Aluminium complexes salen-type

Table 2. Neutral, mononuclear complexes of aluminium with dianionic salen-type (Rl) groups. R2 = other ligand, L = Lewis base, C.N. = coordination number of the metal...

A hither facet of research has involved the structural characterisation of aluminium complexes which incorporate polydentate salen-type ligands. These have been noted in both neutral and monocationic (ion-separated) contexts (the latter requiring that the metal centre be stabilised by an external Lewis base) [35]. While such charged systems are invariably mononuclear the same is only usually true of their neutral analogues by virtue of the sterically demanding bis(aryloxide), chelating ligand. In the context of these latter complexes, dimerisation has been noted [251] while, more recently, the employment of flexible alkyl chains between two salen-coordinated aluminium ions has enabled the observation of dinuclear compounds [160, 161]. 

Highly enantioselective catalytic conjugate addition of A-heterocycles, namely purines, benztriazole, benzimidazole, and 5-phenyltetrazole, to a,ft-unsaturated ketones and imides has been attained with chiral, salen-type (Jacobsen) aluminium complexes as catalysts.142... 

---