The He(I) photoelectron spectra of the propenoyl halides

1987 ◽  
Vol 65 (4) ◽  
pp. 683-686 ◽  
Author(s):  
Dieter Klapstein ◽  
Robert T. O'Brien
Keyword(s):  
Related Species ◽  
Molecular Orbitals ◽  
Photoelectron Spectra ◽  
Mo Calculations ◽  
Sum Rule ◽  
Orbital Energies ◽  
Out Of Plane ◽  
Semi Empirical

The He(I) photoelectron spectra of propenal and the propenoyl halides, CH2=CHCOX, X = H, F, Cl, Br, were measured and interpreted with the aid of semi-empirical MO calculations, comparison with results for structurally related species, and a sum-rule for the out-of-plane orbital energies. Information concerning the identities and relative energies of the higher occupied molecular orbitals of the neutral molecules could be deduced from the spectra.

The He(I) photoelectron spectra of 2-butynal and related oxyalkynes

1988 ◽  
Vol 66 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Dieter Klapstein ◽  
Robert T. O'Brien
Keyword(s):  
Related Species ◽  
Ionization Energy ◽  
Photoelectron Spectra ◽  
Localized Orbitals ◽  
Mo Calculations ◽  
Energy Bands ◽  
Resonance Effects ◽  
Energy Variation ◽  
Semi Empirical ◽  
Related Compounds

The He(I), λ = 58.4 nm, photoelectron spectra of 2-butynal and the related compounds 2-butynol, 2-butynoic acid, 2-butynoyl fluoride, and 2-butynoyl chloride were obtained. The lower ionization energy bands may be assigned to photoionization from specific orbitals by comparison within the series, with related species and with the use of semi-empirical MO calculations. The energy variation of the more localized orbitals with substituent variation may be rationalized in terms of the inductive and resonance effects of the substituents.

The electronic structure of cyclopentadienylindium

1982 ◽  
Vol 60 (6) ◽  
pp. 699-702 ◽  
Author(s):  
C. S. Lin ◽  
Dennis G. Tuck
Keyword(s):  
Electronic Structure ◽  
Dipole Moment ◽  
Related Species ◽  
Lone Pair ◽  
Photoelectron Spectra ◽  
Covalent Interaction ◽  
Orbital Energies ◽  
Calculated Dipole Moment ◽  
Dominant Feature ◽  
Cndo Calculations

CNDO calculations have been carried out for the molecule InC5H5 of C5υ symmetry. Overlap populations were calculated and compared with those for related species. The bonding between In and the organic moiety can be described as essentially a covalent interaction involving mainly indium 5s and 5p orbitals with ring pπ orbitals. A lone pair on indium is a dominant feature of the structure, and is largely responsible for a (calculated) dipole moment of 4.75 D. The calculated orbital energies are compared with experimental photoelectron spectra.

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 Conformational behavior and electronic structure of silylketenes studied with quantum chemical calculations and photoelectron spectroscopy

1997 ◽  
Vol 75 (12) ◽  
pp. 1851-1861 ◽  
Author(s):  
Heidi M. Muchall ◽  
Nick H. Werstiuk ◽  
Jiangong Ma ◽  
Thomas T. Tidwell ◽  
Kuangsen Sung
Keyword(s):  
Electronic Structure ◽  
Quantum Chemical Calculations ◽  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
Computational Study ◽  
Photoelectron Spectra ◽  
Conformational Behavior ◽  
Torsional Angle ◽  
Orbital Interaction ◽  
Orbital Energies

The He(I) photoelectron spectra of silylketenes (Me3Si)2C=C=O (1), Me5Si2CH=C=O (2), Me2Si(CH=C=O)2 (3), MeSi(CH=C=O)3 (4), (SiMe2CH=C=O)2 (5), and (CH2SiMe2CH=C=O)2 (6) have been recorded and their structures and orbital energies have been calculated by ab initio methods. Orbital energies for disilanes 2 and 5 are strongly dependent on a Si-Si-C-C torsional angle due to σ–π orbital interaction. Comparisons between experimental and simulated spectra show that 2 and 5 prefer conformations in which the Si—Si bond and ketene group(s) are approximately orthogonal (113° and 111°, respectively). Silylalkenes Me5Si2CH=CH2 (7) and (SiMe2CH=CH2)2 (8), which have been included in the computational study, show the same behavior as their corresponding silylketenes. Silylbis- and trisketenes 3–6 do not exhibit π–π interaction of any significance. For Si—Si containing compounds, the best agreement between experimental and computed data was obtained when Becke3LYP/6-31G*//HF/3-21G* was employed. Keywords: conformational behavior, electronic structure, photoelectron spectroscopy, quantum chemical calculations, silylketenes.

Semi Empirical Study of a System Containing a Six-membered Ring

2004 ◽  
Vol 59 (11) ◽  
pp. 853-856
Author(s):  
H. Kara ◽  
Y. Yahsi ◽  
Y. Elerman ◽  
A. Elmali
Keyword(s):  
Chemical Potential ◽  
Chair Conformation ◽  
Membered Ring ◽  
Chemical Hardness ◽  
Mo Calculations ◽  
Lumo Energy ◽  
Conformational Interconversion ◽  
Homo And Lumo ◽  
Semi Empirical ◽  
Homo And Lumo Energy

Semi-empirical AM1 SCF-MO calculations have been used to find the structure optimization and conformational interconversion pathways of a system containing a six-membered ring. The system has the two symmetrical energy-minimum conformations, chair and twist. The chair conformation has the most stable geometry. Some quantum parameters such as HOMO and LUMO energy, the chemical hardness and chemical potential are discussed

Assignment of the valence molecular orbitals of cis-[PtR2L2] complexes: UV photoelectron spectra and SCF-MS-X.alpha. calculations

1989 ◽  
Vol 28 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Dong Sheng Yang ◽  
G. Michael Bancroft ◽  
John D. Bozek ◽  
R. J. Puddephatt ◽  
John S. Tse
Keyword(s):  
Molecular Orbitals ◽  
Photoelectron Spectra

Molecular orbital calculations for sulphur-nitrogen heterocycles. I. The 3-hydroxyisothiazole system

1968 ◽  
Vol 21 (5) ◽  
pp. 1113 ◽  
Author(s):  
JR Christie ◽  
B Selinger
Keyword(s):  
Molecular Orbital ◽  
Perturbation Analysis ◽  
Related Species ◽  
Nitrogen Heterocycles ◽  
Chemical Properties ◽  
Molecular Orbital Calculations ◽  
Semi Empirical ◽  
Scf Calculations

LCAO-SCF calculations of various types have been performed for 3-hydroxy-isothiazole and related species. A perturbation analysis has shown that the values assigned to some of the semi-empirical parameters affect the results to a greater extent than has been supposed. Some of the chemical properties can be rationalized on the basis of these calculations.

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