He I and He II spectra of 2-halopyridines
The He I and He II ultraviolet photoelectron spectra of 2‐fluoro‐, 2‐chloro‐, 2‐bromo‐, and 2‐iodopyridine have been recorded and interpreted in terms of a composite‐molecule model. The sequence of the four lowest ionization energies for 2‐fluoro‐ and 2‐chloropyridine is: π3 (1a2) > nN (11a1) >...
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| Published in: | Journal of heterocyclic chemistry Vol. 32; no. 1; pp. 89 - 96 |
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| Main Authors: | , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Hoboken
Wiley-Blackwell
01-01-1995
Wiley‐Blackwell |
| Online Access: | Get full text |
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| Summary: | The He I and He II ultraviolet photoelectron spectra of 2‐fluoro‐, 2‐chloro‐, 2‐bromo‐, and 2‐iodopyridine have been recorded and interpreted in terms of a composite‐molecule model. The sequence of the four lowest ionization energies for 2‐fluoro‐ and 2‐chloropyridine is: π3 (1a2) > nN (11a1) > π2 (2b1) > πpyr (7b2), whereas for 2‐bromo‐ and 2‐iodopyridine the assignment is: π3 (1a2) ‐ πX > nN (11a1) > πX > π2 (2b1), where X represents a bromine and iodine lone‐pair. Comparison of the He I and He II band intensities confirmed this assignment. However, ab initio calculations at the STO‐3G*/STO‐3G* and 6–31G**/STO‐3G* levels did not agree with the sequence predicted by either the composite‐molecule model, simple correlations and the He I/He II cross‐section ratios. For the 2‐fluoropyridine, a comparison using the HAM/3 model was found to be in agreement with this assignment. |
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| Bibliography: | ark:/67375/WNG-H9KRMBCQ-L istex:821C0BDE6317C30605EACB2080F354B3DBCC8948 ArticleID:JHET5570320116 |
| ISSN: | 0022-152X 1943-5193 |
| DOI: | 10.1002/jhet.5570320116 |