Coordination behaviour of acetylacetone-derived Schiff bases towards rhenium(I) and (V)

The oxo-bridged dinuclear rhenium(V) complex [(μ-O){ReOCl(amp)}2] (1) was prepared by the reaction of trans-[ReOCl3(PPh3)2] and 6-amino-3-methyl-1-phenyl-4-azahept-2-ene-1-one (Hamp) in acetone. The characterization of 1 by elemental analysis, infrared and 1H NMR spectroscopy and X-ray crystallography shows that amp is coordinated as a monoanionic NNO-donor chelate as an amino-amido ketone. However, the reaction of the similar ligand 7-amino-4,7-dimethyl-5-aza-3-octen-2-one (Hada) with [Re(CO)5Br] produced fac-[Re(CO)3Br(Hada)], with Hada coordinated as a neutral bidentate N,N-donor amino-imino-ketone.

Two complexes of Re(I) and (V), containing potentially tridentate Schiff base ligands, based on acetylacetone, were prepared. With Re(I) the ligand coordinates solely via the two nitrogen atoms, but with Re(V) tridentate NNO coordination is observed.Figure optionsDownload as PowerPoint slide