Carsten Donsbach

Mercurates from a Revised Ionothermal Synthesis Route: The Pseudo-Flux Approach.

K2Hg6Se7, Na2Hg3S2.51Se1.49, K2Hg3S1.03Se2.97, and K2Hg3S2.69Se1.31 were prepared by ionothermal treatment of K2Hg2Se3, Na2HgSe2, and K2Hg3Se4, respectively, in a nonclassical hydrosulfide ionic liquid (EMIm)(SH). In contrast to their lighter congeners, the title compounds could so far not be synthesized by inorganic polychalcogenide salt flux techniques. The applied method hence mimics polychalcogenide flux conditions, while operating at much lower temperatures below the decomposition temperature of the ionic liquid. It might thus be viewed as a pseudo-flux approach.

Solvothermal and ionothermal syntheses and structures of amine- and/or (poly-)chalcogenide coordinated metal complexes

Abstract A series of five compounds, namely [Ba(trien)2]3[SbSe4]2·trien (1) (trien=diethylenetriamine), [(Se3)Cr(en)2(Se2)Cr(en)2(Se3)]2 (2) (en=ethylenediamine), [(pren)3 Eu(Te3)2 Eu(pren)3] (3) (pren=1,3-diaminopropane), [(en)4 Ba(pren)Ba(en)4](Te3)2 (4) and [enH]4[Sn2 Se6] (5), which illustrate the transition of classical polychalcogenides to metalates, are presented, where mixed amine/(poly-)chalcogenide interaction with metal centers are in the focus of interest. A conventional aminothermal synthesis is discussed in comparison with ionothermal approaches. The compounds are considered useful precursors to study in situ interconversion of selenido- and telluridometalates under ionothermal conditions.

Alkali and Alkaline Earth Metal Derivatives of Disila-Bridged Podands: Coordination Chemistry and Structural Diversity

Within this study, the synthesis and coordination chemistry of open-chain ligands bearing disila-units is presented. Instead of basic 1:1 complexes, structural diversity was discovered in the variety of ligand and salt. Stable complexes of alkali and alkaline earth metal complexes were obtained by equimolar reactions of different salts with the disila-bridged podands 8,9-disila-EO5 (1) and 11,12-disila-EO7 (2) (EO5 = pentaethylene glycol; EO7 = heptaethylene glycol). The respective alkaline earth metal complexes of the type [Ca(8,9-disila-EO5)(OTf)2] (3), [Sr(8,9-disila-EO5)I2] (5), [Sr(11,12-disila-EO7)I]I (6), and [Ba(11,12-disila-EO7)OTf2] (7) (OTf = CF3SO3-) were characterized via single-crystal X-ray diffraction analyses. Within the reaction of the alkali metal salt NaPF6 with 1, the sodium ion acts as a template during the complexation process. Under elimination of one molecule of diethylene glycol, the dinuclear species [Na2(8,9,17,18-tetrasila-EO8)(PF6)2]·EO2 (4) (EO8 = octaethylen glycol, EO2 = diethylene glycol) is obtained, in which the sodium cations are 7-fold coordinated within a disilane-bearing framework. The reaction of 2 with CsOTf failed, leading to recrystallization of anhydrous CsOTf. By means of DFT calculations it was shown that the disila-bearing ligands are burdened with negative hyperconjugation interactions between the silicon and the oxygen atoms, but the coordination by sufficiently hard cations can easily overcompensate the competing polarization. In contrast, soft Lewis acids barely share interactions with silicon-bonded oxygen atoms. All findings are consistent with observations made in solution according to 29Si NMR spectroscopical studies.