Preparation, solution behavior, and solid-state structures of (1,3-R{sub 2}C{sub 5}H{sub 3}){sub 2}UX{sub 2}, where R is CMe{sub 3} or SiMe{sub 3} and X is a one-electron ligand
- Lawrence Berkeley Lab., CA (United States)
High-yield preparations of the uranium metallocenes [1,3-(Me{sub 3}Si){sub 2}C{sub 5}H{sub 3}]{sub 2}UCL{sub 2}(Cp{double_prime}{sub 2}UCL{sub 2}) and [1,3-(Me{sub 3}C){sub 2}C{sub 5}H{sub 3}]{sub 2}UCL{sub 2} (Cp{sup {double_dagger}}{sub 2}UCL{sub 2}) have been developed from the reaction of UCl{sub 4} and the corresponding magnesocenes Cp{double_prime}{sub 2}Mg and Cp{sup {double_dagger}}{sub 2}Mg in diethyl ether. The chloride ligands can be exchanged with either Me{sub 3}SiBr or Me{sub 3}SiI to give the uranium metallocene bromides or iodides. The fluorides were prepared by the reaction of BF{sub 3}{center_dot}OEt{sub 2} with Cp{double_prime}{sub 2}U(NMe){sub 2}, Cp{sup {double_dagger}}{sub 2}U(OMe){sub 2}, or Cp{sup {double_dagger}}{sub 2}UMe{sub 2}. The crystal structures of Cp{double_prime}{sub 2}UCl{sub 2}, Cp{sup {double_dagger}}{sub 2}UCl{sub 2}, Cp{double_prime}{sub 2}UMe{sub 2}, Cp{sup {double_dagger}}{sub 2}UF{sub 2}, and dimeric (Cp{double_prime}{sub 2}UF{sub 2}){sub 2} are reported. The idealized symmetry of the monomers Cp{double_prime}{sub 2}UX{sub 2} and Cp{sup {double_dagger}}{sub 2}UCl{sub 2} is C{sub 2{nu}} when X is F, Cl, or Br and C{sub 2} when X is I or Me; in the dimer, the idealized symmetry is C{sub i}. This preference is rationalized by intramolecular and intermolecular steric effects. The solution ring conformations and intramolecular exchange processes have been studied by variable-temperature {sup 1}H NMR spectroscopy. In all cases, the low-temperature limiting spectra are consistent with the idealized symmetry observed in the solid state.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States); USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 343700
- Journal Information:
- Organometallics, Vol. 18, Issue 7; Other Information: PBD: 29 Mar 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Solution structure and behavior of dimeric uranium(III) metallocene halides
Expanding the Chemistry of Actinide Metallocene Bromides. Synthesis, Properties and Molecular Structures of the Tetravalent and Trivalent Uranium Bromide Complexes: (C5Me4R)2UBr2, (C5Me4R)2U(O-2,6-iPr2C6H3)(Br), and [K(THF)][(C5Me4R)2UBr2] (R = Me, Et)