Stereochemistry of seven-membered heterocycles. 2. IR spectra, dipole moments, and inductive effect of the alkyl groups in 2-alkylbenz[e]-1,3-dioxepanes

1980 ◽  
Vol 29 (2) ◽  
pp. 211-215 ◽  
Author(s):  
B. A. Arbuzov ◽  
E. N. Klimovitskii ◽  
A. B. Remizov ◽  
G. N. Sergeeva
Keyword(s):  
Ir Spectra ◽  
Inductive Effect ◽  
Dipole Moments ◽  
Alkyl Groups

Échelles pKHB et enthalpique du pouvoir accepteur de liaison hydrogène de thioéthers, thiols et disulfures

2005 ◽  
Vol 83 (2) ◽  
pp. 138-145 ◽  
Author(s):  
Christian Laurence ◽  
Michel Berthelot ◽  
Karine Evain ◽  
Bertrand Illien
Keyword(s):  
Hydrogen Bond ◽  
Inductive Effect ◽  
Resonance Effect ◽  
Substituent Effects ◽  
Hydrogen Bond Acceptor ◽  
Frequency Shifts ◽  
Ir Spectrometry ◽  
Distinctive Features ◽  
Alkyl Groups ◽  
Polarizability Effect

The hydrogen bond acceptor (HBA) strength of 31 tetrahedral sulfur bases (thioethers, thiols, disulfides) has been measured by IR spectrometry from: (i) their 1:1 complexation constants with 4-fluorophenol in CCl4 at 25 °C (the pKHB scale); (ii) their HB enthalpies; and (iii) the frequency shifts, Δν(OH), of the ν(OH) band of 4-fluorophenol hydrogen bonded to sulfur. The comparison of the pKHB, ΔH°, and Δν(OH) scales points to their distinctive features. The HBA strength depends on: (i) the nature of the atomic site: oxygen bases are always stronger than sulfur bases, in agreement with the hard and soft acids and bases principle; (ii) the functionality of this atom (for sulfur bases: phosphine sulfur > thioamide > thioketone > thioether > thiol > isothiocyanate ~ disulfide); and (iii) the substituent effects on the function. The main substituent effects are: (i) the polarizability effect of alkyl groups; (ii) the field-inductive effect; (iii) the resonance effect; and (iv) the cyclization effect, which changes the percentage of the s character of sulfur lone pairs. In addition to the attachment to the sulfur atom, IR spectra show the attachment of 4-fluorophenol to the chlorine of MeSCH2Cl and MeSCH2CH2Cl, and the interaction to the π cloud of PhSMe, Ph2S, PhCH2SMe, and EtSCH=CH2. Key words: hydrogen bond, thioethers, thiols, disulfides, pKHB scale.

IR spectra, dipole moments, and conformations of bis(dichloroarsino)methane

1989 ◽  
Vol 29 (5) ◽  
pp. 701-706
Author(s):  
A. B. Remizov ◽  
F. G. Khalitov ◽  
F. G. Garieva
Keyword(s):  
Ir Spectra ◽  
Dipole Moments

Assessing the Effect of Ligand Proximity on Chiroptical and Other Properties in Cobalt(III) Model, Tyrosine-Like Complexes

1995 ◽  
Vol 60 (12) ◽  
pp. 2097-2106 ◽  
Author(s):  
František Jursík ◽  
Ronald D. Archer
Keyword(s):  
Amino Acid ◽  
Inductive Effect ◽  
Lewis Acidity ◽  
Side Chain ◽  
Ground State Structure ◽  
Amino Acid Side Chain ◽  
State Structure ◽  
Reduction Potentials ◽  
Alkyl Groups ◽  
C Nmr

A series of new cobalt(III) octahedral complexes of the general formula Na[Co(ohb-aa)2] (ohb-aa = N-(o-hydroxybenzyl)amino acid anion); amino acid = glycine, (S)-α-alanine, α-aminoisobutyric acid, (S)-valine, (S)-norvaline and (S)-leucine) were prepared by the charcoal catalyzed reaction of the appropriate ligand with [Co(NH3)6]3+ in alkaline aqueous solution. Complexes obtained have, regardless of the amino acid used, the same facial all-trans symmetry (CoN2O4 chromophore) with the vicinal effects as the entire source of the optical activity. 13C NMR spectra reveal that the leucine derivative has, due to the steric reasons, a different ground state structure. Absorption maxima reflect a positive inductive effect from the amino acid side chain carbon atoms. Complexes of the ligands bearing electrophobic alkyl groups exhibit more negative E1/2 in comparison with the glycine derivative, reduction of which occurs at a more positive potential. Reduction potentials do not correlate with cobalt(III) Lewis acidity modulated by ligands.

Synthesis, separation, and identification of 4-bromoadamantan-2-one stereoisomers

1980 ◽  
Vol 45 (10) ◽  
pp. 2670-2674 ◽  
Author(s):  
Luděk Vodička ◽  
Jan Tříska ◽  
Milan Hájek
Keyword(s):  
Ir Spectra ◽  
Hydrobromic Acid ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Dipole Moments ◽  
Hydroxylamine Hydrochloride ◽  
Shift Reagent ◽  
One Step ◽  
Elution Chromatography ◽  
The Eu

A one-step synthesis of mixture of stereoisomers of 4-bromoadamantan-2-one based on the reaction of adamantan-2-one with hydroxylamine hydrochloride in hydrobromic acid is described. The pure stereoisomers were isolated by elution chromatography on silica gel, and their NMR spectra with the Eu(FOD)3 shift reagent, mass spectra, IR spectra, and dipole moments were measured.

scholarly journals The structure and reactivity of the halogenobenzens

1946 ◽  
Vol 185 (1000) ◽  
pp. 119-126
Keyword(s):  
Transition State ◽  
Charge Distribution ◽  
Aromatic Compounds ◽  
Inductive Effect ◽  
Dipole Moments ◽  
Aromatic Nucleus ◽  
Side Chain ◽  
Chain Reactions ◽  
State Resonance ◽  
Inductive Effects

The structure of the halogenobenzenes is described in terms of an inductive effect acting on the meta -positions and polarization between neighbouring atoms, in addition to the well-recognized mesomeric and inductive effects at the ortho - and para -positions. Data on the side-chain reactions of aromatic compounds are correlated with those on nitration (with recognition of the effect of transition-state resonance in the latter case) to provide estimates of the charge distribution in the aromatic nucleus. The dipole moments of the halogenobenzenes are calculated.

scholarly journals Molecular structure of calcium, magnesium, strontium and barium m-nitrobenzoates

2010 ◽  
Vol 24 (3-4) ◽  
pp. 433-437 ◽  
Author(s):  
Mariola Samsonowicz
Keyword(s):  
Molecular Structure ◽  
Electronic Structure ◽  
Ir Spectra ◽  
Dipole Moments ◽  
Atomic Charges ◽  
Barium Ions ◽  
Nitrobenzoic Acid ◽  
Calcium Magnesium ◽  
Ft Ir

The effect of calcium, magnesium, strontium and barium ions on the electronic structure of m-nitrobenzoates was studied. The FT-IR spectra of m-nitrobenzoic acid and its salts were registered, assigned and analyzed. Characteristic shifts and changes in intensities of bands along the metal series were observed. The structures of m-nitrobenzoic acid and its calcium, magnesium, strontium and barium salts were optimized at the B3LYP/LANL2DZ level. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated.

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