A condensation reaction between two cis-[PtCl2(Hmtpo)(2)] (where Hmtpo = 4,7-H-5-methyl-7-oxo[1,2,4]triazolo[1,5a]pyrimidine) molecules takes place in neutral aqueous media, giving [Pt2Cu-mtpo)(4)]. 4H(2)O (1). The X-ray structure of the recrystallization product of 1 in DMSO:EtOH (1:1) (DMSO =, dimethyl sulfoxide), namely, [Pt2Cu-mtpo)(4)]. 2DMSO (2) has been determined. Compound 2 crystallizes in the orthorhombic space group Pbcn with unit cell dimensions a = 14.207(3) Angstrom, b = 15.187(3) Angstrom, c = 17.165(3) Angstrom, and Z = 4. The molecular structure shows that the two Pt atoms are bridged by four mtpo ligands. Thus, it presents two face to face PtN4 units with a Pt ... Pt 2.744(2) Angstrom separation. Compound 1 has also been characterized by H-1 and Pt-195 NMR. The very short Pt(II)... Pt(II) contact suggests an interaction between the two metal centers, supported by the great deshielding observed for the platinum nuclei in the Pt-195 NMR spectrum (delta = -2005 ppm) compared to a Pt(II) in a typical N-4 environment. In order to make an approach to the possible bonding nature of the Pt(II) Pt(II) interaction, a theoretical analysis has been performed on the basis of the properties of the electronic charge density distribution, derived from ab initio MO calculations for the model compound {Pt-2[NHCHN(C(CH2)(CH3))]4} using RHF/LANL2DZ and B3LYP/LANL2DZ wave functions; both take into account relativistic effects and the second electronic correlation also. A significant directional interaction between the two metal centers has been found. Thus, a bond critical point appears between the two platinum nuclei, with a density of charge rho(b) = 0.056, e . bohr(-3), which is half of that found for the platinum nitrogen bond. Moreover, a value of the energy density, E(d)(r(b)) < 0 (E(d)(r) = -0.0175 hartree . bohr(-3)), at this point, shows the bonding nature of the interaction.