Application of photoelectron spectroscopy to intramolecularly hydrogen-bonded systems. Part II. On the n–π* blue shift of carbonyl-containing molecules

1976 ◽  
Vol 54 (20) ◽  
pp. 3203-3205 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Photoelectron Spectroscopy ◽  
Blue Shift ◽  
Photoelectron Spectra ◽  
Ultraviolet Spectra ◽  
Hydrogen Bonded Systems ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The photoelectron spectra of 2-hydroxycyclohexanone and 2-methoxycyclohexanone, show that the ionization assigned to removal of the carbonyl n-electron is 0.6 eV higher in the former, presumably due to the intramolecular hydrogen bond. The ultraviolet spectra of these molecules also exhibit a marked blue shift of the n → π* transition in the former of roughly 0.5 eV. A discussion of the observations includes consideration of the effect of the intramolecular hydrogen bond on the ground and excited or ion state.

Application of photoelectron spectroscopy to intramolecularly hydrogen-bonded systems. Part IV. π-Systems; the photoelectron spectra of syn- and anti-7-norbornenol

1976 ◽  
Vol 54 (20) ◽  
pp. 3206-3209 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Hydrogen Bond ◽  
Photoelectron Spectroscopy ◽  
Ionization Energy ◽  
Geometric Isomer ◽  
Photoelectron Spectra ◽  
Orbital Interactions ◽  
The Difference ◽  
Hydrogen Bonded Systems ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

In an effort to determine the effect of an intramolecular hydrogen bond on the ionization energy of a simple π-system, the photoelectron spectra of syn- and anti-7-norbornenol have been determined. The difference in the ionization energy of the π(C—C) and nÖH orbitals is 0.30 eV for the former, and 0.85 eV for the latter. The photoelectron spectrum of the syn- isomer shows that the π(C—C) bond is roughly 0.2 eV more difficult to ionize than its counter-part in the non-hydrogen bonded geometric isomer and has been interpreted as arising from hydrogen bond induced stabilization of the π-bond. That the spectral differences in the alcohols is not simply due to differing orbital interactions between the two isomers can be demonstrated by the photoelectron spectra of syn- and anti-7-methoxynorbornene. In these systems which allow no possibility of hydrogen bonding the π(C—C) – nÖR difference is the same for both isomers.

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.

Application of photoelectron spectroscopy to intramolecularly hydrogen-bonded systems. Part III. The photoelectron spectra of cis and trans 2-substituted cyclopentanols and cis and trans 2-substituted cyclohexanols

1976 ◽  
Vol 54 (12) ◽  
pp. 1929-1937 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Hydrogen Bonding ◽  
Photoelectron Spectroscopy ◽  
Intramolecular Hydrogen Bonding ◽  
Photoelectron Spectra ◽  
Molecular Orbital Calculations ◽  
Cis And Trans Isomers ◽  
Koopmans Theorem ◽  
Hydrogen Bonded Systems ◽  
Intramolecular Hydrogen ◽  
Cis And Trans

The photoelectron spectra of several well defined molecules exhibiting intramolecular hydrogen bonding has been determined and the analysis of the spectra is in accord with recent molecular orbital calculations of related systems. The experimentally determined enthalpies of the hydrogen bonds in cis-2-aminocyclopentanol and cis- and trans-2-aminocyclohexanol do not correlate in any simple fashion with the shifts in the ionization energies of the nO and nN orbitals compared to a model which precludes hydrogen bonding. The spectral differences attributed to hydrogen bonding in the cis and trans 2-substituted cyclanols cannot be attributed to differences in the through-bond interaction of the n orbitals on either atom since the cis and trans isomers of 1,2-dimethoxycyclopentane and 1,2-dimethoxycyclohexane show virtually identical pe spectra. A discussion of the applicability of Koopmans' theorem and the effect of the hydrogen bond in both the ion and ground states is presented.

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