[2.2.2]Paracyclophane, preference for η⁶ or η¹⁸ coordination mode including Ag(i) and Sn(ii): a survey into the cation–π interaction nature through relativistic DFT calculations

Abstract

[2.2.2]Paracyclophane is a versatile π-cryptating structure, which can exhibit η2:η2:η2 and η6:η6:η6 coordination with metal ions, involving two or six carbon atoms in each aromatic ring.

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

“…These findings are directly related with our previously reported results for [2.2.2]paracyclophane . 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.…”

“…The calculated cavity diameter for the isolated nanobelt 1 is 5.696 Å, while 5.676 Å is observed by single crystal X‐ray data . The inclusion of the Ag + and Cd 2+ cations into the cavity leads to slight increase in the cavity diameter, in agreement with the rigidity expected for the all‐sp 2 carbon backbone, whereas for the related [2.2.2]paracyclophane, an opening of the above face is accounted . Such finding is also supported by the small values of preparation energies, Δ E prep , obtained from EDA‐NOCV analysis, as discussed in the next section.…”

“…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 …”

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

“…Interestingly, such host for cations exhibits two well‐defined coordination modes toward ns and ( n ‐1) p elements, given as described for Ag + and Sn 2+ , respectively, involving a η 2 : η 2 : η 2 for the former, and η 6 : η 6 : η 6 for the latter. These different coordination behaviors were studied by relativistic DFT methods and it was found that the 5 seconds‐Ag shell is close in energy to the frontier orbitals of paracyclophane, resulting in the formation of a bonding scheme with the symmetric combination of the π 2 ‐type levels. This leads to a conformation where Ag is located in one face along the symmetric C 3 ‐axis (Figures and ).…”

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 ,…”