scholarly journals Ionization potentials of nitriles — Photoelectron spectra of succinonitrile and glutaronitrile

2006 ◽  
Vol 84 (9) ◽  
pp. 1124-1131 ◽  
Author(s):  
Heidi M Muchall ◽  
Nick H Werstiuk
Keyword(s):  
Energy Region ◽  
Photoelectron Spectrum ◽  
Lone Pair ◽  
Low Energy ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Proton Affinities ◽  
Nitrogen Lone Pair ◽  
D Model ◽  
Highest Occupied Molecular Orbitals

The He(I) photoelectron spectra of succinonitrile (1) and glutaronitrile (2), both with extensive overlap of ionization bands in the low-energy region, are reported. To assign ionizations, we studied the conformational behaviour and resulting ionization energy dependence of 1 and 2 computationally with the B3LYP/6-31+G(d) model chemistry based on the fact that it reliably reproduces the ionization potentials of eleven mono- and di-nitriles, both saturated and unsaturated. The correlation of proton affinities with observed ionization potentials of 1, 2, and malononitrile establishes the orbital sequence of four C≡N π orbitals followed by two nitrogen lone pair orbitals as the highest occupied molecular orbitals for all three compounds.Key words: photoelectron spectrum, ionization potential, conformational dependence, nitrile, DFT.

scholarly journals Photoelektronen-Spektren und Moleküleigenschaften, LXIII Ionisierungsenergien von Phenyl-Methyl-Tellurid und Vergleich der Effekte von Sauerstoff-, Schwefel-, Selen- und Tellur-Substituenten auf das Benzol-π-System / Photoelectron Spectra and Molecular Properties, LXIII Ionization Energies of Phenyl Methyl Telluride and Comparison of Effects of Oxygen, Sulphur, Selenium and Tellurium Substituents on the Benzene π System

1976 ◽  
Vol 31 (12) ◽  
pp. 1611-1615 ◽  
Author(s):  
Galina Tschmutowa ◽  
Hans Bock
Keyword(s):  
Gas Phase ◽  
Dihedral Angle ◽  
Energy Region ◽  
Phenyl Ring ◽  
Photoelectron Spectrum ◽  
Lone Pair ◽  
Low Energy ◽  
Molecular Properties ◽  
Photoelectron Spectra ◽  
Overlapping Bands

The photoelectron spectrum of H5C6-Te-CH3 displays in its low energy region overlapping bands of gas-phase conformers. Depending on the dihedral angle between the plane of the phenyl ring and the tellurium lone pair, the π conjugation amounts to only 0.1 eV and 0.3 eV, respectively. These values are compared to the considerably larger ones found for the analogous phenyl derivatives H5C6-X-CH3 with X = O, S and Se.

A Discussion on photoelectron spectroscopy - Orderings of π and σ ionization potentials in carbocyclic and heterocyclic aromatic compounds

1970 ◽  
Vol 268 (1184) ◽  
pp. 131-140 ◽  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Aromatic Compounds ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Light Sources ◽  
Orbital Energies ◽  
Substituted Pyridines ◽  
Nitrogen Lone Pair ◽  
Electron Correlation Effects

Data on calculated orbital energies and experimentally measured ionization potentials of carbocyclic and heterocyclic aromatic compounds are compared and contrasted. The ordering or orbital energies and ionization potentials do not always seem to parallel one another, probably owing to either electron correlation effects, or to deviations from Koopman’s theorem. The effects on photoelectron spectra of using different light sources and analysers are discussed in relation to their bearing on the orbital orderings of aromatic compounds. The high resolution He 584 A. photoelectron spectrum of pyridine is shown to be open to two interpretations regarding the ordering of the ionization potentials of the π orbitals and the ‘nitrogen lone pair’ (n). One of the interpretations involves the three lowest pyridine ionization potentials being π (9.2 eV), π L (9.5 eV) and n (10.5 eV) whilst the other has the first three ionization potentials being the order π , n, π . The photoelectron spectra of substituted pyridines and diazines are discussed in the light of the two possible explanations for the pyridine spectrum.

The photoelectron spectra of some molecules containing the C≡N group

1970 ◽  
Vol 317 (1529) ◽  
pp. 187-198 ◽  
Keyword(s):  
Cyanogen Bromide ◽  
Lone Pair ◽  
Vibrational Structure ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Spin Orbit Coupling ◽  
Ethyl Vinyl ◽  
Cyanogen Chloride ◽  
Nitrogen Lone Pair ◽  
Cyanogen Iodide

The photoelectron spectra of a number of molecules containing the C≡N group have been measured over the range 6 to 21 eV. For cyanogen chloride, cyanogen bromide and cyanogen iodide, ionization potentials have been determined and assigned to particular molecular orbitals on the basis of the vibrations coupled with the ionization processes, and of the splitting due to spin-orbit coupling. Differences in these features among the three compounds have been discussed in terms of the delocalization of electrons in these molecules. From the spectra of methyl, ethyl, vinyl and allyl cyanides, potentials have been determined for ionization from the C=C π, C≡N π and nitrogen lone pair orbitals, and other higher ionization potentials have been determined but not assigned explicitly. A number of ionization potentials have been determined for mono-, di-, and tri-chloro-methyl cyanides, but absence of accompanying vibrational structure and the additional complexity caused by the levels derived from 3p electrons in the chlorine atoms make specific assignments impossible.

