Authors: Otte, Felix
Kleinheider, Johannes
Grabe, Bastian
Hiller, Wolf
Busse, Franziska
Wang, Ruimin
Kreienborg, Nora M.
Merten, Christian
Englert, Ulli
Strohmann, Carsten
Title: Gauging the strength of the molecular halogen bond via experimental electron density and spectroscopy
Other Titles: Dedicated to Professor Klaus Jurkschat on the occasion of his 70th birthday.
Language (ISO): en
Abstract: Strong and weak halogen bonds (XBs) in discrete aggregates involving the same acceptor are addressed by experiments in solution and in the solid state. Unsubstituted and perfluorinated iodobenzenes act as halogen donors of tunable strength; in all cases, quinuclidine represents the acceptor. NMR titrations reliably identify the strong intermolecular interactions in solution, with experimental binding energies of approx. 7 kJ/mol. Interaction of the σ hole at the halogen donor iodine leads to a redshift in the symmetric C–I stretching vibration; this shift reflects the interaction energy in the halogen-bonded adducts and may be assessed by Raman spectroscopy in condensed phase even for weak XBs. An experimental picture of the electronic density for the XBs is achieved by high-resolution X-ray diffraction on suitable crystals. Quantum theory of atoms in molecules (QTAIM) analysis affords the electron densities and energy densities in the bond critical points of the halogen bonds and confirms stronger interaction for the shorter contacts. For the first time, the experimental electron density shows a significant effect on the atomic volumes and Bader charges of the quinuclidine N atoms, the halogen-bond acceptor: strong and weak XBs are reflected in the nature of their acceptor atom. Our experimental findings at the acceptor atom match the discussed effects of halogen bonding and thus the proposed concepts in XB activated organocatalysis.
Subject Headings: Diffraction
Electron density
Energy density
Group 17 compounds
Issue Date: 2023-06-05
Rights link:
Appears in Collections:Lehrstühle für Anorganische Chemie

Files in This Item:
File Description SizeFormat 
acsomega.3c00619.pdfDNB4.15 MBAdobe PDFView/Open

This item is protected by original copyright

This item is licensed under a Creative Commons License Creative Commons