Aluminum complexes of a hemilabile pyrrolylaldiminate ligand

Abstract

OverviewThis study describes the synthesis, characterization, and reactivity of aluminum complexes containing the amine‐functionalized pyrrolylaldiminate ligand N‐(2‐dimethylaminoethyl)‐5‐tert‐butyl‐pyrrol‐2‐ylaldiminate ([PyImN]−).SynthesisThe condensation reaction of N,N‐dimethylethylenediamine with 5‐tert‐butylpyrrole‐2‐carbaldehyde in methanol at room temperature produces H[PyImN]. Alkane elimination reactions of MeAlCl2 with H[PyImN] in toluene at 110°C and AlR3 (R = Me, Et) with H[PyImN] in toluene at −35°C afford [PyImN]AlCl2 and [PyImN]AlR2, respectively.CharacterizationSolution NMR studies reveal the coordination preferences of [PyImN]—whose hemilabile amine donor is bound to the aluminum center in [PyImN]AlCl2 but unbound in [PyImN]AlR2 (R = Me, Et).CatalysisThe catalytic activities of [PyImN]AlMe2 in controlled ring‐opening polymerization of ε‐caprolactone are discussed.