New platinum(II) complexes A2Pt(OOC)2CCR2 (1, A2 = 3-aminohexahydroazepine, R2 = -(CH25-; 2, A2 = 3-aminohexahydroazepine, R = CH3; 3, A2 = 3-aminohexahydroazepine, R2 = -SCH2CH2S-; 4, A = cyclopropylamine, R2 = -SCH2CH2 S-) have been prepared and characterized. The molecular structures of the representative complexes 1 · 2H2O and 4 · C3H7NO were determined by X-ray analysis. The platinum atoms for 1 · 2H2O and 4 · C3H7NO achieve a typical square planar arrangement with each nitron atom in cis position. For 1 · 2H2O an unusually short CC bond [1.298(18) Å] has been observed in contrast to the corresponding bond [1.374(9)Å] in 4 · C3H7NO. The spectroscopic and physicochemical data disclose that these platinum complexes are stable and their molecular structures are retained in aqueous solution.