Reaction of germanes and digermanes with triflic acid: The route to novel organooligogermanes

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.

Hypercoordinated Oligosilanes Based on Aminotrisphenols

The hypercoordinated silicon chlorides ClSi[(o-OC₆H₄)₃N] (3) and ClSi[(OC₆H₂Me₂CH₂)₃N] (5) were used for the synthesis of catenated derivatives (Me₃Si)₃SiSi[(o-OC₆H₄)₃N] (9), (Me₃Si)₃SiSiMe₂SiMe₂Si(SiMe₃)₂Si[(o-OC₆H₄)₃N] (11), and (Me₃Si)₃SiSi[(OC₆H₂Me₂CH₂)₃N] (13) in reactions with (Me₃Si)₃SiK·THF (7) or (Me₃Si)₃SiK·[18-crown-6] (8). It was found that the nature of the (Me₃Si)₃SiK solvate determines the product of interaction, resulting in the formation of (Me₃Si)₃Si(CH₂)₄OSi[(OC₆H₂Me₂CH₂)₃N] (12) or 13. Compounds obtained were characterized using multinuclear NMR and UV-vis spectroscopy and mass spectrometry. The molecular structures of 3, 9, and 11-13 were investigated by single-crystal X-ray analysis, featuring hypercoordinated Si atoms in a trigonal-bipyramidal coordination environment with O atoms in the equatorial plane. The structure of the side product [N(CH₂C₆H₂Me₂O)₃Si]₂O (6) was also studied, indicating highly tetrahedrally distorted trigonal-bipyramidal environment at the Si atoms, which was confirmed by crystal density functional theory calculations indicating the very weak Si ← N interaction. The Si···N interatomic distances span a broad range (2.23-2.78 Å). The dependence of structural and NMR parameters for hypercoordinated catenated compounds from the type of the ligand was established.

Oligothienyl catenated germanes and silanes: synthesis, structure, and properties

The synthesis of two new groups of oligothienyl catenated silanes and germanes, Me5M2Thn (1a-b), Me5M2ThnM2Me5 (2a-c) (terminal), and ThnM2Me4Thn (3a-d) (internal) (M = Si, Ge; n = 2, 3; Th = 2- or 2,5-thienyl), is reported. The study of their structural parameters as well as of their spectral (NMR), electrochemical (CV) and optical (UV/vis absorbance, luminescence) properties has been performed in detail; in addition, the unexpected compound [Th2Si2Me4Th]2 (3a') is also studied. Theoretical investigations have been performed for model compounds in order to establish structure-property relationships. The molecular structures of 2a (Me5Si2Th2Si2Me5), 2b (Me5Ge2Th2Ge2Me5), 3a (Th2Si2Me4Th2) and 3b (Th2Ge2Me4Th2) have been investigated by X-ray diffraction analysis. An effective conjugation with flattening of both Th planes in terminal 2a and 2b was observed. The main trends in the dependence of the optical and electrochemical properties on the structural parameters have been established. All of the compounds studied exhibit a strong emission within the 378-563 nm range, and the maximal quantum yield (up to 77%) is observed for the Si derivative 3a'. For the majority of the compounds, the quantum yields (20-30%) are significantly larger than for 2,2'-bi- and 2,2':5',5''-terthiophenes. Due to their good emission properties, these compounds could be used to develop new materials with specific spectral properties.

Molecular Oligogermanes and Related Compounds: Structure, Optical and Semiconductor Properties

The optical (UV/Vis absorbance, fluorescence in the solid state and in solution) and semiconducting properties of a number of di- and trigermanes as well as related silicon- and tin-containing germanes, 1-6 ((p-Tol)₃ GeGeMe₃ (1), Ph₃ SnGe(SiMe₃ )₃ (2), (C₆ F₅ )₃ GeGePh₃ (3), (p-Tol)₃ GeSiMe₂ SiMe₃ (4), (p-Tol)₃ GeGeMe₂ Ge(p-Tol)₃ (5), (p-Tol)₃ GeSiMe₂ SiMe₂ Ge(p-Tol)₃ (6)) were investigated. Molecular structures of 5 and 6 were studied by X-ray diffraction analysis. All compounds displayed luminescence properties. In addition, a band gap (of about 3.3 eV) was measured for compounds 1-6 showing that those molecules display semiconductor properties.

