Cyclopentadienyl/scorpionate magnesium

Fig. 14 Hybrid cyclopentadienyl/scorpionate magnesium complexes (bpzcpjMgR (47-52) by Sanchez-Barba and coworkers [69]...

Hybrid scorpionate/cyclopentadienyl-Mg (63) and -Zn (64,65) complexes were structurally characterized and reported to catalyze the formation of PLAs with medium molecular weights and narrow polydispersities [85]. Among them, the magnesium complex 63 is much more active than the others, giving a polymerization of L-lactide in toluene at 90 °C with 97% conversion in 2.5 h. However, it takes 30 h for zinc complexes 64 and 65 to reach similar results under the same conditions. Some representative structures of magnesium and zinc complexes are summarized in Table 2 as they display closely related ROP activity of lactide, and often stmcrnrally similar ligand systems are employed to construct these initiators. 

Garces A, Sanchez-Barba LF, Alonso-Moreno C, et al. Hybrid scorpionate/ cyclopentadienyl magnesium and zinc complexes synthesis, coordination chemistry, and ring-opening polymerization studies on cyclic esters. Inorg Chem. 2010 49 2859-2871. 

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