%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 = {2022-06-15T11:26:56.000+0200}, author = {Kaim, Wolfgang and Lichtblau, Alexander and Hausen, Hans-Dieter.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/257b98ec4f8220d21dd0f967be7c5e3dc/huebleriac}, 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 = {2022-06-15T09:26:56.000+0200}, title = {Correlation between structure and electron transfer in organometallic model compound for flavin with {\dq}Butterfly{\dq} conformation}, volume = 456, year = 1993 }