Synthesis and characterization of Zn(II) and Cu(II) complexes bearing (chiral substituent)(diethyl)-ethanediamine derivatives as precatalysts for rac-lactide polymerisation

Synthesis, structures, and catalytic efficiency in ring opening polymerization of rac-lactide with tridentate vs. bidentate cobalt(ii), zinc(ii), and cadmium(ii) complexes containing N-substituted N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amine ligands

“…Moreover, conducting the ROP reaction using [L n MX 2 ] (L n ¼ L A or L B ; M ¼ Co or Zn, with X ¼ Cl; M ¼ Cd, with X ¼ Br) in the absence of MeLi resulted in negligible amounts of PLA. 31,85 77 e Probability of heterotactic enchainment (P r ) were calculated on the basis of homonuclear decoupled 1 H NMR spectra according to literature. [55][56][57][58] The stability of the studied systems was determined implementing a sequential ve-stage rac-LA polymerization reaction using [L B ZnCl 2 ]/MeLi system at 25 C (Table S4; Fig.…”

Synthesis and Characterization of Zinc(II), Cadmium(II), and Palladium(II) Complexes with the Thiophene-Derived Schiff Base Ligand

“…To activate the dichloro complexes for ROP, an in situ approach was used with dichloro M­(II) complexes pretreated by LiO i Pr to form the metal-isopropoxide derivatives. Earlier, the preactivation strategy was reported as an effective means to generate highly efficient initiators. , The M n values of PLA obtained with gel permeation chromatography (GPC) indicated a low-molecular-weight polymer; almost half of the theoretical M n values suggested the growth of two polymer chains per metal center. The low-molecular-weight PLA was attained because of two reasons.…”

Highly active cobalt(II) and copper(II) complexes supported by aminomethylquinoline mediating stereoselective ring‐opening polymerization of rac‐lactide

“…10 Recent advancements in developing efficient stereoselective catalysts are based on late transition metal initiators with different ancillary ligands toward the ROP of rac-LAs. [11][12][13][14][15][16] We recently established the role of the initiating groups, namely, LiMe, LiO i Pr, and LiCl, based on their basicity, for Zn(II) complexes in a controlled ROP of rac-LA. 17 In our previous studies on LA polymerization, we focused on the LiMe system.…”

“…This pre-activation strategy has been a successful method for generating highly efficient initiators. 13,25 Four complex catalysts [LCoCl 2 ]/LiMe, [LCuCl 2 ]/ LiMe, [LCoCl 2 ]/LiO i Pr, and [LCuCl 2 ]/LiO i Pr were then employed for the polymerization of rac-LA as an initiator (Table 1 and Figures S6-S17). All catalysts showed reasonably controlled polymers with high monomer conversion (>97%) and narrow molecular weight distributions (MWDs <1.3) within 10 min.…”

“…Various catalytic systems have been judiciously designed with the [LMR] formula, where M and L represent metals and an ancillary ligand, respectively, and R denotes the initiation group, such as an alkoxide, phenoxide, and/or amide 10 . Recent advancements in developing efficient stereoselective catalysts are based on late transition metal initiators with different ancillary ligands toward the ROP of rac ‐LAs 11–16 . We recently established the role of the initiating groups, namely, LiMe, LiO i Pr, and LiCl, based on their basicity, for Zn(II) complexes in a controlled ROP of rac ‐LA 17 .…”