Zinc‐Catalyzed Transformation of Carbon Dioxide

Terpolymerization of β-Butyrolactone, Epoxides, and CO2: Chemoselective CO2-Switch and Its Impact on Kinetics and Material Properties

“…Polycarbonates derived from epoxides and CO 2 are a promising class of polymers because they display an attractive method to use carbon dioxide as a C1-feedstock; however, they suffer from poor mechanical stability. − Meanwhile, the ring-opening polymerization (ROP) of cyclic esters, e.g., β-butyrolactone (BBL), enables the synthesis of polyesters with defined tacticities and molecular weights. − Both polymer classes are industrially produced via condensation reactions but are also accessible via ring-opening of the respective monomers through a suitable catalyst . The predominant class of catalysts for the copolymerization of epoxides and CO 2 and the ROP of different lactones are homogeneous complexes.…”

Exploring the Sequence of Comonomer Insertion into Growing Poly(ether carbonate) Chains with Monte Carlo Methods

“…With a certain probability, the polymer chain binds in a chelating fashion with the last ether linkage (Scheme A for t ≥ 2) or the last carbonate moiety (Scheme B for t = 1) also to a second neighboring zinc center. This zinc center is, however, required for activation of the next epoxide molecule, enabling the terminal alkoxide of the growing polymer chain to open the epoxide ring. It is important to note that two metal centers are found in the vicinity also in comparable bimetallic Zn catalysts. ,, It is known that the relative coordination strength , of an ether group to a zinc center is much weaker than the respective coordination of a carbonate group. , This is also indicated by much longer bond lengths for typical zinc···O­(alkyl) 2 moieties (2.1–2.4 Å) than those for zinc···OC­(O–alkyl) 2 moieties (1.8–1.9 Å) .…”

“…With a certain probability, the polymer chain binds in a chelating fashion with the last ether linkage (Scheme 2A for t ≥ 2) or the last carbonate moiety (Scheme 2B for t = 1) also to a second neighboring zinc center. This zinc center is, however, required for activation of the next epoxide molecule, 41 enabling the terminal alkoxide of the growing polymer chain to open the epoxide ring. It is important to note that two metal centers are found in the vicinity also in comparable bimetallic Zn catalysts.…”

“…This surprisingly narrow distribution is related to the particularities of the heterogeneous DMC catalyst employed in the synthesis of poly­(ether carbonate)­s. The narrow distribution is explained readily by the fact that two zinc centers in the vicinity are needed for incorporating epoxide. , Moreover, because the coordinating strength of an ether group to a zinc center of DMC is weaker than that of a carbonate group, an incoming epoxide molecule displaces a coordinating ether group more readily than a coordinating carbonate group. This results in a statistical preference for formation of segments with n = 3–4 units.…”

Electrocatalytic Reduction of CO2 and H2O with Zn(II) Complexes Through Metal‐Ligand Cooperation

“…[16,17] On the other hand, Zn complexes are found almost exclusively in the redox inactive, divalent oxidation state and as a result, lack the ability to undergo the fundamental redox steps typical of homogeneous catalyzed reactions. [18,19] Complexes of Zn are reported to catalyze the capture and insertion of CO 2 [17,[20][21][22][23] and zinc bromide was reported to facilitate the reaction of PEt 3 /CH 2 I 2 with CO 2 to form CO. [24] Furthermore, complexes A-F represent exceptional Zn-based catalysts for CO 2 reduction. The hydride complex [k 3 -Tptm]ZnH (Tptm = tris(2-pyridylthio)methyl), A, is a catalyst for the hydrosilylation of CO 2 .…”