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.

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).

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

2,6-Bis(hydroxyalkyl)pyridines were used in the synthesis of Al complexes. The structure of the ligand determines the complex nature. Compounds were used as initiators of lactone ROP.

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.

Synthesis and Crystal Structure of the Germatrane E-N(CH)2CH2O3GeC(Br)=C(Br)Ph

The reaction of (phenylacetylenyl)triethoxygermane, (EtO)3GeC≡CPh (3), with bromine in CHCl3/CCl4 solution leads to a mixture of Z- and E- (EtO)3GeC(Br)=C(Br)Ph (4) in the ratio Z/E = 3/1. Treatment of this product with N(CH2CH2OH)3 affords a mixture of Z- and EN(CH2CH2O)3GeC(Br)=C(Br)Ph (2) in high yield. Compound E-2 was isolated in 16% yield. The molecular composition and the structure of all new compounds have been established by elemental analyses, 1H and 13C NMR spectroscopy. The crystal structure of E-2 is reported. The possible reasons for the different Z/E ratios in the products of the bromination of 3 and N(CH2CH2O)3GeC≡CPh (1) are discussed using DFT calculations.

1-Allylgermatrane. Synthesis, Structure and Reaction with Diazomethane

Reaction of allyltribromogermane (2), readily available from dibromo(1,4-dioxane)germanium(II) (1) and allylbromide, with tris(2-tributylstannoxyethyl)-amine (4) gives 1-allylgermatrane (3) in almost quantitative yield. 3 crystallizes from n-pentane as a colourless crystalline solid which was characterized by 1H and 13C NMR spectroscopy and by an X-ray crystal structure study. The “atrane” skeleton shows a strong conformational disorder; the Ge-N distance of 2.208(3) Å suggests the presence of a coordinative Ge-N bond. Treatment of 1-allylgermatrane (3) with CH2N2 in the presence of catalytic amounts of Pd(OAc)2 affords 1-cyclopropylmethylgermatrane (5) in high yield

Synthesis and Characterization of 1-Allyl-3,7,10-trimethylgermatrane and 1-Allylazagermatranes

The reaction between Br3GeAll (1) and N(CH2CHMeOSnBu3)3 (2, mixture of isomers) yielded N(CH2CHMeO)3GeAll (3) as a mixture of diastereomers. Three azagermatranes of the type N(CH2CH2NR)3GeAll (9, R = H; 10, R = Me; 11, R = Me3Si) have been synthesized from the reaction of (Me2N)3GeAll (5) with N (CH2CH2NHR)3 (R = H, 6; Me, 7; Me3Si, 8). Composition and structures of the new compounds were established by elemental analyses, 1H and 13C NMR spectroscopy and mass spectrometry.

Syntheses and Characterization of 1-Haloazagermatranes

Germanium, Azagermatranes The reaction of tris(dimethylamino)halogermanes, (Me2N)3GeHal (7, Hal = Cl; 8 , Hal = Br), with tris(2-aminoethyl)amines, N(CH2CH2NHR)3 (5, R = H; 6 , R = Me), yield l-halo-N,N',N"-azagermatranes (1, X = Cl, R = H; 2, X = Br, R = H; 3, X = Cl, R = Me; 4, X = Br, R = Me). Treatment of 4 with n-butyllithium affords l-n-butyl-N,N',N"-trimethylazagermatrane (14) in high yield. Reactions of n-BuLi with 7 or (Me2N)4Ge (13) lead to the formation of (Me2N)3Ge-n-Bu (15). On treatment of 15 with 5 the 1 -n-butylazagermatrane 16 was obtained. The molecular composition and the structures of all new compounds were established by elemental analyses, 1H and 13C NMR spectroscopy and mass spectrometry.

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

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

{2,2'-[Ethane-1,2-diylbis(nitrilo-methan-yl-yl-idene)]diphenolato}(iso-propano-lato)aluminium di-chloro-methane hemisolvate

In the title compound, [Al(C16H14N2O2)(C3H7O)]·0.5CH2Cl2, the salen complex is monomeric and the dichlormethane solvent mol-ecule lies on a crystallographic twofold axis. The central Al atom is fivefold coordinated and possesses a square-based pyramidal environment. The Al-OAlk( (i) prop-yl) bond [1.7404 (14) Å] is much shorter than the Al-OAr(salen) bond lengths [1.7974 (15) and 1.8094 (14) Å]. The iso-propyl-oxo group forms an intra-molecular C-H⋯N hydrogen bond. In the crystal, the complex mol-ecules are linked by weak C-H⋯O inter-actions.

