119209-59-5Relevant academic research and scientific papers
Electron-Rich Compounds with Thiophosphinamide, Carboxamide, O-Silylurethane, and O-Silylisourea Functionality. Synthesis, Spectroscopy, Chemical and Electrochemical Reactivity
Bessenbacher, Christian,Kaim, Wolfgang,Stahl, Thomas
, p. 933 - 940 (2007/10/02)
1,4-Dihydropyrazines with the N,N'-substituents C(O)OSiMe3 (5), C(NPh)OSiMe3 (6), P(S)Me2 (7) and C(O)Me (9) have been synthesized by reductive addition to pyrazine (7, 9) or by insertion of CO2 (5) or phenyl isocyanate (6) into the N-Si bonds of the N,N'-bis(trimethylsilyl) derivate 3.At room temperature, 1H-NMR spectroscopy reveals hindered rotation around the N-C(=X) "single" bonds in compounds 5, 6, and 9 but not in 7 or in the C(O)NMe2-disubstituted compound 8.NMR shifts, colours, the oxidation potentials from cylic voltammetry, and the reactivity towards air and TCNE illustrate that the electron-withdrawing capability increase in the substituent order SiR3 C(O)OSiMe3 C(NPh)OSiMe3 ca.P(S)Me2 C(O)Me.Notwithstanding, the N,N'-bis(thiophosphinyl) (7) and the N,N'-diacetyl derivative 9 are easily converted to persistent radical cations whereas the O-silylated compounds 5 and 6 are only irreversibly oxidized albeit at very low potentials. - Key Words: Pyrazines / Organosilicon compounds / Organophosphorus compounds / Electrochemistry / ESR spectroscopy
