A novel polymeric one-dimensional compound Cu(tn)Cl-2 (tn = 1,3-diaminopropane) was prepared and structurally characterized, and its spectral, magnetic, thermodynamic, and thermal properties were studied. The unique structure shows ladderlike chains composed of Cu-II atoms and chloro bridging ligands [Cu(-mu(3)-Cl-)Cu-2] running along the crystallographic c axis. The coordination geometry about copper (4 + 2) approximates that of a strongly elongated octahedron. The equatorial plane of the coordination octahedron is formed by a chelate N-bonded to ligand and two chloro ligands. One of the chloro ligands is terminal, and the other one, mu(3)-Cl-, forms two additional longer bonds to the neighboring copper atoms and thus occupies the axial octahedral positions. The electronic ground state of the Cu-II ion is of d(z2) symmetry and suggests the activation of intraladder and interladder Cl center dot center dot center dot H-N hydrogen bonds as exchange paths that form a two-dimensional pattern of a triangular symmetry. The interaction due to the hydrogen bonds seems to play an important role in molecular packing and magnetic coupling. The studies of magneto-structural correlations including electron paramagnetic resonance measurements and thermodynamic and magnetic properties revealed a two-dimensional character of magnetic correlations with the effective intralayer exchange coupling J/k(B) approximate to -3 K. No phase transition to the ordered state has been observed down to 60 mK. Cu(tn)Cl-2 with the interlayer coupling J' approximate to 10(-3)J and moderate intralayer interaction represents an excellent example of a two-dimensional magnetic system.