17829-83-3Relevant academic research and scientific papers
Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium
Bousrez, Guillaume,Renier, Olivier,Kelley, Steven P.,Adranno, Brando,Tahavori, Elnaz,Titi, Hatem M.,Smetana, Volodymyr,Tang, Si-Fu,Mudring, Anja-Verena,Rogers, Robin D.
, p. 13181 - 13189 (2021/08/16)
Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C2mim]n[{Ln2(OAc)7}n] and the dimeric [C2mim]2[Ln2(OAc)8], based on the ion size and the ratio of IL used. A reaction with an IL : Ln-salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy?Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal-acetate coordination modes where η2μκ2 is the most represented in both structure types.
Paramagnetic ions as structural probes in solid-state NMR: Distance measurements in crystalline lanthanide acetates
Brough, Adrian R.,Grey, Clare P.,Dobson, Christopher M.
, p. 7318 - 7327 (2007/10/02)
The rare earth acetates M(O2CCH3)3·4H2O (M = Nd, Sm, Eu, Y) and Pr(O2CCH3)3·H2O, and the analogous deuterated compounds, have been studied by 13C MAS-NMR. The paramagnetic materials show a large range of isotropic 13C chemical shifts which result largely from contact interactions with the rare earth electronic moments. They often show substantial linebroadening, which appears to result predominantly from anisotropic bulk magnetic susceptibility broadening for the deuterated compounds; the line widths for the protonated materials are increased further because of incomplete proton decoupling. Proton spectra acquired from a largely deuterated sample indicated that the spread in proton frequencies (40 kHz for Sm(O2CCH3)3·4H2O at 4.7 T, and calculated to be approximately 200 kHz for Eu(O2CCH3)3·4H2O) is too large for decoupling to be effective with attainable 1H power levels. The deuterated materials exhibit sufficiently good resolution to allow analysis of the large 13C spinning sideband manifolds; these result mainly from dipolar coupling to the paramagnetic centers. X-ray diffraction shows that the solid solutions Y(1-x)Lnx(O2CCH3) 3·4H2O (Ln = Pr, Nd, Sm, Eu; x ≤ 0.1) crystallize with the Y(O2CCH3)3·4H2O crystal structure. MAS-NMR spectra of the 13C enriched deuterated analogues contain remarkably narrow resonances of only 100 Hz line width despite having spinning sideband envelopes spanning 1000 ppm. The paramagnetic shift anisotropies could be predicted with reasonable accuracy by considering the interactions of the nuclei with the single nearest paramagnetic ion. Ln-13C distances could also be estimated from the spectra and agreed to within 5% for the carboxyl carbons and 15% for the methyl carbons with the distances available from single-crystal X-ray diffraction studies. The different resonances in the solid solutions could then be assigned by the use of these estimated distances despite the large number of different 13C local environments. These results suggest that in favorable circumstances, paramagnetic centers can provide a means for the determination of structural information and distances from MAS-NMR.
Synthesis and spectroscopic properties of praseodymium(III) acetate hydrate
Hehlen, Markus P.,Riesen, Hans,Güdel, Hans U.
, p. 2273 - 2277 (2008/10/08)
A new synthesis for the quasi-one-dimensional compound Pr(CH3COO)3·H2O and its deuterated analogue Pr(CD3COO)3·D2O is reported. Well-resolved absorption, luminescence, and Raman measurements on single crystals of these compounds as well as the diluted system Ce(CH3COO)3·H2O:1% Pr3+ down to 5 K are reported and analyzed. Due to high-energy O-H stretching vibrations of the directly coordinated water molecule, excited states are efficiently depopulated by nonradiative multiphonon relaxation. In the concentrated crystal, the relaxation rate of the 3P0 excited state at 5 K is ～2 × 108 s-1 and > 109 s-1 for the deuterated and nondeuterated compound, respectively. In addition, cross relaxation contributes to the nonradiative depopulation of the 1D2 excited state. It is thus likely that energy migration along the chain is not important. The 3H4 → 3P0 absorption has a relatively intense sideband, 65% and 20% of the total intensity for Pr(CH3COO)3·H2O and Ce(CH3COO)3·H2O:1% Pr3+, respectively. Double excitations involving nearest neighbors in the chain contribute two-thirds of the sideband intensity of the undiluted compound, one-third being vibronic.
