PREPARATION AND REACTIONS OF PALLADIUM(0)‐DIBENZYLIDENEACETONE COMPLEXES

As an extension of this work, we attempted to investigate the reaction of PdC12 with dibenzylideneacetone (dba), a 1,4-dienone(3)-type compound, and obtained a novel zerovalent palladium complex: Pd(dba)2 . 2 Among the nickel triad, Ni(COD)2, and Pt(COD)2 are well-known zerovalent complexes containing an organic ligand. Since Pd(COD), is unknown, Pd(dba)2 is a useful and interesting zerovalent complex. Hitherto, ligands used for the preparation of palladium(0) complexes have been limited to ph~sphines,~-' ph~sphi tes ,~ a r ~ i n e s , ~ i ocyanides,~ and carbon monoxide.6 Moseley and Maitlis found analogous platinum complexes, Pt(dba)2 and Pt(dba), .' Both groups (Maitlis and Ishii) published papers on the reactions with acetyleni~'.~ and olefinic compounds.1o Recently three papers concerning Pd and Pt-dba complexes were In this paper, the preparations of Pd(dba)2 and Pd2(dba)&olvent) and their structural determination (IR, NMR, UV, and mass and X-ray diffraction) are reported. Pd-dba complexes are reactive, giving (dba)PdL2complexes, a-olefinPdL, , a-acetylenic Pd complexes, and palladiacyclopentadienyl complexes, together with the formation of Pd-quinone(pand o-)L2 complexes, which are described in this paper.

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