Beiträge zur Strukturchemie von Chalkogenotetrelen, Mercuraten und supramolekularen Netzwerken mit Quecksilber : Darstellung, Kristallstrukturen und elektronenmikroskopische Untersuchungen

Based on optimized solid state syntheses (e.g. controlled thermal decomposition of azides) new chalcogenotetrels and -mercurates are prepared and characterized by solid state chemical methods. More advanced aspects of the new compounds are discussed with reference to the structural chemistry of related solids. The following new mixed valence chalcogenotetrels of alkali metals were obtained starting from alkali metal chalcogenides (A 2 X, A: alkali metal, X: chalcogenides) which were prepared before in separate reactions: K 2 Sn 4 S 8 , K 2 Sn 3 GeS 8 , K 2 Sn 2 Ge 2 S 8 and K 2 SnGe 3 S 8 . The new compounds show typical coordination polyhedra for the tetrel atoms in accordance with their oxidation states (e.g. tetrahedral or φ-trigonal bipyramidal coordination for the four and two valent states). Systematic evaluations of results from single crystal structure analyses did not show any evidence for a substitution of Sn(II) by Ge and the existence of K 2 Ge 4 S 8 (corresponding to K 2 Sn 4 S 8 ). Based on investigations of the quasi binary sections A 2 X-HgX (A = Na, K; X = S, Se, Te) the crystal structure of K 2 Hg 3 Se 4 was redetermined. The structure of this solid is characterized by one dimensional infinite HgSe 4/2 (HgSe 2/2 ) 2 -chains, which form pseudo layers via secondary chemical bonding interactions. The layers are separated by alkali metal atoms. In the field of mercury containing host-guest-compounds the two new compounds [Hg 6 Z 4 ](InBr 6 )Br (Z = As, Sb) could be obtained and were structurally characterized. They are isotypic to [Hg 6 Sb 4 ](SbBr 6 )Br. The cationic networks of these solids are based on a three dimensional connection of ethane analogous Z 2 Hg 6/2 -units. In the case of the cationic networks of the new compounds [Hg 2 Sb]MCl 4 (M = Al, Ga) corner sharing (SbHg 4/2 + )- tetrahedra are observed. The tetrahedral anions are located in suitable holes of the network and are reoriented as consequence of a first order phase transition. The compound [Hg 6 Sb 4 ](Ga 2 Br 7 )Br crystallizes in a new structure type. Its cationic network consists of a combination of (SbHg 4/2 + )-tetrahedras and Sb 2 Hg 4/2 E 2 -units (E = free electronpair) formally analogous to the molecule hydrazine.