0000000000810276
AUTHOR
Insa Taden
Aluminum complexes of sterically hindered tetradentate Schiff bases: Synthesis, structure, and reactivity toward ɛ-caprolactone
Abstract The sterically hindered Schiff bases tbmSalenH2 [tbmSalen = N,N′-1,2-ethylenebis(3-tert-butyl-5-methylsalicylideneimine)] and tbmSalcenH2 [tbmSalcen = N,N′-trans-1,2-cyclohexanediyl-bis(3-tert-butyl-5-methylsalicylideneimine)] afforded a series of aluminum complexes of the general formulae [Al(tbmSalen)X] and [Al(tbmSalcen)X] (X = Cl, Me, Et). The molecular structure of [Al(tbmSalcen)Cl] was determined by single-crystal X-ray structural analysis which revealed a five-coordinate aluminum center with a distorted square pyramidal geometry. The alkyl complexes were found to oligomerize ɛ-caprolactone.
Alcoholysis of Aluminum Alkyls Supported by Bulky Phenoxide Ligands: Synthesis, Characterization, and ε-Caprolactone Polymerization Activity of Two Dimeric Aluminum Isopropoxides
Reaction of trialkylaluminum Al2R6 (R = Me, Et) with 2,2′-methylenebis(6-tert-butyl-4-methylphenol) (mbmpH2) gives the dimeric mono(alkyl) complex [Al(mbmp)R]2 with bridging oxygen atoms. Reaction of [Al(mbmp)R]2 with one equiv. of 2-propanol results in the formation of the dimeric isopropoxide [Al(mbmp)(μ-OiPr)]2. Single-crystal X-ray analysis shows a C2h-symmetric structure with a planar Al2O2 core. Monomeric methylbis(2,6-di-tert-butyl-4-methylphenolato)aluminum, AlMe(OC6H2-2,6-tBu2-4-Me)2 (MAD), was found to react with one equiv. of 2-propanol to give a dimeric isopropoxide [AlMe(OC6H2-2,6-tBu2-4-Me)(μ-OiPr)]2 in which the bulky phenolate, instead of the methyl group, has been displaced…