Aluminium compounds containing bidentate ligands: chelate ring size and rigid conformation effects

Polymerization of methyl methacrylate and other polar monomers with alkylaluminum initiators bearing bidentate and tridentate N‐ and O‐donor ligands

“…Although aluminum‐based olefin polymerization systems are yet to be well understood, their discovery has prompted an increased interest in the use of ligated, cationic aluminum complexes for catalytic applications. In addition to a large synthetic effort in the area of tetradentate, N,N ′ ,O,O ′‐ligated SALEN complexes,11 the recent organometallic literature has featured reports of many new alkylaluminum compounds bearing bidentate and tridentate N,N ′‐, N,S ‐, or N,O ‐donor ligands 37–51. These species have the potential to function as very active catalysts because of their less coordinatively saturated nature.…”

An Unusual N‐Bridged (Amido)(hydrido)(phenoxido)aluminium Dinuclear Compound – The Role of Nitrogen Substituents in Determining Nuclearity: A Combined Experimental and Theoretical Study

“…The stability of mononuclear or dinuclear aluminium derivatives with analogous N,O-donor ligands depending on electronic and steric factors have been previously studied. [25,60] In addition, a discussion of the factors affecting the coordination modes of amidate ligands to aluminium has been reported. [55] Thus, we started a computational study in order to clarify and rationalize the structural behaviour observed in the final products obtained in the treatment of AlH 3 ·NEtMe 2 with iminophenol and aminophenol compounds, depending on the nitrogen substituents.…”

“…[37,51] Examples are known with both O and N atoms bridging in hydroxypyridine ligands (in an isolobal disposition to carboxylatebridged ligands) [25] or with an amidate group [52][53][54][55] between two aluminium atoms.…”

“…This structural behaviour contrasts with that found in the literature: O-bridging structures are generally observed in polynuclear aluminium derivatives supported by bridging phenoxido-imino and related ligands. [22,25,39,40] …”

“…Bidentate N,O-donor ligands [20][21][22][23][24][25] constitute simple nonsymmetric chelating structures that impose control over the metal coordination geometry with a sterically demanding chelating structure. Phenoxidoimido [26][27][28] and the closely related phenoxido-amino bidentate systems [29][30][31] have been widely used for transition metals and to produce alkylaluminium complexes and their cationic derivatives, [32][33][34] which can be utilized as catalysts in ROP processes [24] of heterocyclic monomers and in ethylene polymerization reactions.…”