Stereospecific alkyl group effects on amine lone-pair ionization potentials: photoelectron spectra of alkylpiperidines

1982 ◽  
Vol 104 (5) ◽  
pp. 1189-1191 ◽  
Author(s):  
Melvin D. Rozeboom ◽  
K. N. Houk
Keyword(s):  
Alkyl Group ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Pair Ionization ◽  
Group Effects

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.

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 Highly-Excited State Properties of Cumulenone Chlorides in the Vacuum-Ultraviolet

2020 ◽  
Author(s):  
Quynh Nguyen ◽  
William Peters ◽  
Ryan Fortenberry
Keyword(s):  
Excited States ◽  
Vacuum Ultraviolet ◽  
Lone Pair ◽  
Carbon Chain ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Chain Elongation ◽  
Electronic Excitations ◽  
Quantum Chemical Analysis ◽  
Poten Tials

<div><div><div><p>Recent observations of chloromethane in interstellar environments suggest that other organohalo- gens, which are known to be critically important in Earth′s atmosphere, may also be of significance beyond our own terrestrial veil. This raises the question of how such molecules behave under extreme conditions such as when exposed to vacuum ultraviolet (VUV) radiation. VUV photons promote molecules to highly excited states that fragment in non-statistical patterns controlled by the initial femtosecond dynamics. A detailed understanding of VUV-driven photochemistry in complex organic molecules that consist of more than one functional group is a particularly challenging task. This quantum chemical analysis reports the electronic states and ionization potentials up to the VUV range (6 - 11 eV) of the chlorine-substituted cumulenone series molecules. The valence and Rydberg properties of lone-pair terminated, π-conjugated systems are explored for their potential resonance with lone pairs from elsewhere in the system. The carbon chain elongation within the family ClHCnO, where n=1-4, influences the electronic excitations, associated wavefunctions, and ionization poten- tials of the molecules. The predicted geometries and ionization potentials are in good agreement with the available experimental photoelectron spectra for formyl chloride and chloroketene, n=1-2. Furthermore, comparison between the regular cumulenone species and the corresponding chlorinated derivatives exhibit similar behaviors especially for n=3, where the allene backbone in propadienone chloride is severely bent. Most notably for the excited states is that the Rydberg character becomes more dominant as the energy increases, with some retaining valence characters.</p></div></div></div>

Photoelectron Spectra of Phosgene and Thiophosgene

1972 ◽  
Vol 50 (5) ◽  
pp. 737-746 ◽  
Author(s):  
David Chadwick
Keyword(s):  
High Resolution ◽  
Molecular Orbital ◽  
Strong Interaction ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Lone Pair Electrons

The high resolution photoelectron spectra of phosgene and thiophosgene have been obtained and, in each case, all ionization potentials up to 21.2 eV determined. The spectra are interpreted in terms of the molecular orbital structures and it is concluded that there is a strong interaction between the chlorine pπ "lone pair" electrons and those in the C=O or C=S π bond. The measured ionization potentials are compared with those calculated by the CNDO/2 method and with those obtained for similar molecules.

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