753458-70-7Relevant academic research and scientific papers
Palladacyclopentadiene complexes with mono- and didentate imidato ligands: Synthesis, hemilabile behaviour and catalytic application in the stille reaction
Serrano, Jose Luis,Fairlamb, Ian J. S.,Sanhez, Gregorio,Garcia, Luis,Perez, Jose,Vives, Jorge,Lopez, Gregorio,Crawforth, Catherine M.,Taylor, Richard J. K.
, p. 2706 - 2715 (2004)
The binuclear hydroxo complex [NBu4]2[Pd 2(C4(COOMe)4)2-(μ-OH) 2] (1) has been prepared by addition of two equivalents of NBu 4OH to polymeric [Pd{C4(COOMe)4}]n. Complex 1 has been successfully employed as a precursor to three novel binuclear imidate-bridged complexes [NBu4]2[Pd2-(C 4(COOMe)4)2(μ-imidate)2] [imidate = succinimidate (sue) 2, phthalimidate (pht) 3 or maleimidate (mal) 4] 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{C4(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-MeC 6H4NH2 (2e, 3e or 4e), tetrahydrothiophene (2f, 3f or 4f)] with terminal N-bonded imidate ligands. The characterization of the new complexes involved spectroscopic methods (IR, FAB, 1H, 13C, 19F and 31P 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. Wiley-VCH Verlag GmbH and Co. KGaA, 69451 Weinheim, Germany, 2004.
