The Halogen Bond to Ethers - Prototypic Molecules and Experimental Electron Density

ACS Omega, vol. 9, pp. 35037–35045

Abstract

High Resolution Image Download MS PowerPoint Slide Halogen bonds to dialkyl ether molecules have remained largely unexplored. We here address the synthesis and the structural chemistry of the first halogen-bonded noncyclic alkyl ethers, combining 1,4-diiodotetrafluorobenzene and the prototypic or commonly used ethers dimethyl ether, tetrahydrofuran, and methyl- tert -butyl ether as halogen acceptors. Two different structural motifs based on moderately strong halogen bonds were obtained: Discrete trimolecular aggregates are formed, and unexpected halogen-bonded supramolecular chain adducts feature oxygen-bifurcated halogen bonds with 1:1 donor:acceptor ratio. Both structure types may be selectively obtained even for the same ether by adjusting the stoichiometry in the crystallization experiments. The geometric features of the etheric oxygen center were found to be flexible, in contrast to the almost linear geometry about the halogen donor atom. A high-resolution X-ray diffraction experiment on the extended adduct of dimethyl ether allowed us to study the electronic details of the acceptor-bifurcated I···O···I halogen bonds. The electron density in the bond critical points and derived properties such as the Laplacian indicate essentially electrostatic interactions and explain the geometrical flexibility of ethers in halogen bonds. Our studies demonstrate the great versatility of ethers as halogen bond acceptors, that can occur in many geometrical arrangements and whose contribution to nature’s structural designs should not be underestimated.

Authors 7

1. Annika Schmidt

   TU Dortmund University

   Affiliation as printed

   Inorganic Chemistry, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany

2. Anna Krupp

   TU Dortmund University

   Affiliation as printed

   Inorganic Chemistry, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany

3. Johannes Kleinheider

   TU Dortmund University

   Affiliation as printed

   Inorganic Chemistry, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany

4. Tamara M. L. Binnenbrinkmann

   TU Dortmund University

   Affiliation as printed

   Inorganic Chemistry, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany

5. Ruimin Wang Aachen Institute of Inorganic Chemistry

   Shanxi University · RWTH Aachen University

   Affiliation as printed

   Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen, Germany

   Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of the Education Ministry, Shanxi University, Taiyuan, Shanxi 030006, China

6. Ulli Englert corresponding Aachen Institute of Inorganic Chemistry

   Shanxi University · RWTH Aachen University

   Affiliation as printed

   Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen, Germany

   Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of the Education Ministry, Shanxi University, Taiyuan, Shanxi 030006, China

7. Carsten Strohmann corresponding

   TU Dortmund University

   Affiliation as printed

   Inorganic Chemistry, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany