Landvogt, Christian Rudolf: Gold-Tellurium Clusters and Tetrachloridoaurates with Divalent Cations. - Bonn, 2017. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
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author = {{Christian Rudolf Landvogt}},
title = {Gold-Tellurium Clusters and Tetrachloridoaurates with Divalent Cations},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2017,
month = apr,

note = {The solid state reaction of AuX3, Te and a Lewis-acidic metal halide results in a series of compounds containing the new cationic gold-tellurium cluster (Au6Te18Xn)(6-n)+. AuTe2X can be used instead of AuX3, but depending on the kind of Lewis-acidic metal halide the product can be different. The Lewis acids AlX3, GaCl3, ZrCl4, MoOCl3, BiCl3, NbCl5 and TaCl5 have all been used to successfully obtain (Au6Te18)[ZrCl6]3, (Au6Te18)[AlX4]6, (Au6Te18X)[MCl4]5, (Au6Te18Cl)[MoOCl4]5, (Au6Te18Cl2)[Mo2O2Cl8]2, (Au6Te18Cl2)[Bi4Cl16] and (Au6Te18Cl2)[MCl6]4.
With two exceptions the crystal structures of all target compounds were solved, even though the x-ray diffraction data for some compounds give ambiguous results, because of disordered sites within the cation. The structure of the cation itself can be derived from a cube. Taking a 3x3x3 cube, analogous to the Rubik's cube, all 27 blocks represent a possible atom position. The central block of each face is occupied by a gold atom. The cube's centre and two corner positions are unoccupied and the remaining 18 positions are occupied by tellurium. For compounds with halide atoms X attached to the cation, these atoms occupy one or both of the empty corner positions.
Further investigation towards the physical properties of this new class of compounds reveals a high diamagnetic moment for the cation itself (χmol = -8.2 * 10-4 cm3/mol). Both compounds containing isolated MoV atoms show the expected paramagnetism corresponding to their d1 configuration (1.67 µB and 1.83 µB). Semi-conducting behaviour is observed for three of the compounds and is expected for the untested compounds, too, because all samples are of black-metallic appearance. Additionally, the electronic structure of three representatives is investigated by theoretical calculations, which reveal band gaps between 0.4 eV to 2.0 eV. These calculations also provide valuable help for the interpretation of the ambiguous x-ray diffraction data sets. As a second central result achieved in this work, the first salts of divalent metal cations with [AuCl4]- anions are reported. The compounds Cd[AuCl4]2 and Zn[AuCl4]2*(AuCl3)1.115 are obtained from reactions of MCl2 and elemental gold in liquid chlorine and subsequent annealing. The crystal structures of both compounds are reported herein. The latter compound possesses an incommensurately modulated composite crystal structure. The first subsystem contains polymeric chains of zinc(II) tetrachloroaurate(III), while the second subsystem consists of Au2Cl6 dimers, which are located in channels built up by the first subsystem. The structural parameters of these dimers show only small deviations from neat AuCl3. It is revealed from a detailed analysis of the crystal structure that the 4+2 coordination sphere, usually found for Au3+, is only achieved for both subsystems through interaction with each other.},

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