[(Zr₆B)Cl_11-<i>_x</i>I₂₊<i>_x</i>] (0 ≤ <i>x</i> ≤ 6): A New Mixed-Halide Structure with Zigzag Chains of Clusters in Multiply Twinned Crystals

The new [(Zr6B)Cl11-xI2+x] phase (with 0 ≤ x ≤ 6) is obtained from reactions of ZrI4, ZrCl4, and elemental Zr and B for 2−4 weeks in sealed Ta tubing at 800−850 °C. Single crystals of [(Zr6B)Cl6.44(7)I6.56] have been characterized by X-ray diffraction at room temperature (orthorhombic Pbcn, Z = 4, a = 12.365(2) Å, b = 15.485(3) Å, c = 13.405(2) Å). This structure contains zigzag chains of boron-centered (Zr6B) octahedra that are interconnected by Cli-i halides. Further three-dimensional connectivity is achieved by Ia-a-a bridges. The noncluster interconnecting two-bonded Xi sites are occupied statistically by a mixture of Cl and I. For each site both positions were resolved. This structure forms within a phase width of 0 ≤ x ≤ 6 at temperatures between 800 and 850 °C. Crystals of this phase appear to be always multiply twinned.