Synthesis and structural characterization of two five coordinate aluminum alkyl and bis(trimethylsilyl)amino complexes bearing acyclic tetradentate Schiff bases

Two acyclic Schiff-base ligands, bis-5,5′-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-one and bis-5,5′-(1,3-ethanediyldiimino)-2,2-dimethyl-4-hexene-3-one, were used to complex homoleptic triethylaluminum and tris[bis(trimethylsilyl)amino]aluminum, respectively. The acid–base reactions proceeded in excellent yields with elimination of ethane or bis(trimethylsilyl)amine during in situ deprotonation of the protio Schiff-base. The colorless aluminum complexes crystallized from n-pentane and were characterized by standard methods including single crystal X-ray diffraction. Polymerization of racemic lactide, with addition of alcohol, yielded PLA with narrow polydispersities but low molecular weights.

Graphical abstractThe synthesis and characterization of two acyclic Schiff base aluminum complexes are presented. The complexes adopt five coordinate trigonal bipyramidal geometry and can be activated with MeOH to polymerize rac-lactide.Figure optionsDownload full-size imageDownload as PowerPoint slide