Polarity and structure of eight-membered organosilicon compounds with planar fragments

For the first time is determined the polarity of eight-membered silocyns with planar fragments. By the methods of dipole moments and theoretical calculations (DFT B3LYP/6-31G*) of 1,3,2-dioxasilocyns is established that in these compounds occurs the conformational equilibrium of the forms bath-chair and distorted bath with the predominance of the first, in this case the bonds C(sp 3)-S and C(sp 3)-H of the exocyclic MeSCH2 group are in the not eclipsed gauche orientation relative to each other. © 2009 Pleiades Publishing, Ltd

Experimental and theoretical conformation analysis of eight-membered silocines with planar fragments

The dipole moments of 6-thia-4,5: 6,7-dibenzo-1,3,2-dioxasilocines were determined experimentally and calculated at the DFT B3LYP/6-31G*level of theory and by the additivity scheme. The experimental and theoretical (DFT B3LYP/6-31G*) conformation analysis of eight-membered 1,3,2-dioxasilocines having planar fragments showed that these compounds in solution exist as boat-chair, boat-boat, or twist-boat conformers, depending on the presence of unsaturated planar fragment, nature of the heteroatom in position 6 of the eight-membered ring, and substituents on the silicon atom. © 2010 Pleiades Publishing, Ltd

Polarity and structure of silatranes with planar fragments

The structure of silatranes N[CH2(RMeC6H2)O]3SiR1 with planar fragments in six-membered semi-rings was established by the methods of dipole moments and density functional theory calculations. They are endo-structures with transannular interaction N→Si in which the oxygen atoms located adjacent to the silicon participate besides the nitrogen and silicon atoms

Dipole moments, structure, and transannular interactions in silatranes containing planar fragments

The method of dipole moments and theoretical calculations (DFT B3LYP/6-31G*) were used for structural assessment of silatranes N[CH2(RMeC6H2)O]3SiR1 containing planar fragments in the six-membered semirings. They are endo structures with transannular N→Si interaction which involves, along with nitrogen and silicon, oxygen atoms adjacent to silicon. © 2008 MAIK Nauka

Theoretical study of the structure of N-arylmaleimides and bis-maleimides

Conformational analysis of N-arylmaleimides and bis-maleimides was performed by the dipole moment method and quantum chemical calculations. The aromatic ring and heterocycle in N-arylmaleimides are turned with respect to each other through an angle of 42-44, which excludes conjugation between these fragments. No conjugation exists between the dioxopyrrole rings in bridged bis-maleimides. The structure of the examined compounds is controlled by steric factors. Pronounced inductive effect of chlorine atoms in chloro-substituted bis-maleimides is responsible for their reduced dipole moments. © 2013 Pleiades Publishing, Ltd

Conformations of acyclic sulfites

1. Dialkyl sulfites in liquids, vapors, and solutions are represented by structures with trans-trans- and trans-gauche-conformations of the chain R-O-S-O-R. 2. Diaryl sulfites exist in a trans-gauche conformation. © 1974 Consultants Bureau

Configurations and conformations of the α- and β-thiooxides of Δ3-carene

1. Analysis of1H NMR spectra has shown that the thiooxide obtained from the α-oxide of Δ3-carene has the two three-membered rings in the cis-configuration, while the thiooxide obtained from the β-oxide is a trans-isomer. 2. Measurements of the1H and13C NMR spectra and the Kerr effect have shown the predominant conformation of the α-thiooxide molecule to be that of the inverted boat. In the case of the β-thiooxide, a conformational equilibrium is established in which the predominant configuration is that of the inverted boat, according to the NMR data, and that of the boat itself, according to the Kerr effect measurements. © 1977 Plenum Publishing Corporation

Influence of substituents of the conformation of molecules with two geminal C-SR bonds

1,1-Bis(arylthio)ethanes exist in solutions in the form of conformers with trans-gauche and trans-trans conformations of the C-S-C-S-C chain, while geminal disulfones based on them exist in transgauche and gauche-gauche conformations, with the radicals situated on different sides of the plane of S-C-S. © 1975 Plenum Publishing Corporation

Aggregation in a mixture of cetyltrimethylammonium bromide and polyoxyethylene 600 monolaurate solutions

Micellization in the cetyltrimethylammonium bromide (CTAB)-polyoxyethylene 600 monolaurate (PL)-chloroform system is studied with dielcometric titration, NMR self-diffusion (2D DOSY), 13C NMR spectroscopy, and light scattering methods. The formation of mixed aggregates of surfactants is established. It is shown that CTAB and PL polar moieties interact in the inverse micelle core in the vicinity of PL carbonyl group. © Pleiadas Publishing, Inc., 2006

Conformation of trimethylene carbonate and electrical parameters of the carbonate group

1. The dipole moment (2.94 D) and the main semiaxes of the polarizability ellipsoid (3.863, 4.173, 1.115 å) of the carbonate group have been determined. 2. Based on combined structural studies the C-envelope is the most probable conformation of trimethylene carbonate. © 1985 Plenum Publishing Corporation