Isolated zirconium chloride clusters in the phase Rb sub 5 Zr sub 6 Cl sub 18 B. Generalities regarding the bonding, stability, and size of M sub 6 X sub 12 -type clusters with and without interstitial atoms
- Iowa State Univ., Ames (USA)
The cluster-phase Rb{sub 5}(Zr{sub 6}Cl{sub 12}B)Cl{sub 6} is obtained in high yield from reactions of Zr and B powders, RbCl, and a slight deficiency of ZrCl{sub 4} in a sealed Ta container at 850{degree}C. The presence of isolated Zr{sub 6}Cl{sub 18}B{sup 5{minus}} clusters of {approx}D{sub 3d} symmetry was established by single-crystal X-ray diffraction means (space group Pmna; Z = 2; a = 10.914 (4) {angstrom}, b = 9.078 (4) {angstrom}, c = 17.769 (5) {angstrom}; R, R{sub w} = 2.5, 2.7%). Close-packed layers of clusters stack in an eclipsed manner to generate suitable chlorine polyhedra for three types of rubidium cations. The family of phases A{sub z}{sup I}(Zr{sub 6}Cl{sub 12}{sup i}Z)Cl{sub n} always contains interstitial Z within the clusters, and according to extended-Hueckel MO results, the bonding is dominated by strong Zr-Z bonding and a t{sub 2g}{sup 6} metal-metal bonding HOMO configuration. The predominance of 14-electron clusters in the chloride examples, the increased number of 15- and 16-e{sup {minus}} examples found in Zr{sub 6}I{sub 12}Z-type clusters, and the occurrence of only 15- and 16-e{sup {minus}} (Nb,Ta){sub 6}X{sub 12}-type clusters (X = Cl, Br, I) under normal synthetic conditions (but 14- and 15-e{sup {minus}} types for X = F, O) all correlate with the bonding character of the a{sub 2u} HOMO and matrix effects (X{sup i}-X{sup i} repulsions) within the clusters. Larger repulsive distortions with large X, smaller M, or small Z all lead to decreased antibonding M-X{sup i} contributions in the a{sub 2u} HOMO and to 15- or 16-e{sup {minus}} clusters.
- OSTI ID:
- 5117664
- Journal Information:
- Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:9; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKALI METAL COMPLEXES
CHEMICAL BONDS
CHEMICAL PREPARATION
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
COMPLEXES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DIFFRACTION
EXPERIMENTAL DATA
HALIDES
HALOGEN COMPOUNDS
INFORMATION
INTERSTITIALS
NUMERICAL DATA
PHASE STUDIES
POINT DEFECTS
RUBIDIUM COMPLEXES
SCATTERING
SPACE GROUPS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION
ZIRCONIUM CHLORIDES
ZIRCONIUM COMPOUNDS