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Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands
Organometallics ( IF 2.5 ) Pub Date : 2017-08-23 00:00:00 , DOI: 10.1021/acs.organomet.7b00572
Rebecca E. Black 1 , Richard F. Jordan 1
Affiliation  

The synthesis of the phosphine-cyclopentanesulfonate pro-ligands Li/K[2-PPh2-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 (κ2-P,O-2a)PdMe(pyridine) (3a) and (κ2-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(C6F5)3. The borane-coordinated base-free dimer [{2b·B(C6F5)3}PdMe]2 (5b), in which B(C6F5)3 binds to a sulfonate oxygen, was prepared by addition of 1 equiv of B(C6F5)3 per Pd to 4b or addition of 2 equiv of B(C6F5)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 (Mn = 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 −CH2CH(CO2Me)CH2– (80%) in-chain units and −CH2CH(CO2Me)Me (8%) and −CH2CH═CH(CO2Me) (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 −CH2CHFCH2– (∼80%) in-chain units and −CH2CF2H (7%), −CH2CHFCH3 (5%), and −CH2CH2F (8%) chain-end units. Complexes 3b and 4b are more stable and active in ethylene polymerization than analogous (PAr2-CH2CH2SO3)PdR catalysts, but are less active than analogous (PAr2-arenesulfonate)PdR catalysts. Low-temperature 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 (PMe2-cyclopentanesulfonate)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-à-vis analogous (PAr2-arenesulfonate)PdR catalysts results from a higher barrier for migratory insertion of the trans-P,R isomer.

中文翻译:

含膦-环戊烷磺酸盐配体的钯(II)烷基配合物的合成与反应性

膦-环戊烷磺酸盐的配体的合成Li / K [2-PPh 2-环戊烷磺酸盐](Li / K [ 2a ]),Li / K [2-P(2-OMe-Ph)2-环戊烷磺酸盐(Li / K [图2b ]),和H [ 2B ]和相应的Pd(II)的烷基配合物(κ 2 - Pö -图2a)PDME(吡啶)(图3a)和(κ 2 - Pö -图2b)描述了PdMe(吡啶)(3b)。磺酸桥无碱二聚体{(2b)PdMe} 24b)的合成是通过使用B(C 6 F 533b提取吡啶。通过添加1,制备硼烷配位的无碱二聚体[{ 2b· B(C 6 F 53 } PdMe] 25b),其中B(C 6 F 53与磺酸氧结合。当量B(C的6 ˚F 53量钯至4b中或加入2当量B(C的6 ˚F 533B。化合物图3b图4b5b中聚合乙烯与低活性(高达210公斤摩尔-1 ħ -1在250磅和80℃),以线性聚乙烯(中号Ñ主要具有内烯烃的展示位置= 1950-5250道尔顿)。3b4b将乙烯与丙烯酸甲酯共​​聚成线性共聚物,其中线性丙烯酸酯含量最高为11.7 mol%,以-CH 2 CH(CO 2 Me)CH 2-(80%)链内单元和-CH 2 CH的形式引入(CO 2 Me)Me(8%)和-CH 2 CH = CH (CO 2 Me)(12%)链端单元。3b4b还将乙烯与氟乙烯共聚为线性共聚物,该共聚物含有高达0.41 mol%的氟乙烯,以-CH 2 CHFCH 2-(〜80 %)链内单元和-CH 2 CF 2 H(7 %),-CH 2 CHFCH 3(5%)和-CH 2 CH 2 F(8%)链端单元。配合物3b4b在乙烯聚合反应中比类似的(PAr 2 - CH 2 CH 2 SO 3)PdR催化剂更稳定和有活性,但比类似的(PAr 2-芳烃磺酸盐)PdR催化剂。低温NMR研究表明,图4b具有低于-10℃的乙烯反应以形成乙烯加合物的顺式- P- [R - (2B)PDME(乙烯)(图7b),其在5进行乙烯插入℃。DFT计算一个模型(PME 2 -cyclopentanesulfonate)的Pd(PR)(乙烯)物种表明,乙烯的插入通过进入- P- [R /反式- P- [R异构化,随后插入迁徙,而下部活性3B4bVIS-à-VIS类似(PAR 2 -arenesulfonate)从用于的洄游插入较高屏障PDR催化剂的结果反式- P- [R异构体。
更新日期:2017-08-24
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