Isolation of a Relatively Air‐Stable, Bulky Silyl‐Substituted, Neutral Silicon‐Centered Radical

Abstract

The bulky supersilyl‐substituted (tBu3Si) silicon‐centered radical 1 was synthesized and fully characterized by single‐crystal X‐ray crystallography, cyclic voltammetry (CV), and EPR spectroscopy. With its extremely sterically encumbered radical center, 1 is stable in the solid state in air for 16 hours without showing signs of decomposition. Thus 1 is the most robust trisilyl‐substituted silyl radical to date and a promising candidate for application as electrode material in organic radical batteries. Furthermore, it was found to be a strong dehalogenation reagent and therefore might find application in organic syntheses.

Synthesis, Structure and Electronic Properties of a Stable π‐Type 3‐Electron‐2‐Center‐Bonded Species: A Silicon Analogue of a Bicyclo[1.1.0]butane Radical Anion

“…One additional set of 29 Si( β ) satellites (SiMe 3 ) could not be found, probably due to signal overlap with the central signal (Table S4). The hfcc of 29 Si( α ) was approximately half of those of previously reported localized tris(silyl)silyl radicals (5.71–6.5 mT) [10a,b,d–f] and rather similar to those of disilene radical anions (2.45–3.18 mT) [11b,c] . A variable temperature EPR measurement of [K(18‐c‐6)] + 1 .− in THF resulted merely in broadening of the central signal, and the satellite signals could not be observed, preventing further investigations (Figure S34).…”

Radicals and Anions of Siloles and Germoles

“…Relatively large hyperfine couplings are detected for pyramidal radicals such as 8 and 9 , due to the larger contribution of s‐type atomic orbitals of the group 14 element to the SOMO (Figure 3). [31–35] The group 14 element adopts a trigonal planar coordination environment in radicals 10–12 according to XRD investigations and the SOMO has almost pure p‐character [36–41] . Consequently, the hyperfine coupling to the silicon or germanium atom is significantly smaller (Figure 3).…”

“…[31][32][33][34][35] The group 14 element adopts a trigonal planar coordination environment in radicals 10-12 according to XRD investigations and the SOMO has almost pure p-character. [36][37][38][39][40][41] Consequently, the hyperfine coupling to the silicon or germanium atom is significantly smaller (Figure 3). Before this background, the relatively large hyperfine coupling a(E α ) for the heterolyl radicals 3 c and 6 suggest a pyramidal coordination of the tetrel element.…”

One‐ and Two‐Electron Transfer Oxidation of 1,4‐Disilabenzene with Formation of Stable Radical Cations and Dications

“…[3,4] Only recently, a number of organosilicon radicals have been synthesized and characterized by X-ray single-crystal structural analysis. [5][6][7][8][9][10][11][12][13] Benzene and its derivatives are a pivotally important class of basic organic molecules, which feature a 6π-electron delocalization over the C 6 ring and exhibit considerable stability due to the Hückel aromatic nature. [14] Radicals, cations, anions, and radical cations and anions of benzene and the derivatives have been studied and applied widespread.…”

“…Most of them have been detected using spectroscopic investigations [3,4] . Only recently, a number of organosilicon radicals have been synthesized and characterized by X‐ray single‐crystal structural analysis [5–13] …”