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 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 photoelectron spectra and electronic structure of 2-carbonyl furans

1990 ◽  
Vol 68 (5) ◽  
pp. 747-754 ◽  
Author(s):  
Dieter Klapstein ◽  
Charles D. MacPherson ◽  
Robert T. O'Brien
Keyword(s):  
Electronic Structure ◽  
Fine Structure ◽  
Gas Phase ◽  
Carbonyl Group ◽  
Ionization Energy ◽  
Furan Ring ◽  
Photoelectron Spectra ◽  
Energy Bands ◽  
Rotational Isomers ◽  
Inductive Effects

The He(I), λ = 58.4 nm, photoelectron spectra of a series of six 2-carbonyl furans and 2-furonitrile have been measured in the gas phase. The low ionization energy bands are assigned to photoionizations from π orbitals of the furan ring, orbitals localized on the carbonyl group, and orbitals of the carbonyl substituents. Changes in ionization energies within the series can be rationalized in terms of the relative conjugative and inductive effects of the substituents. Substituent inductive effects were found to be dominant. The relatively broad vibrational fine structure on the low IE bands of the carbonyl furans could result from the presence of rotational isomers of the species. Keywords: photoelectron spectra, 2-carbonyl furans, molecular orbitals.

The Photoelectron Spectra of the N-Chloro and N-Bromo Derivatives of Dimethylamine

1979 ◽  
Vol 32 (4) ◽  
pp. 719 ◽  
Author(s):  
F Carnovale ◽  
T Gan ◽  
JB Peel
Keyword(s):  
Energy Range ◽  
Molecular Orbital ◽  
Ionization Energy ◽  
Lone Pair ◽  
Photoelectron Spectra ◽  
Molecular Orbital Calculations ◽  
Ionization Energies ◽  
Resonance Effects ◽  
Derivatives Of ◽  
Lone Pair Interactions

The He I and He II spectra obtained for chlorodimethylamine (CH3)2NCl, and bromodimethylamine (CH3)2NBr, complete the study of the N-chloro and N-bromo derivatives of the small amines. The valence photoelectron spectra are interpreted with the aid of SPINDO molecular orbital calculations. Trends in the observed ionization energies for both series of small halo amines are described in terms of variations in inductive and resonance effects, the latter particularly concerning the nN/nx lone-pair interactions observed in the low ionization energy range.

Synthesis, Optical Properties, Structures and Molecular Orbital Calculations of Subazaporphyrins, Subphthalocyanines, Subnaphthalocyanines and Related Compounds

1999 ◽  
Vol 03 (06) ◽  
pp. 453-467 ◽  
Author(s):  
NAGAO KOBAYASHI
Keyword(s):  
Molecular Orbital ◽  
Magnetic Circular Dichroism ◽  
Soret Band ◽  
Ring Expansion ◽  
Molecular Orbital Calculations ◽  
Mo Calculations ◽  
Key Points ◽  
Adsorption Data ◽  
Ring Expansion Reaction ◽  
Related Compounds

The synthesis of and spectroscopic data on subazaporphyrins, subphthalocyanines, subnaphthalocyanines and their related compounds reported to date are summarized, together with the results of molecular orbital (MO) calculations from our laboratory. Thus the problems and key points in the synthesis of these subazamacrocycles and their electronic absorption and magnetic circular dichroism (MCD) spectra are discussed, together with those of the monosubstituted-type low-symmetrical phthalocyanines obtained by their ring expansion reaction. The Q bands of these subazamacrocycles are orbitally doubly degenerate, and in the Soret band region, three transitions to the orbitally degenerate state are found. The MO calculations suggest that the HOMO levels destabilize considerably while the LUMO levels change slightly with increasing size of the π system. In addition, the electronic adsorption data are reproduced by the calculation only when the two pyrrole hydrogens in the monosubstituted-type phthalocyanines are assumed to be linked to the two pyrrole nitrogens along the short axis.

Transfer Integrals and Band Structures in (Et)2X Salts

1989 ◽  
Vol 173 ◽  
Author(s):  
Oliver H. Leblanc ◽  
Margaret L. Blohm ◽  
Richard P. Messmer
Keyword(s):  
Low Temperature ◽  
Nearest Neighbor ◽  
Spherical Wave ◽  
Tight Binding ◽  
Ab Initio Method ◽  
Energy Bands ◽  
Hubbard Hamiltonian ◽  
Transfer Integrals ◽  
Semi Empirical ◽  
Very Low Temperature

ABSTRACTTransfer integrals (tij) between pairs of nearest neighbor ET molecules were calculated by an ab initio method. Tight-binding one-electron energy bands constructed from the tij are similar to those previously calculated by Mori and by Whangbo and their coworkers by semi-empirical, extended Hückel methods, but quite different from those found by Kübler et al. in β-(ET)2I3 using the augmented spherical wave (ASW) method. However, all these band models are suspect. The Hubbard on-site repulsion parameter U is estimated to be about twice the band widths, indicating that a full treatment of the Hubbard hamiltonian is needed. Also, polaron effects appear to control transport except at very low temperature.

Photoelectron studies on intramolecularly hydrogen-bonded systems. I. The photoelectron spectra of cis- and trans-2-aminocyclopentanol, and cis- and trans-2-(N,N-dimethylamino)cyclopentanol

1976 ◽  
Vol 54 (4) ◽  
pp. 642-646 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Hydrogen Bonding ◽  
Ionization Energy ◽  
Lone Pair ◽  
Intramolecular Hydrogen Bonding ◽  
Photoelectron Spectra ◽  
Hydrogen Bonded Systems ◽  
Intramolecular Hydrogen ◽  
Cis And Trans ◽  
Infrared Data ◽  
Hydrogen Bonded

The photoelectron spectra of cis- and trans-2-aminocyclopentanol and cis- and trans-2-(N,N,-dimethylamino)cyclopentanol have been recorded and interpreted. The cis isomers exhibit N lone pair ionizations at higher ionization energy, and O lone pair ionizations at lower ionization energy than their trans isomers.The results are most consistent with the existence and observation of intramolecular hydrogen-bonding in the cis isomers. Infrared data on these systems also show that the cis isomers exist in the intramolecularly hydrogen-bonded state.

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

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