Synthese, Charakterisierung und quantenchemische Studien zu Zintl-Anionen und intermetalloiden Clustern

Table of Contents: Based on the diploma thesis and work on the binary anions (Tt2Pn2)2− of group 14 (Tt = Sn) and group 15 (Pn = Sb, Bi) by my former colleague, F. Lips, this thesis contributed to the group of intermetalloid clusters of the elemental combination lanthanide tin/lead bismuth. Furthermore, the reactivity of heteroatomic group 13 bismuth Zintl anions of the formula (TrBi3)2− were examined. In a further study, various elemental combinations of lanthanides, lead, and bismuth (lanthanide: La, Ce, Nd, Gd, Sm, Tb) were used and the influence of the interstitial lanthanide atom size on the stability of different types of maingroup metal shell enneahedra was investigated. Results indicate that the smaller lanthanide ions preferred a 13-atom enneahedra over a 14-atom enneahedra. Continued work on the endohedral lanthanide tin bismuth clusters (lanthanide: Nd, Sm) resulted in comparable compounds of samarium (anion of compound 2) and neodymium analogs (anion of compound 3) of the known 13 and 14 atom enneahedra topologies. Despite poor single crystal X-ray diffraction data, it was possible to determine a structural model of the clusters in the compounds 2-3. The purpose of isoelectronic substitution of (Tt2Bi2)2− anions was to select the otherwise co-crystallizing, ternary enneahedra. The use of the binary (InBi3)2− anion in reactions with lanthanide complexes of the type [Ln(CpMe4)3] (Ln = La, Ce, Nd), previously employed in the formation of compounds including intermetalloid tin/lead bismith clusters, resulted in new compounds containing bridged 13 atom cluster anions – {[Ln@In2Bi11](μ–Bi)2[Ln@In2Bi11]}6− (anions of the compounds 4-6) – and a non-bridged anion–[Ce@In2Bi11]4− (anion of compound 7). The analysis of the clusters in the compounds 4-6 disclosed further differences in characteristics and reactivity of (TrBi3)2− anions compared to their isoelectronic (Tt2Bi2)2− analogs. The higher basicity of the indium atoms was in most cases (with the exception of one non-bridged cluster) compensated by the bridging of formal positively charged „Bi+“ atoms. Quantumchemical calculations show that isoelectronic substitution does not result in 14 atom enneahedron for any compound (4-6), as expected additional increase of the basicity of the triel atom by substitution of indium for gallium afforded the first protonated ternary intermetalloid clusters – [Ln@Ga2HBi11]3− and [Ln@Ga3H3Bi10]3− (Ln = La, Sm; anions of the compounds 8 and 10). Again only 13 atom topology was observed. Additionally, the protonation helped to elucidate the formation of the enneahedra. An intense spectroscopic and spectrometric analysis of the byproducts and several quantumchemical calculations clarified the origin of the protons and furthermore explained the redox processes and the whereabouts of the complex ligand CpMe4 . The cluster anions showed C–H and/or C–C bond activation, evidence of possible catalytic activity which warrants further examination. In a reaction, which should end up in a compound including lathanum gallium bismuth clusters (compound 10), a new gallium bismuth anion with unprecedented topology was observed, (Ga2Bi16)4− (anion of compound 11). This observation indicates, that small binary anions might be used under certain conditions as building blocks for larger binary polyhedra, longer chains, layers, or networks. 4. Altering the solvent afforded the first polycyclic anion, Bi3− 11 (anion of the compound 12), the heaviest homologue of the Pn3− 11 “ufosane“ series. The isolation of this anion suggests that even more polycyclic bismuth anions might become accessible. In the course of this study, the replication of P4 activation with isoelectronic Zintl anions was attempted. Initial results using NHCs were promising. The formation of unknown anionic Ga–NHC species detected by ESI-MS and of compound 12 were observed, answering the question of gallium whereabouts. The figure 5.1 gives a résumé.