Synthesis and Reactivity of Actinide Complexes

The rapid growth of the organoactinide chemistry is intimately coupled with the use of the jr-coordinating cyclopentadienyl (Cp) or modified Cp ligands. Since the first report of the complex (CpjaUCl by Wilkinson [2], followed by Fischer s report of cyclopentadienyl compound of U and Th [42], a plethora of Cp actinide complexes have been synthesized. The most interesting part of this chemistry is that it is possible to coordinate one, two, three, or four Cp ligands in an j -coordination mode [43-48] and that it has the ability to stabilize a wide variety of oxidation states and coordination environments [3]. 

Among the bis-, tris- or tetrakis-Cp complexes, a overwhelming number of homoleptic tris-Cp (or modified Cp) complexes of the type (T] -C5H5)3An 

A number of synthetic routes have been reported to generate these species and their tetrahydrofuran (THF) adducts, including direct metathesis with alkali metal salts [50,52-55], or transmetallation with Be(T) -C5H5)2 or Mg(ri -C5Hs)2 [56-62]. In addition, the trivalent compounds may be obtained from chemical [53] or photochemical [63,64] reduction of suitable tetravalent actinide precursors [51,65-67]. Examples of these preparations are given in Eqs. 2-5  

Le Marechal and coworkers [68] showed a new method for the preparation of Cp3U(THE) by the treatment of CP3UCI with sodium amalgam, Na/Hg, in the presence of 18-crown-6-ether and NaH (Eq. 6)  

They also reported the successful synthesis of [Cp3UCl][Na(18-crown-6)], and [(Cp3U)2( x-H)] [Na(THF)2] (Cp = ti -CsHs) by following the same procedure. 

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