Photoelectron spectra of substituted acetophenones. Correlations with reactivity

1980 ◽  
Vol 58 (6) ◽  
pp. 622-626 ◽  
Author(s):  
E. J. McAlduff
Keyword(s):  
Chemical Shifts ◽  
Chemical Reactivity ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Redox Potentials ◽  
Nmr Chemical Shifts ◽  
Monosubstituted Benzenes

Ultraviolet photoelectron spectra of 4-R-acetophenones (R = N(CH3)2, t-Bu, Cl) have been determined and the three lowest ionization potentials assigned. Combination of these data with literature data on other 4-R-acetophenone allows correlations of nO IP with redox potentials, nmr chemical shifts of acetyl protons, and chemical reactivity data. Both PhS and nO IP's correlate with Hammett σP constants of the substituent and PhS IP's are found to be linearly related to the first IP's of the analogous monosubstituted benzenes.

Photoelectron spectra of substituted benzamides

1978 ◽  
Vol 56 (4) ◽  
pp. 495-504 ◽  
Author(s):  
E. J. McAlduff ◽  
B. M. Lynch ◽  
K. N. Houk
Keyword(s):  
Electron Density ◽  
Chemical Shifts ◽  
Amide Group ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Nmr Chemical Shifts ◽  
Linear Relationships ◽  
Substituted Benzamides ◽  
Monosubstituted Benzenes

The photoelectron spectra of the following substituted benzamides have been determined: p-CH3O, p-CH3, p-Cl, H, p-F, p-CN, p-NO2, m-CH3O, m-CH3, m-Cl, and m-NO2. The first six ionization potentials have been assigned with reference to the phenyl and amide moieties. As an aid to the assignment CNDO/S calculations have been performed on the methoxy, methyl, and nitro benzamides. Linear relationships have been shown to exist between the first phenyl IP of disubstituted and monosubstituted benzenes. The slopes of these relationships have been shown to be related to the electron releasing ability of the substituent.By comparison of the pes data with nmr chemical shifts, the first phenyl IP has been shown to be related to the electron density at the position of substitution of the amide group. Likewise, the amide IP centered on the nitrogen has been shown to be related to the electron density on nitrogen.

scholarly journals Substituenteneinflüsse auf die 13C–NMR-chemischen Verschiebungen cis- und trans-konfigurierter Trimethincyanine / Substituent Effects on the 13C NMR Chemical Shifts of Trimethincyanines with cis and trans Configuration

1976 ◽  
Vol 31 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
Walter Grahn
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron Systems ◽  
Coupling Constant ◽  
Electronic Effects ◽  
Nmr Chemical Shifts ◽  
Monosubstituted Benzenes ◽  
Cis And Trans ◽  
C Nmr

The 13C NMR chemical shifts of fifteen 6 substituted 2,3-dihydro-1,4-diazepinium salts (cis trimethincyanines) (1) and twelve 2 substituted bis(dimethylamino)trimethinium salts (trans trimethincyanines) (2) have been determined. A comparison of the substituentinduced shifts (13C SCS) of 1 and 2 allows no distinction between steric and electronic effects. In the three 6 п-electron systems 1, 2 and monosubstituted benzenes the 13C SCS are similar for the substituent bearing carbon atoms. A surprisingly large 4JFCCNC coupling constant has been observed.

Characterization of Tris(Diselenocarbamato)Cobalt(III) and Pentakis(Diselenocarbamato)Dicobalt(III) Complexes by Electrochemical, Cobalt-59 N.M.R. and Mass-Spectrometric Techniques. Comparisons With Dithiocarbamate Analogs

1986 ◽  
Vol 39 (9) ◽  
pp. 1385 ◽  
Author(s):  
AM Bond ◽  
R Colton ◽  
DR Mann ◽  
JE Moir
Keyword(s):  
Electrochemical Oxidation ◽  
Chemical Shifts ◽  
Chemical Reactivity ◽  
Mercury Electrode ◽  
Substituent Effects ◽  
Reduction Process ◽  
Reduced Form ◽  
Platinum Electrodes ◽  
Redox Potentials ◽  
Mercury Electrodes

A series of Co(RR′dsc)3 and [Co2(RR′dsc)5]+ complexes (R, R′ = two alkyl groups or one heterocyclic group; dsc = NCSe2) have been synthesized and their redox behaviour, chemical reactivity and spectroscopic properties compared with the corresponding dithiocarbamate (RR′dtc) complexes. Electrochemical oxidation of Co(RR′dsc)3 in dichloromethane at platinum electrodes occurs at potentials about 0.34 V less positive than for Co(RR′dsc)3. The formally cobalt(IV) complexes [Co(RR′dsc)3]+ can be identified as a product which is then converted into [Co2(RR′dsc)5]+ via dimerization and an internal redox reaction. Despite the enhanced thermodynamic stability implied by the redox potentials, [Co(RR′dsc)3]+ has similar kinetic stability to the analogous dithiocarbamate complexes. Co(RR′dsc)3 is reduced at fairly negative potentials on both platinum and mercury electrodes with extremely rapid loss of [RR′dsc]-. [Co(RR′dsc)3]- is therefore thermodynamically and kinetically more unstable than [Co(RR′dtc)3]- . The [Co2(RR′dsc)5]+ complexes are also more readily oxidized and harder to reduce than the sulfur analogues. Oxidation of [Co2(RR′dsc)5]+ produces [Co2(RR′dsc)5]2+ at low temperatures and fast scan rates, but no stable reduced form of the dimer is accessible on the voltammetric time scale examined. The reduction process for the dimer is consistent with the reaction [Co2(RR′dsc)5]+ +e- → Co(RR′dsc)3+ Co(RR dsc)2. Electrochemical oxidation data obtained at mercury electrodes for the diselenocarbamate complexes are complicated by adsorption but are similar to that found at platinum electrodes. This contrasts with the dithiocarbamates where a mercury electrode specific pathway is observed. Cobalt-59 n.m.r. spectroscopy in dichloromethane shows the non- equivalence of the two cobalt atoms in [Co2(RR′dsc)5]+. The chemical shifts for Co(RR′dsc)3 complexes exhibit similar substituent effects to the dithiocarbamates in cobalt-59 n.m.r. measurements as was the case in oxidative electrochemistry. Cobalt-59 n.m.r. spectroscopy and mass spectrometry demonstrate that exchange, substitution and redox reactions can lead to the formation of mixed ligand diselenocarbamate complexes and mixed dithiocarbamate/diselenocarbamate complexes for both the cobalt(III) monomers and dimers.

Photoelectron spectra of carbonyl halides and related compounds

1972 ◽  
Vol 327 (1568) ◽  
pp. 13-22 ◽  
Keyword(s):  
Chemical Reactivity ◽  
Vibrational Structure ◽  
Molecular Orbitals ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Ionization Process ◽  
Parent Molecule ◽  
Carbonyl Cyanide ◽  
Related Compounds

Photoelectron spectra in the region 6 to 21 eV have been measured for carbonyl halides (fluoride, chloride and bromide) and carbonyl cyanide. In a number of cases, vibrational structure coupled with the ionization process has been resolved and correlated with the known frequencies of the parent molecule. Ionization potentials have been derived for the removal of an electron from orbitals of different kinds, such as the C=O π orbital and various nonbonding molecular orbitals. The results have been correlated with other data on the chemical reactivity of these molecules.

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