Crystal structure of zirconium monochloride. A novel phase containing metal-metal bonded sheets

Abstract

Monocrystals of ZrCl were obtained by the reaction of ZrCl4(g) with a large excess of electropolished Zr in a sealed tantalum tube under a 600-800 OC gradient for 24 days. Integrated diffraction data were secured on an automated diffractometer using Mo Ka radiation. Systematic absences among 203 observed reflections together with tuned diffraction data established a C-centered monoclinic cell with a = 5.943 (6), b = 3.419 (3), c = 9.087 (18) A, p = 102.5 (1)O, Z = 4. The structure was solved by standard Patterson and Fourier techniques to a conventional residual of 0.080 and R, = 0.087. The structure contains homoatomic layers sequenced C1-Zr-ZrC1 so as to generate four-layer sheets, the layers and sheets being geometrically close to cubic close packed along [OOl]. The result is found to be within experimental error of a higher symmetry trigonal cell ( Z = 6) with the rhombohedral space group R3m. The diffraction data were therefore converted, averaged, and refined utilizing 85 independent reflections, half as many positional parameters, and a = 3.424 (2), c = 26.57 (4) to give R = 0.071 and R, = 0.087. Distances are not statistically distinguishable in the two refinements; although the rhombohedral description is formally preferred, the real symmetry probably depends appreciably on the crystalline perfection in the [OOl] direction. Each zirconium atom has three neighbors in the adjacent sheet at 3.09 A (Pauling bond order of O S ) , six more in the same sheet at 3.42 A, and three chlorine atoms on the other side at 2.63 A. Weak chlorine-chlorine interactions between sheets at 3.61 A contrast with the strong metal-metal binding within the sheets; the former are presumably responsible for the graphitic properties and anisotropic conduction of the compound.

Synthesis and crystal structures of hydrogen and carbon stabilized lutetium monochloride, LuClHx and Lu2Cl2C

“…The structure determination of LuCIH, confirms previous results obtained from powder data [5]. The heavy-atom structure is analogous to that known for ZrCl [3]. Hydrogen positions did not refine, although this was attempted for the tetrahedral interstices (0, 0, z with z estimated to 0.197) in analogy to TbC1D,,8 [9].…”

Transition Metal Pnictide-Halides: A Class of Under-Explored Compounds

“…The b-ZrNCl structure shows several similarities to ZrCl, mentioned earlier in this review. ZrCl consists of closely-packed layers of ions in Cl-Zr-Zr-Cl slabs and the stacking sequence of zirconium and chlorine in ZrCl and ZrNCl are identical; |AbcA|B-caB|CabC| [47]. The result is approximately antiprismatic, nearest neighbour, coordination of zirconium and chlorine.…”

Superconducting nitride halides MNX (M = Ti, Zr, Hf; X = Cl, Br, I)

“…In older and recent reports the monohalides of zirconium [83][84][85] and the rare-earth metal halide carbides [86,87], especially Y 2 Br 2 C 2 , were mentioned as prominent examples for related crystal structures. Due to their similar stacking sequences of metal layers and halide anions it is near at hand to compare these compounds with their MNX relatives, particularly since lithium intercalation into YClH x (ZrBr-type structure) succeeded [88].…”