RADICAL IONS .27. RADICAL IONS OF TETRAKIS(TRIMETHYLSILYL)BUTATRIENE

One-electron oxidation and one-electron reduction of the electron-rich acetylene derivative, hexakis(trimethylsilyl)-2-butyne [H3C3)3Si]3CCCC[Si(CH3)3]3, unexpectedly produce the persistent radical cation and radical anion of the hitherto unknown neutral compound, tetrakis(trimethylsilyl)butatriene (R3Si)2CCCC(SiR3)2. The radical anion can also be generated from the corresponding diacetylene, bis(trimethylsilyl)-1,3-butadiyne R3SiCCCCSiR3 and potassium metal, obviously via disproportionation. Photoelectron and electron spin resonance spectroscopic data permit the detection and characterization of the individual species. The stability of both the radical anion and the radical cation of the same molecule can be rationalized by the unique combination of the twofold butatriene π-system with 4 R3Si substituents, which can act either as electron donors or electron acceptors and thus stabilize the ground state of either the cation or the anion. © 1979.