Di-μ-oxido-bis-({2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}titanium(IV)) chloro-form disolvate

In the title compound, [Ti₂(C₁₆H₁₄N₂O₂)₂O₂]·2CHCl₃, the Ti^IV atom in the centrosymmetric complex has a distorted octa­hedral N₂O₄ coordination environment and is linked via two μ₂-oxido bridges into a dinuclear centrosymmetric com­plex, with a Ti⋯Ti separation of 2.7794 (8) Å. In the salen (N,N′-ethyl­enebis(salicyl­imine)) ligand, the two salicyl­imine units make a dihedral angle of 45.31 (5)°. The complex mol­ecules are stacked parallel to [100], forming channels in which the solvent chloro­form mol­ecules are located. C—H⋯O hydrogen-bonding inter­actions between the complex mol­ecules and the solvent mol­ecules consolidate the crystal packing.

6-Benzyl-2-methyl-1,3-bis-(penta-fluoro-phen-yl)-1,3,6,2-triaza-alumocane

In the title compound, [Al(CH₃)(C₂₃H₁₅F₁₀N₃)], the Al^III atom is coordinated in a distorted tetra­hedral geometry by three N atoms from the tridentate amine and by one C atom of the methyl substituent. Further, there is a short intra­molecular Al⋯F contact [2.5717 (11) Å], leading to an overall distorted trigonal–bipyramidal coordination environment around Al^III.

A DFT investigation of alkyne bromination reactions

[Structure: see text]. A DFT calculation study of the addition reaction between molecular bromine and the number of symmetrical or unsymmetrical substituted alkynes 1 (R-CC-R'), where R = R' = H (1a), Me (1b), t-Bu (1c), or Ph (1d), or R = H and R' = Me (1e), t-Bu (1f), or Ph (1g), was performed. Two possible reactions were checked: (a) the reactions suitable for the gas-phase interactions, which start from a 1:1 Br2-alkyne pi-complex and do not enter into a 2:1 Br2-alkyne pi-complex; and (b) the processes passing through a 2:1 Br2-alkyne pi-complex, which look more realistic for the reactions in solutions. The structures of the starting reactants and the final products as well as the possible stable intermediates have been optimized. The transition states of the predicted process have been found. Both trans- and cis-dibromoalkenes (2 and 3) may ensue without the formation of ionic intermediates from a pi-complex of two bromine molecules with the alkyne (solution reactions). The geometry around the double bond forming in dibromoalkenes strongly depends on the nature of the substituents at the triple bond. The "cluster model" was also used for the prediction of solvent influence on the value of the activation barrier of the but-2-yne (1b) bromination reaction.

Synthesis, X-ray Diffraction Studies, and DFT Calculations on Hexacoordinated Germanium Derivatives: The Case of Germaspirobis(ocanes)

Synthesis of the title compounds, viz. [RN(CH2CHR'O)2]2Ge (1, R = Me, R' = H; 2, R = Me, R' = Ph; 3, R = Ph, R' = H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH2CHR'OH)2 (4, R = Me, R' = H; 5, R = Me, R' = Ph; 6, R = Ph, R' = H) with (AlkO)4Ge is reported. Composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy and mass spectrometry as well as elemental analysis data. The single-crystal X-ray diffraction of 2 has clearly indicated the presence of two transannular interactions Ge<--N in the compound. N atoms are cis-orientated. The compound 3 possesses long Ge...N distances. The structural data obtained from geometry optimizations by DFT calculations on 1-3 reproduces experimental results. Both cis- and trans-isomers were studied, and cis-configuration was found to be more thermodynamically stable for all three compounds. The transition states for possible cis <--> trans rearrangement processes in 1-3 were calculated. The properties of the Ge-O and Ge<--N bonds in 1-3 were analyzed by the AIM approach. The interactions between the Ge atom and N atoms as well as O atoms possess predominantly ionic character.

Synthesis and Characterization of N-Methyl-Substituted Germocanes. Crystal Structure of MeN(CH2CH2O)2GeBr2

The reaction of GeHal4 with MeN(CH2CH2OSiMe3)2 affords dihalogermocanes MeN(CH2 CH2O)2GeHal2 (1, Hal = Br; 2, Hal = Cl). Treatment of Me2Ge(NMe2)2 with MeN(CH2CH2OH)2 leads to dimethylgermocane MeN(CH2CH2O)2GeMe2 (3). The composition and structure of 1-3 were established by elemental analyses, 1H, 13C NMR spectroscopy, and mass spectrometry. The crystal structure of 1 is reported; structural data obtained from geometry DFT optimization on 1 are in good agreement with experimental results. Values of the electron density in the N→Ge bond critical point and the Laplacian of charge density for 1-3 indicate a closed-shell interaction between the Ge and N atoms.