Synthesis, structure and catalytic activity of rare-earth metal complexes derived from chiral phosphoryl-sulfonylamides.

A series of rare-earth metal complexes have been prepared from phosphoryl-sulfonylamides. These complexes are active catalysts for the polymerization of rac -lactide, leading to the heterotactic-rich polylactides. [Display omitted] • Five rare-earth metal complexes derived from chiral phosphoryl-sulfonylamides have been prepared. • They are active catalysts for the polymerization of rac-lactide. • Heterotactic-rich polylactides are obtained. A series of rare-earth metal amides derived from (S)- N -(1-(2-(diphenylphosphoryl)phenyl)ethyl)benzenesulfonamide (HL1) and (S)- N -(8-(diphenylphosphoryl)-1,2,3,4-tetrahydronaphthalen-1-ylbenzenesulfonamide(HL2) were prepared, and their catalytic activity for the polymerization of rac- lactide was explored. The amine elimination reactions of Ln[ N (SiMe 3) 2 ] 3 with HL1 or HL2 gave the mono-ligated rare-earth metal amides (L1) Ln[ N (SiMe 3) 2 ] 2 (Ln = Nd (1), Sm (2) and Yb (3)) or bis-ligated rare-earth metal amides (L2) 2 Ln[ N (SiMe 3) 2 ] (Ln = Nd (4), Sm (5)) in good yields. All of these complexes were characterized by elemental analyses and X-ray diffraction analyses. Complexes 1 – 5 are efficient initiators for the ring-opening polymerization of rac- lactide, affording heterotactic-rich polylactides. The ionic radii of the central metals have a significant effect on the catalytic activity. [ABSTRACT FROM AUTHOR]