Hydrogermolysis reactions involving the α-germylated nitriles R3GeCH2CN (R=Ph, Pri, But) and germanium amides R3GeNMe2 (R=Pri, But) with Ph3GeH: Substituent-dependent reactivity and crystal structures of Pri3GeGePh3 and But3Ge[NHC(CH3)CHCN]

Exploring the Versatility of the Amidation of Aryl Acid Fluorides using the Germylamines R3 GeNMe2

The formation of amide bonds is an important process since this linkage is an essential component in proteins, pharmaceuticals, and other medicinally and biologically significant molecules. Recently, it was demonstrated that germylamines R3 GeNR'2 were useful reagents for the conversion of acid fluorides to amides. This transformation occurs readily at room temperature and has a low activation energy. In the present study, the versatility of this amidation reaction with aryl acid fluorides is investigated. A series of thirteen acid fluorides with various substituents on the aromatic ring were reacted with the germylamine Ph3 GeNMe2 and twelve of these were converted to the corresponding amides in high yields, the exception being 1,4-benzenedicarbonyl difluoride. The germylamines Bun 3 GeNMe2 and Pri 3 GeNMe2 also could be used for this interconversion, and both of these species successfully converted 1,4-benzenedicarbonyl difluoride to the corresponding amide. In addition, the crystal structure of Ph3 GeNMe2 is reported. This represents one of only three crystallographically characterized germylamines. The synthesis and 19 F NMR characterization of three fluorogermanes R3 GeF (R=Bun , Pri , and Mes) are also reported herein.

A Three‐Dimensional Inorganic Analogue of 9,10‐Diazido‐9,10‐Diboraanthracene: A Lewis Superacidic Azido Borane with Reactivity and Stability

Herein, we report the facile synthesis of a three‐dimensional (3D) inorganic analogue of 9,10‐diazido‐9,10‐dihydrodiboraantracene, which turned out to be a monomer in both the solid and solution state, and thermally stable up to 230 °C, representing a rare example of azido borane with boosted Lewis acidity and stability in one. Apart from the classical acid‐base and Staudinger reactions, E−H bond activation (E=B, Si, Ge) was investigated. While the reaction with B−H (9‐borabicyclo[3.3.1]nonane) led directly to the 1,1‐addition on N_α upon N₂ elimination, the Si−H (Et₃SiH, PhMe₂SiH) activation proceeded stepwise via 1,2‐addition, with the key intermediates 5_int and 6_int being isolated and characterized. In contrast, the cooperative Ge−H was reversible and stayed at the 1,2‐addition step.

GeI-GeI Coupling Reaction Induced by a Mixture of CoBr2 and a Seven-Membered N-Heterocyclic Carbene

A new digermylene has been synthesized through the reaction of a six-membered cyclic radical germylene precursor with a mixture of CoBr₂ and a seven-membered N-heterocyclic carbene. The density functional theory simulation on the geometry of the digermylene agrees well with the experimental X-ray diffraction result. The digermylene possesses the shortest Ge^I-Ge^I bond [2.4853(6) Å] compared to the known singly bonded analogues, which can be attributed to σ → π* conjugation. In addition, it is revealed that a stable dative bond cannot form for the reductive radical germylene with the oxidative metal centers.

σ-Bond electron delocalization of branched oligogermanes and germanium containing oligosilanes

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Oligogermanes and germaoligosilanes isostructural to oligosilanes were synthesized.

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UV absorption data and X-ray diffraction revealed only marginal differences.

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Conformational flexibility is directly reflected in the UV absorption spectrum.

In order to evaluate the influence of germanium atoms in oligo- and polysilanes, a number of oligosilane compounds were prepared where two or more silicon atoms were replaced by germanium. While it can be expected that the structural features of thus altered molecules do not change much, the more interesting question is, whether this modification would have a profound influence on the electronic structure, in particular on the property of σ-bond electron delocalization.

The UV-spectroscopic comparison of the oligosilanes with germanium enriched oligosilanes and also with oligogermanes showed a remarkable uniform picture. The expected bathochromic shift for oligogermanes and Ge-enriched oligosilanes was observed but its extent was very small. For the low energy absorption band the bathochromic shift from a hexasilane chain (256 nm) to a hexagermane chain with identical substituent patterns (259 nm) amounts to a mere 3 nm.

Synthesis, structure, and properties of the hexagermane Pri3Ge(GePh2)4GePri3

The synthesis of the hexagermane Pri3Ge(GePh2)4GePri3 was achieved starting from the cyclotetragermane (Ph2Ge)4. Ring-opening of (Ph2Ge)4 with Br2 yielded Br(GePh2)4Br that was converted to H(GePh2)4H, and this material was treated with two equiv. of Pri3GeNMe2 to furnish Pri3Ge(GePh2)4GePri3 via the hydrogermolysis reaction. The X-ray crystal structures of (Ph2Ge)4, Br(GePh2)4Br and Pri3Ge(GePh2)4GePri3 were determined. The hexagermane Pri3Ge(GePh2)4GePri3 represents the longest structurally characterized linear oligogermane reported to date and exhibits physical properties that resemble those of the larger polygermane systems. The hexagermane is luminescent and interacts with polarized light, appearing pale yellow under one orientation of polarized light and deep blue under the opposite orientation. The electrochemistry of Pri3Ge(GePh2)4GePri3 was also explored, and this species exhibits the expected five irreversible oxidation waves.

Polygermanes: bandgap engineering via tensile strain and side-chain substitution

Polygermanes: bandgap engineering by strain and side-chain substitution.

Syntheses, structures and properties of linear and branched oligogermanes

This Perspective surveys recent developments in the synthesis and characterization of discrete oligogermanes. The use of the hydrogermolysis reaction, combined with a protection/deprotection strategy for a Ge-H moiety, has resulted in the synthesis of a variety of oligogermanes where the number of catenated atoms and the identity of the organic substituents can be readily controlled. Relationships between the composition of these oligomers and their optical and electronic properties have also been established.