Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands

Abstract

The synthesis of the phosphine-cyclopentanesulfonate pro-ligands Li/K[2-PPh 2 -cyclopentanesulfonate] (Li/K[2a]), Li/K[2-P(2-OMe-Ph) 2 -cyclopentanesulfonate] (Li/K[2b]), and H[2b], and the corresponding Pd(II) alkyl complexes (κ 2 -P,O-2a)PdMe-(pyridine) (3a) and (κ 2 -P,O-2b)PdMe(pyridine) (3b) is described. The sulfonate-bridged base-free dimer {(2b)PdMe} 2 (4b) was synthesized by abstraction of pyridine from 3b using B(C 6 F 5 ) 3 . The borane-coordinated base-free dimer [{2b•B(C 6 F 5 ) 3 }PdMe] 2 (5b), in which B(C 6 F 5 ) 3 binds to a sulfonate oxygen, was prepared by addition of 1 equiv of B(C 6 F 5 ) 3 per Pd to 4b or addition of 2 equiv of B(C 6 F 5 ) 3 to 3b. Compounds 3b, 4b, and 5b polymerize ethylene with low activity (up to 210 kg mol −1 h −1 at 250 psi and 80 °C) to linear polyethylene (M n = 1950−5250 Da) with predominantly internal olefin placements. 3b and 4b copolymerize ethylene with methyl acrylate to linear copolymers that contain up to 11.7 mol % methyl acrylate, which is incorporated as −CH 2 CH(CO 2 Me)CH 2 − (80%) in-chain units and −CH 2 CH(CO 2 Me)Me (8%) and −CH 2 CHCH(CO 2 Me) (12%) chain-end units. 3b and 4b also copolymerize ethylene with vinyl fluoride to linear copolymers that contain up to 0.41 mol % vinyl fluoride, which is incorporated as −CH 2 CHFCH 2 − (∼80%) in-chain units and −CH 2 CF 2 H (7%), −CH 2 CHFCH 3 (5%), and −CH 2 CH 2 F (8%) chain-end units. Complexes 3b and 4b are more stable and active in ethylene polymerization than analogous (PAr 2 -CH 2 CH 2 SO 3 )PdR catalysts, but are less active than analogous (PAr 2 -arenesulfonate)PdR catalysts. Lowtemperature NMR studies show that 4b reacts with ethylene below −10 °C to form the ethylene adduct cis-P,R-(2b)PdMe(ethylene) (7b), which undergoes ethylene insertion at 5 °C. DFT calculations for a model (PMe 2cyclopentanesulfonate)Pd(Pr)(ethylene) species show that ethylene insertion proceeds by cis-P,R/trans-P,R isomerization followed by migratory insertion, and that the lower activity of 3b and 4b vis-a-vis analogous (PAr 2 -arenesulfonate)PdR catalysts results from a higher barrier for migratory insertion of the trans-P,R isomer.

Late Transition Metal Complexes for Olefin Copolymerization with Polar Monomers

“…Jordan 等 [168] 将苯基骨架改变为非共轭环戊基, 280 [172] , 但是共聚物分子量不高(3100～6100), 极性 基团插入率为 0.2%～3.6%. 膦端苯基对位含有给电子 基团 NMe 2 的 291 可催化乙烯与十一烯酸甲酯、烯己基 氯和乙烯基三甲基硅烷分别共聚 [173] , 共聚物分子量为 4100～7800; [175] , 催化剂活性不高(1000), 极性基团插入率分别为 2%、1.2%和 1.5%.…”

Pd‐Iminocarboxylate Complexes and Their Behavior in Ethylene Polymerization

“…[2] It has been demonstrated on many occasions that ethylene oligomerization catalyst can be tamed to yield high molecular weight polyethylene (PE) by suitable tailoring of steric and electronic features of the ligand.F or example, ap alladium complex of phosphonebenzenesulfonate ligand can be tailoredt op roduce polyethylene with molecular weight of 6700 gmol À1 to 169 000 gmol À1 . [4] Thus, ligands dominate the outcomeo fa ne thylene oligomerization or polymerization reaction. [4] Thus, ligands dominate the outcomeo fa ne thylene oligomerization or polymerization reaction.…”

“…[3] An ethylene dimerization Pd-phosphine-sulfonatec atalyst can be tweaked to yield high molecular weight PE. [4] Thus, ligands dominate the outcomeo fa ne thylene oligomerization or polymerization reaction. [5][6][7] Figure 1( D = Lewis base or ad onor atom/solvent) depicts some of the representative catalysts employedi nt he ethylene polymerization reaction.…”

“…[9] Along the same lines, phosphine-sulfonate based palladium catalystt olerates broad range of polar monomers in functional olefin copolymerization ( Figure 1C, 3). [10] While, specially designed ligand backbone comprising N-heterocyclic carbene were found to be active in ethylene polymerization (Figure 1C,4). [11] Based on the above discoveries, we pondered about the choice of the bidentate ligand that can yield single component neutralm etal complex, which may catalyzee thylene polymerization reaction.…”

“…For example, a palladium complex of phosphonebenzenesulfonate ligand can be tailored to produce polyethylene with molecular weight of 6700 g mol −1 to 169 000 g mol −1 . An ethylene dimerization Pd‐phosphine‐sulfonate catalyst can be tweaked to yield high molecular weight PE . Thus, ligands dominate the outcome of an ethylene oligomerization or polymerization reaction…”