Synthesis and Crystal Structure of the Copper Complex of bis[(2-Aminoethyl)aminomethyl] malonate

Condensation of bis(ethanediamine) copper(II) perchlorate with formaldhyde and diethyl malonate in basic methanol generates the amino acid ester complex (diethyl bis[(2-aminoethyl)aminomethyl] malonatecopper(II) perchlorate), [Cu(L1)](ClO4)2. Base-catalyzed ester hydrolysis in water of [Cu(L1)]2+ yields bis[(2-aminoethyl)aminomethyl] malonatocopper(II) tetrahydrate, CuL2 · 4 H2O. The two copper(II) complexes were characterized by element analysis, molar conductance, infrared, and electronic spectra studies. The structure of CuL2 · 4 H2O was determined by X-ray diffraction (XRD). The crystal structure reveals that the copper ion is an octahedra with four nitrogens at the equational position and two oxygens at the axial positions.