Uranium pentalene

Bis(pentalene) uranium complexes, preparation, 4, 221—222 Bis(pentamethylcyclopentadienyl)actinide(IV) compounds, synthesis and reactions, 4, 210 Bis(pentamethylcyclopentadienyl)actinide(V) compounds, synthesis and reactions, 4, 210 Bis(pentamethylcyclopentadienyl)actinide(VI) compounds, synthesis and reactions, 4, 210... 

In order to reflect the order in which the research was carried out, chemistry of the Pent /Cp uranium systems will be discussed first. Pentalene is an eight-membered bicyclic carbocycle the planar dianion is a IQn Hiickel... 

The dianionic ligands COT and pentalene act as stronger electron donors for uranium than the anionic Cp Ugands, due to the additional 5-interactions, and the U(IV) compounds U(COT)2 and U(C8H4 I )2 are extremely stable under anaerobic conditions. Use of the Ugands with the lower oxidation state, U(III), would be expected to make these compounds even more electron-rich than the U(Cp )3(THF)x systems (i.e. more reducing) and, at least partly... 

This article has reviewed the synthesis and reactivity towards small molecules of a range of U(lll) cyclooctatetraene and pentalene complexes. It is evident that in many cases the uranium centre is capable of tt back-bonding through the 5/ orbitals additionally, a C - C agostic interaction between a bound substrate and a U(IV) centre has been observed. Clearly uranium is capable of bonding with a degree of covalency , and this is perhaps why the reduction chemistry of U(III) is so rich and diverse, and not simply an iteration of low-valent lanthanide chemistry. 

Cloke FGN, Hitchcock PB. Reversible binding and reduction of dinitrogen by a uranium(III) pentalene complex. J Am Chem Soc. 2002 124 9352-9353. 

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