Lanthanide diketonato complexes

An analysis of the shift reagent properties of lanthanide 3-diketonato-complexes, (1 R = R = Bu Ln = Eu, R = CF3, R = Bu ), with respect to mono- and di-functional substrates, has been given. The ability of these complexes to form 1 1 and 1 2 adducts with the substrates seemed to be determined by the nature of the substrate and the relative concentrations of the... 

We can visualise the capability of suitable lanthanide (Ln) compounds (J, 6), e.g. as homogeneous catalysts with respect to olefins, by invoking similar intermediates. Although the series of reportedly catalytically active Ln-complexes spans from the pure trihalide via tris(B-diketonato)complexes to the organo-metallic tris(cyclopentadienyl) and tetra(allyl)complexes (8), respectively, no really optimal combination of ligands on a Ln-element has been found so far. Promising aspects are, however, based on some evidence for "reaction steering" in that either cis- or trans-polybutadienes can be obtained from 1,3-dienes, and either polymers or metathesis products from monoolefins, respectively (Table I). 

The quenching of the luminescence of lanthanide complexes by the presence of water [51] can be supressed by encapsulating lanthanide complexes such as, e.g., europium-P-diketonato complexes (europium-(2-naphthoyl trifluoroacetone)3, (Eu(NTFA)3, and europium-(2-naphthoyl trifluoroacetone)3(trioctylphosphine oxide)2, (Eu(NTFA)3(TOPO)2), in polystyrene (PS) nanoparticles. The luminescence observed in aqueous dispersions and the increase of luminescence lifetime indicate protection from the environmental water [52]. 

Vancaeyzeele et al. [70] encapsulated unsymmetrical lanthanide-P-diketonato [lanthanide tris(4,4,4-trifluoro-l-(2-naphthyl-1,3-butanedione)] complexes (Pr, Ho, La, Tb, Eu) in crosslinked polystyrene nanoparticles. They found that the entire amount of the complex is encapsulated in the nanoparticle. Both single element and multi-element particles of different sizes were obtained. The lanthanide content of the particles was determined by inductively coupled plasma mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). The particles were used to quantify the amount of differently sized element-encoded particles in different, clinically relevant cell lines. 

The author also determined the symmetrical point groups of the lanthanide complexes concerned with the locations of phosphine oxide and )8-diketonato linker species (Fig. 5.7). The symmetrical point groups of Eu(hfa)3(fBu-xantpo), Eu(hfa)3(dpepo), Sm(hfa)3(fBu-xantpo) and Sm(hfa)3(dpepo) were found to be quasi-Ci. On the other hand, those of Eu(hfa)2(xantpo)2 and Sm(hfa)2(xantpo)2 were categorized as quasi-C2 because of their two coordinated xantpo ligands. 

The ability of the coordinatively unsaturated tris(/3-diketonato)lanthanide complexes to expand their coordination sphere by adduct formation with Lewis bases is not only of importance for their application as NMR shift reagents (see section 9). This ability can also be nsed to prepare liquid stationary phases for gas chromatography, which are able to separate organic compounds on the basis of their nucleophilicity. Feibush et al. (1972) studied the retention of different alkanes, alkenes, alcohols, ketones and ethers by GC colttmns with solutions of [R(/9-diketonato)3] complexes in squalane as the stationary phase. Brooks and Sievers (1973) investigated by GC the interaction of ketones and alcohols with a stationary phase consisting of the NMR shift reagent [Eu(fod)3] in squalane. The alcohols were fotmd to form more stable complexes with [Eu(fod)3] than ketones. Picker and Sievers (1981) considered the use... 

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