Günther Thiele

K4[PbSe4]⋅en⋅NH3: A Non‐Oxide, Non‐Halide Inorganic Lead(IV) Compound

The first inorganic lead(IV) compound without oxygen, nitrogen or halogen ligands attached to the lead atom was obtained as the potassium salt of the tetraselenidoplumbate(IV) anion [Pb(IV) Se4 ](4-) . It is stable under inert conditions which may enable the transfer of the chemistry of chalcogenidogermanate(IV) or chalcogenidostannate(IV) materials, to the lead homologues.

{μ-PbSe}: a heavy CO homologue as an unexpected ligand.

Reactions of [K(18-crown-6)]2 [Pb2 Se3 ] and [K([2.2.2]crypt)]2 [Pb2 Se3 ] with [Rh(PPh3 )3 Cl] in en (ethane-1,2-diamine) afforded ionic compounds with [Rh3 (PPh3 )6 (μ3 -Se)2 ](-) and [Rh3 (CN)2 (PPh3 )4 (μ3 -Se)2 (μ-PbSe)](3-) anions, respectively. The latter contains a PbSe ligand, a rather uncommon homologue of CO that acts as a μ-bridge between two Rh atoms. Quantum chemical calculations yield a significantly higher bond energy for PbSe than for CO, since the size of the ligand orbitals better matches the comparably rigid Rh-Se-Rh angles and the resulting Rh⋅⋅⋅Rh distance. To rationalize the bent coordination of the ligand, orbitals with significant ligand contributions and their dependence on the bonding angle were investigated in detail.

Stable Alkali-Metal Complexes of Hybrid Disila-Crown Ethers

The complexation ability of hybrid disilane and ethylene containing crown ether ring systems was analyzed using 1,2-disila[12]crown-4 (1), 1,2-disila[15]crown-5 (2), 1,2-disila[18]crown-6 (3), and 1,2,7,8-tetrasila[12]crown-4 (7). Alkali-metal complexes (Li(+), Na(+), K(+)) were obtained and analyzed via X-ray diffraction. The complex stability of [Li(1,2-disila[12]crown-4)](+) and [Li(1,2,7,8-tetrasila[12]crown-4)](+) was determined, in relation to the lithium complex of [12]crown-4, by density functional theory (DFT) calculations employing the BP86/def2-TZVP level of theory. In solution, the exchange of lithium cations between pure [12]crown-4 and hybrid [12]crown-4 is on even terms, as has been shown from the relative binding affinity of compounds 1 and 7 by means of dynamic proton nuclear magnetic resonance (NMR) spectroscopy.

Synthesis and coordination ability of a partially silicon based crown ether

The first hybrid crown ether with two adjacent disilane fragments was synthesized through reaction of O(Si2Me4Cl)2 (3) with O(C2H4OH)2. By means of DFT calculations, the complexation ability of 1,2,4,5-tetrasila[12]crown-4 (7) towards Li+ was determined to be considerably higher compared to [12]crown-4.

Crystalline beryllium carboxylate frameworks containing inorganic chains of BeO4 tetrahedra

Two crystalline beryllium carboxylates, Be2(OH)2(bdc) (BCF-3) and Be4(OH)4(btec) (BCF-4), have been prepared under hydrothermal conditions. BCF-3 has a novel zeolitic topology containing 3-ring and 14-ring windows. BCF-4 has a porous framework with a CO2 uptake capacity of 48.2 cm3 g−1 (298 K, 760 Torr).

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.

Synthesis, structure and thermolysis of oxazagermines and oxazasilines

Seven new spirocyclic amido alkoxides of silicon and germanium were synthesized by the reactions of substituted 2-(aminomethyl)phenols with silicon(IV) and germanium(IV) chloride, respectively. The spirocyclic compounds 1–7 exhibit the general structural motif M[OC6H3(CH2NR1)-2-R2-4]2 [M = Si, R1 = Ph, R2 = H (1), Me (2), Br (3); M = Ge, R1 = Ph, R2 = H (4), Me (5), Br (6); M = Ge, R1 = i-Pr, R2 = H (7)]. The use of 2-(ethylamino)benzylalcohol and germanium(IV) chloride as starting materials afforded the spirocyclic compound Ge[EtNC6H4(CH2O)-2]2 (8). The structurally related germylene, germanium(II)-2-(phenylamidomethyl)phenolate (9), was prepared by the reaction of Ge[N(SiMe3)2]2 with 2-(phenylaminomethyl)phenol. The tetravalent compounds were isolated as racemates, with the exception of the spirocyclic germanium compound 8, for which the R and the S isomers crystallized separately. The compounds were characterized by single-crystal X-ray diffraction analysis, NMR spectroscopy (1H, 13C{1H}, 29Si{1H} for 1–3), IR spectroscopy, and TGA analysis. Porous Ge@C composites were observed after the carbonization of compounds 4–9 under argon. The as-prepared Ge@C materials were analyzed by elemental analysis, nitrogen physisorption measurements, powder X-ray diffraction analysis, Raman spectroscopy, and SEM/EDX analysis.

Excavating hidden adsorption sites in metal-organic frameworks using rational defect engineering

Metal–organic frameworks are known to contain defects within their crystalline structures. Successful engineering of these defects can lead to modifications in material properties that can potentially improve the performance of many existing frameworks. Herein, we report the high-throughput computational screening of a large experimental metal–organic framework database to identify 13 frameworks that show significantly improved methane storage capacities with linker vacancy defects. The candidates are first identified by focusing on structures with methane-inaccessible pores blocked away from the main adsorption channels. Then, organic linkers of the candidate structures are judiciously replaced with appropriate modulators to emulate the presence of linker vacancies, resulting in the integration and utilization of the previously inaccessible pores. Grand canonical Monte Carlo simulations of defective candidate frameworks show significant enhancements in methane storage capacities, highlighting that rational defect engineering can be an effective method to significantly improve the performance of the existing metal–organic frameworks.Defects in metal-organic frameworks have an important impact on the properties of resultant materials. Here, based on computational screening the authors identify 13 frameworks that experience drastic improvements in their methane storage capacities upon introduction of linker vacancy defects.

Crystalline chalcogenido metalates – synthetic approaches for materials synthesis and transformation

Abstract The formation and transformation of crystalline chalcogenido metalates in ionic liquids as solvents is discussed as a new synthetic approach for the generation of novel materials. A comparison to conventional solvothermal reactions, classical high-temperature syntheses and chemical solution based approaches in common is discussed.