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Synthesis and characterization of zirconium-chloride clusters stabilized by small interstitial atoms

Thesis/Dissertation ·
OSTI ID:5477326

Over thirty new zirconium chloride cluster compounds based on discrete Zr/sub 6/Cl/sub 12/ clusters centered by Be, B, C, N and H have been prepared in high yield and structurally characterized. The compounds fall into the family M/sub x/ (Zr/sub 6/Cl/sub 12/Z)Cl/sub n/, where n ranges from zero to six, and span eleven structure types and two new stoichiometries for M/sub 6/X/sub 12/-type clusters, namely M/sub 6/X/sub 13/ and M/sub 6/X/sub 16/. Six new structure types, KRz/sub 6/Cl/sub 13/Be, K/sub 2/Zr/sub 6/Cl/sub 15/B, K/sub 3/Zr/sub 6/Cl/sub 15/Be, Cs/sub 3/Zr/sub 6/Cl/sub 16/C, Na/sub 4/Zr/sub 6/Cl/sub 16/Be and Rb/sub 5/Zr/sub 6/Cl/sub 18/B, and several variations on known structure types are involved. Nine new examples of compounds in the Nb/sub 6/Cl/sub 14/ structure are included. M/sub x/Zr/sub 6/Cl/sub 15/Z compounds in four structure types, Ta/sub 6/Cl/sub 15/, CsNb/sub 6/Cl/sub 15/, K/sub 2/Zr/sub 6/Cl/sub 15/B, and K/sub 3/Zr/sub 6/Cl/sub 15/Be and several variations thereon are described. Compounds in three new structure types with unshared terminal chlorine atoms, Na/sub 4/Zr/sub 6/Cl/sub 16/Be, Cs/sub 3/Zr/sub 6/Cl/sub 16/C and Rb/sub 5/Zr/sub 6/Cl/sub 18/B are also given. Extended-Hueckel calculations on empty and centered M/sub 6/X/sub 18/ clusters demonstrate the s and p valence orbitals of the interstitial atom interact strongly with symmetry equivalent Zr-Zr bonding cluster orbitals to form four lower lying metal-interstitial bonding orbitals. The matrix effect and the strength of the zirconium to interstitial bonding are implicated in the differences in electron count observed between centered zirconium chloride clusters and the related centered zirconium iodide and empty niobium and tantalum halide clusters.

Research Organization:
Iowa State Univ. of Science and Technology, Ames (USA)
OSTI ID:
5477326
Country of Publication:
United States
Language:
English