Photoelectron Spectra and Molecular Properties, XLVIII Carbonates and Thiocarbonates

1975 ◽  
Vol 30 (11-12) ◽  
pp. 862-874 ◽  
Author(s):  
K. Wittel ◽  
E. E. Astrup ◽  
H. Bock ◽  
G. Graeffe ◽  
H. Juslén
Keyword(s):  
Ionization Potential ◽  
Substituent Effects ◽  
Lone Pair ◽  
Emission Spectra ◽  
Low Energy ◽  
Photoelectron Spectra ◽  
Energy Bands ◽  
Open Chain ◽  
First Ionization Potential ◽  
Cndo Calculations

Photoelectron (PE) spectra of ethylene and vinylene carbonates and thiocarbonates as well as of methylene trithiocarbonate and some open-chain derivatives are reported.The low energy bands, well separated in the unsaturated compounds, are assigned to lone pair and π type ionizations. The assignment is based on comparison of PE spectra, modified CNDO calculations, and sulfur Κβ emission spectra. The pronounced substituent effects due to which the first ionization potential varies from 8.4 eV to 11.1 eV are discussed.

Photoelectron Spectrum and Electronic Structure of Tetrathiofulvalene (TTF)

1974 ◽  
Vol 52 (19) ◽  
pp. 3373-3377 ◽  
Author(s):  
A. John Berlinsky ◽  
James F. Carolan ◽  
Larry Weiler
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Molecular Orbital ◽  
Photoelectron Spectrum ◽  
Crystal Packing ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Molecular Orbital Calculations ◽  
Conducting Salt

The electronic structure of tetrathiofulvalene (TTF) has been determined from its photoelectron spectrum and the photoelectron data for the tetrahydro derivative of TTF and 1,3-dithiolane. Correlations of the ionization potentials (i.p.) and several molecular orbital calculations are used in the assignment of the photoelectron spectra of these three compounds. The first five i.p. of TTF and their assignment are as follows: 6.92 (3b1u), 8.67 (2b2g), 9.73 (2b1u), 10.16 (au) and 10.49 eV (b3g). The sixth i.p. at 11.00 eV is tentatively assigned to the 1b2g level. The electronic structure of TTF is important in understanding the crystal packing and band structure of the highly conducting salt, TTF•TCNQ.

scholarly journals A G2(MP2) theoretical study of substituent effects on H3BNHnCl3−n (n= 3-0) donor-acceptor complexes

2008 ◽  
Vol 6 (3) ◽  
pp. 400-403 ◽  
Author(s):  
Hafid Anane ◽  
Soufiane Houssame ◽  
Abdelali Guerraze ◽  
Abdeladim Guermoune ◽  
Abderrahim Boutalib ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Substituent Effects ◽  
Lone Pair ◽  
Proton Affinities ◽  
Lone Pair Orbital ◽  
Chlorine Substitution ◽  
Donor Acceptor ◽  
Nitrogen Lone Pair ◽  
The Stability ◽  
N Compounds

AbstractThe complexation energies of H3BNHnCl3−n (n= 3-0) complexes and the proton affinities of NHnCl3−n compounds have been computed at the G2(MP2) level of theory. G2(MP2) results show that the successive chlorine substitution on the ammonia decreases both the basicity of the NHnCl3−n ligands and the stability of H3BNHnCl3−n complexes. The findings are interpreted in terms of the rehybridisation of the nitrogen lone-pair orbital. The NBO partitioning scheme shows that the variation of the N-H and N-Cl bond lengths, upon complexation, is due to variation of “s” character in these bonds.

Infrared and photoelectron spectra, and keto—enol tautomerism of acetylacetones and acetoacetic esters

1975 ◽  
Vol 342 (1630) ◽  
pp. 327-339 ◽  
Keyword(s):  
Wide Temperature Range ◽  
Photoelectron Spectrum ◽  
Equilibrium Constants ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Temperature Range ◽  
Related Compounds

The infrared and photoelectron spectra of some substituted acetylacetones have been measured, and interpreted in terms of enolic and ketonic structures. Ionization potentials from specific orbitals have been assigned. With different substituents, the proportion of the two forms varies considerably. From measurements of the photoelectron spectrum over a wide temperature range, the equilibrium constants for keto-enol forms have been determined and estimates made of the enthalpy of the tautomeric change. Conclusions about the tautomerism have been correlated with earlier measurements by other methods. For comparison, the spectra of acetoacetic esters and related compounds have been measured. The proportions of keto-enol forms have been estimated and ionization potentials assigned to particular orbitals.

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