I. A. Murav'eva

Behavior of rare-earth dipivaloylmethanates and acetylacetonates under gas chromatography conditions

Summary1.Undesirable sorption of REM dipivaloylmethanates by the packing of a GC column decreases along the series La-Lu. Other conditions being equal, sorption of dipivaloyl-methanates is lower than that of the corresponding acetylacetonates.2.A β-diketonate is sorbed chiefly by the liquid phase, and in the form of a bis-β-diketonate cation with the separation of an equivalent amount of free protonated ligand.

Synthesis and IR spectroscopic study of rare-earth tris(acetylacetonates)

ConclusionsThe various hydrate forms of the tris(acetylacetonates) of the whole series of RE have been prepared and studied by IR spectroscopy. For a given hydrate form the IR spectra in the RE series do not alter. The differences in the IR spectra of dehydrated preparations are explained by a variation in the RE series of the degree of hydrolysis of the tris(acetylacetonates) and also by the high stability of the octahedral configuration of the anhydrous tris(acetylacetonate) for the heaviest RE.

GAS CHROMATOGRAPHIC STUDY OF RARE EARTH PIVALOYLTRIFLUOROACETONATES

ConclusionsThe existence of dimeric forms of pivaloyltrifluoroacetoantes of rare earth elements in the gas and stationary liquid phases has been demonstrated by GLC. Adduct formation permits monomerization of the complexes. The stability of the adducts under GLC conditions is influenced not only by the donor number of the adduct-former but also by its volatility.

Acetylacetoniminates of rare earth element chlorides

ConclusionsComplexes of anhydrous REE chlorides with acetylacetone imine have been synthesized and studied by a variety of physical chemical methods. They have been found to have non-chelate structures. It has also been demonstrated that the composition, structure, and properties of the isolated products, such as their solubility, for instance, vary systematically across the REE series.

Solid phase synthesis and study of complexes of rare earth element chlorides with acetylacetone imine

ConclusionsAnyhdrous complexes of REE chlorides with acetylacetone imine have been prepared by solid phase synthesis starting from REE chloride hydrates; the composition and structure of these complexes have been investigated and conclusions concerning the change in the structures of these complexes in the series of REE have been drawn and interpreted.

Influence of alkyl phosphates on the behavior of the dipivaloylmethanates of the rare-earth metals in the yttrium subgroup during gas chromatography

ConclusionsThe influence of the additional ligands of moderate donor strength on the Chromatographic characteristics of the dipivaloylmethanates of the rare-earth elements in the yttrium subgroup is consistent with the hypothesis that adducts of the tris-dipivaloylmethanates of lutetium, holmium, and ytterbium with trialkyl phosphates form and decomose in the GC column.

Gas chromatography of adducts of ree dipivaloylmethanates with triphenylphosphine oxide

ConclusionsA gas Chromatographic method for the determination of the conditional stability constants of adducts of rare-earth element dipivaloylmethanates with triphenylphosphine oxide was proposed, and it was shown that the stability of the ML3·TPPO adducts decreases in the series from Ho to Lu.It was shown that chromatography of ML3 in the presence of TPPO increases the separation coefficients of different rare earth elements.

Influence of trihexyl phosphate on the behavior of the dipivaloylmethanates of holmium, ytterbium, and lutetium during gas chromatography

Conclusions1.The retention times of the chelates ML3 chromatographed in the presence of THP differ significantly from the retention times for the individual ML3, as a consequence of the formation of the adducts ML3·THP.2.Adduct formation increases the difference between the retention times of the complexes of different rare-earth metals, creating prospects for the use of THP as an addition for the gas chromatography of rare-earth dipivaloylmethanates.

Production of volatile trisacetylacetonates of rare-earth elements by heating their hydrates

ConclusionsThe heating of the hydrates of the trisacetylacetonates of heavy rare-earth elements under vacuum in an atmosphere saturated with dry acetylacetone vapor leads to the sublimation of the anhydrous acetylacetonates and, in a number of cases, their hydrated or hydrolyzed forms. The light rare-earth elements do not form compounds which sublime under these conditions. In the series of rare-earth elements of the yttrium subgroup the yield of the sublimate, which is insignificant for dysprosium, increases to 100% in lutetium and ytterbium.

Effect of adduct formation on the valence state of cerium in its β-diketonates

Conclusions1.Physicochemical investigation of the cerium(III, IV)-β-diketone-additional ligand system showed that the capacity ofβ-diketonates for adduct formation decreases in the order thenoyltrifluoroacetonate > acetylacetonate > dibenzoylmethanide > benzoylacetonate.2.Adduct formation in the cerium(III, IV)β-diketonates stabilizes the cerium in the trivalent state, whereas the degree of oxidation of 4+ is stable in the tetrakis-β-diketonates.3.According to the effect on the stabilization of cerium(III) in itsβ -diketonates the additional ligands can be arranged in the following order: tributyl phosphate < trioctylphosphine oxide < triphenylphosphine oxide