Mainz 2017 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 4: Spectroscopy of Cold Molecules and Complexes

MO 4.4: Vortrag

Montag, 6. März 2017, 17:45–18:00, N 25

[B₁₂Cl₁₁]⁻: An anionic superelectrophile? — Markus Rohdenburg¹, •Martin Mayer², Max Grellmann², Carsten Jenne³, Tobias Borrmann¹, Florian Kleemiß⁴, Vladimir A. Azov¹, Knut R. Asmis², Simon Grabowsky⁴, and Jonas Warneke⁵ — ¹University of Bremen, Institute of Applied and Physical Chemistry — ²Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig — ³Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften — ⁴University of Bremen, Institute of Inorganic Chemistry and Crystallography — ⁵Physical Science Devision, Pacific Northwest National Laboratory, USA

Noble-gas (Ng) binding at room temperature is characteristic of superelectrophilic dications. Here, we report on the binding of krypton and xenon by the closo-dodecaborate anion [B₁₂Cl₁₁]⁻. The [B₁₂Cl₁₁Ng]⁻ complexes are thermodynamically stable species with Ng binding energies of 80 to 100 kJ/mol and contain B-Ng bonds with a significant degree of covalent interaction. The electrophilic nature of the boron binding site in [B₁₂Cl₁₁]⁻ is spectroscopically confirmed by the observation of a blue shift of the CO stretching mode in [B₁₂Cl₁₁CO]⁻. The characteristic electric field in front of the reactive site of [B₁₂Cl₁₁]⁻ results in a barrier for polar molecules, promoting the formation of Ng-complexes that are not detected with reactive cations like C₆H₅⁺. This introduces the new chemistry of "dipole discriminating electrophilic anions". Implications for noble gas compounds and the fundamental concept of electrophilicity are discussed.