromatic rings . A notorious difference between the characterized complexes of Ag(I) and Sn(II) with [2.2.2]pCp, is given by the location of the cation denoting an η 2 : η 2 : η 2 coordination mode for the former, and a contrasting η 6 : η 6 : η 6 fashion for Sn(II) involving a richer bonding scheme owing to the ligand→5p‐Sn shell charge donation, which encourage us to evaluate their plausible incorporation in the helicene chemistry ,…”