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.

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

A series of substituted pyridine dialcohols (2,6-bis(hydroxyalkyl)pyridines), 1-4, was used for the synthesis of various types of aluminum complexes. Aluminum methyl derivatives, 2-4a, were obtained by the reaction of AlMe3 with the corresponding ligand or transmetallation reactions of germylenes. Aluminum chloride complexes, 3-4b, were obtained by substitution of the Me group under the action of chlorinating agents. Methoxy-, 2-4c, or benzyloxy-, 2d, aluminum complexes were synthesized in transalkoxylation reaction of Me2Al(OX) (X = Me, Bn) by the corresponding ligand. All complexes obtained were thoroughly investigated by multinuclear NMR and X-ray analysis. It has been established that the structure of the ligand (number of carbon atoms) determines the nature of the complexes formed. Compounds were used as initiators of ring-opening polymerization of l-lactide and ε-caprolactone and showed moderate activity with controlled or immortal character.

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).

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

The first example of an oligogermane, N(CH2CH2O)3Ge-Ge(SiMe3)3 (1), containing a hypercoordinate germanium atom was prepared and characterized by various methods (NMR, UV/vis, and X-ray analysis). The electronic structure of compound 1 was investigated via DFT calculations.

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

The mol-ecule of the title compound, C40H42Ge4, lies with its central Ge-Ge bond on an inversion centre giving rise to a zigzag backbone of four tetra-hedrally coordinated Ge atoms. The symmetrically independent Ge-Ge bonds are slightly shorter than in other organo-tetra-germanes whereas the Ge-CPh (Ph = phen-yl) and Ge-CMe (Me = meth-yl) distances have their usual values. In the crystal, (010) layers of Ph6Me4Ge4 mol-ecules 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.

Palladium complexes with stabilized germylene and stannylene ligands.

The syntheses of novel Pd complexes with germylene and stannylene ligands are reported. [MeN(CH2CH2NC6F5)2Sn]4Pd (2) and [MeN(CH2CPh2O)(CH2CH2O)Ge]4Pd (8) were obtained by different methods including ligand substitution in (Ph3P)4Pd or by the reaction of the free corresponding germylene or stannylene with (Ph3P)2PdCl2 or Pd(OAc)2. Crystal structures of complexes 2, 8 were determined by single crystal X-ray diffraction analysis. The catalytic activity of complexes 2, 8 was examined in the Suzuki-Miyaura and Heck cross-coupling.

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 octa-hedral N2O4 coordination environment and is linked via two µ2-oxido bridges into a dinuclear centrosymmetric com-plex, with a Ti⋯Ti separation of 2.7794 (8) Å. In the salen (N,N'-ethyl-enebis(salicyl-imine)) ligand, the two salicyl-imine units make a dihedral angle of 45.31 (5)°. The complex mol-ecules are stacked parallel to [100], forming channels in which the solvent chloro-form mol-ecules are located. C-H⋯O hydrogen-bonding inter-actions between the complex mol-ecules and the solvent mol-ecules consolidate the crystal packing.

{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.

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

In the title compound, [Al(CH(3))(C(23)H(15)F(10)N(3))], the Al(III) atom is coordinated in a distorted tetra-hedral geometry by three N atoms from the tridentate amine and by one C atom of the methyl substituent. Further, there is a short intra-molecular Al⋯F contact [2.5717 (11) Å], leading to an overall distorted trigonal-bipyramidal coordination environment around Al(III).

Crystal packing in the structures of diethanolamine derivatives.