Selective Synthesis and Derivatization of Germasilicon Hydrides

Mixed Si/Ge hydrides SixGeyHz are valuable precursors for the deposition of binary Si-Ge alloys. This work describes the synthesis and full characterization of the previously unknown germaisotetrasilane Ph3GeSi(SiH3)3 (2) on a multigram scale from the reaction of the lithium silanide LiSi(SiH3)3 with Ph3GeCl. The stability of the Si-Ge bond in 2 versus electrophiles and nucleophiles has been investigated with the primary aim of developing new approaches to mixed sila-H-germanes (H3Ge)xSi(SiH3)4-x. With 1 equiv of MeLi, 2 reacted cleanly under cleavage of one Si-Si bond to give Ph3GeSi(SiH3)2Li, which is a valuable synthon for further derivatization. In contrast, the dephenylation reaction of 2 with 1 or 2 equiv of CF3SO3H/iBu2AlH proceeded much less selectively and afforded the desired Ph/H-germasilanes Ph2HGeSi(SiH3)3 and PhH2GeSi(SiH3)3 along with considerable amounts of Si-Ge scission products.

Synthesis of Bis(pentafluoroethyl)germanes

The chemistry of bis(pentafluoroethyl)germanes (C2F5)2 GeX2 is presented. The synthesis of such species requires Br2 GePh2 , wherein the phenyl substituents function as suitable protecting groups. After treatment with two equivalents of LiC2 F5, (C2F5)2 GePh2 is produced. The replacement of the phenyl rings is smoothly effected by gaseous HBr or HCl in the presence of a Lewis acidic catalyst. The trigermoxane [(C2F5)2 GeO]3 results from the reaction of (C2F5)2 GeBr2 with Ag2 CO3. Its crystalline 1,10-phenanthroline adduct was fully characterised by X-ray diffraction. The combination of (C2F5)2 GeBr2 with Bu3 SnH gave rise to the formation of (C2F5)2 GeH2 .

Tunable porosity of 3D-networks with germanium nodes

Eight hyper cross-linked polymers based on tetrakis(4-ethynylphenyl)germanium and tetrakis(4-ethynylphenyl)methane are presented.

Crystal structure of (tert-butyl-dimethyl-sil-yl)tri-phenyl-germane, Ph3Ge-SiMe2(t-Bu)

In the title compound, Ph3Ge-SiMe2(t-Bu) or C24H30GeSi, the Si and Ge atoms both possess a tetra-hedral coordination environment with C-E-C (E = Si, Ge) angles in the range 104.47 (5)-114.67 (5)°. The mol-ecule adopts an eclipsed conformation, with three torsion angles less than 29.5°. In the crystal, neighbouring mol-ecules are combined to dimers by six T-shaped C-H⋯π inter-actions, forming sixfold phenyl embraces (6PE).

Crystal structure of 2,2,3,3-tetra-methyl-1,1,1,4,4,4-hexa-phenyl-tetra-germane

The mol­ecule of the title compound, C₄₀H₄₂Ge₄, lies with its central Ge—Ge bond on an inversion centre giving rise to a zigzag backbone of four tetra­hedrally coordinated Ge atoms. The symmetrically independent Ge—Ge bonds are slightly shorter than in other organo­tetra­germanes whereas the Ge—C_Ph (Ph = phen­yl) and Ge—C_Me (Me = meth­yl) distances have their usual values. In the crystal, (010) layers of Ph₆Me₄Ge₄ mol­ecules with a parallel orientation of the Ge₄ backbone exist, held together by van der Waals forces only. Main bond lengths in organo-substituted oligogermanes are compared.

New oligogermane with a five coordinate germanium atom: the preparation of 1-germylgermatrane

The first example of a hypercoordinate oligogermane was prepared and characterized.