Dipole Moments of meta and para Substituted Benzoyl Isothiocyanates

1993 ◽  
Vol 58 (2) ◽  
pp. 378-384 ◽  
Author(s):  
Ivan Danihel ◽  
Gejza Suchár
Keyword(s):  
Dipole Moments ◽  
Vector Addition ◽  
Mndo Calculations ◽  
Benzoyl Isothiocyanates ◽  
Confirmation Analysis

For a series of meta and para substituted benzoyl isothiocyanates, the dipole moments were determined experimentally and calculated by vector addition of the bond and group dipole moments. Confirmation analysis revealed the preference of the synclinal conformation (τ ∀ 60°), which emerges from the rotation about the C(7)-N bond. MNDO calculations were also performed for the compounds, and the dipole moments obtained were compared with those from the above procedure.

A study of structure of meta and para substituted phenyl and benzoyl isothiocyanates by the MNDO method

1987 ◽  
Vol 52 (9) ◽  
pp. 2115-2124 ◽  
Author(s):  
Ivan Danihel ◽  
Pavol Kristian ◽  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Electron Distribution ◽  
Dipole Moments ◽  
Point Of View ◽  
Mndo Method ◽  
Mndo Calculations ◽  
Non Linear ◽  
Benzoyl Isothiocyanates

On the basis of the optimized MNDO calculations of a selected series of meta and para substituted phenyl and benzoyl isothiocyanates it has been found that the –NCS group is non-linear in both the cases (the deviation from linearity is about 9°). For the phenyl isothiocyanates the values of CNC angles are in the region of 146.1° - 149.0°, and for the benzoyl isothiocyanates the respective regions for the CNC and OCN angles are 146.4° - 152.1° and 117.1° - 118.5°. In the meta substituted benzoyl isothiocyanates the –CONCS group is perpendicular to the phenyl residue. The results are discussed from the point of view of the electron distribution and dipole moments of the compounds studied.

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.

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 of 2- and 4-Substituted 9-Isothiocyanatoacridines

1996 ◽  
Vol 61 (11) ◽  
pp. 1615-1619
Author(s):  
Ivan Danihel ◽  
Gejza Suchár ◽  
Pavol Kristian ◽  
Stanislav Böhm
Keyword(s):  
Dipole Moments ◽  
Vector Addition

Dipole moments of a series of 2- and 4-substituted 9-isothiocyanatoacridines were determined and compared with the values calculated by vector addition using bond and group dipole moments. The results are discussed from the viewpoint of geometrical and conformational structures of the compounds investigated.

MNDO calculations of the molecular and electronic structure of thionitroso, dithionitro and related compounds

1988 ◽  
Vol 53 (9) ◽  
pp. 2116-2127 ◽  
Author(s):  
Achim Mehlhorn
Keyword(s):  
Electron Capture ◽  
Infrared Spectra ◽  
Dipole Moments ◽  
Radical Cations ◽  
Electron Affinities ◽  
Mndo Calculations ◽  
Stabilization Effect ◽  
Related Compounds ◽  
Molecular And Electronic Structure

Compounds with the formulae RNS and RNS2 (thionitroso I and dithionitro compounds II, dithionitrites III, N-thiosulfinylamines IV, dithia-aziridines V and thiazylthiols VI, R = H, CH3, C6H5)and the corresponding radical cations HNS2+ and anions HNS2- have been investigated by MNDO calculations with respect to their molecular geometries, relative stabilities, ionization and electron capture properties and dipole moments. For the simplest representatives (R = H) the infrared spectra have been calculated. The lengths of NS triple (in VI), double (in I, III, IV) and partial double (in II, III) bonds are predicted to be in the region of 147-150, 152-155 and 158-162 pm, respectively. Within these regions systematic shifts result from different substituents R. Contraction of NS bonds (1-6 pm) is observed in the case of ionization whereas electron capture causes bond elongation (2-6 pm). The MNDO sequence of stability deviates from that of ab initio calculations for compounds with tetravalent sulfur the stabilization effect of which is obviously underestimated by the MNDO approach. All compounds studied are characterized by negative non-vertical electron affinities suggesting vigorous reactivity with nucleophilic reactants. The patterns of infrared spectra enable recognition, discrimination and characterization of these mostly unknown compounds which might be accessible as short-living transients.

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.

N,N-Linked biazoles. III. MNDO calculations on the conformation of N,N-linked biazoles and their quaternary salts

1984 ◽  
Vol 62 (4) ◽  
pp. 687-695 ◽  
Author(s):  
Maria Luisa Castellanos ◽  
Santiago Olivella ◽  
Nuria Roca ◽  
Javier De Mendoza ◽  
José Elguero
Keyword(s):  
Electronic Properties ◽  
Excellent Agreement ◽  
Theoretical Study ◽  
Dipole Moments ◽  
Mndo Method ◽  
Quaternary Salts ◽  
Mndo Calculations ◽  
Full Optimization ◽  
Experimental Values ◽  
Orthogonal Form

A theoretical study of fourteen N,N-linked biazoles has been carried out using the MNDO method with full optimization of the geometries. The variation of energy as a function of the conformation around the central N—N bond shows in all cases the higher stability of the orthogonal or near-orthogonal form. The contribution of the three main types of "ortho" interactions [Formula: see text] and the effect of quaternization have been evaluated. Of the electronic properties calculated, one must emphasize the excellent agreement of dipole moments with 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.

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