title: Hydrogen-bonded complexes between dimethyl sulfoxide and monoprotic acids: molecular properties and IR spectroscopy.
abstract: MP2/6-31++G(d,p) and DFT B3LYP/6-31++G(d,p) calculations were performed of the structure, binding energies, and vibrational modes of complexes between dimethyl sulfoxide (DMSO) as a proton acceptor and monoprotic linear acids HX (X = F, Cl, CN) as well as monoprotic carboxylic acids HOOCR (R = -H, -CH3, -C6H5) in 1:1 and 1:2 stoichiometric ratios. The results show that two different structures are possible in the 1:2 ratio: in the first, the DMSO molecule interacts with both acid molecules (leading to a "Y" structure); in the second, the DMSO interacts with only one monoprotic acid. The second structure shows a lower stability per hydrogen bond. The spontaneities of the reactions to form the 1:1 and 1:2 complexes are greatly influenced by the X group of the linear acid. With the exception of HCN, all the reactions are spontaneous. In the 1:2 complexes with Y structure, we observed that the hydrogen atoms of the linear acid are coupled in symmetric and asymmetric modes, while this type of coupling is absent from the other 1:2 complexes.
authors.affiliation: Departamento de Química Fundamental, Universidade Federal de Pernambuco (UFPE), 50740-540, Recife, PE, Brazil.
authors.forename: Márcia K D L
authors.initials: MK
authors.lastname: Belarmino
authors.forename: Vanessa F
authors.initials: VF
authors.lastname: Cruz
authors.forename: Nathália B D
authors.initials: NB
authors.lastname: Lima
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D003198:Computer Simulation; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004735:Energy Transfer; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011522:Protons; D012997:Solvents / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013329:Structure-Activity Relationship; D014732:Vibration
chemical_list: D002264:Carboxylic Acids; D011522:Protons; D012997:Solvents; D004121:Dimethyl Sulfoxide