Uranium complexes electron-transfer reactions

Another most interesting and unusual result has been reported regarding the formation of an U(III) oxide complex, [(Cp )2U]2( x-0) (Fig. 5) obtained by the (r] -C5Me5)3U reduction system (Scheme 4) [107]. This has been claimed to be the first molecular trivalent uranium oxide so far reported. The complex was isolated from a reaction of (r -C5Me5)3U with KCg in toluene. Probably this is the first example of an SIR process in which the CsMes" reduction precedes the U(III) electron transfer. 

The reduction of uranyl ion by titanium(m) has been investigated in various solvents. In acetonitrile or DMF, at ambient temperature, there is a rapid reaction involving the chloro-complexes of the reductant and the complexed uranyl ion to yield TiOCla and UCls , whereas in acetone or (BuO)bPO the uranium product is UCU". The uncharged UCI5 complex predominates in methanol. The mechanism of the reaction is however attributed to direct electron- and oxygen-atom-transfer between the inner co-ordination spheres of the titanium(in) and uranium. 

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