Beiträge zur Chemie schwerer Chalkogenidometallate

Die vorliegende Arbeit hatte das Ziel, einen optimierten Syntheseweg zur Darstellung bekannter und neuer binärer Chalkogenidometallatanionen der schwersten, nicht-radioaktiven Elemente zu finden. Die so erhaltenen Verbindungen sollten zu ternären Metallatanionen umgesetzt werden. Alle erhaltenen Ver...

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Bibliographic Details
Main Author: Thiele, Günther
Contributors: Dehnen, Stefanie (Prof. Dr.) (Thesis advisor)
Format: Dissertation
Language:German
Published: Philipps-Universität Marburg 2015
Chemie
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Table of Contents: The aim of the present work has been the optimization of the synthesis of known and new binary chalcogenido metalate anions of the heaviest, non-radioactive elements. Those compounds were to be used for reactions towards ternary metalate anions. All obtained compounds were to be investigated towards their physical properties. Two synthetic routes towards chalcogenido plumbates were successfully identified. On the one hand via the in-situ-reduction of chalcogen-rich lead chalcogenides with elemental potassium in ethylene diamine to yield the trichalcogenido diplumbate in high yield and abundance. On the other hand the tetraselenido ortho-plumbate(IVI, as the first non-oxidic lead(IVI-chalcogene compound, could be obtained under solvothermal reaction conditions. The method of in-situ -reduction could be applied analogously for the synthesis of binary anions of the chalcogenido mercurates, thallates, and bismutates. Solutions of the trichalcogenido diplumbates react with noble transition metal compounds towards molecular compounds with transition metal chalcogen bonds, while the plumbate serves as oxidizing agent and/or chalcogenide transferring agent on the one hand; on the other hand the selenido plumbate can also generate the new {PbSe} ligand. Solvothermal extractions of AxMyChz, that was generated via solid-state high temperature methods, yields – besides the unexpected ortho-plumbate(IVI – a variety of new chalcogenido mercurates and thallates that were characterized in detail. Furthermore a simple access towards chalcogenido bismutates has been identified. The stoichiometry of (A2Ch):(MxChy )I purports the spacial extension of the anionic substructures, while the choice of solvent – probably due to the corresponding Lewis basicity – of the reaction solution is of importance for the generation of the corresponding anionic motifs. In side reactions, polychalcogenides could crystallographically and spectroscopically be identified. Ethylene diamine oligomerizes upon addition of alkali metals such as potassium or its heavier homologues. Acetonitrile oligomerizes in the presence of Ni2+- or Pb2+-ions under solvothermal reaction conditions, while the pH-value seems to determine the degree of oligomerization. By means of molecular quantum chemical calculations the stability of the ortho-plumbate (IVI could be rationalized. Furthermore the analogy of the {PbSe} ligand to the known CO ligand could be illustrated and the optical and NMR-chemical data of polychalcogenides could be interpreted. New conformations of polychalcogenides could be predicted by comparison of absolute energies. Via quantum chemical calculations with periodic boundary conditions the impact of alkali metal ions and the corresponding crystal packing effects on the NMR chemical shift of polytellurides was determined, as well as the development of band gaps within ternary chalcogenido mercurates. K2Hg2Se3 was identified as a material of high photo conductivity and low thermal conductivity. The determination of the ZT value for this compound, as those for K2Hg2Te3, K3Hg6Se7, K2Hg2Se3 and K6TlSe4-H2O, that are not all discussed in detail within the present work, are still pending. For ionothermal reaction conditions, the Lewis basicity of the reaction solution alongside the generation of ion pairs – according to the (SAB concept – seems to be of overriding importance. In conclusion, a new synthetic access toward chalcogenido metalates in solution was found and a variety of new metalate compounds was synthesized and characterized. Alongside, the first ortho-selenido plumbate (IVI and a metal complex including a {PbSe}-ligand were obtained.