The aluminium complexes {[κ2-N,O-(t-BuNCOPh)]AlMe2}2 (2), [κ2-N,O-(t-BuNCOPh)]2AlMe (3), and [κ2-N,O-(t-BuNCOPh)]3Al (4) were prepared through the protonolysis reaction between trimethylaluminium and one, two, or three equivalents, respectively, of N-tert-butylbenzamide. Complex 2 was also prepared via a salt metathesis reaction between K(t-BuNCOPh) and dimethylaluminium chloride. Complexes 2–4 were characterized using 1H and 13C NMR spectroscopy. Single-crystal X-ray diffraction analysis of the complexes corroborated ligand : metal stoichiometries and revealed that all the amidate ligands coordinate to the aluminium ion in a κ2 fashion. The Al–amidate complexes 2–4 were viable catalyst precursors for the Meerwein–Ponndorf–Verley–Oppenauer reduction–oxidation manifold, successfully interconverting several classes of carbonyl and alcohol substrates.
Conformational analysis of some model crown ethers and analogues via 1H and 13C NMR spectroscopy and X-ray crystallography.
