Eric A. Appel, Victor Y. Lee, et al.
Chemical Communications
The cyclobutapyrazine derivative, endo-3,4-pyrazinotricyclo[4.2.1.02,5]nonane (3), has been synthesized and subjected to a spectroscopic investigation. An inequivalence of the two faces of the pyrazine π system is revealed by the measured relative polarization directions of the 1nπ* and 1ππ* electronic transitions and is ascribed to a delocalization of the pyrazine orbitals into the low-symmetry saturated polycyclic system. A striking red shift of the 1nπ* transition in 3 relative to 2,3-dimethylpyrazine and a similar shift of the n+ionization energy to lower values are ascribed to an enhanced through-bond coupling of the two nitrogen lone-pair orbitals due to distortion of bond angles at carbons 2 and 3 and to the resulting enhancement of the p character of the σ bond orbital through which the coupling occurs. © 1982, American Chemical Society. All rights reserved.
Eric A. Appel, Victor Y. Lee, et al.
Chemical Communications
Christopher R. Moylan, I.-Heng Mccomb, et al.
Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals
Gerrit Klärner, Jeong-Ik Lee, et al.
Advanced Materials
Gian C. Gobbi, William W. Fleming, et al.
JACS