Dichloropalladium complexes ligated by 4,5-bis(arylimino)pyrenylidenes: Synthesis, characterization, and catalytic behavior towards Heck-reaction

Abstract

A series of 4,5-bis(arylimino)pyrenylidenes palladium(II) chloride complexes (C1-C4) were synthesized and characterized by FT-IR and NMR spectroscopy, elemental analysis as well as by single crystal X-ray diffraction for the representative complexes C1 and C3, which revealed a square planar geometry at the palladium centre.All palladium complexes exhibited high activity for the Heck cross-coupling reaction, which were effective when conducted in various solvents. Furthermore, the in-situ mixture of palladium dichloride and the ligand (L1) provided an effective catalytic system for the Heck-reaction.

Enhancing catalytic activity towards Heck-reaction by using 4,5,9,10-tetra(arylimino)pyrenylidenyldipalladium tetrachlorides

“…27 Both mono-and binuclear palladium catalysts showed high thermal stability. The binuclear palladium complexes are stable in its solid state and major solvents.…”

“…Therefore the title palladium complexes efficiently promote the Heck reaction with a good thermostability. 27 In addition, all investigated palladium compounds are applicable as catalysts towards the Heck reaction. There were slight variations observed for different complexes, conrming the inuences of the ligands used; however, it is difficult to a conclusion of a general tendency.…”

“…Meanwhile, new palladium catalysts have been obtained to promote the coupling reactions of less active haloarenes or alkenes. 27 In order to enhance ethylene polymerization by binuclear nickel complex pre-catalysts, 28 the 4,5,9,10-tetra(arylimino)pyrenylidene derivatives were synthesized. Design of binuclear palladium catalysts is still an interesting topic in the perspective of easy ligand preparation.…”

“…[16][17][18][19][20] There are a few binuclear palladium catalysts which have been explored, 21,22 with the observation of positive synergetic performances; 22 however, the ligands used are difficult to synthesize. 27 Herein the synthesis and characterization of the title binuclear palladium complexes are reported in detail, and their catalytic performances towards Heck reaction are investigated and discussed. The N,N-bidentate ligands are commonly incorporated into efficient palladium catalysts.…”

Geometry Constrained N-(5,6,7-Trihydroquinolin-8-ylidene)arylaminopalladium Dichloride Complexes: Catalytic Behavior toward Methyl Acrylate (MA), Methyl Acrylate-co-Norbornene (MA-co-NB) Polymerization and Heck Coupling

“…Both complexes Pd4 and Pd5 displayed a similar molecular structure that adopts a distorted square planar geometry around the palladium metal center and the square plane is comprised of two nitrogen atoms from the ligand as forming a chelate ring with Pd metal center and two chloride atoms. The structural features correspond to classical N,N-bidentate palladium complexes [51][52][53][54][55][56]. The molecular structures of Pd4 and Pd5 are shown in Figure 2 and the selected bond lengths and bond angles are listed in Table S1 (ESI).…”