Dipole moments induced in larger molecules. 1- And 4-substituted diamantanes

1980 ◽  
Vol 45 (9) ◽  
pp. 2400-2409 ◽  
Author(s):  
Otto Exner ◽  
Václav Jehlička ◽  
Luděk Vodička ◽  
Pavel Jakoubek
Keyword(s):  
Benzene Solution ◽  
Dipole Moments ◽  
Adamantane Derivatives ◽  
Basic Assumptions ◽  
Eyring Theory

Dipole moments of fourteen monofunctional diamantane derivatives were measured in benzene solution. The values found are almost equal for 1-substituted (IIa-IIg) and 4-subtituted (IIIa to IIIg) isomers but both are distinctly higher than those of the corresponding adamantane derivatives (I). This trend is not accounted for in terms of the classic Smith-Eyring theory of induced moments which works reasonable well for smaller molecules. Probably some basic assumptions of the theory of dielectrics (a spherical molecular cavity with a dipole in its centre) are no more fulfilled for diamantane derivatives.

Dipole moments induced in larger molecule. Long-chain aliphatic esters

1982 ◽  
Vol 47 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Otto Exner ◽  
Ayfer Bapçum
Keyword(s):  
Benzene Solution ◽  
Dipole Moments ◽  
Straight Chain ◽  
Basic Assumptions ◽  
Donor Acceptor ◽  
Eyring Theory ◽  
Aliphatic Esters ◽  
Long Chain

Dipole moments of straight-chain aliphatic esters Ia-Ic and IIa-IIf were measured in benzene solution. The observed trends are poorly reproduced by the classical Smith-Eyring theory; the reason may be partly the unknown conformation, partly even donor-acceptor complexes with the solvent. No deviations were observed with the highest members of the series, attributable to violation of some basic assumptions of the theory of dielectrics.

Dipole moments and conformation of α-disulphones. The gauche effect

1985 ◽  
Vol 50 (10) ◽  
pp. 2245-2251 ◽  
Author(s):  
Otto Exner ◽  
Václav Jehlička
Keyword(s):  
Dihedral Angle ◽  
Graphical Method ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Statistical Treatment ◽  
X Ray ◽  
Gauche Effect

The dipole moments of substituted diphenyl disulphones I-III were measured in benzene solution and interpreted by the previously described graphical method. The results suggest an equilibrium of the ap and sc conformations in the ratio 3 : 1, at variance with various empirical rules and theories of the so-called gauche effect. A statistical treatment of X-ray data of various sulphonyl derivatives revealed essentially two preferred conformations: the more stable sc, with a broadened dihedral angle, and the less stable ap.

PHOSPHONITRILIC COMPOUNDS: PART I. THE MECHANISM OF PHOSPHONITRILIC CHLORIDE POLYMERIZATION CAPACITANCE, CONDUCTANCE, AND ELECTRON-SPIN RESONANCE STUDIES

1964 ◽  
Vol 42 (2) ◽  
pp. 447-455 ◽  
Author(s):  
H. R. Allcock ◽  
R. J. Best
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Ring Cleavage ◽  
Preliminary Step ◽  
Polymerization Mechanism ◽  
Spin Resonance ◽  
Nitrogen Ring

Capacitance and conductance measurements were carried out with molten (NPCl2)3 and [NP(OC6H5)2]3 and dipole moments were determined in benzene solution. Attempts to detect free radicals in molten samples of the same compounds were unsuccessful. Evidence was obtained that homolytic or heterolytic phosphorus–nitrogen ring cleavage is not involved in the primary initiation process. The results favor, instead, a polymerization mechanism for (NPCl2)3 in which phosphorus–chlorine ionization is a preliminary step.

