During the last years, research on coordination chemistry of platinum has aroused great interest due to their potential biological applications. Herein, we report the interaction of PtCI₄^2- with different polyazacyclophanes containing a pyridine unit as aromatic spacer. Formation of complexes has been studied by ¹H and ¹⁹⁵Pt NMR spectroscopy. Analysis of the recorded spectra of D₂O solutions containing L and PtCl₄^2- in a 1:1 molar ratio at acidic pH shows the evolution with time of the ¹H and ¹⁹⁵Pt signals. Different crystal structures have been solved by X-ray diffraction analysis. At acidic pHs, the metal ion is coordinated by the central amino group of the macrocyclic cavity and three chloride or bromide atoms, in a square planar geometry. Formation of [Pt(H₂L1)Br₃]Br (1) and [Pt(H₂L2)Br₃]Br (2) reveals the rapid substitution of chloride ligands in PtCl₄^2- by bromide ligands. However, as reveals the crystal structure obtained for [Pt^IVL3Br₂](PtBr₄)(H₂O) (4), at slightly higher pH values, the metal ion is coordinated through all nitrogen atoms of the macrocyclic cavity and an oxidation to Pt(IV) occurs.