摘要

TlAlCl4 and TlGaCl4 crystallize isotypic in the BaSO4 structure type. Both, TlAll(4) and TlGal(4) crystallize isotypic in a distorted LiAlCl4 structure type. In contrast to the tetrachloro and tetraiodo compounds, the tetrabromoaluminate and -gallate crystallize not isotypic with each other. TlAlBr4 is found to crystallize isotypic with KAlBr4 whilst TlGaBr4 crystallizes in its own structure type. Despite the high diversity in structure types adopted by the studied TlMX4 compounds, all of them can be regarded as distortions from the BaSO4 structure type resulting from rotation Of the MX4 tetrahedra against each other. Because of this, low symmetry coordination environments around the thallium cation are generated. Comparison with isotypic alkali metal compounds shows that the strongly distorted thallium surroundings cannot be attributed to a stereochemical activity of the 6s(2) lone pair.

  • 出版日期2009