10.1021/om401047r.s002 Joice S. Klitzke Joice S. Klitzke Thierry Roisnel Thierry Roisnel Evgeny Kirillov Evgeny Kirillov Osvaldo de L. Casagrande Osvaldo de L. Casagrande Jean-François Carpentier Jean-François Carpentier Yttrium– and Aluminum–Bis(phenolate)pyridine Complexes: Catalysts and Model Compounds of the Intermediates for the Stereoselective Ring-Opening Polymerization of Racemic Lactide and β‑Butyrolactone American Chemical Society 2014 Racemic Lactide ONOMe yttrium centers carbonyl group PHB Yttrium compounds 1 ROP aluminum complexes parent methyl BBL aluminum compounds heterotactic PLAs racemic LA 13 C NMR data Model Compounds carbonyl groups Optimal conditions 1 equiv 2014-01-13 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Yttrium_and_Aluminum_Bis_phenolate_pyridine_Complexes_Catalysts_and_Model_Compounds_of_the_Intermediates_for_the_Stereoselective_Ring_Opening_Polymerization_of_Racemic_Lactide_and_Butyrolactone/2333398 Yttrium and aluminum complexes of an original pyridine-bis­(phenolate) ligand have been prepared. Reactions of {ONO<sup>Me,Cumyl</sup>}­Y­[N­(SiHMe<sub>2</sub>)<sub>2</sub>]­(THF)­(Et<sub>2</sub>O) (<b>1</b>) with 1 equiv of methyl (<i>R</i>)-3-hydroxybutyrate and methyl (<i>S,S</i>)-lactyllactate afforded respectively {ONO<sup>Me,Cumyl</sup>}­Y­((<i>R</i>)-OCH­(CH<sub>3</sub>)­CH<sub>2</sub>COOMe) (<b>2</b>) and {ONO<sup>Me,Cumyl</sup>}­Y­((<i>S</i>,<i>S</i>)-OCH­(CH<sub>3</sub>)­CO<sub>2</sub>CH­(CH<sub>3</sub>)­CO<sub>2</sub>Me) (<b>3</b>), which are rare models of the active species in the ring-opening polymerization (ROP) of β-butyrolactone (BBL) and lactide (LA), respectively. <sup>13</sup>C NMR data for <b>2</b> and <b>3</b> indicate that, in solution, the carbonyl groups coordinate onto the yttrium centers, forming mononuclear species with six- and five-membered cycles, respectively. The aluminum compounds {ONO<sup>Me,Cumyl</sup>}­Al­(<i>i</i>Pr (<i>S</i>)-lactate) (<b>5</b>), {ONO<sup>Me,Cumyl</sup>}­Al­((<i>R</i>)-OCH­(CH<sub>3</sub>)­CH<sub>2</sub>COOCH<sub>3</sub>) (<b>6</b>), and {ONO<sup>Me,Cumyl</sup>}­Al­((<i>rac</i>)-OCH­(CF<sub>3</sub>)­CH<sub>2</sub>CO<sub>2</sub>C<sub>2</sub>H<sub>5</sub>) (<b>7</b>) were prepared analogously from the parent methyl complex {ONO<sup>Me,Cumyl</sup>}­AlMe (<b>4</b>). NMR data and the solid-state structure of <b>6</b> confirm the coordination of the carbonyl group. Yttrium compounds <b>1</b> and <b>2</b> are active initiators for the ROP of racemic LA and BBL. Their performances (activity, control of the molecular weights, tacticity) are much affected by the nature of the solvent or by the addition of just a few equivalents of pyridine. Optimal conditions are quite contrasted for the ROP of <i>rac</i>-LA and <i>rac</i>-BBL, highlighting fundamental differences between these two monomers. In the best cases, highly heterotactic PLAs (<i>P</i><sub>r</sub> up to 0.96) and syndiotactic-enriched PHB (<i>P</i><sub>r</sub> up to 0.86), with good control over the molecular weights, were obtained.