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Synthesis and structure of dimeric Rh-bis(tertiary phosphine) complexes, exceptionally useful synthetic precursors

TitleSynthesis and structure of dimeric Rh-bis(tertiary phosphine) complexes, exceptionally useful synthetic precursors
Publication TypeJournal Article
Year of Publication2002
AuthorsMarcazzan, P, Ezhova, MB, Patrick, BO, James, BR
JournalComptes Rendus Chimie
Volume5
Pagination373-378
Date PublishedMay
Type of ArticleArticle
ISBN Number1631-0748
Keywordsarene complexes, CATIONIC RHODIUM COMPLEXES, EXCHANGE, imines, LIGANDS, METAL-COMPLEXES, OLEFINS, PHOSPHINE COMPLEXES, Rh complexes, SELECTIVE HYDROGENATION, X-ray structures
Abstract

Removal of the MeOH and hydrogen from the known cis, trans, cis-Rh-111-dihydrido complexes [Rh(H)(2)(PR3)(2)(MeOH)(2)]PF6 (R= Ph, p-tolyl) results in formation of the dimeric species [Rh-2(PR3)(4)][PF6](2); X-ray analysis shows the complexes to be [(Ph3P)Rh(mu-PhPPh2)](2)(PF6](2) (and the p-tolyl analogue) containing bridged eta(6)-arene moieties, while H-1 and C-13 NMR data in CD2Cl2 provide evidence for Teta(4)-coordination of the arene within the dimer. In more strongly coordinating solvents, formation of cis-{Rh(PR3)(2)(solvent)(2)}PF6 is observed, while formation of [(PR3)(2)Rh(eta(6)-toluene)]PF6 is evident in toluene solution, and this exists in equilibrium with the bis(solvent) species in the presence, for example, of acetone or MeOH. At ambient conditions, none of the arene-containing complexes effected catalytic H-2-hydrogenation of toluene.

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