in water; acetone byproducts: AgI, NaNO3; dissolving of cis-Pt(NH3)2I2 (1 mmol) in C3H6O, addn. of AgNO3 (2.2 mmol), stirring for 10-20 min, removal of ppt.(AgI), evapn. of filtrate, crystn. of Pt(NH3)2(ONO2)2 in Et2O, drying in vac., dissolving in H2O, addn. of Na2C3H2O4, stirring for 4-5 days; filtration, evapn. of filtrate to dryness, addn. of MeOH, filtration, washing with Et2O, drying in vac.;