Preparation, Solution Behavior, and Solid-State Structures of (1,3-R 2 C 5 H 3 ) 2 UX 2 , Where R Is CMe 3 or SiMe 3 and X Is a One-Electron Ligand
1999; American Chemical Society; Volume: 18; Issue: 7 Linguagem: Inglês
10.1021/om9805988
ISSN1520-6041
AutoresWayne W. Lukens, Sharon M. Beshouri, Laura L. Blosch, Anthony L. Stuart, Richard A. Andersen,
Tópico(s)Synthesis and characterization of novel inorganic/organometallic compounds
ResumoHigh-yield preparations of the uranium metallocenes [1,3-(Me3Si)2C5H3]2UCl2 (Cp' '2UCl2) and [1,3-(Me3C)2C5H3]2UCl2 (Cp⧧2UCl2) have been developed from the reaction of UCl4 and the corresponding magnesocenes Cp' '2Mg and Cp⧧2Mg in diethyl ether. The chloride ligands can be exchanged with either Me3SiBr or Me3SiI to give the uranium metallocene bromides or iodides. The fluorides were prepared by the reaction of BF3·OEt2 with Cp' '2U(NMe)2, Cp⧧2U(OMe)2, or Cp⧧2UMe2. The crystal structures of Cp' '2UCl2, Cp⧧2UCl2, Cp' '2UMe2, Cp⧧2UF2, and dimeric (Cp' '2UF2)2 are reported. The idealized symmetry of the monomers Cp' '2UX2 and Cp⧧2UCl2 is C2v when X is F, Cl, or Br and C2 when X is I or Me; in the dimer, the idealized symmetry is Ci. This preference is rationalized by intramolecular and intermolecular steric effects. The solution ring conformations and intramolecular exchange processes have been studied by variable-temperature 1H NMR spectroscopy. In all cases, the low-temperature limiting spectra are consistent with the idealized symmetry observed in the solid state.
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