K{sub 2}La{sub 6}I{sub 12}Os: A new structure type for isolated clusters that is generated by cation requirements
- Iowa State Univ., Ames, IA (United States). Dept. of Chemistry
Reaction of KI, La, LaI{sub 3}, and Os in a welded niobium tube at 800 C yields black, air-sensitive crystals of K{sub 2}-La{sub 6}I{sub 12}Os. The phase was characterized by single-crystal X-ray diffraction. The structure contains tetragonally compressed La{sub 6}I{sub 12} clusters centered by Os and interbridged by I{sup a} atoms according to the general pattern of (R{sub 6}Z)I{sub 6}{sup i}I{sub 6/2}{sup i-a}I{sub 6/2}{sup a-i} for all examples with X:R ratios of 2:1. However, the detailed pattern of three-bonded I{sup i-a} and I{sup a-i} bridging is new owing to the need to accommodate a relatively large, distorted cluster and two potassium ions in a more open structure. One type of I{sup i-a} and I{sup a-i} bridging defines zigzag chains of clusters with strain evident in the interconnections. EHMO calculations show that the observed 0.49 {angstrom} tetragonal compression of the 16-electron cluster (relative to an optimal 18-e) splits the nominal t{sub 1u}{sup 4} HOMO into a two-below-one patterns and gives a closed-shell configuration. The compound accordingly exhibits only a small and typical temperature-independent paramagnetism, {approximately}6 {times} 10{sup {minus}4} emu/mol.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States); USDOE, Washington, DC (United States)
- OSTI ID:
- 642377
- Journal Information:
- Inorganic Chemistry, Vol. 37, Issue 8; Other Information: PBD: 20 Apr 1998
- Country of Publication:
- United States
- Language:
- English
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