Syntheses, structures and efficient catalysis for C–C coupling of some benzaldehyde thiosemicarbazone complexes of palladium

详细信息    查看全文

• 作者：Piyali Paul^a ; Sayanti Datta^a ; Sarmistha Halder^a ; Rama Acharyya^a ; Falguni Basuli^a ; Ray J. Butcher^b ; Shie-Ming Peng^c ; Gene-Hsiang Lee^c ; Alfonso Castineiras^d ; Michael G.B. Drew^e ; Samaresh Bhattacharya^a ; ^{samaresh_b@hotmail.com"" rel=""nofollow}
• 关键词：Benzaldehyde thiosemicarbazones ; Palladium complexes ; Syntheses ; Structures ; Catalytic properties
• 刊名：Journal of Molecular Catalysis A: Chemical
• 出版年：2011
• 出版时间：17 June 2011
• 年：2011
• 卷：344
• 期：1-2
• 页码：62-73
• 全文大小：1162 K

文摘

Reaction of the 4-R-benzaldehyde thiosemicarbazones (denoted in general as L-R; R = OCH₃, CH₃, H, Cl and NO₂) with trans-[Pd(PPh₃)₂Cl₂] afforded a group of mixed-ligand complexes (denoted in general as 1-R) incorporating a N,S-coordinated thiosemicarbazone, a triphenylphosphine and a chloride. Similar reaction with Na₂[PdCl₄] afforded a family of bis-thiosemicarbazone complexes (denoted in general as 2-R), where each ligand is N,S-coordinated. Crystal structures of 1-CH₃, 1-NO₂, 2-OCH₃, 2-NO₂ and L-NO₂ have been determined. In all the complexes the thiosemicarbazones are coordinated to the metal center, via dissociation of the acidic proton, as bidentate N,S-donors forming five-membered chelate rings. With reference to the structure of the uncoordinated thiosemicarbazone, this coordination mode is associated with a conformational change around the CN bond. All the 1-R and 2-R complexes display intense absorptions in the visible region. Catalytic activity of the 1-R and 2-R complexes towards some C–C coupling reactions (e.g. Suzuki, Heck and Sonogashira) has been examined and while both are found to be efficient catalysts, 1-R is much better catalyst than 2-R.