The title complex trans-[Cu(sac)(2)(en)(2)] (sac = saccharinato, en ethylenediamine) has been obtained accidentally by the reaction of piperazine (ppz) with [Cu(sac)(2)(H2O)(4)] center dot 2H(2)O in butanol solution. During the reaction, ppz was presumably decomposed to produce en which then coordinated to copper(II) to yield the title complex. trans-[Cu(sac)(2)(en)(2)] has been characterized by elemental analysis, IR, UV- VIS, magnetic measurements and single crystal X-ray diffraction. The compound crystallizes in space group P (1) over bar ( No. 2) and it consists of neutral units linked by bi- and trifurcated N-H center dot center dot center dot O hydrogen bonds into chains which are further connected by aromatic pi-pi stacking interactions forming a three-dimensional supramolecular network. The copper( II) ion in [Cu(sac)(2)(en)(2)] sits on a inversion centre and is octahedrally coordinated by two neutral en and two anionic sac ligands. An elongated distorted octahedral geometry along the Cu - N-sac bonds is a consequence of the Jahn - Teller effect. The en ligand acts as a bidentate (N, N') chelating ligand, while sac is N-coordinated. IR and UV spectra and thermal analysis are in agreement with the crystal structure.