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Chemical Research in Chinese Universities ›› 1999, Vol. 15 ›› Issue (3): 211-217.

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Synthesis and Crystal Structure of Dicesium trans-Dicarbonatotetraaquomagnesium, Cs2[Mg(CO3)2(H2O)4]

ZHENG Yue-qing1, ADAM Arnold2   

  1. 1. Chemistry Department, Ningbo University, Ningbo 315211, P. R. China;
    2. Institute für Anorganische Chemie, Universitāt zu Köln, D-50674 Köln, Germany
  • Received:1998-07-24 Online:1999-08-24 Published:2011-08-17

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Abstract: The title compound, Cs2[Mg(CO3)2(H2O)4], was synthesized by the dropwise addition of an aqueous solution of Mg(NO3)2 to a stirred aqueous Cs2CO3/CsHCO3 solution. A colorless needle shaped crystal was formed by slow evaporation. The crystal structure was established on the basis of the single crystal X-ray diffraction data. Cs2[Mg(CO3)2(H2O)4] crystallized in the orthorhombic space group Pbca (No. 61) with a =0.658 4(1) nm, b =1.257 9(1) nm, c =1.301 3(1) nm, V =1.077 8 nm3, Z =4, Dx=2.971 g·nm-3, μ =69.20 nm-1, F (000)=888, T =298 K, final R =0.029 and Rw=0.024 for 1 037 observed reflections. The crystal consists of Cs+ cations and the complex trans-[Mg(CO3)2(H2O)4]2- anions with each Mg atom coordinated by the six oxygens of two carbonate groups and four water molecules [ d (Mg_O)=0.203 6(4), 0.207 4(4), 0.213 4(4) nm]. The complex trans-[Mg(CO3)2(H2O)4]2- anions are arranged in a strongly compressed bcc pattern. A 3D network was formed through the intermolecular hydrogen bonds. The Cs+ cations are located in cavities, each being surrounded by nine oxygens of five complex anions with d (Cs_O)=0.306 1-0.348 8 nm. The CO32- group reveals a lowering of D3h symmetry due to site and coordination effects, but not any observable deviation from co-planarity [ d (C_O)=0.127 2(6), 0.127 5(7), 0.130 5(6) nm and O_C_O=119.6(5)°, 120.1(5)°, 120.4(5)°].

Key words: Synthesis, Cs2[Mg(CO3)2(H2O)4], Dicesium trans-dicarbonatotetraaquomagnesium, Crystal structure, Complex carbonate