Copolymerization of carbon dioxide and cyclohexene oxide with zinc/β‐ketoiminato complexes: Investigating the influence of the electron structure of zinc/β‐ketoiminato complexes on the catalytic activity and resultant copolymer properties

Abstract

A series of LZnX zinc/β‐ketoiminato complexes [L = CH3C(OH)C(CH2CHCH2)C(CH3)NAr (L1), CH3C(OH)C(CH2CH2CN)C(CH3)NAr (L2), CH3C(OH)C(CH2C6H5)C(CH3)NAr (L3), or CH3C(OH)CHC(CH3)NAr (L4); Ar = 2,6‐iPr2C6H3; and initiation group X = alcoholate or acetate (for L1) or alcoholate (for L2–L4)] were synthesized, and their activities toward the copolymerization of carbon dioxide with cyclohexene oxide were determined. The 3‐position substituents on the β‐ketoiminato ligand backbone of the zinc/β‐ketoiminato complexes played an important role not only in the catalytic activity but also in the intrinsic viscosity, chemical composition, and refined microstructure of the resultant copolymers. The order of the catalytic activity of L1ZnX with different initiation groups (X = OMe, OiPr, or OAc) was L1Zn (OiPr) > L1Zn (OMe) > L1Zn (OAc), being the opposite of the order of the leaving ability of the initiation groups. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6243–6251, 2006

Synthesis, characterization, and steric hindrance comparisons of selected transition and main group metal β-ketoiminato complexes

“…Moving right across the periodic table, the reactions of L 1 and L 2 with diethyl zinc were performed, Scheme 3. b-Diketoiminato complexes with zinc [16] have been studied extensively for their catalytic ability and this has been extended to ketoiminato ligands [19]. Previous work by Liu et al studied the reaction of L 0 , that is similar to L 1 except has a hydrogen atom in the c position, as a potential catalyst for the copolymerization of CO 2 and cyclohexene oxide [20]. No structural analysis of the zinc complexes were performed but the postulated product from the 1:1 reaction of L 0 with ZnEt 2 was L 0 ZnEt.…”

Ring-opening polymerization of ε-caprolactone and cyclohexene oxide initiated by aluminum β-ketoamino complexes: steric and electronic effect of 3-position substituents of the ligands

“…Keywords:Gring-opening polymerization, ε-caprolactone, cyclohexene oxide, aluminum β-ketoamino complexesU Introdution Mono-anionic β-ketoamino ligand has emerged as one of the most versatile ligands in coordination chemistry for their strong metal-ligand bonds [1][2][3][4][5][6][7][8][9][10][11] and for their relatively facile tunablility to access derivatives containing a range of substituents around the ligands' skeleton. In the past, most work paid their attentions to the steric and electronic effects of substituents (R) on the nitrogen donor atom and side groups (R 1 and/or R 2 ) of these ligands backbone (see the Scheme I) of metal complexes on the catalyst behavior.…”

“…[4][5][6][7][8][9] However, few investigations were focused on the effect of the substituents (X) on the 3-position of the β-ketoamino ligands skeleton. 10 The aluminum complexes draw considerable attention for both organic synthesis 12 and polymerization, 13 due to their strong Lewis acidity, relatively low toxicity, and ready availability. Up to date, many kinds of ligands with sterically bulky have been used in organo-aluminum chemistry to form aluminum complexes.…”

Hafnium(IV) chloride complexes with chelating β-ketiminate ligands: Synthesis, spectroscopic characterization and volatility study

“…deposition (MOCVD) for the growth of thin films. This is because of their easy accessibility of ligands synthesis, inexpensive, ready availability of the starting material, and controllable of steric and electronic effects [1][2][3][4][5][6][7][8].…”

“…are in good agreement with the bond distances found in similar six coordinated slightly distorted octahedral Zr(IV) and Ti(IV) complexes[28,29].The C-C-C bond angles in aromatic rings are around 120°with the variation being less than 2°, which is characteristic of sp 2 -hybridized carbons. The bond angles O1)94.20(5), N(1)-Hf(1)-Cl(1)169.49(6), N(2)-Hf(1)-Cl(1)86.79(6) and Cl(2)-Hf(1)-Cl(1)95.74…”