1,2-Bis(triazolyl)tetraphenyldigermanes: Synthesis, Structure and Properties

Using the [3+2] cycloaddition reaction of [HC≡C-GePh2 -]2 (1) and a number of RCH2 N3 , this work described the synthesis of a series of novel heterocyclic digermanes, bitriazoles [1,4-C2 HN3 (CH2 R)GePh2 -]2 , 2-12 (R=Ph, p-Tol, p-C6 H4 NMe2 , p-C6 H4 OMe, p-C6 H4 Br, m-C6 H4 NO2 , 2-Naphth, CH2 -p-OC6 H4 CHO, CH2 -p-OC6 H4 COOMe, CH2 P(O)(OEt)2 , COOEt), difficult to produce by other methods. The structural peculiarities of these compounds were studied in detail by NMR spectroscopy and by XRD analysis (for 6, 9 and 10). The properties of 1-12 were studied by UV/vis and luminescence emission spectroscopy, electrochemistry and DFT calculations, indicating an effective conjugation in their molecules.

Structural Motifs in Aryl Organogermanium Ge-O Derivatives for Material Design

The aim of this work was to understand the main structural features and ways of formation of Ge-O bonds in organogermanium compounds under the conditions of ArnGeHal4-n (Hal = halide) hydrolysis. The structural types of these compounds were considered, providing 11 blocks (A-K). The molecular structures of the novel compounds [(p-FC6H4)3Ge]2O (1), [(p-F3CC6H4)3Ge]2O (2), and cyclo-[(p-F3CC6H4)2GeO]4 (3) were studied through XRD (X-ray diffraction) analysis. The molecular structure of [(p-F3CC6H4)3GeO]4Ge (4), representing a novel structural type, was also investigated. The data presented in this study will be important in the design of materials with useful properties based on group 14 element derivatives with element-oxygen bonding.

Oligoorganogermanes: Interplay between Aryl and Trimethylsilyl Substituents

Derivatives of main group elements containing element-element bonds are characterized by unique properties due to σ-conjugation, which is an attractive subject for investigation. A novel series of digermanes, Ar₃Ge-Ge(SiMe₃)₃, containing aryl (Ar = p-C₆H₄Me (1), p-C₆H₄F (2), C₆F₅ (3)) and trimethylsilyl substituents, was synthesized by the reaction of germyl potassium salt, [(Me₃Si)₃GeK*THF], with triarylchlorogermanes, Ar₃GeCl. The optical and electronic properties of such substituted oligoorganogermanes were investigated spectroscopically by UV/vis absorption spectroscopy and theoretically by DFT calculations. The molecular structures of compounds 1 and 2 were studied by XRD analysis. Conjugation between all structural fragments (Ge-Ge, Ge-Si, Ge-Ar, where Ar is an electron-donating or withdrawing group) was found to affect the properties.

Characterization of Highly Coordinated Allylgermanes: Pivotal Players for Enhanced Nucleophilicity and Stereoselectivity

Allylgermanes with a 4-, 5-, and 6-coordinated germanium center were characterized by X-ray crystallography. Cationic 6-coordinated group 14 allylmetals, which were hitherto assumed to be a transition-state structure of allylations, were successfully isolated. Forming high coordination states significantly enhanced the reactivity of the allylgermanes. In contrast to the 4-coordinated allylgermanes with low reactivity, the highly coordinated species readily reacted with several aldehydes. Furthermore, the high coordination states exerted a significant effect on the E/Z selectivity of allylation depending on external additives. The coordination structure had a dramatic influence on the electronic and steric environments around the Ge center, enabling the geometrically controlled allylation of aldehydes.