Complex of formula [Cu(L-Arg)(phen)Cl)Cl center dot 2H(2)O (1) was synthesized in crystalline form (triclinic crystal system, P1 (No. 1) space group with a = 9.376(1) angstrom, b = 10.415(1) angstrom, c = 12.209(2) angstrom and Z = 2). The relations between the crystal structure, DFT calculations, spectroscopic properties (FT-IR, FT-Raman, NIR-Vis-UV, EPR) as well as the parameters of magnetic data were investigated. The square pyramidal geometry around copper (II) cations is very slightly distorted toward bipyramid geometry. The DFT-calculated interaction energies (AE) for the L-Arg zwitterion and phen ligands are -135.31 and -54.17 kcal mol(-1), respectively. The g tensor diagonal components obey the relationship g(parallel to) > g(perpendicular to) (g(perpendicular to) = 2.063, g(parallel to) = 2.23) which suggested the pure d(x2-y2) ground state orbital. Analysis of the crystal structure shows two possible magnetic exchange pathways: the neighboring [Cu(L-Arg)(phen)Cl](+) cations are linked in dimeric units by the N-H center dot center dot center dot Cl type hydrogen bonds, and almost parallel phenanthroline molecules provide pi-pi stacking interaction between the dimers. Analysis of the magnetic data, using an alternating ferro- and antiferromagnetic chain model for S = 1/2 spins, reveals the existence of weak antiferromagnetic coupling within the dimers (J(AF) = -0.23 cm(-1)) and weak ferromagnetic interaction between dimers (J(F) = 0.11 cm(-1)).