Crystal Structures and Characterization of Copper(II) Complexes of N,N,N'N'-Tetrakis(2-pyridylmethyl)-1,2-ethanediamine

The structure of [Cu(tpen)](ClO4)2 (tpen = N,N,N',N'-tetrakis(2-pyridylmethyl)-1,2-ethanediamine) has been identified by X-ray crystallography. The copper(II) ion is surrounded by two amine N atoms and three pyridine N atoms of the ligand, making a distorted trigonal-bipyramid. Among the six potential N donor atoms (two amine N and four pyridine N atoms), only one pyridine N atom remains uncoordinated. We examined structural changes on addition of Cl− to [Cu(tpen)] (1). The addition of Cl− in methanol resulted in the formation of a novel dinuclear copper(II) complex [Cu2Cl2(tpen)](ClO4)2·H2O. The structure of the dinuclear complex was verified by X-ray crystallography. Each copper(II) ion in the dinuclear complex showed a distorted square planar geometry with two pyridine N atoms, one amine N atom and one Cl− ion.