TY - JOUR
T1 - Mechanisms of Metal Ion Transfer into Room-Temperature Ionic Liquids
T2 - The Role of Anion Exchange
AU - Jensen, Mark P.
AU - Neuefeind, Jörg
AU - Beitz, James V.
AU - Skanthakumar, S.
AU - Soderholm, L.
PY - 2003/12/17
Y1 - 2003/12/17
N2 - The structure and stoichiometry of the lanthanide(III) (Ln) complexes with the ligand 2-thenoyl-trifluoroacetone (Htta) formed in a biphasic aqueous room-temperature ionic liquid system have been studied by complementary physicochemical methods. Equilibrium thermodynamics, optical absorption and luminescence spectroscopies, high-energy X-ray scattering, EXAFS, and molecular dynamics simulations all support the formation of anionic Nd(tta) 4- or Eu(tta)4- complexes with no water coordinated to the metal center in 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C4mim+Tf 2N-), rather than the hydrated, neutral complexes, M(tta)3(H2O)n (n = 2 or 3), that form in nonpolar molecular solvents, such as xylene or chloroform. The presence of anionic lanthanide complexes in C4mim+Tf2N - is made possible by the exchange of the ionic liquid anions into the aqueous phase for the lanthanide complex. The resulting complexes in the ionic liquid phase should be thought of as weak C4mim +Ln(tta)4- ion pairs which exert little influence on the structure of the ionic liquid phase.
AB - The structure and stoichiometry of the lanthanide(III) (Ln) complexes with the ligand 2-thenoyl-trifluoroacetone (Htta) formed in a biphasic aqueous room-temperature ionic liquid system have been studied by complementary physicochemical methods. Equilibrium thermodynamics, optical absorption and luminescence spectroscopies, high-energy X-ray scattering, EXAFS, and molecular dynamics simulations all support the formation of anionic Nd(tta) 4- or Eu(tta)4- complexes with no water coordinated to the metal center in 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C4mim+Tf 2N-), rather than the hydrated, neutral complexes, M(tta)3(H2O)n (n = 2 or 3), that form in nonpolar molecular solvents, such as xylene or chloroform. The presence of anionic lanthanide complexes in C4mim+Tf2N - is made possible by the exchange of the ionic liquid anions into the aqueous phase for the lanthanide complex. The resulting complexes in the ionic liquid phase should be thought of as weak C4mim +Ln(tta)4- ion pairs which exert little influence on the structure of the ionic liquid phase.
UR - http://www.scopus.com/inward/record.url?scp=0348109459&partnerID=8YFLogxK
U2 - 10.1021/ja037577b
DO - 10.1021/ja037577b
M3 - Article
AN - SCOPUS:0348109459
SN - 0002-7863
VL - 125
SP - 15466
EP - 15473
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 50
ER -