Palladium complexes based on tridentate pyrazolyl-ligands: Synthesis, structures and use in Suzuki cross-coupling reactions
作者:Kácris Matos、Lucilene L. de Oliveira、Cristiano Favero、Adriano L. Monteiro、Manfredo Hörner、Jean-François Carpentier、Marcelo P. Gil、Osvaldo L. Casagrande
DOI:10.1016/j.ica.2009.04.014
日期:2009.9
The reaction of [PdCl(Me)(cod)] (cod = 1,5-cyclooctadiene) with tridentate bis(pyrazolyl) ligands affords the alkyl-palladium(II) complexes [Pd(CH3)(NZN)][BF4] (1, NZN = 1,1'-(2,20-oxybis(ethane-2,1-diyl)bis(3,5-dimethyl-1H-pyrazole); 2, NZN = bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]sulfane) in good yield. Compounds 1-2 were characterized by elemental analysis, multinuclear NMR spectroscopy, and X-ray structural analysis. Single crystal X-ray structural analyses indicate that the complexes are monomeric and the palladium center resides in a slightly distorted square planar environment. Furthermore, despite their intrinsic similarity, the NON and NSN ligands adopt different coordination modes around the palladium metal center. Additionally, the [PdCl2(NON)] (3) was shown to be an efficient catalyst precursor for the coupling of aryl bromides and iodides with arylboronic acids, esters and borate salts. (C) 2009 Elsevier B.V. All rights reserved.