Intermolecular C-H center dot center dot center dot O interactions in cyclopentanone: An inelastic neutron scattering study

Abstract

The inelastic neutron scattering (INS) spectra of cyclopentanone were obtained for pure and 50% CCl4 solution forms. Spectra are compared with infrared and Raman data, and with DFT calculated eigenvectors. This exercise aims to find spectroscopic evidence in the neutron spectra for the presence of C-H center dot center dot center dot O hydrogen bonds. These are weak interactions with an energy of ca. -6 kJ mol(-1) as predicted by DFT. The neutron spectra show narrow and sharp bands which allows for an assignment of the vibrational modes. The simulated neutron spectrum of C-H center dot center dot center dot O bonded cyclopentanone dimers matches the experimental spectrum of the pure compound, whereas the monomer simulation monomer matches the experimental spectrum of the diluted solution, meaning that such interaction can be probed by INS. Assignment of the 95 cm(-1) band to the nu H center dot center dot center dot O anti-translational mode, being supported by DFT results and in agreement with previous literature data, is considered and discussed. (C) 2013 Elsevier B. V. All rights reserved.