Coordination chemistry of dinucleating P₂N₂S ligands: preparation and characterization of cationic palladium complexes

Abstract

The thioethers (4-tert-butyl-2,6-bis((2-(diphenylphosphino)ethylimino)methyl)phenyl)(tert-butyl)sulfane (tBuL3) and (4-tert-butyl-2,6-bis((2-(diphenylphosphino)ethylamino)methyl)phenyl)(tert-butyl)sulfane (tBuL4) react readily with [Pd(NCMe)2Cl2] to give the dinuclear palladium thiophenolate complexes [(L3)Pd2(Cl)2]+ and [(L4)Pd2(micro-Cl)]2+ (HL3=2,6-bis((2-(diphenylphosphino)ethylimino)methyl)-4-tert-butylbenzenethiol, HL4=2,6-bis((2-(diphenylphosphino)ethylamino)methyl)-4-tert-butylbenzenethiol). The chlorides in could be replaced by neutral (MeCN) and anionic ligands (NCS-, N3-, I-, CN-) to give the dinuclear PdII complexes [(L3)Pd2(NCMe)2]3+, [(L3)Pd2(SCN)2]+, [(L3)Pd2(N3)2]+, [(L3)Pd2(I)2]+, and [(L3)Pd2(CN)2]+. The acetonitrile ligands in are readily hydrated to give the corresponding amidato complex [(L3)Pd2(NHCOMe)]2+. All complexes were isolated as perchlorate salts and studied by infrared, 1H, and 31P NMR spectroscopy. In addition, complexes [ClO4].EtOH, [ClO4]2, [ClO4], [ClO4].EtOH, and [ClO4]2.MeCN.MeOH have been characterized by X-ray crystallography. The dipalladium complex was found to catalyse the vinyl-addition polymerization of norbornene in the presence of MAO (methylalumoxane) and B(C6F5)3/AlEt3.

A dinuclear Bi(III) complex of a 1,3-disubstituted imidazole-2-thione and its use as a transmetallation agent toward Pd(II)

“…Reported structures that contain the dinuclear fragment Pd(µ-S)(µ-X)Pd (X = halogenido) all include either sulfide [46] or thiolates as S-donating groups and a chloride as the second bridging ligand. The S-donors in these complexes can broadly be classified in three groups, according to the organic group and the nature of the ligand: (monodentate) alkylthiolates [47][48][49][50][51], (monodentate) arylthiolates [48,52,53], and polydentate difunctional ligands in which an arylthiolate is the central donor group [54][55][56]. The relevance of this classification becomes clear in Figure 3a that shows boxplots (each box corresponds to 50% of the data measured, one quarter of the data lying above the median value, one quarter below) for all Pd-(µ-S) bonds of the bridging S-donor within each of these categories.…”

Metal catalysts for the vinyl/addition polymerization of norbornene

“…Compound Pd-36 with its dinucleating P 2 N 2 S ligand was tested for the norbornene polymerization in combination with MAO or B(C 6 F 5 ) 3 /AlEt 3 [193]. Activities between 10 5 and 10 6 g PNB /mol Pd h were obtained.…”

Synthesis and Characterization of NiII and PdII Complexes Bearing N,N,S Tridentate Ligands and Their Catalytic Properties for Norbornene Polymerization

“…In addition, palladium complexes 4-6 also showed much higher activity for norbornene polymerization than the dinuclear tridentate P,N,S palladium complexes reported by Kersting and coworkers with MAO as a cocatalyst [8.7 ϫ 10 5 g/(mol of Pd) h]. [21] To further investigate the reaction parameters affecting norbornene polymerization, complex 2 was typically investigated by changing the polymerization temperature, Al/Ni ratio, and the monomer concentration ( Table 2). The 2/ MAO catalytic system showed high activities over a large range of reaction temperature.…”

“…The obtained polynorbornenes catalyzed by nickel catalysts can dissolve in common organic solvents, but those obtained catalyzed by palladium catalysts are insoluble in any solvents, which has been noted before by Janiak and other groups. [21,28] Moreover, steric hindrance of the aryl substituent of the complexes also affects their catalytic activities and the molecular weights of the polynorbornene. The nickel and palladium complexes with bulky aryl substituents showed higher activity toward norbornene polymerization and produced higher molecular weight polymers.…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) search has been carried out to elucidate the influence of the sterics of the ligands and the electronic effects of the ligands on polymerization reactions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In addition, the sidearm approach had also proven to be an efficient strategy for the design of organometallic catalysts in olefin polymerization, [15][16][17][18][19][20][21] and the sidearm effect of the extra donor had a strong influence on catalytic polymerization. In particular, metal complexes with N, P, O, and S atoms in the sidearm were mainly reported.…”