Reactivity, organoactinide

The Effect of Coordination Pattern and 5/Electron Configuration on Organoactinide Reactivity... 

Are 5f electrons really active in organoactinide reactivity Some insights from DFT studies, L. Castro, A. Yahia, L. Maron, ChemPhysChem 2010, 11,990. 

Studies of organoactinide surface chemistry and catalysis have been carried out by the Marks group under rigorously anhydrous/anaerobic conditions on either partially dehy-droxylated alumina (PDA) or DA at surface coverages of 0.25 0.50 molecules nm. The PDA and DA surfaces are represented schematically in equation (68). Product yields, isotopic labeling, and surface reactivity indicate that the irreversible y-alumina adsorption chemistry of Cp 2AnMe2 can be described by three methane-evolving pathways (equations 69-71). Equation (69) dominates on PDA. On DA,... 

Attempts to trap the mono(acetylide)complex Cp 2An(C=CR)(Me) were successful only for the transient species Cp 2U(C=CPr1)(Me). The bis(acetylide) complexes are active catalysts for the linear oligomerization of terminal alkynes HC=CR. The regioselectivity and the extent of oligomerization depend strongly on the alkyne substituent R, whereas the catalytic reactivities are similar for both organoactinides. Oligomerization with less bulky alkyl- and... 

Organoactinide complexes of Cp show reactivity with CO analogous to that found for the Zr system outlined above, e.g., equation (e), which proceeds in 50% isolated yield. ... 

The different catalytic reactivity found for structurally similar organoactinides, which is unprecedented in the chemistry of organoactinides, is always a driving force to studying the stoichiometric reactivity of these complexes, Cp 2AnMe2 (An = Th (1), U (2)) [55] as outlined in Schemes 3 and 4 for Th and U, respectively. 

The organoactinide complexes Cp 2AnR2 (An = Th, U R = Me, NHR R = alkyl) and the bridge complexes 3-6 were found to be excellent precatalysts for the intermolecular hydroamination of terminal aliphatic and aromatic alkynes in the presence of primary aliphatic amines to yield the corresponding imido compounds [56, 99]. The reactivity exhibited for the thorium complexes was different, depending on the alkynes, from that for organouranium complexes. 

Scheme 7 Contrasting reactivity of the different organoactinide-imido complexes in their metathesis reactions with terminal alkynes...

This two-electron oxidation/reduction catalytic process represents a novel type of reactivity for organoactinide complexes. The involvement of U(VI) species strongly argues again for the participation of the f-orbitals in the catalytic process. 

In 1978, Manriquez et al. reported [248] new bis(pentamethylcyclopenta-dienyl) derivatives of thorium and uranium, which may be considered as the most chemically reactive and versatile organoactinides prepared up to that time. Following this, a number of communications came out with the... 

Although such complexes represent potentially useful entries into organoactinide derivatives, so far there is only one report (see eq. 76) on the reactivity of the above mentioned and related actinide-pyrazolyborates with anionic organic reagents. Most of the known mixed cyclopentadienylpyrazolborate complexes, have been obtained from MCPX3 starting materials (eq. 73) (89,90). The H and in some cases... 

In the last few years the interest in application of organoactinides has experienced some decline as compared to the worldwide interest during the 1950-1960 s despite their very interesting reactivity and their possible use (mainly of U and Th) in industry. 

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