Source:http://linkedlifedata.com/resource/pubmed/id/18842037
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| Predicate | Object |
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| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
21
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| pubmed:dateCreated |
2008-10-28
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| pubmed:abstractText |
To probe the correlation of unusual (C5Me5)(1-) reactivity with steric crowding in complexes such as (C5Me5)3UMe and (C5Me5)3UCl, slightly less crowded (C5Me5)2(C5Me4H)UX analogues (X = Me, Cl) were synthesized and their reactivity was evaluated. The utility of the cationic precursors [(C5Me5)2UMe](1+), 1, and [(C5Me5)2UCl](1+), 2, in the synthesis of (C5Me5)2(C5Me4H)UMe, 3, and (C5Me5)2(C5Me4H)UCl, 4, was also explored. Since the use of precursor [(C5Me5)2UMe][MeBPh3], 1a, is complicated by the equilibrium between 1a and (C5Me5)2UMe2/BPh3, the reactivity of [(C5Me5)2UMe(OTf)]2, 1b, (OTf = O3SCF3) prepared from (C5Me5)2UMe2 and AgOTf, was also studied. Both 1a and 1b react with KC5Me4H to form 3. Complex 4 readily forms by addition of KC5Me4H to [(C5Me5)2UCl][MeBPh3], generated in situ from (C5Me5)2UMeCl and BPh3. Complex 1b was preferred to 1a for the synthesis of (C5Me5)2(C5H5)UMe, 5, and (C5Me5)2UMe[CH(SiMe3)2], 6, from KC5H5 and LiCH(SiMe3)2, respectively. Complex 6 is the first example of a mixed alkyl uranium metallocene complex. Sterically induced reduction (SIR) reactivity was not observed with 3-6 although the methyl displacements from the (C5Me5)(1-) ring plane for 3 are the closest observed to date to those of SIR-active complexes. The (1)H NMR spectra of 3 and 4 are unusual in that all of the (C5Me4H)(1-) methyl groups are inequivalent. This structural rigidity is consistent with density-functional theory calculations.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Nov
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| pubmed:issn |
1520-510X
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| pubmed:author | |
| pubmed:issnType |
Electronic
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| pubmed:day |
3
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| pubmed:volume |
47
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
10169-76
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| pubmed:year |
2008
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| pubmed:articleTitle |
Synthesis of (C5Me5)2(C5Me4H)UMe, (C5Me5)2(C5H5)UMe, and (C5Me5)2UMe[CH(SiMe3)2] from cationic metallocenes for the evaluation of sterically induced reduction.
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| pubmed:affiliation |
Department of Chemistry, University of California, Irvine, California 92697-2025, USA. wevans@uci.edu
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| pubmed:publicationType |
Journal Article
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