Synthesis and Crystal Structure of Cesium Nitratometalates(II), Cs2[M(NO3)4] (M = Mn,Co, Ni,Zn)

Crystalline cesium nitratometalates(II), Cs₂M(NO₃)₄] (M = Mn ( I ), Co ( II ), Ni ( III ), and Zn ( IV )) were synthesized from M(NO₃)₂ · n H₂O and CsNO₃ by heating at 80–120 °C over 10–12 h. According to X-ray crystal structure analysis, the compounds are built from Cs⁺ cations and M(NO₃)₄]^2– anions. The latter differ by the type of metal coordination: a dodecahedron for Mn in I (CN = 8, r_Mn–O 2.24–2.37 Å), a seven coordination for Co in II (CN = 4 + 3, r_Co–O 2.03–2.16 Å and 2.21–2.35 Å) and a tetrahedral distorted dodecahedron for Zn in IV (CN = 4 + 4, r_Zn–O 1.98–2.15 Å and 2.38–2.72 Å). Ni atom in III has a distorted octahedral NiO₆ environment provided by two unidentate and two bidentate NO₃ groups with Ni–O distances of 2.01–2.14 Å. The differences in metal coordination are discussed in terms of valence electron configurations, ionic radii, and the packing effects.