A new nanostructured coordination polymer of divalent lead with the ligand 2,9-dimethyl-1,10-phenanthroline (dmp), [Pb(dmp)(μ-N3)(μ-NO3)]n (1), was synthesized by sonochemical methods. The polymer was characterized by scanning electron microscopy, X-ray powder diffraction, IR, 1H NMR, and 13C NMR spectroscopy, and elemental analyses. Compound 1 was structurally characterized by single-crystal X-ray diffraction. The single-crystal analysis shows that the coordination number of PbII ions is seven, (PbN4O3) has a “stereo-chemically active” electron lone pair, and the coordination sphere is hemidirected. The chains interact with each other through π–π stacking interactions to create a 3D framework. The structure of the title complex was optimized by density functional calculations. The calculated structural parameters and the IR spectrum of the title complex are in agreement with the crystal structure.