Crystal structure of the ferromagnetic polymer potassium Bis(carbonato)cuprate(II)

Abstract

The crystal structure of the title compound, K₂Cu(CO₃)₂, has been determined by single-crystal X-ray diffraction at 295(1) K, and refined by least squares to a residual of 0.027 for 1441 'observed' reflections. Crystals are orthorhombic, space group Fdd2, a 11.425(3), b 17.658(4), c 6.154(2) A, Z 8. The structure comprises potassium cations embedded in an infinite three-dimensional polymeric anionic array of square-planar coordinated copper atoms with bridging carbonate groups [Cu-O 1.934(2), 1.936(2) Ǻ]. Within the latter, the non- coordinating oxygen-carbon bond is shorter [1.259(3) Ǻ] than the other two [1.303(3), 1.307(2) Ǻ] and the O-C-O angle opposite it is correspondingly reduced to 117.1(2)°. The CO₃ plane lies at 83.9° to the CuO₄ 'plane'.