Actinide alkoxides

Actinide Alkoxides and Other O-Containing Complexes and Salts... 

Table 5.11 Preparation of Actinide Alkoxides and Related O-Containing Complexes...

Some actinide alkoxide complexes can exist in equilibrium, for example, the homoleptic complex Th2(OCH-/-Pr2)8, obtained from a metallacyclic precursor after treatment with HOCH-/-Pr2 (5.50) ... 

Actinide hydrides are rather hydridic and nndergo rapid reactions typical of snch systems for example, reactions with ketones and halocarbons provide actinide alkoxides and halides, respectively. Rapid qnantitative addition of terminal alkenes (the reverse of /S-hydride elimination) is consistent with the known bond disruption enthalpies (eqnation 66). ... 

Various cyclopentadienyl-ligated early metal and actinide alkoxides were prepared by reactions of the alcohols with the metal hydride precursors to eliminate hydrogen gas,266,275,277,278 g j.jy metal alkoxides, as well as their high-valent late-metal analogs, can also be formed by attack of an alkyl group at an oxo ligand, where the alkyl could be added as a carbocation, a radical, or a carbanion (Equation 4.59). ... 

Straightforward metathesis chemistry can be used to prepare bis(penta-methylcyclopentadienyl)actinide alkoxides, amides, and bidentate [106] pyrazo-lates (pz ) [106-108] ... 

Two additional problems in understanding heterogeneous catalytic CO reduction concern the means by which MrO bonds are cleaved to produce alcohols and the fate of the metal oxides once formed. In regard to the former issue, most metal alkoxides (including those of actinides) readily undergo protolysis to form alcohols (97) (eq.(31)). The source of the protons could be... 

Metallotropic rearrangement, in mercury tri-azenide complexes, 30 41 Metals, see also Heterobimetallics specific element Transition metal complex alkoxides, 15 159-297 of actinides, 15 290-293 of alkali metals, 15 260-263 of alkaline earths, 15 264-266 of aluminium, 15 266-272 of beryllium, 15 264-266 double type, 15 293-294 of gallium, 15 266-272 of lanthanides, 15 290-293 of magnesium, 15 264-266 properties of, 15 260 of transition metals, 15 272-290 trialkylsilyloxides, 15 295-297 of zinc, 15 264-266... 

The alkoxides of actinides are rarely studied except the derivatives of uranium and thorium, as interest in the alkoxides of these 2 elements has increased by the hope to use them in the isotope-separation processes. The study of uranium alkoxides was initiated by groups led by Gilman and Bradley in the 1950s. The major part of this work is still carried out at the Nuclear Research Center at Los Alamos in the United States by the group of Sattelberger et al. [1671]. The detailed data on alkoxides ofuranium is provided in a number of... 

As with the case of the trivalent actinides, the tren, trisamidoamine (NNj), ligand has been used to stabilize An complexes. The preparation of [An(NN) )C1]2 is accomplished by the reaction of the trilithium salt of NNj with AnCLt (An = Th, U). The chloride ligand can be exchanged using metathetical reactions to form AnlTSINjlX (X = Br, I, NR2, OR). Anionic complexes, An(NN))XX (X = OR, X = OR ) can also be formed by addition of alkoxide salts to the neutral species. Complexes of Arf with diamidoamine ligands have also been studied. ... 

The actinides have a high degree of specificity for neutral and anionic oxygen-containing organic molecules. The actinide complexes with O -donor ligands that are most widely studied include alkoxides, aryloxides amide, carboxylates, and oxalates. Complexes with alcohols, ethers, esters, ketones, aldehydes, ketoenolates, and carbamates have also been reported. 

Alkoxide and aryloxide ligands are excellent ligands for the actinides. As a result, these ligands have been studied extensively in the coordination chemistry and reactivity of tri-, tetra-, penta-, and hexavalent actinides. The alkoxides and aryloxides can be synthesized by a variety of routes the two most popular routes include direct reaction of actinide halides with alkali metal salts of the alkoxide or aryloxide of interest and protonolysis of actinide amides by alcohols. 

It is important to note that efforts to synthesize metal alkoxides and aryloxides (particularly lanthanide and actinide complexes) have sometimes produced unexpected products, incorporating halide or oxide ligands, for example. As a result, some early literature may contain incorrect formulations. ... 

Only one study has suggested the formation of an actinide(IID alkoxide (-OR) compound in which R is an alkyl. A recent investigation of the reactivity of Pu wo-propoxide, prepared in situ from the reaction of Pu[N(SiMe3)2]3 and three equivalents HOPr , indicates that the trivalent alkoxide complex is an effective catalyst in the Meerwein-Ponndorf-Verley reduction of ketones by isopropanol. ... 

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