Cationic Palladium(II) Complexes for CO/Vinyl Arene Copolymerization in the Presence of Carbon Dioxide

Abstract

New dicationic and monocationic palladium complexes with 2,2'-bipyridine ligands bearing perfluorinated ponytails have been prepared and used as catalysts for CO/4-tert-butylstyrene (TBS) and CO/styrene (ST) copolymerization in supercritical carbon dioxide (scCO2) and in CO2-expanded liquids. Best catalytic performances were achieved carrying out the copolymerization in carbon dioxide expanded substrates in the presence of 2,2,2-trifluoroethanol (TFE). The dicationic systems with 5,5’-substituted ligands [Pd(N-N)2][X]2 generated the most active and productive catalysts with up to 532 g copolymer CP/g Pd•h for CO/TBS and led to polyketones with high molecular weight and narrow polydispersity (molecular weight up to Mw = 692000 for CO/ST; Mw/Mn = 1.2-3.3). MALDI-TOF mass spectrometry analysis of copolymer end groups revealed that the main initiation and termination steps involved the insertion of the alkene into the Pd-H bond and the -H-elimination on the Pd-alkyl bond, respectively

Mononuclear Ru(II) PolyPyridyl Water Oxidation Catalysts Decorated with Perfluoroalkyl C8H17‐Tag Bearing Chains

“…In addition to that, to the best of our knowledge, there are no reports on Ru(II)‐based OEC decorated with perfluorocarbon (PFC) pendants, there exists only a few reports on metal complexes bearing fluorous tails, and even fewer structural studies on metal complexes having pyridine‐based ligands . This is probably due to the difficulties in crystallizing compounds with long fluorous tails (vide infra).…”

Solvent Effects on Nitrogen Chemical Shifts

“…16) is summarized in Table 9. The Δ 15N coord obtained upon Rh(I) complexation of 1-methylpyrazole (143) and analogous imidazole (144) suggest metal coordination at position N2 (À79.3 ppm) and N3 (À64.6 ppm), respectively [103]. For the octahedral cationic Ir(III) (145) and Ru(III) (146) complexes of three coordinated pyrazoles in acetoned 6 , N2-coordination was shown by Otting and coworkers [97].…”

“…In an investigation of the potential use of cationic palladium complexes with bidentate N-N perfluorinated 2,2 0 -bipyridine ligands as catalysts in carbon monoxide/α-olefin copolymerization processes [144] HOESY for the PF 6 À along with diffusion NMR studies indicated that BArF À does not coordinate, whereas the OTs À and PF 6 À tightly interact with the cation. The complex encompassing the non-coordinating BArF À shows the most shielded pyridinyl nitrogens and the largest jΔ 15N coord j (Table 18), whereas those with OTs À and PF 6 À counterions showed a significant deshielding, due to tight ion pairing.…”

“…e δ 15N lig for 2-(2-pyridyl)-3-(2-pyridylmethyl)-4-methyl-5-phenyl-1,3-oxazolidine in CD 2 Cl 2 [143]. f δ 15N lig for 5-methyl-5 0 -(4-perfluorooctyl-n-butyl)-2,2 0 -bipyridine in CD 2 Cl 2 [144]. g Original δ 15N compl and δ 15N lig in CDCl 3 referenced to 90% CH 3 NO 2 in CDCl 3 and are given here re-referenced to neat CH 3 NO 2 by subtracting 380.5 ppm relative to the original chemical shift.…”

Nickel, palladium and platinum

“…56 The CO/vinyl arene copolymerization was catalysed by cationic Pd(II) complexes in the presence of CO 2 . 57 Silacarboxylic acids were found to be efficient CO releasing molecules in Pd-catalyzed carbonylation reactions. 58 The efficient copolymerizations of methylacrylate with CO and ethylene with norbornene were reported, catalysed by a Pd-phosphinosulfonate system [o-(o-MeOC 6 H 4 ) 2 P)C 6 H 4-SO 3 ].…”