Synthesis and Properties of a New Class of Highly Reactive Trivalent Actinide Organometallic Compounds. Derivatives of Bis(pentamethylcyclopentadienyl)uranium(III)

Paul J. Fagan, Juan M. Manriquez, Tobin J. Marks*, Cynthia S. Day, Victor W. Day, Sara H. Vollmer, Victor W. Day

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

163 Scopus citations


Hydrogenolysis of the uranium(IV) alkyl complexes U[η6-(CH3)5C6]2(R)C1 results in clean reduction to the uranium(III) complex {U[η5-(CH3)5C5]2(η-Cl)}3, which has been structurally characterized by single-crystal X-ray diffraction. This molecule crystallizes in the monoclinic space group C2/c—C2h6 (No. 15) with four molecules in a unit cell of dimensions a = 21.886 (7) Å, b = 14.236 (5) Å, c = 24.517 (7) Å, and β = 128.65 (2)∘. Least-squares refinement led to a value for the conventional R index (on F) of 0.042 for 6813 independent reflections having 2θMoKᾱ < 65.2° and I > 3σ (I). The molecular structure consists of approximately D3h trimers with pseudotetiahedral U[η5-(CH3)5C5]2 units connected by bridging chloride ligands. The average U-C distance is 2.768 (11) Å, and the average U-Cl, 2.900 (2) Å. The average Cl-U-Cl angle is 83.8 (1)∘. The trimer reacts with Lewis bases to form adducts U[η5-(CH3)6C5]2C1·L, where L = THF, pyridine, P(CH3)3, and (C2H5)2O. Stable, monomeric uranium(III) alkyl and amide complexes, U[η5-(CH3)5C5]2CH[Si(CH3)3]2 and U[η5-(CH3)5C5]2N[Si(CH3)3]2 can be prepared by the reaction of the chloride trimer with LiCH[Si(CH3)3]2 and NaN[Si(CH3)3]2, respectively. Reaction of unsaturated organic molecules with {U[η5-(CH3)5C5]2(μ-Cl)}3 results in an interesting “disproportionation” reaction in which the trimer formally donates 1.5 equiv each of U[η5-(CH3)6C5]2 and U[η5-(CH3)6C5]2Cl2. In particular, the reaction of diphenylacetylene, tetraphenylcyclopentadienone, and 9,10-phenanthrenequinone produces, respectively, [formula omitted] U[η5-(CH3)5C5]22-COC4(C6H5)4], and {U[η5-(CH3)5C5]2[9,10-phenanthrenequinonate]}x with an equivalent amount of U[η5-(CH3)5C5]2Cl2 formed in each case. The reduction of U[η5-(CH3)5C5]2Cl2 has been accomplished with sodium amalgam and, after workup, yields the complex U[η5-(CH3)5C5]2Cl2Na·(THF)x. Sodium amalgam reduction of U[η5-(CH3)5C5]2Cl2 in the presence of diphenylacetylene produces the uranotetraphenylcyclopentadiene complex in good yield. Overall, the organometallic chemistry of U(III) has distinct similarities to that of Ti(III), as well as to that of lanthanides in the +3 oxidation state.

Original languageEnglish (US)
Pages (from-to)170-180
Number of pages11
Issue number1
StatePublished - 1982

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry


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