Hydrogen bonding, configuration and conformation of substituted α-oxo oximes and hydrazones

1979 ◽  
Vol 44 (8) ◽  
pp. 2494-2506 ◽  
Author(s):  
Otto Exner ◽  
Jorga Smolíková ◽  
Václav Jehlička ◽  
Ahmad S. Shawali
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Intramolecular Hydrogen Bond ◽  
Benzene Solution ◽  
Dipole Moments ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Configuration And Conformation

Substituted 2-bromo-1-phenylglyoxal 2-phenylhydrazones IIIa-f exist in tetrachloromethane or benzene solutions prevailingly in E-configuration and in conformation A with an intramolecular hydrogen bond. The latter was evidenced by the N-H valence frequency at 3 290 cm-1 and by 1H NMR shifts with reference to derivatives without a carbonyl group - α-chlorobenzaldehyde phenylhydrazones V. From dipole moments of IIIa-d, measured in benzene solution, the contribution of the hydrogen bond (μH) was evaluated to 17 . 10-30 C m. This quantity is twice larger than in any other reported compound but the direction of the vector is as usual: approximately from H to N. In structurally similar derivatives of hydroxylamine, substituted 2-phenylglyoxylhydroximoyl chlorides IVa-d, no intramolecular hydrogen bond was detected; the dipole moments found were interpreted in terms of the Z-configuration and the prevailing conformation G.

A study of dipole moments of substituted isothiocyanates of 1,3-diphenyl-2-propen-1-one

1984 ◽  
Vol 49 (10) ◽  
pp. 2382-2386 ◽  
Author(s):  
Gejza Suchár ◽  
Milan Dzurilla ◽  
Pavol Kristian
Keyword(s):  
Electronic Structure ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Vector Addition

The dipole moments have been measured of various substituted isothiocyanates of 1,3-diphenyl-2-propen-1-one in benzene solution. The measured values have been compared with the dipole moments obtained by the vector addition of the bond dipole moments, and the comparison has been used for a discussion of their electronic structure and interactions of the NCS group.

Dipole moments and conformation of some olefinic and ortho-substituted aromatic methoxy derivatives

1989 ◽  
Vol 54 (5) ◽  
pp. 1291-1298 ◽  
Author(s):  
Drahomír Hnyk ◽  
Radek Fajgar ◽  
Václav Všetečka ◽  
Otto Exner
Keyword(s):  
Benzene Solution ◽  
Dipole Moments

Dipole moments of stereoisomeric 3-methoxypropenenitriles (I,II), substituted 2-methoxybenzonitriles (III-VI) and substituted 2-chlorophenyl methyl ethers (VII-X) were measured in benzene solution and analyzed in terms of group moments. Aromatic derivatives III-X exist in the prevailing conformation ap (CH3 trans to Cl or to CN). Any minor conformation was not detected; small differences between experimental and calculated dipole moments were explained by induction of the two adjacent dipoles. Conformations of 3-methoxypropenenitriles were estimated to prevailing sp for I and practically only ap for II. Irrespective of the conformations, dipole moments revealed a strong conjugation of the CN and OCH3 groups in I and II. The intensity of this conjugation in various derivatives thus decreases steeply in the series: olefinic E > olefinic Z > aromatic para > aromatic ortho.

Electric moments, sulfur bonding, and conformations of substituted thiochloroformate esters in benzene solutions

1969 ◽  
Vol 47 (2) ◽  
pp. 343-348 ◽  
Author(s):  
A. Queen ◽  
T. A. Nour ◽  
E. Bock
Keyword(s):  
Sulfur Atom ◽  
Halogen Atom ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Vector Model ◽  
Hydrocarbon Group ◽  
Electron Release ◽  
D Orbitals

The dipole moments of a series of aryl and alkyl thiochloroformate esters have been determined in benzene solution at 25 °C and compared with the corresponding values for chloroformate and fluoroformate esters. The results have been interpreted in terms of conjugative and hyperconjugative electron release by the hydrocarbon group to the d-orbitals of the sulfur atom in the thio compounds. Vector model, bond moment calculations indicate that, as in the cases of the chloroformate and fluoroformate esters, the preferred conformations of the thiochloroformates are those in which the hydrocarbon group and the halogen atom are cis to each other.

Calculations of induced dipole moments: adamantane derivatives

1989 ◽  
Vol 197 ◽  
pp. 361-366 ◽  
Author(s):  
Ljiljana Došen-Mićović ◽  
Otto Exner
Keyword(s):  
Dipole Moments ◽  
Adamantane Derivatives ◽  
Induced Dipole
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