Centered zirconium chloride cluster compounds with the Ta 6Cl 15 structure

Abstract

The phases Zr 6Cl 15N, Na 0.5Zr 6Cl 15C and Na 2Zr 6Cl 15B, all isostructural with Ta 6Cl 15, are prepared by reactions of zirconium powder, ZrCl 4, NaCl when necessary, and ZrNCl, NaN 3, NH 4Cl, graphite or amorphous boron as appropriate in sealed tantalum containers at 700 °C (N) and 850 °C (B, C). Structures of the first two phases have been refined by single-crystal X-ray diffraction (space group Ia3 d, a = 21.171(1), 21.466(1) Å, R = 6.1, 3.2%; R w = 4.9, 3.4%, respectively). The non-metal atoms are centered in all Zr 6 trigonal antiprisms ( d(Zr-N) = 2.273(1) A ̊ , d(Zr-C) = 2.7758(5) A ̊ ) with sodium in the latter disordered over one-sixth of the 48 g positions. According to tuned single-crystal diffractometer data, the third phase exhibits a small tetragonal distortion of the parent structure. The connectivity of the (Zr 6Cl 12Z)Cl 6 2 units in this structure is described and the structure contrasted with those of three other, non-interconvertible structures with the same connectivity, CsNb 6Cl 15, K 2Zr 6Cl 15B and Nb 6F 15.