Homoallylic interaction between a nitrogen lone pair and a non-adjacent π-bond. Part 6. Nature of the lone-pair electrons in n,π-homoconjugated aliphatic amines

1977 ◽  
pp. 1057-1062 ◽  
Author(s):  
Kenichi Yoshikawa ◽  
Akira Matsui ◽  
Isao Morishima
Keyword(s):  
Lone Pair ◽  
Aliphatic Amines ◽  
Nitrogen Lone Pair ◽  
Lone Pair Electrons

N.M.R. spectra and stereochemistry of the bipyridyls. III. 2,2'-Bipyridyl and dimethyl derivatives, 3,3'- bipyridyl, and 4,4' - bipyridyl

1967 ◽  
Vol 20 (6) ◽  
pp. 1227 ◽  
Author(s):  
TM Spotswood ◽  
CI Tanzer
Keyword(s):  
Hydrogen Bonding ◽  
Electrostatic Field ◽  
Field Effect ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Diamagnetic Anisotropy ◽  
Equal Importance ◽  
Nitrogen Lone Pair ◽  
Lone Pair Electrons ◽  
Derivatives Of

The analysis of the n.m.r, spectra of 2,2?-, 3,3?-, and 4,4?-bipyridyl and three dimethyl-2,2?-bipyridyls is reported and the factors determining the relative chemical shifts of the ring protons and methyl groups in several solvents are discussed. The diamagnetic anisotropy of the neighbouring ring and electrostatic field effect of the nitrogen lone pair electrons are shown to be of roughly equal importance for derivatives of 2,2?-bipyridyl except in hydrogen bonding solvents. Attenuation of the electrostatic field effect in polar, and particularly in hydrogen bonding solvents, is established for 4- picoline, and for the bipyridyls, and this effect is responsible for striking changes in the spectrum of 2,2?-bipyridyl in hydrogen bonding solvents. An approximate interplanar angle of 58� is derived for 3,3?- dimethyl-2,2?-bipyridyl, and 2,2?-bipyridyl and its 4,4?- and 5,5?- dimethyl derivatives appear to be trans coplanar in all solvents. 3,3?- Bipyridyl and 4,4?-bipyridyl are probably highly twisted in all solvents, or alternatively, behave as essentially free rotors. The predicted conformations are in good agreement with the electronic spectral data.

Molecular Complexes of Cyclophanes, Part XVII Charge-Transfer Complexes of [2.2]- and [2.2.2]Paracyclophane-carbamates with π-Acceptors

1987 ◽  
Vol 42 (9) ◽  
pp. 1147-1152 ◽  
Author(s):  
Aboul-fetouh E. Mourad ◽  
Verena Lehne
Keyword(s):  
Charge Transfer ◽  
Functional Group ◽  
Lone Pair ◽  
Molecular Complexes ◽  
Charge Transfer Complexes ◽  
Electronic Interactions ◽  
H Nmr ◽  
Ct Complex ◽  
Nitrogen Lone Pair ◽  
Lone Pair Electrons

Charge-transfer (CT) complexation between some [2.2]- and [2.2.2]paracyclophane-carbamates as donors with 2,3-dichloro-5.6-dicyanobenzoquinone (DDO ) as well as tetracyanoethylene (TCNE) as π-acceptors has been evidenced by VIS. 1H NMR and IR spectroscopy. The site of interaction in the two different donor systems was determined. The results reveal no contribution of the nitrogen lone pair electrons of the carbamate functional group in the CT complexation. and the interaction is mainly of π-π* type. In addition, the existence of the transannular electronic interactions in [2.2]paracyclophane derivatives is responsible for CT complex formation.

Elektronendichte und chemische Verschiebung der Styryldiazin- und Diazaphenanthrenprotonen / Electrondensity and Proton Chemical Shift of Styryldiazines and Diazaphenanthrenes

1972 ◽  
Vol 27 (2) ◽  
pp. 310-319
Author(s):  
H.-H. Perkampus ◽  
Th. Bluhm ◽  
J. Knop
Keyword(s):  
Ring Current ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Current Effect ◽  
Electron Densities ◽  
Paramagnetic Effect ◽  
Nitrogen Lone Pair ◽  
Chemische Verschiebung ◽  
Lone Pair Electrons ◽  
Proton Chemical Shifts

AbstractProton chemical shifts in styryldiazines and diazaphenanthrenes linearly correlate with SCF-π-electron densities of the attached carbon atom and with the electron densities of the hydrogen atom (calculated by the CNDO/2 method). The observed deviations from linearity are discussed in terms of ring current effect, steric effects and the paramagnetic effect of the nitrogen lone pair electrons. An appreciable weakening of ring current is found for diazaphenanthrenes with two adjacent N-atoms. Under the same condition the paramagnetic effect on ortho-hydrogens is increased.

The lattice energy of S -triazine

1968 ◽  
Vol 304 (1479) ◽  
pp. 501-512 ◽  
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Lone Pair ◽  
Lattice Energy ◽  
Pressure Measurements ◽  
Cell Dimensions ◽  
Repulsive Potentials ◽  
Probable Effect ◽  
Nitrogen Lone Pair ◽  
Lone Pair Electrons

The contributions of the dispersive and repulsive potentials to the lattice energy of S -triazine are calculated on the basis of bond-bond and atom-atom interactions respectively. The cell dimensions obtained by minimizing the energy agree with the experimental data to within 4% and the heat of sublimation derived from the vapour pressure measurements is quite close to the calculated lattice energy. The probable effect of the electrostatic forces is dis­cussed and found to be of only marginal importance in determining the crystal structure. No evidence is found for anomalously large repulsions by the nitrogen-lone pair electrons.

Pulse radiolytic formation of solvated electrons in hydrazine

1976 ◽  
Vol 54 (17) ◽  
pp. 2807-2812 ◽  
Author(s):  
William Arthur Seddon ◽  
John Wallace Fletcher ◽  
Fred Charles Sopchyshyn
Keyword(s):  
Room Temperature ◽  
Transition Energy ◽  
Optical Transition ◽  
Lone Pair ◽  
Solvated Electrons ◽  
Optical Absorption Band ◽  
Optical Transition Energy ◽  
Nitrogen Lone Pair ◽  
Basic Solutions ◽  
Lone Pair Electrons

The spectrum and yield of solvated electrons in anhydrous hydrazine have been investigated by pulse radiolysis. At room temperature the optical absorption band has a maximum at 1.22 eV (1015 nm) with a molar extinction coefficient of 2.2 ± 0.1 × 104 M−1 cm−1 and a temperature coefficient of 1.5 × 10−3 eV deg−1 from 7–45 °C. The oscillator strength is estimated to be 0.6. The optical transition energy is in reasonable agreement with an empirical correlation of solvent properties proposed by Freeman provided that only the polarisability of the nitrogen lone-pair electrons contribute to Emax. Comparisons are made with liquid amides which also have lone-pair polarisable groups and with water and liquid ammonia which have physical properties very similar to hydrazine. Electron yields increase from [Formula: see text] in pure hydrazine to 2.65 + 0.15 in basic solutions containing ≥0.1 M sodium hydrazide.

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