A novel copper(II) complex with a pendant Schiff base: An unprecedented monodentate bonding mode of the potentially tridentate ligand

The 1:1 condensation of 1-benzoylacetone and 1,2-diaminopropane yields 6-amino-3-methyl-1-phenyl-4-azahept-2-en-1-one (HL). When copper(II) perchlorate is added to the methanolic solution of HL, followed by triethylamine in 1:2:1 molar ratio, an unusual copper(II) complex, [Cu(L)(HL)]ClO4, is separated out where the deprotonated ligand, L, is coordinated in the usual chelating tridentate manner but HL is coordinated to Cu(II) only through the amine N, i.e. it acts as a pendant ligand. The complex is characterized by X-ray crystal structure analysis.