A Bulky Pd(II) α-Diimine Catalyst Supported on Sulfated Zirconia for the Polymerization of Ethylene and Copolymerization of Ethylene and Methyl Acrylate

Abstract

The reaction of (N∧N)PdMe 2 (N∧N is Ar−NCMe-MeCN−Ar; Ar = 2,6-bis(diphenylmethyl)-4-methylbenzene) and sulfated zirconia (SZO) in diethyl ether forms organometallic Pd-sites that polymerize ethylene and copolymerize ethylene and methyl acrylate. The Pd-sites bind CO and were studied by infrared and solid-state NMR spectroscopies. Analysis of the reaction mixture shows that more methane than expected evolves during the grafting reaction, suggesting that some Pdsites do not contain a Pd-Me group. Consistent with this observation, deuterium labeling experiments show that ∼9% of palladium sites are active in polymerization reactions. (N∧N)PdMe 2 /SZO polymerizes ethylene with activity as high as 1342 kg PE /(mol active Pd *h) and incorporated up to 0.46% methyl acrylate in copolymerization reactions.

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

“…In the process of exploring various Brookhart catalysts, various olefinic monomers have been polymerized and copolymerized. 27,31,[125][126][127] The applicable monomers have also been rapidly growing to include linear 128,129 and branched 130,131 α-olefins, cycloalkyl substituted α-olefins, 132-136 cycloolefins, 137 dienes, 138 trienes, 139,140 internal olefins, [141][142][143][144] norbonene type monomers, [101][102][103][104] and different polar comonomers. 3,27,28 It should be noted that the continuous interest in Brookhart-type catalysts largely originates from their capabilities in copolymerizations of olefins with polar functionalized comonomers.…”

Al(ORF)3 (RF = C(CF3)3) activated silica: a well-defined weakly coordinating surface anion

“…2c). [26][27][28][29][30][31] However, titrations of the -OH sites on sulfated oxides with phosphines are inconsistent with superacid -OH sites. 32 This data is consistent with DFT calculations showing that sulfated oxides are weaker acids than zeolites.…”

Emerging Palladium and Nickel Catalysts for Copolymerization of Olefins with Polar Monomers

“…[67,68] In contrast, the corresponding studies using late-transition-metal catalysts, especially for the purpose of polar monomer copolymerization, have remained largely unexplored. [70,71] Thed evelopment of high-performance heterogeneous catalysts to address the polar monomer problem could be ak ey motivation for industry to get involved in this challenging area of research. Conely and co-workers described the immobilization of adiimine nickel and palladium catalysts on sulfated zirconia, and studied their properties in ethylene polymerization and copolymerization with polar monomers.…”