Structure and NMR and electronic spectra of europium(III)-crown ether complexes in solution
Complexes were formed in acetonitrile solution between trivalent europium and ytterbium and the crown ethers 15-crown-5, benzo-15-crown-5, and naphtho-15-crown-5. Contrary to previous reports, the authors find that these ligands produce crystal field splittings on the order of 100 cm/sup -1/ for several europium f in equilibrium f transitions and large shifts and broadening of the crown proton resonances in the NMR spectrum. The crystal field splitting patterns are consistent with a C/sub 5nu/ geometry for the complex, providing evidence for the symmetrical crown structure in solution for the first time. Europium fluorescence is quenched by benzo-15-crown-5, but bands are split and shifted without quenching in the 15-crown-5 complex. New, broad absorption bands are observed for Eu/sup 3 +/ and Yb/sup 3 +/ (but not Nd/sup 3 +/) and all three crowns which are assigned as ether oxygen to metal charge-transfer bands. Electrical conductance and spectral data show a concentration dependence which is interpreted as formation of strongly bound 1:1 lanthanide-crown complexes, with some ion pairing to the perchlorate anion. At higher crown concentrations the data suggest 2:1 crown-metal complexes without ion pairing. These studies demonstrate that the choice of anion and dryness of solvent are crucial to the formation of these solution complexes. 36 references, 8 figures, 1 table.
- Research Organization:
- Williams College, Williamstown, MA
- OSTI ID:
- 6036594
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 89:26; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ABSORPTION SPECTROSCOPY
ALCOHOLS
CHEMICAL SHIFT
COMPLEXES
DATA
EMISSION SPECTROSCOPY
EUROPIUM COMPLEXES
EXPERIMENTAL DATA
FLUORESCENCE SPECTROSCOPY
GLYCOLS
HYDROXY COMPOUNDS
INFORMATION
LIGANDS
MAGNETIC RESONANCE
MAGNETISM
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PARAMAGNETISM
POLYETHYLENE GLYCOLS
POLYMERS
RARE EARTH COMPLEXES
RESONANCE
SPECTRA
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
VISIBLE SPECTRA
YTTERBIUM COMPLEXES