Synthesis of N-Methyl-o-phenylenediamine-Bridged Bis(phenolato) Lanthanide Alkoxides and Their Catalytic Performance for the (Co)Polymerization of rac-Butyrolactone and l-Lactide

Abstract

A series of lanthanide alkoxo complexes supported by ONNO salalen ligands were synthesized and characterized. A one-pot reaction of LH)) with LnCp 3 (THF) in a 1:1 molar ratio followed by the addition of 1 equiv of ROH (R = Bn, i Pr, and CF 3 CH 2 ), afforded the dimeric lanthanide alkoxo complexes 5), and [L 2 Yb(μ-OCH 2 CF 3 )] 2 (6) in good isolated yields. All these lanthanide complexes were characterized by elemental analysis and FT-IR spectroscopy. In addition, complex 1 has been characterized by NMR spectroscopy. Singlecrystal X-ray diffraction analysis of complexes 1, 2, 5, and 6 showed that these lanthanide alkoxo complexes are dimeric in the solid state. Complexes 1−6 showed good activity toward the homopolymerization of rac-butyrolactone (rac-BBL) to give atactic PHB, and ionic radii of central metals have profound influence on the polymerization. The polymerization behavior of L-lactide (L-LA) initiated by complex 2 was also explored. The kinetic study revealed that the polymerizations of rac-BBL and L-LA initiated by salalen lanthanide akoxide are first order for both the monomer and the initiator concentrations. Furthermore, it was found that complexes 1 and 2 showed good activity in the copolymerization of L-LA and rac-BBL, affording gradient copolymers.

Synthesis of Mono- and Dinuclear Aluminum Complexes Bearing Aromatic Amino-Phenolato Ligands: A Comparative Study in the Ring-Opening Polymerization of Cyclohexene Oxide

“…Recently, metal complexes bearing amino-bridged poly­(phenolato) ligands have been widely used as polymerization initiators, , where the ligand provides rich coordination modes that facilitate metal center stabilization. Additionally, these ligands are readily available and adjustable, enabling a thorough investigation of the relationship between the ligands and the catalytic activity of the metal complexes.…”

Tailoring the Properties of Polyhydroxyalkanoates from Plastics to Elastomers via Stereoselective Copolymerizations of rac‐β‐Butyrolactone and β‐Propiolactone

“…[ 36‐37 ] Similarly, copolymerization of rac ‐ β ‐BL and lactide (LA) was employed to modulate the thermal properties according to their composition in the resultant gradient copolymer. [ 38‐39 ] To our knowledge, poly(3‐hydroxypropionate) (P3HP), obtained through biosynthetic [ 40‐42 ] or chemosynthetic [ 43‐47 ] routes, is a ductile material with good toughness ( σ B ~ 27 MPa, ε B ~ 600%) and biodegradation. [ 48 ] However, its low T m of ~77 °C makes it difficult to apply in certain high‐temperature applications.…”

High-Throughput Approach in the Ring-Opening Polymerization of β-Butyrolactone Enables Rapid Evaluation of Yttrium Salan Catalysts

“…The lack of stereocontrol in ROP of β-BL is also in stark contrast to the highly heterotactic polylactide (PLA) obtained, when these complexes were applied in the ROP of rac -lactide (LA) . Such a behavior has similarly been observed with other catalysts showing high stereocontrol in ROP of LA but diminishing stereoselectivity in ROP of β-BL (or vice versa). − …”