[Cu(NH3)2](NO3)2 (I) and [Cu(NH3](NO3)2 (II) were synthesized by interaction of molten NH4NO3 with [Cu(NH3)4](NO3)2 and Cu(NO3)2 · 3 H2O, respectively, at 180 to 195°C for 24 hr. According to X‐Ray single crystal analysis, I is orthorhombic (sp. gr. Pbca) with a = 5.678(1), b = 9.765(2), c = 11.596(2) Å, Z = 4, R = 0.060; II is monoclinic (sp. gr. P21/c) with a = 6.670(1), b = 8.658(2), c = 9.661(2) Å, β = 101.78(2)°, Z = 4, R = 0.027.
In both structures, the nearest coordination environment of Cu is a slightly distorted square formed by N (from NH3) and O atoms (from NO3 groups). The structure of I consists of centrosymmetrical [Cu(NH3)2](NO3)2 molecules linked by hydrogen bonds. The CuN and CuO distances are 1.98 and 2.01 Å, respectively. In II, the CuN distance is 1.95 Å, the CuO distances are 1.96, 2.02, and 2.03 Å. The [CuO3NH3] squares are connected by NO3 bridges into zigzag chains, which are linked into layers by longer CuO interactions (2.31 Å). Obviously, the layers are additionally strengthened and held together by hydrogen bonds.