Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

Abstract

A series of substituted pyridine dialcohols (2,6-bis(hydroxyalkyl)pyridines), 1-4, was used for the synthesis of various types of aluminum complexes. Aluminum methyl derivatives, 2-4a, were obtained by the reaction of AlMe3 with the corresponding ligand or transmetallation reactions of germylenes. Aluminum chloride complexes, 3-4b, were obtained by substitution of the Me group under the action of chlorinating agents. Methoxy-, 2-4c, or benzyloxy-, 2d, aluminum complexes were synthesized in transalkoxylation reaction of Me2Al(OX) (X = Me, Bn) by the corresponding ligand. All complexes obtained were thoroughly investigated by multinuclear NMR and X-ray analysis. It has been established that the structure of the ligand (number of carbon atoms) determines the nature of the complexes formed. Compounds were used as initiators of ring-opening polymerization of l-lactide and ε-caprolactone and showed moderate activity with controlled or immortal character.

Acidity of Al–O(H)–Al Sites in Molecular Aluminosilicate Models Enables Alcohol Dehydration Reactions

“…The bridging μ-O 13 CH 3 groups show a single resonance at δ = 53.2 ppm in the 13 C­{ 1 H} NMR spectrum at room temperature. This is in agreement with the reported values of chemical shifts for −Al–O­(CH 3 )–Al– moieties in molecular compounds. − It should be mentioned that CH 3 OH could principally also be trapped in the cage structure of 1 . The diameter of CH 3 OH calculated from the Stockmayer potential is 2.4 Å.…”

Oxidation of Methylalumoxane Oligomers

“…Me 2 AlOMe was prepared according to literature procedures . MAO (10 and 30 wt % in toluene) was obtained from Albemarle and stored in the glove box freezer upon receiving.…”

Diamidoamine Aluminum Complexes: Synthesis, Structure, L–Lactide and ϵ‐Caprolactone Polymerization

“…Earlier we successfully applied transmetallation strategy for the synthesis of aluminum methyl complex from germylenes [31] . Now we used it for the synthesis of aluminum methyl complexes based on dialkylenetriamines starting from stannylene 1 c or germylene 2 c .…”