The first mixed-halide zirconium cluster compounds: Zr{sub 6}Cl{sub 1.6}I{sub 10.4}Be, Zr{sub 6}Cl{sub 1.3}I{sub 10.7}B, and Zr{sub 6}Cl{sub 11.5}I{sub 1.5}B. Matrix effects and halogen substitution in compact network structures
- Iowa State Univ., IA (United States)
Investigations of the effect of halogen size on structure stability have been conducted in well-reduced and heavily interbridged zirconium chloride-iodide cluster systems. The title compounds are obtained in good yields from reactions of Zr, ZrCl{sub 4}, ZrI{sub 4}, and B or Be in sealed Ta tubes for {approximately} 4 weeks at 850 {degrees}C. Single-crystal diffraction at room temperature established these as Zr{sub 6}Cl{sub 1.65(4)}I{sub 10.35(4)}Be and Zr{sub 6}Cl{sub 1.27/(3)}. These are derivatives of the Zr{sub 6}I{sub 12}C and orthorhombic Zr{sub 6}Cl{sub 13}B structures, respectively, the latter containing unusual linear chains of clusters interbridged by Cl{sup i-i} that are in turn interconnected by three-bonded Cl{sup a-a-a} atoms. The random substitution of fractional Cl at specific I sites in the first two, and I for certain Cl in the third, was positionally resolved in all cases. The replacement always occurs at two-bonded X{sup i}, so that single types of halogen are left in sites that interconnected clusters and generate the three-dimensional array. Structural changes seen in both structures are specifically related to relief of X{hor_ellipsis}X crowding in the parent structure (matrix effects). Substitution of Cl for I{sup i} in the Zr{sub 6}I{sub 12}C type greatly reduces intercluster I{hor_ellipsis}I repulsions and allows, among other things, a 0.20 {Angstrom} (5.8*5) reduction in Zr-I{sup 1-i} intercluster bond lengths. Increased Cl{hor_ellipsis}I repulsions caused by I substitution in orthorhombic Zr{sub 6}Cl{sub 11.5}I{sub 1.5}B. Phase widths found are 0{le} x {le} 1.4 for Zr{sub 6}Cl{sub x}I{sub 12-x}Z (Z=B, Be) and 0 {le} x {le} 1.5 for Zr{sub 6}Cl{sub 13-x}I{sub x}B. The limit for iodine substitution in the chlorine-rich rhombohedral Zr{sub 6}Cl{sub 12-x}I{sub x}Be is about x=2.5.
- OSTI ID:
- 263759
- Journal Information:
- Inorganic Chemistry, Vol. 35, Issue 6; Other Information: PBD: 13 Mar 1996
- Country of Publication:
- United States
- Language:
- English
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