X-ray diffraction investigations and spectral analyses of monoclinic SmKFe(CN) 6 · 3H 2O

Abstract

Single-crystal and powder X-ray diffraction data, X-ray fluorescence and thermal gravimetric analyses, conoscopic results, and infrared spectral data are presented for SmKFe(CN) 6 · 3H 2O. The compound crystallizes in the monoclinic space group P2 1 m (No. 11), a = 7.329(2), b = 13.689(4), c = 7.324(3) Å, β = 119.97(3)°, Z = 2, D m = 2.37(1) Mg m −3, and D x = 2.376 Mg m −3. Final least-squares full-matrix refinement yielded R = 0.0574 and R w = 0.0568 for 2138 unique reflections. The samarium ion is nine-coordinated forming a tricapped trigonal prism geometry. The octahedral FeC 6 groups are linked to the SmN 6(H 2O) 3 groups by cyanide bridging. The coordinated water molecules occupy general positions at two-thirds occupancy. The uncoordinated water molecule and the potassium ion (each at 0.5 occupancy) occupy holes in the structure. Important mean bond distances are: SmN = 2.478(5); SmO = 2.678(4); FeC = 1.899(5); and CN = 1.156(3) Å.