Aluminum, Indium, and Mixed Yttrium–Lithium Complexes Supported by a Chiral Binap-Based Fluorinated Dialkoxide: Structural Features and Heteroselective ROP of Lactide

The
new chiral Binap-based fluorinated dial­cohol proteo-ligand
{ONNO}­H2 has been prepared under its enantiomerically pure
and racemic forms following reaction of (R)- or (rac)-1,1′-binaphthyl-2,2′-diamine with 5,5,5-trifluoro-4-hydroxy-4-(trifluoromethyl)­pentan-2-one.
The racemic proteo-ligand reacts with the trivalent metallic precursors
AlEt2Cl and In­(CH2SiMe3)3 to yield the complexes (rac)-{ONNO}­AlCl (1) and (rac)-{ONNO}­In­(CH2SiMe3) (2), while the reaction of (R)-{ONNO}­H2 with a 1:1 mixture of Y­(N­(SiMe3)2)3 and LiN­(SiMe3)2 gives
the enantiomerically pure heterobimetallic ­[((R)-{ONNO})2Y·Li] (3). Complex 3 acts as a single-component
initiator for the near-perfect heteroselective ring-opening polymerization
(ROP) of racemic lactide, yielding polymers with Pr up to 0.99 under mild conditions. It also
produces syndiotactic-enriched polylactide (Pr = 0.80) by ROP of meso lactide.