Structures of substituted-cyclopentadienyl uranium(III) dimers and related uranium metallocenes deduced by EXAFS
- Lawrence Berkeley Lab., CA (United States)
The crystal structures of [Cp{double_prime}{sub 2}UF]{sub 2} and [Cp{sup {double_dagger}}{sub 2}UO]{sub 2} are reported, where Cp{double_prime} is 1,3-(Me{sub 3}-Si){sub 2}C{sub 5}H{sub 3} and Cp{sup {double_dagger}} is 1,3-(Me{sub 3}C){sub 2}C{sub 5}H{sub 3}. Both complexes have idealized C{sub 2h} symmetry, and their U{hor_ellipsis}U distances are 3.85 and 3.39 {angstrom}, respectively. The X-ray absorption spectra of several uranium metallocene complexes, and the numerical results from fitting the EXAFS spectra, are reported. For [Cp{sup {double_dagger}}{sub 2}UF]{sub 2}, the U{hor_ellipsis}U distance was found by EXAFS to be similar to that in [Cp{double_prime}{sub 2}UF]{sub 2}, implying that [Cp{sup {double_dagger}}{sub 2}UF]{sub 2} is dimeric. A structural model is advanced that correlates the U{hor_ellipsis}U distance with the orientation of the cyclopentadienyl rings; the orientation is due to a subtle combination of steric repulsions between ligands on the same metal center and between ligands on adjacent metal centers.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 343702
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 7 Vol. 18; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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