Zinc complexes of a macrocyclic N3O2 ligand for the functional modelling of alcoholdehydrogenase

The macrocyclic ligand 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane (L) and the zinc halides form the complexes L·ZnHal2 (1a–c, Hal=Cl, Br, I) and [L·ZnHal]2 ZnHal4 (2a, b, Hal=Cl, Br). The structure determination of 2a has shown that the oxygen donors of the macrocycle remain uncoordinated and there is tetrahedral ZnN3Cl coordination. The complexes catalyse the hydrogenation of aromatic aldehydes with BNAH and the dehydrogenation of isopropanol with BNA+. Although the catalytic efficiency is rather small, it surpasses that of previously reported zinc complexes.