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Organoactinides Promote the Dimerization of Aldehydes: Scope, Kinetics, Thermodynamics, and Calculation Studies


Sharma, M and Andrea, T and Brookes, NJ and Yates, BF and Eisen, MS, Organoactinides Promote the Dimerization of Aldehydes: Scope, Kinetics, Thermodynamics, and Calculation Studies, Journal of the American Chemical Society, 133, (5) pp. 1341-1356. ISSN 0002-7863 (2011) [Refereed Article]

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Copyright 2011 American Chemical Society

DOI: doi:10.1021/ja105696p


Surprising catalytic activities have been found for the actinide complexes Cp*(2)ThMe(2) (1), Th(NEtMe)(4) (2), and Me(2)SiCp ''(2)Th(C(4)H(9))(2)(3) toward oxygenated substrates. During the catalytic dimerization of benzaldehydes to their corresponding esters, complexes 1 and 2 gave 65 and 85% yield in 48 h, respectively, while the geometry-constrained complex 3 gave 96% yield in 24 h. Exploring the effect of substituents on benzaldehyde, it has been found that, in general, electron-withdrawing groups facilitate the reaction. Kinetic study with complexes 1 and 3 reveals that the rate of the reaction is first order in catalyst and substrate, which suggests the rate equation "rate = k[catalyst](1)-[aldehyde](1)". The activation energy of the reaction was found to be 7.16 +/- 0.40 and 3.47 +/- 0.40 kcal/mol for complexes 1 and 3 respectively, which clearly indicates the advantage of the geometry-constrained complex. Astonishing are the reactivity of the organoactinide complexes with oxygen-containing substrates, and especially the reactivity of complex 3, toward the dimerization of substrates like p-methoxybenzaldehyde, m/p-nitrobenzaldehyde, and furanaldehyde and the reactivity toward the polymerization of terephthalaldehyde. Density functional theory mechanistic study reveals that the catalytic cycle proceeds via an initially fourcentered transition state (+6 kcal/mol), followed by the rate-determining six-centered transition state (+13.5 kcal/mol), to yield thermodynamically stable products.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Inorganic chemistry
Research Field:Organometallic chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Sharma, M (Dr Manab Sharma)
UTAS Author:Brookes, NJ (Dr Nigel Brookes)
UTAS Author:Yates, BF (Professor Brian Yates)
ID Code:72716
Year Published:2011
Web of Science® Times Cited:54
Deposited By:Chemistry
Deposited On:2011-08-31
Last Modified:2012-05-11

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