通过两步合成制备了{ONSO}型配体新家族的六个成员-四齿-二阴离子亚胺-硫代双(酚盐)配体。它们的[{ONSO} Zr(O t Bu)2 ]配合物形成为具有不同通量度的单个非对映异构体,取决于两个酚盐环的取代方式。该配合物在1-丙交酯和外消旋丙交酯的聚合反应中具有活性。由外消旋-丙交酯制备的聚乳酸的立构规整度从杂规倾斜到无规倾斜逐渐变为等规倾斜。最灵活的配合物和最刚性的配合物分别给出了最高程度的异规整度和全同规整度。
Copolymerization of carbon dioxide and cyclohexene oxide catalyzed by chromium complexes bearing semirigid [ONSO]-type ligands
作者:Bing Han、Li Zhang、Samuel J. Kyran、Binyuan Liu、Zhongyu Duan、Donald J. Darensbourg
DOI:10.1002/pola.28052
日期:2016.7.1
Chromium complexes supported by tetradentate dianionic imine‐thioether‐bridged bis(phenol) ligands were prepared and employed in the synthesis of poly(cyclohexene carbonate) via the copolymerization of CO2 and cyclohexeneoxide. The catalytic activity, product selectivity, and kinetic behaviors of these [ONSO]CrIII complexes have been systematically investigated. Results indicate the presence of electron‐withdrawing
Zirconium Complexes of Phenylene-Bridged {ONSO} Ligands: Coordination Chemistry and Stereoselective Polymerization of <i>rac</i>-Lactide
作者:Ayellet Stopper、Konstantin Press、Jun Okuda、Israel Goldberg、Moshe Kol
DOI:10.1021/ic501164c
日期:2014.9.2
Sequential tetradentate dianionic thio-imine diphenolate ligands featuring an ortho-phenylene core and their zirconium complexes are described for the first time. Ligands that include different combinations of bulky-alkyl groups and halo groups on the two phenol arms were prepared by a substitution/condensation reaction sequence. An unexpected fac-fac wrapping mode was found in the solid state for the ligands in the octahedral [ONSO}Zr((OBu)-Bu-t)(2)] complexes. The complexes were all fluxional, and the barrier for enantiomer interconversion was found to depend on the phenolate substituents. The complexes were found to catalyze the polymerization of rac-lactide to poly(lactic acid) in solution with polymer tacticities varying from heterotactic to atactic which showed correlation to the nature of phenolate substituents but not to the degree of complex fluxionality.