Palladacyclopentadiene complexes with mono- and didentate imidato ligands: Synthesis, hemilabile behaviour and catalytic application in the Stille reaction

J L Serrano, I J S Fairlamb, G Sanchez, L Garcia, J Perez, J Vives, G Lopez, C M Crawforth, R J K Taylor

Research output: Contribution to journalArticlepeer-review

Abstract

The binuclear hydroxo complex [NBU4](2)[Pd-2(C-4(COOMe)4)2(p-OH)21 (1) has been prepared by addition of two equivalents of NBu4OH to polymeric [Pd(C-4(COOMe)(4))](n). Complex 1 has been successfully employed as a precursor to three novel binuclear imidate-bridged complexes [NBu4](2)[Pd-2-{C-4(COOMe)(4)}(2)(mu-imidate)(2)] [imidate = succinimidate (suc) 2, phthalimidate (pht) 3 or maleimidate (mal) 41 in which the imidate group displays a bidentate N,O-coordination mode. The hemilabile behaviour of the imidate ligands has been investigated by reaction with a variety of P, N and S ligands, affording the corresponding mononuclear derivatives [NBu4][Pd{C-4(COOMe)(4)}(imidate)L] [L = PPh3 (2a, 3a or 4a), P(P-C6H4F)(3) (2b, 3b or 4b), PBu3 (2c, 3c or 4c), py (2d, 3d or 4d), p-MeC6H4NH2 (2e, 3e or 4e), tetrahydrothiophene (2f, W or 4f)] with terminal N-bonded imidate ligands. The characterization of the new complexes involved spectroscopic methods (IR, FAB, H-1, C-13, F-19 and P-31 NMR) and X-ray crystallographic analysis for 1, 4b and 4e. The mononuclear derivatives are shown to catalyse the Stille cross-coupling of benzyl bromide 7 with ethyl Z-vinylstannyl carboxylate (8) in high yields. Yields and reaction times are dependent on the presence and type of imidate ligand, which suggests an important role for it in the catalytic cycle. ((C) Wiley-VCH Verlag GmbH and Co. KGaA, 69451 Weinheim, Germany, 2004).

Original languageEnglish
Pages (from-to)2706-2715
Number of pages10
JournalEUROPEAN JOURNAL OF INORGANIC CHEMISTRY
Issue number13
DOIs
Publication statusPublished - 5 Jul 2004

Keywords

  • catalysis
  • cross-coupling
  • N,O ligands
  • palladium
  • Stille reactions
  • CROSS-COUPLING REACTIONS
  • CRYSTAL-STRUCTURES
  • ENYNE METATHESIS
  • COORDINATION CHEMISTRY
  • ORGANIC ELECTROPHILES
  • ORGANOTIN REAGENTS
  • ARYL CHLORIDES
  • PALLADIUM
  • PLATINUM
  • OLEFINS

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