Effect of diene ligands in the rhodium-catalyzed polymerization of phenylacetylene
Effect of diene ligands in the rhodium-catalyzed polymerization of phenylacetylene
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DOI：
10.1021/ma061689g
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发表时间：
2006-11
期刊：
影响因子：
5.5
通讯作者：
Irfan Saeed;M. Shiotsuki;T. Masuda
中科院分区：
文献类型：
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作者：
Irfan Saeed;M. Shiotsuki;T. Masuda
考察了1，5-环辛二烯(CoD)、2，5-降冰片二烯(NBD)、内二环戊二烯(DCP)、四氟苯并二茂烯(Tfb)和四氯苯并二茂烯(Tcb)等不同二烯配体在Rh催化苯乙炔聚合反应中的作用，旨在开发新型活性催化剂。新型催化剂[(Tfb)RhCl]2 4和tcb催化剂[(Tcb)RhCl]2 5比相应的传统COD催化剂1和催化剂2具有更高的活性。例如，催化剂4(聚合物产率=92−10 0%)在极性溶剂(四氢呋喃、C2H5OH、CH3CN和二甲基甲酰胺)中的活性高于催化剂2(聚合物产率=69−81%)。这是由于与其他配体相比，TFb的π-酸性较高，其低的LUMO能量(0.21eV)和相当大的4位烯烃质子的前场位移(Δδ=3.10ppm)证明了这一点。因此，从Rh的4d填充轨道到Tfb的LUMO的强烈回馈使得Rh金属在催化剂4中高度缺电子，从而促进了配位反应的进行。
The effect of various diene ligands, namely 1,5-cyclooctadiene (cod), 2,5-norbornadiene (nbd), endo-dicyclopentadiene (dcp), tetrafluorobenzobarrelene (tfb), and tetrachlorobenzobarrelene (tcb), was examined in the Rh-catalyzed polymerization of phenylacetylene, aiming at the development of novel active catalysts. The new tfb catalyst [(tfb)RhCl]2 4 and tcb catalyst [(tcb)RhCl]2 5 are more active than the corresponding conventional cod catalyst 1 and nbd catalyst 2. For example, catalyst 4 (polymer yield = 92−100%) was more active than 2 (polymer yield = 69−81%) when employed in polar solvents (THF, C2H5OH, CH3CN, and DMF). This is attributable to the high π-acidity of tfb compared to other ligands, as evidenced by its significantly low LUMO energy (0.21 eV), and a considerably large upfield shift of olefinic protons in 4 (Δδ = 3.10 ppm). Consequently, a strong back-donation from filled 4d orbitals of Rh to LUMO of tfb renders the Rh metal highly electron-deficient in catalyst 4, facilitating the coordina...