title: C-H...O hydrogen bonds in cyclohexenone reveal the spectroscopic behavior of Csp3-H and Csp2-H donors.
abstract: C-H...O hydrogen bonds in liquid 2-cyclohexen-1-one are studied to assess the vibrational spectroscopic behavior of the Csp2-H and Csp3-H donors. The presence of a pseudo-isosbestic point in the vC = O region supports the assignment of the two observed bands to two species in equilibrium, considered to be the free and 1:1 associated forms. The values of deltaH degrees =-18.5 +/- 0.6 kJmol(-1) and deltaS degrees = -76 +/- 2 J K(-1) mol(-1) for the dimerization through C-H...O hydrogen bonds were obtained from the dimerization constant at different temperatures. The concentration-dependent intensity of the vCH2 band profile is ascribed to the presence of a blue-shifted band from the hydrogen-bonded Csp3-H group. However, the most surprising result is the absence of concentration- or temperature-dependent intensities in the bands assigned to the stretching modes of the Csp2-H donors.
authors.affiliation: Departamento de Química-CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Mariela M
authors.initials: MM
authors.lastname: Nolasco
authors.forename: Paulo J A
authors.initials: PJ
authors.lastname: Ribeiro-Claro
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods*; D003512:Cyclohexanones / Q000737:chemistry*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D016011:Normal Distribution; D010100:Oxygen / Q000737:chemistry; D012984:Software; D012997:Solvents / Q000737:chemistry; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D013696:Temperature; D013816:Thermodynamics
chemical_list: D003512:Cyclohexanones; D012997:Solvents; D000431:Ethanol; D002244:Carbon; D006859:Hydrogen; D010100:Oxygen