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Actinide Elements 235

5
TABLE XIV (continued) of (η − C 5 H 5 ) 3 AnL complexes have been structurally
5
characterized. (η − C 5 H 5 ) 3 UCl and other organometal-
Type Compound a Color
lic compounds of the 5 f elements show a greater degree
5 ∗
(η − C 5 Me 5 ) 2 AnR 2 Cp U(CH 3 ) 2 Orange of covalency than their lanthanide analogues.
2
∗ White The reaction of actinide tetrachlorides (thorium through
Cp Th(CH 3 ) 2
2
Cp U(CH 3 )Cl Red-orange plutonium) with the potassium salt of cyclo-octatetraene
∗
2
∗
Cp Th(CH 3 )Cl White (COT) results in the formation of “actocene” complexes,
2 8
∗ Orange (η − C 8 H 8 ) 2 An, named by analogy with ferrocene. All
Cp U[CH 2 Si(CH 3 ) 3 ] 2
2
∗ White these compounds have a sandwich structure in which two
Cp Th[CH 2 Si(CH 3 ) 3 ] 2
2
Cp U[CH 2 Si(CH 3 ) 3 ]Cl Red planar COT rings enclose a metal atom.
∗
2
Cp Th[CH 2 Si(CH 3 ) 3 ]Cl White In the search for catalytically active species, heterobi-
∗
2
∗ Brown and polynuclear molecules containing both U(III) and a
Cp U[CH 2 C(CH 3 ) 3 ] 2
2
∗ White transition metal (palladium, platinum, rhodium, or ruthe-
Cp Th[CH 2 C(CH 3 ) 3 ] 2
2
∗ Black nium) strongly bonded in close proximity but without a
Cp U(CH 2 C 6 H 5 ) 2
2
∗
Cp U(CH 2 C 6 H 5 )Cl Black direct metal–metal bond were synthesized. Difunctional
2
∗ White bridging ligands like cyclopentadienylphosphido ligands
Cp Th(CH 2 C 6 H 5 ) 2
2
∗
Cp Th(CH 2 C 6 H 5 )Cl White were used to form such complexes.
2
∗ Orange-brown Only recently were the actinide containing metallo-
Cp U(C 6 H 5 ) 2
2 fullerenes Am@C 82 , Np@C 82 , and U@C 82 , which consist
∗ White
Cp Th(C 6 H 5 ) 2
2 of actinide atoms being encapsulated into the carbon cage
∗
Cp Th(C 6 H 5 )Cl White
2
∗
Cp U[C 4 (C 6 H 5 ) 4 ] Brown of fullerene compounds, prepared and characterized.
2
∗ White
Cp Th(CH 2 CH 3 ) 2
2
8
(η − C 8 H 8 ) 2 An COT 2 Th Yellow
SEE ALSO THE FOLLOWING ARTICLES
COT 2 U Green
COT 2 Np Yellow-red
CRYSTALLOGRAPHY • NUCLEAR CHEMISTRY • RADIO-
COT 2 Pu Red
ACTIVITY • URANIUM
a Cp, cyclopentadienyl; Cp*, pentamethylcyclopentadienyl; COT,
cyclooctatetraenyl.
BIBLIOGRAPHY
actinide compounds has been found to be a sensitive func- Bagnall, K. W. (1972). “The Actinide Elements,” Am. Elsevier, New
tion of the metal’s coligands, and these compounds react York.
readily with alkyllithium and Grignard reagents to give Choppin, G. R., and Rydberg, J. (1980). “Nuclear Chemistry—Theory
and Applications,” Pergamon, Oxford.
σ-bonded carbon compounds. The resulting alkyl com-
Cotton, F. A., and Wilkinson, G. (1999). “Advanced Inorganic Chem-
pounds are highly reactive and extremely air and moisture istry,” 6th ed., Wiley, New York.
sensitive. Hydrogenolysis yields organoactinide hydrides. Edelstein, N. M., ed. (1980). “Lanthanide and Actinide Chemistry and
The dihydrocarbyls react with carbon monoxide to form Spectroscopy,” Am. Chem. Soc., Washington, DC.
metal–oxygen and carbon–carbon double bonds, reactions Edelstein, N. M., ed. (1982). “Actinides in Perspective,” Pergamon,
Oxford.
which are of interest in catalysis.
Freeman, A. J., and Darby, J. B., Jr., eds. (1974). “The Actinides: Elec-
Some representative organoactinide compounds are tronic Structure and Related Properties,” Vols. 1 and 2, Academic
5
given in Table XIV. (η − C 5 H 5 ) 2 AnCl 2 compounds are Press, New York.
5
unstable. These compounds disproportionate to (η − Freeman, A. J., and Lander, G. H. (1984, 1985, 1987). “Handbook on
5
C 5 H 5 ) 3 AnCl and (η − C 5 H 5 )AnCl 3 . Compounds of the Physics and Chemistry of the Actinides,” Vols. 1, 2, and 5, North-
Holland, Amsterdam.
5
type (η − C 5 H 5 ) 2 AnX 2 have been prepared either by
“Gmelin Handbook of Inorganic Chemistry,” Supplement Vol. on
placing the cyclopentadienyl ligands on the metal last Thorium: AIa(1990), A2(1986), A3(1988), A4(1989), A5(1990),
or by using charged multidentate acetyl acetonate, di- C3(1987), C5(1986), C7(1988), D1(1988), D2(1985), D3(1990),
hydrobis(pyrazolyl) borate, or hydrotris(pyrazolyl) bo- E(1985); Supplement Vol. on Uranium: B2(1989), C5(1986),
5
rate ligands to stabilize the (η − C 5 H 5 ) 2 AnX 2 configu- C12(197). Springer-Verlag, Berlin.
Greenwood, N. N., and Earnshaw, A. (1998). “Chemistry of the Ele-
ration. Trivalent triscyclopentadienyl compounds of the
ments,” 2nd ed., Butterworth-Heinemann, Oxford.
actinides can be prepared starting from AnCl 3 . These Gschneidner, K. A., Jr., Eyring, L., Choppin, G. R., and Lander, G.
compounds readily form adducts, and a large number H., eds. (1994). “Handbook on the Physics and Chemistry of Rare