Synthesis and structure of four-coordinate dimethyl aluminium complexes incorporating new N,O-chelating arylamido ligands

Abstract

A new type of arylamido ligands with an intramolecular coordinating ortho-ether-substituent (i.e. a O,N − chelating ligand) is introduced. The achiral and chiral 4-coordinate dimethyl aluminium complexes [2-ROC 6H 4NR′]AlMe 2 ( 4a: R=R′=Cy; 4b: R=(−)-menthyl, R′=Cy, 4c: R=(−)-menthyl, R′=CPh 3) have been prepared by reaction of the appropriate amido Li salt with ClAlMe 2. Complex 4a could also be obtained, via methane elimination, by reaction of AlMe 3 with the corresponding ligand. The presence of two rotamers in solution at room temperature for 4b and for 4c is most likely due to a restricted rotation of the (−)-menthyl group at this temperature due to severe steric interactions with the rest of the complex.