A cryospectroscopic study of the blue-shifting $C-H\cdots O$ bonded complexes of pentafluoroethane with dimethyl ether-$d_{6}$, acetone-$d_{6}$ and oxirane-$d_{4}$

The infrared spectra of solutions of pentafluoroethane, CHF2CF3, and dimethyl ether-d6, acetone-d6, or oxirane-d4 dissolved in liquid krypton were investigated, at temperatures between 118 and 168 K. In all spectra, evidence was found for the formation of CHcdots, three dots, centeredO hydrogen bonded complexes that are characterized by a blue shift in the CH stretching fundamental. The shifts were found to be +15.1 cm−1 (dimethyl ether-d6), +24.3 cm−1 (acetone-d6) and +20.3 cm−1 (oxirane-d4), while the corresponding intensity ratios εcom/εmon were derived to be 0.35(1), 0.42(5) and 0.54(2). Using spectra recorded at different temperatures the complexation enthalpy ΔexpHring operator for the complexes were determined to be −12.1(1), −12.9(1) and −12.6(1) kJ mol−1, respectively. The results are compared with theoretical data obtained by combining ab initio complexation energies with thermal and solvent corrections obtained from statistical thermodynamical calculations and Monte Carlo-Free Energy Perturbation simulations. The results are also compared with experimental and theoretical data obtained for the complexes formed between the same proton acceptors and fluoroform.

Jaar van publicatie:2010

Trefwoorden:A1 Journal article

BOF-keylabel:ja

BOF-publication weight:1

CSS-citation score:1

Authors from:Higher Education

Toegankelijkheid:Closed