Crystal structure and physical properties of anhydrous sodium copper carbonate
The crystal structure of the title compound has been established by single-crystal X-ray diffraction methods from photographic data. The structure was solved by conventional Patterson and Fourier heavy-atom methods and refined by block-diagonal least-squares techniques to R 0籱 for 286 independent reflections. Crystals are monoclinic, space group p21/a, with Z= 2 in a unit cell with dimensions : a= 6籸(2), b= 8籹(2), c= 5綴(2)Ŭ = 116粨2)The asymmetric unit is one half of the formula unit. The structure consists of copper atoms occupying special positions of symmetry , co-ordinated by four planar oxygen atoms [Cu-O(1) 1繵(1); Cu-O(2) 1繰(1)Ŭ O(1)-Cu-O(2) 88編5)੬ the distortion from the exact square plane not being significant. The copper atoms are bridged by, but not coplanar with, carbonate groups in an infinite two-dimensional polymeric puckered sheet in the ab plane, successive sheets being interleaved by sodium ions. The carbonate ions, although planar, are significantly distorted, the non-co-ordinated bond being much shorter [C-O(3), 1粲(2)ũ than the other two (C-O(1), 1糶(2); C-O(2), 1粹(2)ŝ. The i.r. spectrum displays splittings providing supporting evidence for distorted stereochemistries of the CuO4 and CO3 groups, the metal-oxygen and carbon-oxygen asymmetric stretching modes being appreciably split, and possibly characteristic of the bridging carbonate group. The magnetic moment of 1繲 ᠰ簴 BM over the temperature range 100-400 K is consistent with the requirements of square planar co-ordinated copper(II) and is indicative of little or no copper-copper interaction (CuCu, 4縹 ũ.
Journal of the Chemical Society : Dalton Transactions : Inorganic Chemistry
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