Cyclopentadienyl complexes actinide

An approach other than steric hindrance has been used to overcome the previously mentioned instability of the actinide homoalkyls. It was found that the inclusion of jT-bonding ligands in the coordination sphere considerably enhanced the stability of the alkyl complex. Recently, the same line of reasoning has also yielded a new series of 7r-cyclopentadienyl lanthanide alkyls (C5H5)2LnR where Ln =Gd, Er, Yb and R = C=C, and CH3 120,121). The infrared data for these complexes are consistent with u-bonded structures and the room temperature magnetic susceptibilities are very close to the free ion values. The actinide complexes (75,... 

Pentalenediyl compounds, cyclopentadienyl actinide complexes, 4, 221 Pentalenes... 

Tebakis(cyclopentadienyl) actinide complexes, ( 5115)4An, were among the earliest organoactinide complexes synthesized and can be prepared by metathesis see Metathesis) of the anhydrous tetrachlorides (AnCLi) with potassium cyclopentadieitide (KCp) in refluxing benzene (equation 1, for An = Th, U, and Np). Another member of this series, Cp4Pa,... 

Tris(cyclopentadienyl) actinide complexes are strong Lewis acids and form adducts with a wide variety of Lewis bases. Many routes exist for their preparation, but a fairly general route to the THF adducts is via reduction of Cp3 And (An = Th, U, Np) in THF solution (equation 18). By introducing bulky substituents on the Cp ring, Andersen was... 

Several general review articles [19-41] dealing mostly with the synthesis of new actinide complexes confirm the broad and rapidly expanding scope of this field. Those reviews dealt with the structure, stability, and reactivates of complexes with cyclopentadienyl, dienyls (pentadienyl, cyclohexadienyl, indenyl, phospholyl), cyclooctatetraenyl, arene ligands, hydrocarbyls, and hydrides ligands. 

In this particular review we will provide an overview of the preparation and properties of the major classes of actinide complexes containing different cyclopentadienyl ligands. Discussions are classified on the basis of formal oxidation states and we are confining our discussions only to the oxidation... 

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]. 

Similar to the tris(cyclopentadienyl)actinides, bis(cyclopentadienyl)actin-ide complexes also undergo insertion reaction of various imsaturated substrates such as CO, CNR, CO2, and CS2 into U-C, U-Si, U-N, and U-S bonds [221,249,265,273,284] and commonly have ti -C(R) = E types of bonding and might exists with a carbene-like structure [288] ... 

Working with the tri-substituted cyclopentadienyl ligand, 1,2,4-trimethyl-silylcyclopentadienyl, Edelman and coworker [301] reported the first mono tns-substituted actinide complex [U ri -C5H2(SiMe3)3-l,2,4 Cl2(THF) ( x-Cl)2Li(THF)2] and found to have an approximately octahedral environment around the U center, with four equatorial Cl ligands, trans-axial sub-... 

This is a special volume of Inorganic Syntheses that focuses on complexes that are likely to be useful as starting materials for the preparations of new transition metal coordination and organometallic compounds. There are chapters on complexes with weakly coordinated and therefore easily displaced ligands, low-valent complexes that undergo oxidative-addition reactions, substituted metal carbonyl complexes, nucleophilic metal carbonyl anions, transition metal clusters, a variety of cyclopentadienyl complexes, lanthanide and actinide complexes, and a range of other useful ligands and complexes. 

An unprecedented cyclic structure was found in a rare example of an organo-actinide complex associated via 7r-interactions. The reaction of ThBr4(thf)4 in THF with one equivalent of cyclopentadienyl thallium followed by treatment with three equivalents of KOPr led to the formation of the highly unusual hexanuclear complex [(C5H5)Th2(OPr )v]3, 106 [102]. In the cyclic molecule three dinuclear Th2(OPr )v units are connected by bridging cyclopentadienyl ligands. The... 

The second review is due to Pepper and Bursten (1991). This review focussed on the electronic structure of actinide-containing molecules. Note that the present chapter complements this in that our chapter is mostly on lanthanide-containing species. Consequently, the reader is referred to the excellent review by Pepper and Bursten (1991) for a comprehensive summary of the electronic structure of actinide-containing species. The review by Pepper and Bursten (1991) contains the details of calculations on actinide hydrides, actinide halides, actinide oxides, cyclopentadienyl-actinide complexes, aetinocenes, metal-metal bonding in actinide systems and miscellaneous other actinide systems. This review also consists of descriptions of theoretical techniques employed to study the actinide-containing molecules. The reader is directed to this review for further details on such calculations on actinide-containing molecules. 

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