Alkylation of schleyer's lithiocarbon C4Li4 by methyl iodide

Alkylation of lithiocarbon C₄Li₄ gives the hydrocarbon C₈H₁₂ to which the structure of tetramethyltetrahedrane has been ascribed.     

Conformational States of Triosmium Clusters with Aminoacid Ligands: A Theoretical Study

The conformational state of triosmium clusters with aminoacid ligands (-H)Os₃( -NHCH(R)CO₂Et)(CO)₁₀ (R = H, CH₃) has been studied theoretically. The conformational analysis was performed using the MERA model. The potential curves of the internal rotation of organic ligands in the cluster complexes relative to the HN–CH bond were determined both for individual substances and their solutions. The structures of possible conformers are considered, reasons for their stability are revealed, and variations in the potential curves of internal rotation in various solvents are discussed. The barrier to rotation relative to the HN–CH bond of the alanine derivative is 76.8-78.7 kJ/mole in different media, which hinders free rotation. For the glycine derivative, the same barrier is 37.5-37.9 kJ/mole, which allows for substantial rotational vibrations.     

Structural Features of Silatranes and Germatranes

In stabilization of the endo configuration of silatranes and germatranes, a major role is played not only by the Si (or Ge) and N atoms, but also by oxygen and other atoms of the atrane core, which is manifested in molecular orbital parameters. Calculation of the system of interacting methyltrimethoxysilane and trimethylamine shows that the energy of the system grows as the distance between the Si and N atoms is decreased from 5 to 2 Å. The Si-N interaction in methylsilatrane, according to the calculations and precision X-ray diffraction studies, is the interaction of filled electronic shells and is electrostatic in nature. Analysis of the thermodynamic functions of formation of 1-methyl- and 1-hydroxysilatranes and -germatranes reveals an increase in the enthalpy and the decisive contribution of the entropy factors to stabilization of the reaction products. A ¹H NMR study of ethylgermatrane in aqueous solution revealed its equilibrium with the hydro- lyzed form. The transition state in the first step of hydrolysis of methyl- and hydroxysilatranes and -germatranes was studied by methods of quantum chemistry (AM1, PM3; basis sets STO-3G, 6-31G, 6-31G*, 6-31G** B3LYP method).     

Optically active triosmium clusters containing the cysteine ligand

The reactions of cysteine ethyl ester with a series of triosmium clusters have been studied. Enantiomeric (-H)Os₃{-SCH₂CH(CO₂Et)NH₂}(CO)₁₀ and diastereomeric (-H)Os₃{-²-SCH₂CH(CO₂Et)NH₂}(CO)₉ forms of the optically active cluster complexes have been obtained. Diastereomeric clusters have been separated by TLC on Silufol plates. The treatment of the enantiomeric complex (-H)Os₃{-SCH₂CH(CO₂Et)NH₂}(CO)₁₀ with the trimethylamine oxide yields the diastereomeric pair (-H)Os₃{-²-SCH₂CH(CO₂Et)NH₂}(CO)₉. The structures of the complexes obtained have been established on the basis of IR,¹H NMR and mass spectrometry as well as X-ray analysis data.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1981–1984, November, 1993.     

Preparation and reactivity of metal-containing monomers

Starting with the trinuclear clusters, M₃(CO)₁₂ (where M=Os or Ru), Os₃(CO)₁₁(NCCH₃), Os₃(CO)₁₀(NCCH₃)₂, and (-H)Os₃(-OR)(CO)₁₀ (where R=H or Ph), and polyfunctional organic compounds containing vinyl or allyl groups, a number of cluster monomeric complexes have been synthesized containing ligands with an uncoordinated C=C bond,viz.: (-H)Os₃(-4-Vpy)(CO)₁₀, (-H)Os₃(-O₂CCH=CH₂)(CO)₁₀, (-H)Os₃(-OCNHCH₂CH=CH₂)(CO)₁₀, and (-H)M₃(-SCH₂CH=CH₂)(CO)₁₀. The (-H)Os₃(-4-Vpy)(PPh₃)(CO)₉ complex was investigated by X-ray diffraction analysis.For part 30, seeRuss. Chem. Bull., 1993,42, 1016.Vpy is the vinylpyridine ligand.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1293–1298, July, 1993.     

Reactions of triosmium clusters Os3(CO)11(MeCN) and (μ-H)Os3(CO)10(μ-OH) withL-α-serine ethyl ester and ethanolamine

A series of novel chiral complexes with ,¹and ,² coordination of organic ligands were prepared by reactions of Os₃(CO)₁₁(MeCN) and (-H)Os₃(CO)₁₀(-OH) withL--serine ethyl ester and ethanolamine. The diastereomeric cluster complexes with serine ligands were separated by crystallization or chromatography. The structures of the compounds obtained were confirmed by¹H NMR and IR spectroscopy, mass-spectrometry, elemental analysis, and X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 525–530, March, 1994.     

Two similar lactone-hydrochlorides with different types of hydrogen bonding networks: Crystal structure of (R,S)-α-amino-γ-caprolactone hydrochloride and racemic α-amino-γ-methyl-γ-valerolactone hydrochloride semihydrate

The X-ray crystal structure of (R,S)--amino--caprolactone hydrochloride (compound1) and -amino--methyl--valerolactone hydrochloride semihydrate (compound2) are presented. Both compound1 and compound2 belong to the orthorhombic system. Caprolactone-hydrochloride1 crystallizes in the space groupP2₁2₁2₁ witha=5.1948(7),b=8.7404(8),c=17.907(1) Å.V=813.0(2) ų,Z=4. Valerolactone-hydrochloride2 crystallizes in the space groupP na2₁ witha=26.771(8),b=5.1598(7),c=13.201(3) Å,V=1823.5(7) ų,Z=8. The lactone cations maintain the same, open envelope conformation in both crystals. The lactone-hydrochloride packing arrangements in1 and2 are distinctly different. While in1 N–H...Cl and N–H...O hydrogen bonding creates two dimensional nets in the form of puckered layers perpendicular to the [001] direction, in2 a water molecule of crystallization with an additional OW–H...Cl hydrogen interaction assists in forming a three-dimensional hydrogen-bond network throughout the crystal.     

Doping-addition of arylsulfenyl chlorides to the tricyclo[4,2,2,02,5]deca-3,7,9-triene system: skeletal rearrangements and serendipitious products

“doping-addition” of 2-NO₂C₆H₄SCl to the tricyclo[4,2,2,0^2,5]deca-3,7,9-triene system

occurs to give unusual products: (i) rearranged caged cyclopropane

and (ii) the stable cross-perchlorate

.     

Structural characteristics of different types of nanoparticles synthesised in mesomorphic metal alkanoates

The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC₈) and of the cobalt octanoate (CoC₈). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained.