Synthesis and X‐Ray Structure of New Copper(II) Nitrates: Cu(NO 3 ) 2 · H 2 O and β‐modification of Cu(NO 3 ) 2

Blue crystals of a Cu(NO 3 ) 2 · H 2 O were synthesized by interaction of CuO with boiling 100% HNO 3 . Stable β‐Cu(NO 3 ) 2 modification was obtained by the sublimation of copper(II) nitrate in evacuated ampoule over the 150→100°C temperature gradient for 24 hr. According to X‐Ray single crystal analysis Cu(NO 3 ) 2 · H 2 O is monoclinic with a = 6.377(1), b = 8.548(1), c = 9.769(1) Å, β = 100.41(1)°, Z = 4, and space group P2 1 /c. β‐modification Cu(NO 3 ) 2 is orthorhombic with a = 14.161(5), b = 7.516(3), c = 12.886(2) Å, Z = 12, and space group Pbcn. In the both structures Cu atoms are square coordinated by 4 O atoms at the distances ranging from 1.92 to 2.02 Å. In each structure there are also additional CuO bonds with the distance of 2.33 or 2.35 Å and some weaker ones with the distances in the range of 2.65–2.72 Å. In the Cu(NO 3 ) 2 · H 2 O structure the [CuO 4 ] squares are connected by the bridging NO 3 groups into zigzag chains, which are linked into layers by the longer CuO bonds. In the β‐Cu(NO 3 ) 2 structure the [CuO 4 ] fragments of two types are joined by the bridging NO 3 groups in a three‐dimensional framework. Some correlations were found between NO distances and coordination functions of O atoms.