%0 Journal Article %1 Bessenbacher.1989g %A Bessenbacher, Christian %A Kaim, Wolfgang %A Stahl, Thomas. %D 1989 %J Chemische Berichte %K NMR addn carbon cation chloride;silyldihydropyrazine dihydropyrazine dihydropyrazine;pyrazine dioxide electrochem;ESR electron insertion isocyanate radical redn rich thiophosphine %N 5 %P 933--939 %T Electron-rich olefins. 4. Electron-rich compounds with thiophosphinamide, carboxamide, O-silylurethane and O-silylisourea functionality. Synthesis, spectroscopy, chemical and electrochemical reactivity %V 122 %X N,N'-Disubstituted 1,4-dihydropyrazines I; R = CO2SiMe3, C(:NPh)OSiMe3, P(S)Me2, COMe were prepd. by reductive addn. to pyrazine or by insertion of CO2 or Ph isocyanate into the N-Si bonds of the N,N'-bis(trimethylsilyl) deriv. At room temp. 1H-NMR data show hindered rotation around the N-C(:X) single bonds in I R = CO2SiMe3, C(:NPh)OSiMe3, COMe but not in I R = P(S)Me2 or in the CONMe2 disubstituted compd. NMR shifts, colors, the oxidn. potentials from cyclic voltammetry, and reactivity towards air and TCNE illustrate that the electron-withdrawing capability increases in the substituent order SiR3 \textless CO2SiMe3 \textless C(:NPh)OSiMe3 $\approx$ P(S)Me2 \textless COMe. Notwithstanding, the N,N'-bis(thiophosphinyl) and the N,N'-diacetyl deriv. are easily converted to persistent radical cations whereas the O-silylated compds. are only irreversibly oxidized, albeit at very low potentials. on SciFinder(R)

@article{Bessenbacher.1989g, abstract = {N,N'-Disubstituted 1,4-dihydropyrazines [I; R = CO2SiMe3, C(:NPh)OSiMe3, P(S)Me2, COMe] were prepd. by reductive addn. to pyrazine or by insertion of CO2 or Ph isocyanate into the N-Si bonds of the N,N'-bis(trimethylsilyl) deriv. At room temp. 1H-NMR data show hindered rotation around the N-C(:X) single bonds in I [R = CO2SiMe3, C(:NPh)OSiMe3, COMe] but not in I [R = P(S)Me2] or in the CONMe2 disubstituted compd. NMR shifts, colors, the oxidn. potentials from cyclic voltammetry, and reactivity towards air and TCNE illustrate that the electron-withdrawing capability increases in the substituent order SiR3 {\textless} CO2SiMe3 {\textless} C(:NPh)OSiMe3 $\approx$ P(S)Me2 {\textless} COMe. Notwithstanding, the N,N'-bis(thiophosphinyl) and the N,N'-diacetyl deriv. are easily converted to persistent radical cations whereas the O-silylated compds. are only irreversibly oxidized, albeit at very low potentials. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Bessenbacher, Christian and Kaim, Wolfgang and Stahl, Thomas.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/298738960bd76246db822a1232ec80f6d/huebleriac}, interhash = {ca8cae0fa389458426cc26d2c20e2e65}, intrahash = {98738960bd76246db822a1232ec80f6d}, issn = {0009-2940}, journal = {Chemische Berichte}, keywords = {NMR addn carbon cation chloride;silyldihydropyrazine dihydropyrazine dihydropyrazine;pyrazine dioxide electrochem;ESR electron insertion isocyanate radical redn rich thiophosphine}, number = 5, pages = {933--939}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Electron-rich olefins. 4. Electron-rich compounds with thiophosphinamide, carboxamide, O-silylurethane and O-silylisourea functionality. Synthesis, spectroscopy, chemical and electrochemical reactivity}, volume = 122, year = 1989 }