Campus Units

Chemistry, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

2009

Journal or Book Title

Inorganic Chemistry

Volume

48

Issue

12

First Page

5403

Last Page

5411

DOI

10.1021/ic900383d

Abstract

Two La3Al11 type derivatives have been discovered in the Ca−Au−Ge system and structurally characterized by single-crystal X-ray diffraction. Compositions Ca3Au7.16(6)Ge3.84(6) (1) and Ca3Au7.43(9)Ge3.57(9) (2) lie within a non-centric Imm2 phase region with a ≈ 4.40 Å, b ≈ 13.06 Å, c ≈ 9.60 Å. The Au-richer and electron-poorer Ca3Au7.50(1)Ge3.50(1) (3) and Ca3Au8.01(1)Ge2.99(1)(4) occur within a centric Pnnm phase region with a ≈ 9.50 Å, b ≈ 13.20 Å, c ≈ 4.43 Å. Both phases contain complex [Au,Ge]116− polyanionic networks made up of hexagonal and pentagonal prisms that are filled with the electropositive Ca atoms. Both 3:11 phases represent opposed 1 × 3 × 1 superstructure distortions of CaAu2Ge2 (ThCr2Si2 type, I4/mmm), the structure of which has also been re-determined in this work. Linear muffin-tin-orbital (LMTO) calculations reveal that the symmetry variations induced by changes of the Au contents in the present 3:11 phases are consequences of bonding and structural optimizations. The hypothetical “CaAu2.33−2.67Ge1.33−1.00◻0.33” compositions, which are close to those of 14, follow through creation and elimination of vacancies within the electronegative networks of CaAu2Ge2.

Comments

This is an article from Inorganic Chemistry 48 (2009): 5403, doi: 10.1021/ic900383d. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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