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Title
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A cryospectroscopic infrared and Raman study of the halogen bonding motif : complexes of the , , and with ethyne, propyne and 2-butyne
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Author
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Abstract
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| Experimental information on the Csingle bondX⋯π halogen bonding motif was obtained by studying the formation of molecular complexes of CF3Cl, CF3Br and CF3I with ethyne, propyne and 2-butyne in liquid krypton, using FTIR and Raman spectroscopy. For CF3Br, experimental evidence was found for the formation of 1:1 complexes with propyne and 2-butyne only, while for CF3I spectroscopic features confirming the existence of the halogen bonded complexes were observed for ethyne, propyne and 2-butyne. In addition, at higher concentrations of CF3I and 2-butyne, weak absorptions due to a 2:1 complex were also observed. The experimental complexation enthalpies, obtained by using spectra recorded at temperatures between 120 K and 140 K, are −5.9(3) kJ mol−1 for CF3I.ethyne, −5.6(3) kJ mol−1 for CF3Br.propyne, −8.1(2) kJ mol−1 for CF3I.propyne, −7.3(2) kJ mol−1 for CF3Br.2-butyne, −10.9(2) kJ mol−1 for CF3I.2-butyne and −20.9(7) kJ mol−1 for (CF3I)2.2-butyne. The experimental study is supported by theoretical data obtained from ab initio calculations at the MP2/aug-cc-pVDZ(-PP) and MP2/aug-cc-pVTZ(-PP) levels, and Monte Carlo Free Energy Perturbation (MC-FEP) simulations. The experimental and theoretical values on the Csingle bondX⋯π halogen-bonding motifs studied are compared with previously reported data for the complexes with ethene and propene and with preliminary results obtained for benzene and toluene. |
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Language
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English
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Source (journal)
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Spectrochimica acta: part A: molecular and biomolecular spectroscopy. - Oxford
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Publication
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Oxford
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2015
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ISSN
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1386-1425
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DOI
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10.1016/J.SAA.2014.04.141
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Volume/pages
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136
:A
(2015)
, p. 16-26
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ISI
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000347584900003
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Pubmed ID
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24910010
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Full text (Publisher's DOI)
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Full text (open access)
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Full text (publisher's version - intranet only)
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