Facile C–H Bond Metathesis Mediated by a Stannylene

Abstract

The diarylstannylene, :Sn(Ar ) (Ar = CH-2,6-(CH-2,6- Pr)), undergoes C-H metathesis with toluene, m-xylene, or mesitylene in solutions of these solvents at 80 °C. The products, [Ar Sn(CHAr)] (Aryl=CH (1a), CH-3-Me (1b), CH-3,5-Me(1c)) were characterized via H,C and Sn NMR, UV-vis and IR spectroscopy, and by X-ray crystallography for 1a and 1b. A stoichiometric amount of the arene, ArH, was also produced in these reactions. The use of EPR spectroscopy indicated the presence of a new type of one-coordinate, tin-centered radical, :ṠnAr , resulting from Sn-C bond cleavage in Sn(Ar).

Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

“…10 The low-temperature EPR measurements revealed a pronounced Sn • signal allowing for further characterization. 43 Bismuth radicals also exhibit much greater hyperfine coupling than lighter Group 15 radicals. 33 For instance, the isotropic hyperfine coupling constant for Bi is more than five times greater than As, meaning that even the minutest s orbital contribution will significantly broaden the spectrum.…”

Bismuth Amides Mediate Facile and Highly Selective Pn–Pn Radical‐Coupling Reactions (Pn=N, P, As)

“…[1] Recent progress in the chemistry of heavy p-block elements has allowed a glimpse of their potential in the development of controlled radical reactions. [2,3] Examples include CH activation reactions by tin radicals, [4] the activation of P 4 and S 8 by bismuth radicals, [5] bismuth-catalyzed radical dehydrocoupling reactions, [6] the radical cyclo-isomerization of iodoolefins, [7] and controlled radical olefin polymerization. [8] While recent developments in heavy p-block chemistry exploit isolable radical species [9] and the homolytic cleavage of EÀE bonds, [3a,b] the homolysis of EÀX bonds as a source of radicals XC without the need for a radical initiator is only little explored (E = heavy p-block element; X = C,N,O).…”

Bismutamide als einfache Vermittler hochselektiver Pn−Pn‐Radikal‐Kupplungsreaktionen (Pn=N, P, As)

“…[1] Jüngere Fortschritte in der Chemie der schweren p-Block-Elemente zeigen deren Potential für die Entwicklung kontrollierter Radikalreaktionen. [2,3] Beispiele reichen von CH-Aktivierungsreaktionen durch Zinnradikale, [4] über die Aktivierung von P 4 und S 8 durch Bismutradikale, [5] bis hin zu Bismut-katalysierten Radikal-Dehydrokupplungsreaktionen, [6] Radikal-Cycloisome-risierungen von Iodoolefinen [7] und kontrollierten, radikalischen Olefinpolymerisationen. [8] Die letzten Entwicklungen setzen dabei vor allem auf isolierbare Radikalspezies [9] und die homolytische Bindungsspaltung von E À E-Bindungen, [3a,b] wohingegen die radikalstarterfreie Homolyse von E À X-Bindung als Radikalquelle von XC nur wenig untersucht ist (E = schweres p-Block Element; X = C, N, O).…”