Highly active bimetallic nickel catalysts for alternating copolymerization of carbon dioxide with epoxides

Abstract

Catalyst 1 was reported for the first time to be effective for nickel-catalyzed CO2/CHO copolymerization at 1 atm CO2 pressure.

Bimetallic Nickel Complexes Containing Benzotriazole-Derived Diamine-Bisphenolate Ligands as Highly Active Catalysts for the Copolymerization of Carbon Dioxide with Cyclohexene Oxide: Synthesis, Catalysis, and Kinetics

“…The average Ni–O­(O 2 CCF 3 ) bond length in 1 was found to be 2.1308(19) Å, which is significantly larger than that (2.073(2) Å) of Ni–O­(acetato) in complex A , suggesting that the electron-withdrawing O 2 CCF 3 coligands are more labile carboxylates to coordinate Ni ions. Note that the distance between the two nickel atoms for 1 is 2.8101(5) Å, which approximates the Ni–Ni separation (∼3.0 Å) for nickel complexes reported to be highly active catalysts toward CO 2 /CHO copolymerization. , The ORTEP drawing in Figure illustrates that 8 is a homologous dinickel dicarboxylate species, except that two 4-methoxybenzoate groups assume different bonding modes and one water molecule also coordinates with the Ni atom. Not surprisingly, the average bond distances between the nickel ion and O­(phenoxy), N­(benzotriazole), and N­(amine) are respectively 2.0410(18), 2.102(2), and 2.113(2) Å for complex 8 , which are all similar to those of the isostructural Ni complex [( C8MEA DiBTP )­Ni 2 (OAc) 2 (H 2 O)] ( B ) containing a benzotriazole-supported salan-type ligand, as shown in Table .…”

“…Considering that the highly active copolymerization catalysis of CO 2 and epoxides could be successfully achieved by dinuclear metal complexes, our group has prepared a number of bimetallic cobalt and nickel complexes that are constructed by well-tailored hexadentate ligand scaffolds. − These ancillary ligands are mainly classified as benzotriazole-containing bis­(iminophenolate) and benzotriazole-based bis­(aminophenolate) ligand skeletons: namely, salen-type and salan-type ligand frameworks in this study, respectively. Most of the dinickel complexes served as single-component catalysts for mediating high-pressure CO 2 copolymerization of alicyclic epoxides.…”

“…The average Ni−O(O 2 CCF 3 ) bond length in 1 was found to be 2.1308(19) Å, which is significantly larger than that (2.073(2) Å) of Ni−O(acetato) in complex A, suggesting that the electron-withdrawing O 2 CCF 3 coligands are more labile carboxylates to coordinate Ni ions. Note that the distance between the two nickel atoms for 1 is 2.8101(5) Å, which approximates the Ni−Ni separation (∼3.0 Å) for nickel complexes reported to be highly active catalysts toward CO 2 / CHO copolymerization 32,33. The ORTEP drawing in Figure2illustrates that 8 is a homologous dinickel dicarboxylate species,…”

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

“…Considering the next most active catalyst in the series, Mg(II)Ni(II) catalyst, 6 , and comparing it to other known Ni(II) catalysts also reveals some promising features [31,42] . Ko and co‐workers pioneered Ni(II) catalysts, reporting a series of high activity di‐Ni(II) complexes, coordinated by modified benzotriazole Schiff‐base ligands (TOF=9600 h −1 , 0.01 mol%, 140 °C, 21 bar) [31,42b,43] . The catalysts also perform well at 1 bar CO 2 pressure, for example showing a TOF of 96 h −1 (0.06 mol%, 100 °C, 1 bar) [42b] .…”

Alternating Copolymerization of Carbon Dioxide with Epoxides Using Highly Active Dinuclear Nickel Complexes: Catalysis and Kinetics

“…Despite no significant increase of the catalyst activity on altering 1,2diamine-substituted DiBTP derivatives as the mutidentate ligands, 34 the well-tailored dinickel diacetate catalyst bearing a 1,3-diamine-linked DiBTP skeleton copolymerized CO 2 and CHO with an outstanding catalytic performance and good controllability of molecular weight. 35 On the basis of the previous catalysis results from metal complex-catalyzed CO 2copolymerization of CHO, 23,31 the choice of carboxylate ligands on metal atoms has a great influence on the catalytic efficiency. Furthermore, no 1,3-diamine-bridged DiBTPsupported Ni complexes containing other bidentate carboxylate initiators/coligands such as trihaloacetate or benzoate derivatives have been isolated to date.…”