Multiple Multidentate Halogen Bonding in Solution, in the Solid State, and in the (Calculated) Gas Phase.
The binding properties of neutral halogen-bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X-ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X-ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas-phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors.
Fakultät für Chemie und Biochemie, Ruhr Universität Bochum, Universitätsstrasse 150, 44801 Bochum (Germany).|Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching (Germany).
Stefan H
SH
Jungbauer
Fakultät für Chemie und Biochemie, Ruhr Universität Bochum, Universitätsstrasse 150, 44801 Bochum (Germany).|Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching (Germany).
Severin
S
Schindler
Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching (Germany).
Eberhardt
E
Herdtweck
Molecular Biophysics, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663 Kaiserslautern (Germany). mail@sandrokeller.com.
Sandro
S
Keller
Fakultät für Chemie und Biochemie, Ruhr Universität Bochum, Universitätsstrasse 150, 44801 Bochum (Germany). stefan.m.huber@rub.de.|Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching (Germany). stefan.m.huber@rub.de.
Stefan M
SM
Huber
anions; halogen compounds; molecular recognition; noncovalent interactions; thermodynamics