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Zaragoza, Spain

Di Giuseppe A.,University of Zaragoza | Castarlenas R.,University of Zaragoza | Castarlenas R.,ARAID Foundation Researcher | Oro L.A.,University of Zaragoza | Oro L.A.,King Fahd University of Petroleum and Minerals
Comptes Rendus Chimie | Year: 2015

The purpose of this review is to analyze the different reaction mechanisms of the H/D exchange on organic substrates catalyzed by transition metal complexes in homogeneous phase. The metal-catalyzed H/D exchange is a multifaceted reaction whose mechanism depends strongly on the reaction conditions and on the metal complex used as a catalyst. It is possible to group the different mechanisms into three main families depending on the "role" and behavior of the catalyst: (i) Lewis acid-base catalysis; (ii) C. H activation (iii) insertion/β-elimination. For each macro-group, several representative examples are discussed and critically evaluated in order to provide the reader with keys to the understanding of how the different catalytic systems act and how their modification may affect their performance in terms of activity and selectivity. This knowledge is fundamental for designing improved organometallic H/D catalysts for labeling organic products in greener conditions with more cost-effective processes. © 2015 Académie des sciences.

Di Giuseppe A.,University of Zaragoza | Castarlenas R.,University of Zaragoza | Castarlenas R.,ARAID Foundation Researcher | Perez-Torrente J.J.,University of Zaragoza | And 3 more authors.
Chemistry - A European Journal | Year: 2014

A series of neutral and cationic RhIII-hydride and Rh III-ethyl complexes bearing a NHC ligand has been synthesized and evaluated as catalyst precursors for H/D exchange of styrene using CD 3OD as a deuterium source. Various ligands have been examined in order to understand how the stereoelectronic properties can modulate the catalytic activity. Most of these complexes proved to be very active and selective in the vinylic H/D exchange, without deuteration at the aromatic positions, displaying very high selectivity toward the positions. In particular, the cationic complex [RhClH(CH3CN)3(IPr)]CF 3SO3 showed excellent catalytic activity, reaching the maximum attainable degree of vinylic deuteration in only 20 min. By modulation of the catalyst structure, we obtained improved α/β selectivity. Thus, the catalyst [RhClH(κ2-O,N-C9H 6NO)(SIPr)], bearing an 8-quinolinolate ligand and a bulky and strongly electron-donating SIPr as the NHC, showed total selectivity for the β-vinylic positions. This systematic study has shown that increased electron density and steric demand at the metal center can improve both the catalytic activity and selectivity. Complexes bearing ligands with very high steric hindrance, however, proved to be inactive. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Azpiroz R.,University of Zaragoza | Rubio-Perez L.,University of Zaragoza | Castarlenas R.,University of Zaragoza | Castarlenas R.,ARAID Foundation Researcher | And 3 more authors.
ChemCatChem | Year: 2014

The gem-selective cross-dimerization and -trimerization of silylacetylenes with alkynes through C-H activation using a rhodium(I)-pyridine-N-heterocyclic carbene catalyst have been developed. This reaction is applied to various aliphatic or aromatic terminal alkynes, internal alkynes, and gem-1,3-disubsituted enynes to afford the corresponding enynes and dienynes with high regio- and stereoselectivities and in good isolated yields (up to 91%). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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