Synthesis, characterization, and structural analysis of (1:2) mixed cationic lanthanide potassium hexacyanoferrate(II) tetrahydrate

The crystal structural investigation of 1:2 (La/Pr)KFe(CN)(6). 4H(2)O (I) has been determined from three-dimensional, single-crystal, X-ray diffraction data and refined by least-squares method to yield a final reliability (R) factor of 0.016 based on 363 unique reflections. The title compound crystallizes in the hexagonal space group P6(3)/m (No. 176) with a = 7.381(1), c = 13.855(3) Angstrom. For Z = 2, the calculated density is 2.354 Mg m(-3) (exp., 2.347 (4) Mg m(-3)). The coordination about the lanthanide central atoms is nine, and the geometric polyhedron is a tricapped trigonal prism (TTP). Cyanide bridging links the octahedral FeC6 groups to the 9-coordinated (La/Pr)N-6(H2O)(3) groups. The uncoordinated water molecule and the potassium ion occupy holes in the lattice along the threefold axis above and below the lanthanide atoms. Selected bond distances and angles are presented as well as discussions of the synthesis, TGA, IR, and digital SEM/EDS results, and other peripheral studies of I. (C) 1999 Elsevier Science S.A. All rights reserved.