摘要：

The binuclear complex [(acac)Pd( oxam)Pd(acac)] 1 ( oxam: tetraphenyl oxalic amidinate) has been prepared from H 2 oxam and Pd(acac) 2 in excellent yield. The complex was characterized by elemental analyses, mass spectroscopy, 1H NMR, 13C NMR spectroscopy and in the solid state by X-ray single crystal diffraction analyses. 1 consists of a bimetallic centrosymmetric unit in which the planar oxam ligand acts in a bis-chelating fashion. Each palladium center is in a planar environment. The complex 1 acts as highly selective pre-catalyst in the copper-free Sonogashira reaction between 4-bromoacetophenone and phenylacetylene. Its long-time catalytic activity is higher than that of the related binuclear complex 2 ( oxam: tetra- p-tolyl oxalic amidinate) or that of the trinuclear compound [(acac)Pd( oxam)Zn( oxam)Pd(acac)] ( 3), the solid-state structure of which was also determined by an X-ray structural analysis of single crystals. In addition, 2 is an active and extremely selective pre-catalyst for the Negishi reaction between 3,5,6,8-tetrabromophenanthroline and R–C C–ZnCl (R: Ph, ( iprop) 3Si) to form tetra-alkyne-substituted derivatives.

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