SrAu4In4 and Sr4Au9In13: Polar intermetallic structures with cations in augmented hexagonal prismatic environments

TitleSrAu4In4 and Sr4Au9In13: Polar intermetallic structures with cations in augmented hexagonal prismatic environments
Publication TypeJournal Article
Year of Publication2008
AuthorsPalasyuk A, Dai JC, Corbett JD
Journal TitleInorganic Chemistry
Volume47
Pages3128-3134
Date PublishedApr
Type of ArticleArticle
ISBN Number0020-1669
Accession NumberISI:000254902000033
Keywordscluster, crystal-structure, examples, gold substitution, indides, metals, networks, rb, STABILIZATION, ZIGZAG CHAINS
Abstract

The title compounds were synthesized via high-temperature reactions of the elements in welded Ta tubes and. characterized by single-crystal X-ray diffraction analyses and band structure calculations. SrAu3.76(2)In4.24 Crystallizes in the YCo5In3 structure type with two of eight network sites occupied by mixtures of Au and In: Pnma, Z = 4, a = 13.946(7), b = 4.458(2), c = 12.921(6) angstrom. Its phase breadth appears to be small. Sr4Au9In13 exhibits a new structure type, P (6) over barm(2), Z= 1, a = 12.701(2), c = 4.4350(g) degrees. The Sr atoms in both compounds center hexagonal prisms of nominally alternating In and Au atoms and also have nine augmenting (outer) Au + In atoms around their waists so as to define 21-vertex Sr@Au9M4In8 (M = Au/In) and Sr@Au9In12 polyhedra, respectively. The relatively larger Sr content in the second phase also leads to condensation of some of the ideal building units into trefoil-like cages with edge-shared six-member rings. One overall driving force for the formation of these structures can be viewed as the need for each Sr cation to have as many close neighbors as possible in the more anionic Au-In network. The results also depend on the cation size as well as on the flexibility of the anionic network and an efficient intercluster condensation mode as all clusters are shared. Band structure calculations (LMTO-ASA) emphasize the greater strengths (overlap populations) of the Au-In bonds and confirm expectations that both compounds are metallic.

DOI10.1021/ic702145y
Alternate JournalInorg. Chem.