Topologically diverse shape-persistent bis-(Zn–salphen) catalysts: efficient cyclic carbonate formation under mild conditions

Abstract

By adopting a shape-persistent bimetallic design approach, high initial molecular turnover frequencies (up to 14,800 h(-1)) for coupling of CO2 with epoxides in conjunction with (n)Bu4NI, plus excellent yields under mild conditions (1 bar of CO2, 45 °C) have been achieved for catalysts containing cofacial Zn-salphen units.

Pacman Compounds: From Energy Transfer to Cooperative Catalysis

“…The previously mentioned Schiff base (salphen) complexes (Figure ) with xanthene or dibenzofuran backbones were not only applied in photophysical studies but also CO 2 consuming catalysis. Cofacial bis‐zinc–salphen complexes (Figure ) catalyze the coupling of CO 2 with epoxides in conjunction with n Bu 4 NI with a high initial molecular turnover frequencies (up to 14 800 h −1 ) to yield cyclic carbonates under mild conditions . Especially the compound containing the dibenzofuran backbone and bearing tert ‐butyl groups (R 1 =R 2 = t Bu, Figure ) showed outstanding abilities surpassing the ones of the momeric counterpart or the one with a xanthene backbone.…”

Sustainable Heterogeneous Catalysts for CO2 Utilization by Using Dual Ligand ZnII/CdII Metal–Organic Frameworks

“…MOFs with Lewis acidic metal centers along with strong nucleophiless uch as tetraalkylammonium halides NR 4 X( R= Et, Bu) as ac o-catalyst are well known to promotet he CO 2 cycloaddition. For selection of as uitable co- catalyst, CO 2 cycloaddition was performed in the presence of differentc o-catalysts [tetrabutylammonium bromide (TBAB), tetrabutylammoniumi odide (TBAI),a nd potassium iodide (KI)] by using the reaction conditions solvent-free, 80 8C, 0.8/1 MPa P CO2 ,a nd 1.8 mol %e ach of catalyst and co-catalyst loading ( Table 1, entries [5][6][7][8][9][10][11][12][13][14]. APCyield of 98 %, with 96 %P Oconversion, and 99 %s electivity was observed for 1 and 2 in the presence of TBAB as ac o-catalyst with the set reactionp arameters within 18 h( Table 1, entries 7a nd 12).…”

“…[1][2][3][4][5][6][7] Nevertheless, the thermodynamic stabilitya nd kinetic inertness of CO 2 are the major limitations for its conversion at mild conditions. [8][9][10] Hence, development of new catalyticm aterials for the selectivec apture and conversion of CO 2 into useful chemicals at ambient conditions has gaineds ignificant importance. [11][12][13][14][15][16] Cycloadditiono fC O 2 to epoxidesf or generation of cyclic carbonates by as uitable catalytic materialisone of the mostpromising methods for utilization of CO 2 to give value-added products.…”

“…Intensive ongoing efforts for the efficient utilization of CO 2 to value‐added chemicals by catalytic reactions has become one of the most urgent tasks in the CO 2 research field . Nevertheless, the thermodynamic stability and kinetic inertness of CO 2 are the major limitations for its conversion at mild conditions . Hence, development of new catalytic materials for the selective capture and conversion of CO 2 into useful chemicals at ambient conditions has gained significant importance .…”

Zinc–Azatrane Complexes as Efficient Catalysts for the Conversion of Carbon Dioxide into Cyclic Carbonates

“…Herein, we wish to report on the synthesis and characterization of a series of Zn II –azatrane complexes of varying stereoelectronic properties and their utilization in the coupling of CO 2 with epoxides. In addition to being inexpensive and biorelevant, several Zn complexes bearing N 2 O 2 ligands, and two examples with N 4 ‐donor ligands, have already proven their efficiency for the production of organic carbonates. To the best of our knowledge, no examples of a C 3 ‐symmetric N 4 ‐chelated Zn complex have been reported for this transformation.…”