Principle of additivity of dipole moments: 1,3- and 1,3,5-derivatives of benzene

1985 ◽  
Vol 50 (1) ◽  
pp. 188-199 ◽  
Author(s):  
Juraj Koudelka ◽  
Otto Exner
Keyword(s):  
Dipole Moments ◽  
Bond Angles ◽  
Vector Addition ◽  
Inductive Interaction ◽  
Donor Acceptor ◽  
Experimental Values ◽  
Derivatives Of

Dipole moments of fourteen 1,3-derivatives and thirteen 1,3,5-derivatives of benzene, with axially symmetrical substituents only, were measured in two solvents. After excluding the compounds forming the donor-acceptor complexes with benzene, the experimental values are well reproduced by the vector addition of group moments, i.e. the accuracy achieved is sufficient for practical purposes. Nevertheless, small systematic deviations were observed: the experimental moments were as a rule less than additive in the case of 1,3-derivatives but greater in the case of 1,3,5-derivatives. These deviations cannot be accounted for by deformation of bond angles from the hexagonal geometry but they can be semiquantitatively interpreted by mutual inductive interaction of dipoles. The latter interpretation was supported by CNDO/2 calculations.

Principle of additivity of dipole moments: Halogen derivatives of adamantane

1985 ◽  
Vol 50 (1) ◽  
pp. 200-207 ◽  
Author(s):  
Otto Exner ◽  
Juraj Koudelka
Keyword(s):  
Dipole Moments ◽  
Tetrahedral Geometry ◽  
General Applicability ◽  
Smith Method ◽  
Vector Addition ◽  
Moment Approach ◽  
Experimental Values ◽  
Derivatives Of ◽  
Mutual Induction

Dipole moments of halogenated adamantanes II-IV were measured in two solvents using the Guggenheim-Smith method. The reliability of the method was checked on non-polar symmetrical compounds I, V. The dipole moments of 1,3-dihalogen and 1,3,5-trihalogen derivatives reveal small but real deviations from the additive behaviour: the experimental values are less than those calculated by vector addition from the moments of monoderivatives, assuming tetrahedral geometry. This fact can be explained by mutual induction of dipole rather than by angle deformation, although both effects can contribute. The deviations from the additive behaviour are qualitatively represented by CNDO/2 calculations with fixed geometry. However, even the greatest deviations observed amount only several percent in relative values and do not impair the general applicability of the bond moment approach.

Dielectric properties of hexafluoroacetone and hexachloroacetone

1969 ◽  
Vol 47 (12) ◽  
pp. 2253-2256 ◽  
Author(s):  
R. K. Chan
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid State ◽  
Dipole Moments ◽  
Dielectric Constants ◽  
Pure Liquid ◽  
Gaseous State ◽  
Vector Addition ◽  
Inductive Effects ◽  
Experimental Values

The dielectric constants of hexafluoro- and hexachloro-acetone are measured in the solid and liquid state. They show negligible association in the liquid state. The dipole moments are 0.648 D measured in the gaseous state and 0.63 D in pure liquid for hexafluoroacetone, and 1.24 D in carbon tetrachloride solution and 1.34 D in pure liquid for hexachloroacetone. If the differences between inductive effects due to CX3 and C=O groups can be ignored, the vector addition of bond moments gives values of dipole moment which are compatible with the experimental values.

Configuration and Conformation Study of S-Allyl O-Methyl N-(2- and 4-Substituted Acridin-9-yl)thiocarbonimidates in Relation to Their [3,3] Sigmatropic Rearrangement

1998 ◽  
Vol 63 (3) ◽  
pp. 387-393 ◽  
Author(s):  
Ivan Danihel ◽  
Kalevi Pihlaja ◽  
Ján Imrich ◽  
Gejza Suchár ◽  
Pavol Kristian ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Chair Conformation ◽  
Sigmatropic Rearrangement ◽  
Difference Spectra ◽  
Vector Addition ◽  
Chloro Derivatives ◽  
Experimental Values ◽  
Configuration And Conformation

Configuration and conformations of S-allyl O-methyl N-(2- and 4-substituted acridin-9-yl)thiocarbonimidates were studied by means of NMR spectroscopy, dipole moments and quantum chemical calculations. The E configuration was proved for the unsubstituted and 2-chloro derivatives from the NOE-difference spectra. Experimental values of dipole moments were related to those obtained from vector addition. Quantum chemical calculations pointed to the chair conformation of these compounds in transition state for above-mentioned rearrangement.

The effective viscosity of suspensions of spherical particles

1956 ◽  
Vol 237 (1208) ◽  
pp. 90-116 ◽  
Keyword(s):  
Legendre Polynomials ◽  
Effective Viscosity ◽  
Dipole Moments ◽  
Spherical Particles ◽  
Mathematical Treatment ◽  
Laplace’S Equation ◽  
Laplace's Equation ◽  
Experimental Values ◽  
Derivatives Of ◽  
Good Agreement

A method has been devised for solving the hydrodynamic problem involving swarms of particles moving in an incompressible fluid, assuming that the inertia terms in the equation of motion can be neglected. It is used to calculate the effective viscosity of a supension of spherical particles whose volume concentrations are less than. 10 %, assuming a statistical distribution of particles, under circumstances similar to those in a rotating viscometer. The viscosity is determined from the rate of shear at the walls. A special form of the model gives values of the effective viscosity up to concentrations as high as 25 % which are in good agreement with experimental values. The mathematical treatment involves the calculation of the potential due to point charges amongst a collection of earthed conducting spheres, coinciding with the particles. The simpler approximations allowing only for the induced charge on these spheres and the dipole moments about their centres are sufficiently accurate for concentrations of less than 10%, but a more complicated estimate is required for greater concentrations, which includes the effect of quadrupole and other multipole moments. Such calculations are elaborate but they are completed by means of expansions in solutions of Laplace’s equation V 2 0 = 0 which are derivatives of the elementary solution (1/r), instead of the more usual expansion in Legendre polynomials. A suitable algebra for these solutions is evolved which enables us to avoid problems which arise in changing the origin and axes of the Legendre polynomials. Using this algebra solutions of the equation V 2 0 = k 2 0 are manipulated almost as easily as those of Laplace’s equation. In the Anal results for the effective viscosity, the effect of the multipoles is found to be small.

