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Interaction of rhodium(I) bisphosphine complexes with semicarbazones to give orthometallated rhodium(III) complexes

TitleInteraction of rhodium(I) bisphosphine complexes with semicarbazones to give orthometallated rhodium(III) complexes
Publication TypeJournal Article
Year of Publication2003
AuthorsEzhova, MB, Patrick, BO, James, BR, Ford, ME, Waller, EJ
JournalRussian Chemical Bulletin
Volume52
Pagination2707-2714
Date PublishedDec
Type of ArticleProceedings Paper
ISBN Number1066-5285
KeywordsACTIVATION, ASYMMETRIC HYDROGENATION, BENZALDEHYDE SEMICARBAZONE, C-H, C-H BONDS, CATALYTIC-HYDROGENATION, COMPLEXES, CRYSTAL-STRUCTURE, FINE CHEMICALS, INTRAMOLECULAR ACTIVATION, molecular structure, orthometallation, phosphines, rhodium, SELECTIVE HYDROGENATION, semicarbazones, SYNTHESIS, TRANSITION-METAL-COMPLEXES, UNPRECEDENTED CHEMICAL TRANSFORMATION
Abstract

Interaction of the cis-[Rh(PR3)(2)(Solv)(2)]PF6 complexes (R = Ar or R-3 = Ph2Me, Solv solvent) under Ar with semicarbazones bearing a phenyl group on the imine-C atom gives the rhodium(III)-hydrido-bis(phosphine)-orthometallated semicarbazone species [RhH(PR3)(2){(o-C6H4(R’)C=N-N(H)CONH2}]PF6 (R’ = Me or Et), which are characterized generally by elemental analysis, P-31{H-1} and H-1 NMR spectroscopy, and mass-spectrometry. The PPh3-containing complex with R’ = Me, structurally characterized by X-ray analysis, reveals coordination of the semicarbazone by the ortho-C atom, the imine-N atom, and the amide-carbonyl group. For a semicarbazone containing no Ph group, the rhodium(I) complex [Rh(PR3)(2)(Et(Me)C=N-N(H)CONH2)]PF6, containing the eta(2)-semicarbazone bonded via the imine-N and carbonyl, is formed. Attempts to hydrogenate the C=N moiety in the complexes or to catalytically hydrogenate the semicarbazones were unsuccessful.

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