About the Crystal Structure of CuNb(OH, F)7 · 3H2O

✍ Scribed by M.P. Crosnier-Lopez; H. Duroy; J.L. Fourquet

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 152 KB
• Volume: 108
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1994.1058

✦ Synopsis

Single crystals of (\mathrm{CuNb}\left(\mathrm{OH}, \mathrm{F}{7} \cdot 3 \mathrm{H}{2} \mathrm{O}\right.) have been grown from aqueous HF solutions. Their crystal structure is isotypic with that of (\mathrm{CuTiF}{6} \cdot 4 \mathrm{H}{2} \mathrm{O}) and consists of bent chains of trans- (F)-linked alternate (\mathrm{Cu}\left(\mathrm{H}{2} \mathrm{O}, \mathrm{OH}, \mathrm{F}\right){6}) and (\mathrm{Nb}\left(\mathrm{OH}, \mathrm{F}{6}\right.) octahedra, running along the ([101]) direction of the monoclinic unit cell ( (P 2{1} / c, a=) 5.590 (1) (\AA, b=9.978(4) \AA, c=7.544(1) \AA), and (\beta=103.36(1)^{\circ}); (R=0.0272) and (R_{\mathrm{w}}=0.0272) for 459 reflections and 58 parameters). Bond valence calculations reveal a partial disorder between (\mathrm{OH}^{-}), (\mathrm{F}^{-}), and water molecules on all the nonbridging anionic sites. The (\mathrm{CuX} \mathrm{X}_{6}) octahedra are classically distorted by the Jahn-Teller effect. A network of (\mathrm{O}-\mathrm{H} \ldots). . Fhydrogen bonds ensures the tridimensional cohesion of the structure. ") 1994 Academic Press. Ine.