Synthesis, crystal structures, and application of two new pincer type palladium(II)-Schiff base complexes in C-C cross-coupling reactions

• Published in: Inorganica Chimica Acta Vol. 471; pp. 345 - 354
• Main Authors: Agrahari, Bhumika, Layek, Samaresh, Anuradha, Ganguly, Rakesh, Pathak, Devendra D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 24.02.2018; Elsevier Science Ltd
• Subjects: Additives; C-C cross-coupling reaction; Carbon 13; Catalysis; Catalysts; Chemical reactions; Chemical synthesis; Cross coupling; Crystal structure; Homogenous catalyst; Imines; Infrared radiation; Ligands; Methanol; NMR; Nuclear magnetic resonance; Palladium; Pd(II) complex; Single crystals; X-ray diffraction; Homogenous catalyst; C-C cross-coupling reaction; Pd(II) complex; Crystal structure
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2017.11.018

Synthesis and characterization of two new pincer type palladium(II) complexes of the general formula [PdL1(PPh3)] 1, and [PdL2(PPh3)] 2, (where L1= 2-(2,3-Dihydroxybenzylideneamino)phenolate and L2 = 2-(2,3-Dihydroxybenzylidene) hydrazinecarbothioamidate) and application of the complexes in C-C cross-coupling reactions. [Display omitted] •Synthesis and crystal structures of two new pincer type Pd(II)-Schiff base complexes.•Characterized by FT-IR, 1H, 13C, 31P NMR, elemental analysis and single crystal X-ray studies.•Efficient catalyst for Suzuki-Miyaura, Heck-Mizoroki and Sonogashira reactions.•Low catalyst loading. Two new pincer type Pd(II)-Schiff base complexes of the general formula [PdL1(PPh3)] 1 and [PdL2(PPh3)] 2, (where L1  =  2-(2,3-Dihydroxybenzylideneamino)phenolate and L2  = 2-(2,3-dihydroxybenzylidene)hydrazinecarbothioamidate) were synthesised by the reaction of the palladium acetate with the corresponding ligand in methanol as yellow crystalline solids in high yields. Both complexes were fully characterized by FT-IR, 1H NMR, 13C NMR, 31P NMR, elemental analysis and single crystal X-ray diffraction studies. The crystal structures confirmed the tridentate nature of the pincer type Schiff base ligands and the distorted square planar geometry around the metal centre in both cases. The triphenylphosphine acted as an auxiliary ligand and occupied the fourth coordination site at palladium. The complexes were found to be efficient homogenous catalysts for a series of Suzuki-Miyaura, Heck-Mizoroki and Sonogashira reactions at a low catalyst loading (0.08 mol%), and without the use of any additives. All organic products were fully characterized by 1H and 13C NMR studies.