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Diiminopyrrolide Copper Complexes: Synthesis, Structures, and rac-Lactide Polymerization Activity
Organometallics ( IF 2.5 ) Pub Date : 2017-09-21 00:00:00 , DOI: 10.1021/acs.organomet.7b00609
Pargol Daneshmand 1 , Solène Fortun 1 , Frank Schaper 1
Affiliation  

2,5-Diiminopyrrole ligands with N-xylyl (L3), N-naphthyl (L4), N-cyclohexyl (L5), N-diphenylmethyl (L6), and N-p-bromobenzyl (L7), as well as the 5-R-2-iminopyrroles with N-S-methylbenzyl (L8, R = H; L10, R = Me; L11, R = Cl) and N-benzyl (L9, R = H) were reacted with Cu(OMe)2 and pyridylmethanol (R1OH) or dimethylaminoethanol (R2OH) to yield the corresponding dinuclear complexes L2Cu2(μ-OR)2. Reactions in the absence of chelating R1OH or R2OH only yielded homoleptic L2Cu or L2Cu2. Complexes with R2OH were obtained with all ligands but L4, complexes with R1OH for all ligands but L3, L4, and L6. All complexes but those with L7 displayed dinuclear crystal structures with pentacoordinated copper centers and bridging alkoxy groups. The alkoxy group and the pyrrolide ligand were consistently found in equatorial positions. Imine, pyridine, or amine occupied the axial position. L7 coordinated both imino groups to copper, yielding a distorted-octahedral coordination geometry. All complexes containing R1OH, with the exception of L7, showed an isotactic bias in the polymerization of rac-lactide, with a maximum Pm value of 0.7. Complexes containing R2OH provided atactic PLA or, in the case of L3 and L6, heterotactic PLA. Reduced stereocontrol in monoiminopyrrolide copper complexes and lack of stereocontrol with octahedrally coordinated L7 indicate that the catalytic site needs to adapt to chain-end chirality and is participating in enantiomer selection.

中文翻译:

二亚氨基吡咯化物铜配合物:合成,结构和外消旋-丙交酯聚合活性

2,5- Diiminopyrrole与配体ñ -二甲苯(L3),Ñ萘基(L4),ñ -环己基(L5),ñ -二苯基甲基(L6),与ñ - p -bromobenzyl(L7),以及5个使具有N - S-甲基苄基(L8,R = H; L10,R = Me; L11,R = Cl)和N-苄基(L9,R = H)的-R-2-亚氨基吡咯与Cu(OMe)2反应和吡啶基甲醇(R 1 OH)或二甲基氨基乙醇(R 2 OH)得到相应的双核络合物L 2 Cu 2(μ-OR)2。在没有螯合的情况下的反应R 1OH或R 2 OH仅产生均质的L 2 Cu或L 2 Cu 2。对于除L4之外的所有配体,获得了具有R 2 OH的配合物,对于除L3,L4和L6之外的所有配体,与R 1 OH的配合物得到了。除了具有L7的那些以外,所有配合物均显示具有五配位的铜中心和桥连的烷氧基的双核晶体结构。始终在赤道位置发现烷氧基和吡咯化物配体。亚胺,吡啶或胺占据轴向位置。L7将两个亚氨基均与铜配位,产生扭曲的八面体配位几何形状。除L7外,所有含R 1 OH的配合物在C的聚合中均表现出全同立构偏向rac-丙交酯,最大P m值为0.7。含有R 2 OH的配合物提供了无规PLA,或者在L3和L6的情况下提供了杂规PLA。单亚氨基吡咯烷基铜配合物中立体控制的降低和八面体配位的L7的立体控制的缺乏表明催化位点需要适应链端手性,并参与对映异构体的选择。
更新日期:2017-09-21
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