The crystal structure anal. of a highly substituted 1,4-dihydropyrazine is described by example of the 1,4-bis(tert-butyldimethylsilyl)-2,3,5,6-tetramethyl deriv. 2. In the solid state, the heterocycle exhibits pronounced deviation from planarity with a dihedral angle of 140.8° along the N-N' axis of the butterfly-shaped 8 p-electron ring. The alkyl groups of the Si(tert-butyl)Me2 substituents are arranged to minimize steric repulsion. Despite the strongly reduced p-electron conjugation caused by non-planarity, compd. 2 is oxidized reversibly to an ESR detectable radical cation 2+· whereas the second oxidn. to the fully arom. dication 22+ is electrochem. irreversible. The strongly diminished difference between the anodic peak potentials for the two oxidn. steps correlates with the non-planar conformation as is shown by comparison with similar 1,4-bis(tri-alkyl- or dialkyl-silyl)-1,4-dihydro-1,4-diazines. The results support the concept of structural-controlled one electron vs. two electron transfer of flavin prosthetic groups in flavoenzymes. [on SciFinder(R)]
%0 Journal Article
%1 Kaim.1993e
%A Kaim, Wolfgang
%A Lichtblau, Alexander
%A Hausen, Hans-Dieter.
%D 1993
%J Journal of Organometallic Chemistry
%K conformation;silyldihydropyrazine crystal cyclic deriv;ESR deriv;flavin dihydropyrazine model mol prepn silyldihydropyrazine structure voltammetry
%N 2
%P 167--173
%T Correlation between structure and electron transfer in organometallic model compound for flavin with \dqButterfly\dq conformation
%V 456
%X The crystal structure anal. of a highly substituted 1,4-dihydropyrazine is described by example of the 1,4-bis(tert-butyldimethylsilyl)-2,3,5,6-tetramethyl deriv. 2. In the solid state, the heterocycle exhibits pronounced deviation from planarity with a dihedral angle of 140.8° along the N-N' axis of the butterfly-shaped 8 p-electron ring. The alkyl groups of the Si(tert-butyl)Me2 substituents are arranged to minimize steric repulsion. Despite the strongly reduced p-electron conjugation caused by non-planarity, compd. 2 is oxidized reversibly to an ESR detectable radical cation 2+· whereas the second oxidn. to the fully arom. dication 22+ is electrochem. irreversible. The strongly diminished difference between the anodic peak potentials for the two oxidn. steps correlates with the non-planar conformation as is shown by comparison with similar 1,4-bis(tri-alkyl- or dialkyl-silyl)-1,4-dihydro-1,4-diazines. The results support the concept of structural-controlled one electron vs. two electron transfer of flavin prosthetic groups in flavoenzymes. [on SciFinder(R)]
@article{Kaim.1993e,
abstract = {The crystal structure anal. of a highly substituted 1,4-dihydropyrazine is described by example of the 1,4-bis(tert-butyldimethylsilyl)-2,3,5,6-tetramethyl deriv. 2. In the solid state, the heterocycle exhibits pronounced deviation from planarity with a dihedral angle of 140.8° along the N-N' axis of the butterfly-shaped 8 \textgreek{p}-electron ring. The alkyl groups of the Si(tert-butyl)Me2 substituents are arranged to minimize steric repulsion. Despite the strongly reduced \textgreek{p}-electron conjugation caused by non-planarity, compd. 2 is oxidized reversibly to an ESR detectable radical cation 2+· whereas the second oxidn. to the fully arom. dication 22+ is electrochem. irreversible. The strongly diminished difference between the anodic peak potentials for the two oxidn. steps correlates with the non-planar conformation as is shown by comparison with similar 1,4-bis(tri-alkyl- or dialkyl-silyl)-1,4-dihydro-1,4-diazines. The results support the concept of structural-controlled one electron vs. two electron transfer of flavin prosthetic groups in flavoenzymes. [on SciFinder(R)]},
added-at = {2019-07-15T13:41:23.000+0200},
author = {Kaim, Wolfgang and Lichtblau, Alexander and Hausen, Hans-Dieter.},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/257b98ec4f8220d21dd0f967be7c5e3dc/b_schwederski},
interhash = {64b7a6e2cbdb71cded38e16070f3210d},
intrahash = {57b98ec4f8220d21dd0f967be7c5e3dc},
journal = {Journal of Organometallic Chemistry},
keywords = {conformation;silyldihydropyrazine crystal cyclic deriv;ESR deriv;flavin dihydropyrazine model mol prepn silyldihydropyrazine structure voltammetry},
number = 2,
pages = {167--173},
timestamp = {2019-07-15T11:42:10.000+0200},
title = {Correlation between structure and electron transfer in organometallic model compound for flavin with {\dq}Butterfly{\dq} conformation},
volume = 456,
year = 1993
}
