Mixed-ligand benzaldehyde thiosemicarbazone complexes of palladium containing N,O-donor ancillary ligands. Syntheses, structures, and catalytic application in C-C and C-N coupling reactions

作者：Dutta Jayita^*; Datta Sayanti; Seth Dipravath Kumar; Bhattacharya Samaresh

来源：RSC Advances, 2012, 2(31): 11751-11763.

DOI：10.1039/c2ra21078a

The reaction of a 1 : 1 mixture of 4-R-benzaldehyde thiosemicarbazone [denoted in general as HL-R; where H stands for the dissociable acidic proton and R (R = OCH3, CH3, H, Cl and NO2) for the substituent] and 1-nitroso-2-naphthol (abbreviated as Hnn), with an equivalent quantity of Na-2[PdCl4] in ethanolic medium affords a group of mixed-ligand complexes of the type [Pd(L-R)(nn)]. A similar reaction of a mixture of HL-R and quinolin-8-ol (Hq) with Na-2[PdCl4] affords another family of mixed-ligand complexes of the type [Pd(L-R)(q)]. Crystal structures of [Pd(L-Cl)(nn)], [Pd(L-CH3)(q)] and [Pd(L-Cl)(q)] have been determined. In all the complexes the thiosemicarbazones are coordinated to the metal center, via dissociation of the acidic proton, as monoanionic bidentate N, S-donors forming five-membered chelate rings. In the [Pd(L-R)(nn)] complexes, the 1-nitroso-2-naphtholate anion is coordinated as a N, O-donor forming a five-membered chelate ring. Similarly in the [Pd(L-R)(q)] complexes, the quinolin-8-olate anion is bound to the metal center in the N, O-mode forming a five-membered chelate ring. All the [Pd(L-R)(nn)] and [Pd(L-R)(q)] complexes show characteristic H-1 NMR signals, and in dichloromethane solution they all display intense absorptions in the visible and ultraviolet regions. Catalytic activities of the [Pd(L-R)(nn)] and [Pd(L-R)(q)] complexes have been examined towards some C-C and C-N coupling reactions, where both were found to show notable catalytic efficiency.

• 出版日期2012