Dipole Moments of para-Substituted N-Phenylsulfonyl-N'-Allylthioureas

1995 ◽  
Vol 60 (5) ◽  
pp. 856-862
Author(s):  
Gejza Suchár ◽  
Ivan Danihel
Keyword(s):  
Dipole Moments ◽  
Vector Addition ◽  
Stretching Vibrations

Dipole moments of a series of para-substituted N-phenylsulfonyl-N'-allylthioureas were determined. Comparison of the experimentally found dipole moments with those calculated by vector addition of bond and group moments has shown that (E) conformation at the N-C bonds is preferred. The same result was obtained from the N-H stretching vibrations. The results are compatible with a synperiplanar arrangement at the C-C bond of the allyl moiety.

The combined effect of lattice’s uniaxial strains and electron–phonon interaction’s screening on TBEC of the intersite bipolarons

2016 ◽  
Vol 30 (26) ◽  
pp. 1650186
Author(s):  
B. Yavidov ◽  
SH. Djumanov ◽  
T. Saparbaev ◽  
O. Ganiyev ◽  
S. Zholdassova ◽  
...  
Keyword(s):  
Ideal Gas ◽  
Einstein Condensation ◽  
Chain Model ◽  
One Dimensional ◽  
Electron Phonon Interaction ◽  
Model Lattice ◽  
Experimental Values ◽  
Bose Einstein ◽  
Derivatives Of ◽  
The Ideal

Having accepted a more generalized form for density-displacement type electron–phonon interaction (EPI) force we studied the simultaneous effect of uniaxial strains and EPI’s screening on the temperature of Bose–Einstein condensation [Formula: see text] of the ideal gas of intersite bipolarons. [Formula: see text] of the ideal gas of intersite bipolarons is calculated as a function of both strain and screening radius for a one-dimensional chain model of cuprates within the framework of Extended Holstein–Hubbard model. It is shown that the chain model lattice comprises the essential features of cuprates regarding of strain and screening effects on transition temperature [Formula: see text] of superconductivity. The obtained values of strain derivatives of [Formula: see text] [Formula: see text] are in qualitative agreement with the experimental values of [Formula: see text] [Formula: see text] of La[Formula: see text]Sr[Formula: see text]CuO4 under moderate screening regimes.

Experimental and computed dipole moments in donor–bridge–acceptor systems with p-phenylene and p-carboranediyl bridges

2009 ◽  
Vol 74 (1) ◽  
pp. 131-146 ◽  
Author(s):  
Ladislav Drož ◽  
Mark A. Fox ◽  
Drahomír Hnyk ◽  
Paul J. Low ◽  
J. A. Hugh MacBride ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Dipole Moments ◽  
Electronic Effects ◽  
Electronic Interactions ◽  
Donor And Acceptor ◽  
Homo And Lumo ◽  
Pull Systems ◽  
The Difference ◽  
Experimental Values ◽  
2D And 3D

Dipole moments were measured for a series of substituted benzenes, biphenyls, terphenyls, C-monoaryl- and C,C′-diaryl-p-carboranes. For the donor–bridge–acceptor systems, Me2N–X–NO2, where X is 1,4-phenylene, biphenyl-4,4′-diyl, terphenyl and 1,4-C6H4-p-CB10H10C-1,4-C6H4, the measured interaction dipole moments are 1.36, 0.74, 0.51 and 0.00 D, respectively. The magnitude of the dipole moment reflects the ability of the bridge to transmit electronic effects between donor and acceptor groups. Thus, whilst the 1,4-phenylene bridges allow moderate electronic interactions between the remote groups, the p-carboranediyl unit is less efficient as a conduit for electronic effects. Averaged dipole moments computed at the DFT (B3LYP/6-31G*) level of theory from two distinct molecular conformers are in good agreement with the experimental values. Examination of the calculated electronic structures provides insight into the nature of the interactions between the donor and acceptor moieties through these 2D and 3D aromatic bridges. The most significant cooperative effect of the bridge on the dipole moment occurs in systems where there is some overlap between the HOMO and LUMO orbitals. This orbital overlap criterion may help to define the difference between “push-pull” systems in which electronic effects are mediated by the bridging moiety, and simpler systems in which the bridge acts as an electronically innocent spacer unit and through-space charge transfer/separation is dominant.

4. Molecular polarisability. The molar Kerr constants and dipole moments of spiro- and other derivatives of pentaerythritol

1958 ◽  
Vol 0 (0) ◽  
pp. 16-23 ◽  
Author(s):  
C. G. Le Fèvre ◽  
R. J. W. Le Fèvre ◽  
M. R. Smith
Keyword(s):  
Dipole Moments ◽  
Derivatives Of ◽  
Kerr Constants

Use of dipole moments to determine the structure of halogen derivatives of ortho-and meta-carboranes

1968 ◽  
Vol 8 (5) ◽  
pp. 829-832
Author(s):  
V. I. Stanko ◽  
A. I. Echeistova ◽  
I. S. Astakhova ◽  
A. I. Klimova ◽  
Yu. T. Struchkov ◽  
...  
Keyword(s):  
Dipole Moments ◽  
Derivatives Of

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.

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