title: Ligand-exchange processes on solvated lithium cations: DMSO and water/DMSO mixtures.
abstract: Solutions of LiClO(4) in solvent mixtures consisting of dimethylsulfoxide (DMSO) and water, or DMSO and gamma-butyrolactone, were studied by (7)Li NMR spectroscopy (for complexation by cryptands in gamma-butyrolactone as a solvent, see: E. Pasgreta, R. Puchta, M. Galle, N. J. R. van Eikema Hommes, A. Zahl, R. van Eldik, J. Incl. Phen., 2007, 58, 81-88). Chemical shifts indicate that the Li(+) ion is coordinated by four DMSO molecules. In the binary solvent mixture of water and DMSO, no selective solvation is detected, thus indicating that on increasing the water content of the solvent mixture, DMSO is gradually displaced by water in the coordination sphere of Li(+). The ligand-exchange mechanism of Li(+) ions solvated by DMSO and water/DMSO mixtures was studied using DFT calculations. Ligand exchange on [Li(DMSO)(4)](+) was found to follow a limiting associative (A) mechanism. The displacement of coordinated H(2)O by DMSO in [Li(H(2)O)(4)](+) follows an associative interchange mechanism. The suggested mechanisms are discussed in reference to available experimental and theoretical data.
authors.affiliation: Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, 91058 Erlangen, Germany.
authors.forename: Ewa
authors.initials: E
authors.lastname: Pasgreta
authors.forename: Ralph
authors.initials: R
authors.lastname: Puchta
authors.forename: Michael
authors.initials: M
authors.lastname: Galle
authors.forename: Nico
authors.initials: N
authors.lastname: van Eikema Hommes
authors.forename: Achim
authors.initials: A
authors.lastname: Zahl
authors.forename: Rudi
authors.initials: R
authors.lastname: van Eldik
mesh_terms: D002412:Cations / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D008024:Ligands; D008094:Lithium / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012996:Solutions / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D002412:Cations; D008024:Ligands; D012996:Solutions; D014867:Water; D008094:Lithium; D004121:Dimethyl Sulfoxide