Actinide complexes amines

The hydroamination of olefins has been shown to occur by the sequence of oxidative addition, migratory insertion, and reductive elimination in only one case. Because amines are nucleophilic, pathways are available for the additions of amines to olefins and alkynes that are unavailable for the additions of HCN, silanes, and boranes. For example, hydroaminations catalyzed by late transition metals are thought to occur in many cases by nucleophilic attack on coordinated alkenes and alkynes or by nucleophilic attack on ir-allyl, iT-benzyl, or TT-arene complexes. Hydroaminations catalyzed by lanthanide and actinide complexes occur by insertion of an olefin into a metal-amide bond. Finally, hydroamination catalyzed by dP group 4 metals have been shown to occur through imido complexes. In this case, a [2+2] cycloaddition forms the C-N bond, and protonolysis of the resulting metallacycle releases the organic product. 

Aside from the subtle effect of the An-amine binding in the An-DTPA complexes of TALSPEAK, and the chloride, thiosulfate interaction with the actinides in ion-exchange studies, we have not discussed the proposal that there is of slightly greater covalency in actinide complexation (both by hydrophobic and hydrophilic ligands). In this section, the effect of binding of actinides to nitrogen and sulfur donor molecules is discussed within this model. 

A number of actinide complexes have been investigated with respect to their catalytic activity in the intermolecular hydroamination of terminal alkynes with primary ahphatic and aromatic amines [98, 206-209]. Secondary amines generally do not react and the reaction is believed to proceed via an metal-imido species similar to that of group 4 metal complexes. The reaction of Cp 2UMc2 with sterically less-demanding aliphatic amines leads exclusively to the anti-Markovnikov adduct in form of the -imine (31) [207] however, sterically more demanding amines, e.g., t-BuNH2, result in exclusive alkyne dimerization. The ferrocene-diamido uranium complex 12 (Fig. 4) catalyzes the addition of aromatic amines very efficiently (32) [98]. 

Hydrido(trialkylsilyl)silyllithiums, preparation, 3, 424 Hydroacylations, olefins, 10, 142 Hydroalkoxylations and etherification, 10, 672 in etherification, 10, 683 Hydroaluminations for C-E bond formation characteristics, 10, 857 chemoselectivity, 10, 859 mechanism, 10, 858 overview, 10, 839-870 stereoselectivity, 10, 861 total synthesis applications, 10, 865 characteristics, 3, 275 process and examples, 9, 268 via Ti(IV) complexes, 4, 658 Hydroaminations actinide-catalyzed, 4, 237 in aminations... 

Marcus, Y. Anion exchange of metal complexes. XV. Anion exchange and amine extraction of lanthanides and trivalent actinides from chloride solutions, J. Inorg. Nucl. Chem., 28, 209 (1966). 

Spectrophotometric studies were used to identify the anionic hexavalent actinide acetate complexes present in aqueous and nonaqueous solutions, anion exchange resins, and amine extracts. The previously unreported tetraacetate complexes, M02(CJd 0i),, were identified in all these systems. The formation constant for the reaction +... 

The triacetate uranyl complex (24) is structurally similar to the trinitrate uranyl complex (6) (three bidentate ligands arranged equa-torially around the uranyl O—U—O axis). It was expected that the visible, near ultraviolet spectrum of the triacetate uranyl complex would be similar to the spectrum of U02(N03)3 as are the spectra of 1102(804)3, 1102(003)3 , and other uranyl complexes which apparently have the same structure (17). The absorption spectrum of uranyl acetate extracted into tri-n-octylamine in xylene from dilute acetic acid is different from the trinitrato uranyl spectrum. This indicates that the triacetate uranyl complex is probably not the species involved. By analogy to the uranyl nitrate system 14), formation of a tetraacetate uranyl complex might be expected. The purpose of this work is to determine the nature of the anionic hexavalent actinide acetate complexes and to identify the species involved in the amine extraction and anion exchange of the hexavalent actinides from acetate systems. 

The actinide (VI) acetate system discussed here and the actinide (VI) sulfate system to be discussed later (17) represent the only cases known to us in which observable mixtures of labile anionic complexes of a given metal are extracted from an acid solution by susbtituted amines. The present system represents the only one in which the diluent is the only major factor controlling the ratio of species in the organic phase. The principle mechanism by which the nature of the diluent appears to determine the ratio of species in the organic phase in this system is by... 

Amines, hydrazines, and hydroxylamines. Amine complexes are known for tetravalent complexes of the earliest actinides (Th, U), particularly for the halides, nitrates, and oxalates. The complexes are generated either in neat amine, or by addition of amine to the parent compound in a nonaqueous solvent. Some of the known simple amine compounds are presented in Table 6. The molecular structure of ThCl4(NMe3)3 has been determined. The coordination environment about the metal is a chloride capped octahedron. A very limited number of adducts exist in which a tetravalent actinide is coordinated by a hydrazine or hydroxylamine ligand the parent compound is generally a halide or sulfate complex. Cationic metal hydrates coordinated with primary, secondary, or tertiary amines have also been isolated with acetylacetonate, nitrate, or oxalate as counterions. 

Amine N-oxides, phosphine oxides, arsine oxides, and related ligands. The prototypical system for extraction of the uranyl ion from aqueous solution into organic solvent is tributylphosphate in hydrocarbons such as kerosene. This has stimulated interest in understanding the coordination chemistry of actinyl ions with P=0 (and related) functional groups in order to optimize extraction efficiency or discrimination among actinides to be separated. Of all classes of neutral group 16-atom donor ligands, phosphine oxide adducts are the most common examples of complexes of transuranic elements (Np, Pu). 

Spectral investigations of the organic extracts of amine salts from metal chloride solutions are consistent with the extraction of tetrahedral tetrachlorometallate anions for metals such as Fe ", Cu", Zn", Cd", Co" and Mn". 4 Analysis of the metal-saturated organic phases reveals the expected ratio of aminemetalxhloride of 2 1 4 for the divalent metals and 1 1 4 for the trivalent metals. The extractability of the tetravalent actinides also follows the order of the tendency of those metals to form anionic chloro complexes, and the spectra of the organic extracts are those expected for the octahedral MClg species. ... 

This involves the use of tertiary amine extraction of the An ions from acidic 11 M LiCl solutions. Spectroscopic studies have indicated that, in the cases of Am and Nd at least, the octahedral trianionic hexachloro complexes are extracted from 11 M LiCl. Stability constant data for the chloride complexing of Am , and Cfin media of ionic strength 1,0 have been reported. Tertiary amines also extract Pu and a study of extraction from nitrate media by trilaurylamine (TLA) in xylene has been reported. " This showed that the mass transfer rate was controlled by the reactions between Pu from the bulk phase and interfacially adsorbed TLA-HNOs. The separation of individual transplutonium elements from the Tramex actinide product may be achieved using ion exchange or precipitation techniques." ... 

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