Four distinct hydrogen-bonding topologies were observed in the structures of six diethanolamine ligands. These compounds are (1R*,2R*)-2-[(2-hydroxyethyl)(methyl)amino]-1,2-diphenylethanol, C(17)H(21)NO(2), (I), 1-[(2S)-2-(hydroxydiphenylmethyl)pyrrolidin-1-yl]-2-methylpropan-2-ol, C(21)H(27)NO(2), (II), 2-[(2-hydroxyethyl)(methyl)amino]-1,1-diphenylethanol, C(17)H(21)NO(2), (III), 1-{(2-hydroxy-2-methylpropyl)[(1S)-1-phenylethyl]amino}-2-methylpropan-2-ol, C(16)H(27)NO(2), (IV), 1-{[(2R)-2-hydroxy-2-phenylethyl][(1S)-1-phenylethyl]amino}-2-methylpropan-2-ol, C(20)H(27)NO(2), (V), and (1R*,2S*)-2-[(2-hydroxyethyl)(methyl)amino]-1,2-diphenylethanol, C(17)H(21)NO(2), (VI). In each compound, all ;active' hydroxy H atoms are engaged in hydrogen bonding, but the N atoms are not involved in intermolecular hydrogen bonding. In the structures of (I), (II) and (IV)-(VI), molecules are linked into chains by intermolecular O-H...O interactions. These chains are organized in such a way as to hide the hydrophilic groups inside, and so the outer surfaces of the chains are hydrophobic. The structure of (VI) contains two distinct non-equivalent systems of intermolecular O-H...O hydrogen bonds formed by disordered hydroxy H atoms.

Novel derivatives of hypervalent germanium: synthesis, structure, and stability.

Syntheses of a series of novel germanium complexes, viz. RN(CH(2)CH(2)NC(6)F(5))(2)GeHal(2) (, R = Me, Hal = Cl; , R = Me, Hal = Br; , R = PhCH(2), Hal = Cl; , R = PhCH(2), Hal = Br), as well as MeN[CH(2)(2-C(4)H(3)N)](2)GeHal(2) (, Hal = Cl; , Hal = Br), by the reaction of GeHal(4) with dilithium salts of corresponding triamines are presented. PhCH(2)N(CH(2)CH(2)NSiMe(3))(2)GeCl(2) () was prepared analogously from triamine . Other approaches to the synthesized compounds were also tested. Unexpected complexes [N[upper bond 1 start](CH(2)CH(2)NSiMe(3))(2)Ge[upper bond 1 end](Hal)](2) (, Hal = Cl; , Hal = Br) were obtained by the reaction of GeHal(4) with dilithium salt of Me(3)SiN(CH(2)CH(2)NHSiMe(3))(2) (). DFT calculations on this reaction were carried out and discussed. Composition and structures of the novel compounds were established by elemental analyses, (1)H, (13)C, and (19)F NMR spectroscopy. The X-ray structural studies of and clearly indicated the presence of a transannular interaction N(ax)-->Ge for all studied compounds.

Benzyl N,N-bis[2-(pentafluoroanilino)ethyl]carbamate.

The title compound, C24H17F10N3O2, exhibits intramolecular N-H...O hydrogen bonding, as well as intramolecular Ar...Ar(F) face-to-face interactions. The molecules are linked together by N-H...F-C hydrogen bonds, forming chains parallel to the a axis. Adjacent symmetry-related chains are combined in double zipper-like ribbons by parallel Ar(F)...Ar(F) offset pi-stacking interactions.

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 the first azastibatranes and azabismatranes.

Syntheses of title compounds, viz. N(CH2CH2NR)3E (1, E = Sb, R = Me; 4, E = Bi, R = Me; 6, E = Sb, R = SiMe3; 8, E = Bi, R = SiMe3), by the reaction of E(NAlk2)3 (3, E = Sb, Alk = Et; 5, E = Bi, Alk = Me) with N(CH2CH2NMeH)3 (2) or N(CH2CH2NSiMe3H)3 (7) are reported. The reactions of SbCl3 with N[CH2CH2N(Me)Li]3 or N[CH2CH2N(SiMe3)Li]3 and BiCl3 with N[CH2CH2N(SiMe3)Li]3 resulted in compounds 1, 6, and 8, respectively. Composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy and mass spectrometry. The X-ray structural study of 8 clearly indicated the presence of transannular interaction BiNdat in this compound, while 6 possesses a long Sb...Ndat distance. The structural data obtained from geometry optimizations on 6 and 8 reproduce experimental trends, i.e., a decrease in the E-Ndat distance from Sb to Bi. The values of electron density in E-Ndat critical point and the Laplacian of charge density for 8 indicate that a closed-shell interaction exists between the metal atom and Ndat atom.