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Tuning the Halogen/Hydrogen Bond Competition: A Spectroscopic and Conceptual DFT Study of Some Model Complexes Involving CHF 2 I
Author(s) -
Nagels Nick,
Geboes Yannick,
Pinter Balazs,
De Proft Frank,
Herrebout Wouter A.
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201402116
Subject(s) - chemistry , halogen bond , halogen , lewis acids and bases , hydrogen bond , hydrogen , infrared spectroscopy , hydrogen fluoride , raman spectroscopy , medicinal chemistry , polymer chemistry , molecule , inorganic chemistry , organic chemistry , alkyl , physics , optics , catalysis
Insight into the key factors driving the competition of halogen and hydrogen bonds is obtained by studying the affinity of the Lewis bases trimethylamine (TMA), dimethyl ether (DME), and methyl fluoride (MF) towards difluoroiodomethane (CHF 2 I). Analysis of the infrared and Raman spectra of solutions in liquid krypton containing mixtures of TMA and CHF 2 I and of DME and CHF 2 I reveals that for these Lewis bases hydrogen and halogen‐bonded complexes appear simultaneously. In contrast, only a hydrogen‐bonded complex is formed for the mixtures of CHF 2 I and MF. The complexation enthalpies for the CH ⋅⋅⋅ Y hydrogen‐bonded complexes with TMA, DME, and MF are determined to be −14.7(2), −10.5(5) and −5.1(6) kJ mol −1 , respectively. The values for the CI ⋅⋅⋅ Y halogen‐bonded isomers are −19.0(3) kJ mol −1 for TMA and −9.9(8) kJ mol −1 for DME. Generalization of the observed trends suggests that, at least for the bases studied here, softer Lewis bases such as TMA favor halogen bonding, whereas harder bases such as MF show a substantial preference for hydrogen bonding.