Heterobimetallic rare earth metal–zinc catalysts for reactions of epoxides and CO₂ under ambient conditions

Abstract

Rare earth–zinc heterobimetallic complexes are more active than monometallic rare earth complexes in the cycloaddition of CO2 and epoxides under ambient conditions.

Cycloaddition of di-substituted epoxides and CO2under ambient conditions catalysed by rare-earth poly(phenolate) complexes

“…Decreasing catalytic activity (39-86% yield) was observed along with decreasing ionic radii (Table 1, entries 1-4), which is consist-Scheme 4 Synthesis of rare-earth complexes 1-6. ent with reported results. 48,[52][53][54] Bulkier and more electrondonating aryl-substituents lead to higher activity, as complex 1 and 5 outperformed 6 (Table 1, entries 1, 5 and 6). The catalytic difference of 1 and 5 was small, as there is only one different para-substituent.…”

“…A large number of catalysts have been developed to catalyse the cycloaddition reaction, including transition metals (e.g., Cr, [15][16][17] Fe, [18][19][20][21] Co, [22][23][24][25][26][27] and Zn [28][29][30][31][32][33] ), main group metals (e.g., Mg, [34][35][36] Al, [37][38][39][40][41][42] Ca [43][44][45][46] ), rare-earth metal catalysts [47][48][49][50][51][52][53][54][55][56][57] and organocatalysts. 5,[58][59][60][61][62][63]…”

“…76,77 Our group have developed rare earth complexes stabilized by poly( phenolto) ligands to catalyse the cycloaddition reaction of epoxides with CO 2 . 48,49,[51][52][53][54] Neodymium complex NdL A THF (a) bearing a tetra( phenol)derived ligand catalysed cycloaddition of mono-substituted epoxides with 1 bar CO 2 at 85 °C (Scheme 3, left), 48 while changing the ligand to a tris( phenolto) ligand resulted in catalyst LaL B THF (b) active under ambient conditions for mono-substituted epoxides (Scheme 3, middle). 53 In view of the significant improvement resulted from changing the ligand scaffold, we introduced a labile amino moiety (-CH 2 CH 2 NMe 2 ) to the tris ( phenolto) ligand, which led to complex of further enhanced activity (Scheme 3, right).…”

“…, Cr, 15–17 Fe, 18–21 Co, 22–27 and Zn 28–33 ), main group metals ( e.g. , Mg, 34–36 Al, 37–42 Ca 43–46 ), rare-earth metal catalysts 47–57 and organocatalysts. 5,58–65 Some catalysts have been reported to catalyse reactions of mono-substituted epoxides under ambient conditions (1 bar CO 2 and 25 °C).…”

Bifunctional Rare‐Earth Metal Catalysts for Conversion of CO2 and Epoxides into Cyclic Carbonates

“…[42,43] In recent years, our group has developed a series of rare earth metal complexes bearing different ligand frameworks, which have found application in the cycloaddition reaction of CO 2 and epoxides. [36,[44][45][46][47][48][49] In this contribution, we have developed bifunctional rare earth metal complexes as single-component catalysts, which catalyzed the cycloaddition of terminal epoxides under 1 bar CO 2 pressure.…”