Search results for "Periodic table"
showing 10 items of 262 documents
1-Nitroindoline.
2000
In the title compound, C(8)H(8)N(2)O(2), the nitramino group is planar and only slightly twisted with respect to the indoline rings. The bridgehead N--C bond is slightly shorter than in typical secondary aromatic nitramines. The N--N bond has some double-bond character. The molecules are connected by weak C--H...O hydrogen bonds, forming chains parallel to the z direction.
ChemInform Abstract: Nb4Te17I4, a New Pseudo One-Dimensional Solid-State Polytelluride.
2010
The new ternary compound Nb4Te17I4 has been prepared and structurally characterized. It crystallizes in the monoclinic system, space group C2/c with unit-cell parameters a = 16.199(4), b = 8.128(2), c = 27.355(6) A, β = 110.84(2)°, Z = 4. The structure consists of infinite one-dimensional niobium/tellurium chains running parallel to the crystallographic c direction. The chains are separated by iodine atoms. Short and long metal–metal distances alternate in the sequence of three consecutive short bonds ([d ≈ 3.1 – 3.2 A) and one long (d = 4.268 A) metal–metal separation. Each Nb atom is eight-coordinate. The composition of the chain is ∞11[(Nb5+)2(Nb4+)2(Te22−)4(Te32−)3(I−)4].
Effect of structural parameters on the polarizabilities of methanol clusters: a hirshfeld study
2008
The polarizabilities of fifty methanol clusters (CH3OH)n, n = 1 to 12, were calculated at the B3LYP/6-311++G** level of theory and partitioned into molecular contributions using the Hirshfeld-I method. The resulting molecular polarizabilities were found to be determined by the polarizabilities of the two parts of the molecule, the hydrophilic hydroxyl group and the hydrophobic methyl group, each exhibiting a different dependency upon the local environment. The polarizability of the hydroxyl group was found to be dependent on the number, type, and strength of the hydrogen bonds a methanol molecule makes, whereas the polarizability of the methyl groups is mostly influenced by sterical hindran…
The use of topological models in analytical chemistry
2005
In the present paper, the possible analytical applications of two toplogical models, the DARC model and the group contribution model, are discussed. Both models are applied to obtain calibration laws, which relate UV and IR characteristics with the chemical structure of ethylene oxide condensates. The group contribution model is also applied to determine the contribution of each part of the different compounds involved in a chemical interaction process, having established the sensitization parameters of benzodiazepines and anionic surfactants from the micellar enhancement fluorescence.
2,3,4,5,6-Pentabromophenyl phenyl ether
2002
The title compound, C12H5Br5O, belongs to a group of flame retardants known as polybrominated diphenyl ethers (PBDE). Salient features of the packing are stabilization due to intermolecular Br⋯Br contacts in the ab plane and aromatic intermolecular contacts along the c direction.
Benzodiselenagermoles and spirobisbenzodiselenagermoles
1993
Synthesis of benzodiselenagermoles and bisbenzodiselenagermoles was carried out by transmetallation group 4 group 14 between diselenophenylenezirconocenes and dialkyl-, diaryl- or alkylaryldichlorogermanes, aryltrichlorogermane or germanium tetrachloride. The new compounds were studied by 1H, 77Se NMR and mass spectrometry. In the case of compounds with substituted phenyl groups, double irradiation and 2D NMR experiments were performed to determine the chemical shifts of the two selenium atoms. The crystal structure of a spirobisbenzodiselenagermole has been established by X-ray diffraction analysis.
Understanding the Influence of the Trifluoromethyl Group on the Selectivities of the [3+2] Cycloadditions of Thiocarbonyl S ‐methanides with α,β‐Unsa…
2020
ChemInform Abstract: Approaches for the Introduction of Fluorinated Substituents into [1,2,3]Triazolo[1,5-a]pyridines.
2014
Functionalization of [1,2,3]triazolo[1,5-a]pyridines with a trifluoromethyl group is achieved for the first time.
Silicon-guided rearrangement of 10-methyl-4,5-epoxydecalins. Methyl versus methylene migration
2003
The Lewis acid-promoted rearrangement of two 10-methyl-4,5-epoxydecalins bearing a trimethylsilyl (TMS) group on C-1 or C-9 has been studied. Migration of the C-9 methylene group to C-5 is the major reaction pathway when the TMS and the oxirane groups are on the same ring while methyl migration results exclusively when they are on different rings.