title: Self-association and picosecond dynamics in liquid dimethyl sulfoxide.
abstract: Dimethyl sulfoxide (DMSO) has been known for almost 150 years, but its properties as a solvent and reaction medium are far from being understood. In particular, association equilibriums in liquid DMSO have been characterized in just four papers, and the enthalpy of its self-association is unknown. The aims of this paper are to study self-association equilibriums in neat liquid DMSO at various temperatures by means of Raman spectroscopy, to find the enthalpy of self-association, and to solve the problem of hydrogen bonding in this liquid. Time correlation functions of vibrational dephasing and reorientation of coexisting monomers and dimers studied by the C-S-C and C-H symmetric vibrations indicate that external perturbations and vibrational and reorientational dynamics of these particles occur on different time scales. No signatures of H-bonding in DMSO are found. The association constants vary from 0.20 L mol(-1) (23 °C) to 0.081 L mol(-1) (100 °C). Their temperature dependence gives the enthalpy of association of DMSO as -11.7 ± 0.9 kJ mol(-1).
authors.affiliation: Joint Department of Electrochemical Energy Systems, 38A Vernadsky Avenue, 03142 Kyiv, Ukraine. kir@i.kiev.ua
authors.forename: Sviatoslav A
authors.initials: SA
authors.lastname: Kirillov
authors.forename: Margarita I
authors.initials: MI
authors.lastname: Gorobets
authors.forename: Malik M
authors.initials: MM
authors.lastname: Gafurov
authors.forename: Mansur B
authors.initials: MB
authors.lastname: Ataev
authors.forename: Kamil Sh
authors.initials: KSh
authors.lastname: Rabadanov
mesh_terms: D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D013059:Spectrum Analysis, Raman; D013696:Temperature; D013816:Thermodynamics
chemical_list: D004121:Dimethyl Sulfoxide