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Uranium(III)-mediated C-C-Coupling of Terminal Alkynes - Formation of Dinuclear Uranium(IV/IV) Vinyl Complexes.
MedLine Citation:
PMID:  22738030     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The previously reported uranium(III) complex [((AdArO)3N)UIII(DME)]1 (1; Ad = adamantane, DME = 1,2-dimethoxyethane) reacts with the terminal bis-alkynes 1,7-octadiyne or 1,6-heptadiyne in C-C-coupling reactions to form the uranium(IV/IV) vinyl complexes [{((AdArO)3N)UIV}2(-2:1-1,2-(CH)2-cyclohexane)] (2) and [{((AdArO)3N)UIV}2(-2:2-1,2-(CH)2-cyclopentane)] (3). With the mono-alkynes 1 hexyne or 4-tbutyl-phenylacetylene, the complexes [{((AdArO)3N)UIV}2¬( 2(C1):1(C4)-2-nBu-1,3-octadiene)] (4) and [{((AdA-rO)3N)UIV}2(-2(C4):1(C1)-1,3-di-(p-tBu-phenyl)¬butadiene))] (5), are formed. These are the first four examples of vinyl complexes that are reported and crystallographically characterized. In addition, detailed DFT calcu-lations are presented, showing the mechanism of their formation and explaining the differences found for the coordination of the hydrocarbon fragments. In contrast to a previously proposed monometallic pathway for catalytic hydroamination of alkynes,2 and and alkyne dimerization, involving a uranium vinyl intermediate3 at uranium(III) complexes, the calculations clearly show that the energetically most favored pathway is a bimetallic mechanism. This mechanism can also be considered for the catalytic alkyne coupling at transition metals.
Authors:
Boris Kosog; Christos E Kefalidis; Frank W Heinemann; Laurent Maron; Karsten Meyer
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-27
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-6-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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