Reversible Sn–Sn Triple Bond Dissociation in a Distannyne: Support for Charge-Shift Bonding Character

Abstract

The tin–tin triple bond in the distannyne Ar iPr4SnSnAr iPr4, Ar iPr4 = C6H3-2,6­(C6H3-2,6-iPr2)2, undergoes reversible cleavage in deuterated toluene to afford two :SṅAr iPr4 radicals in solution as shown by 1H nuclear magnetic resonance and electron paramagnetic resonance spectroscopy. Variable temperature data afforded an enthalpy of dissociation of ΔH diss = 17.2 ± 1.7 kcal mol–1 via van‘t Hoff analysis.

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

“…In fact, the reversibility of a Sn-Sn triple bond cleavage to form Sn • radicals was supported by the heating of samples to 80°C and UV irradiation for 30 minutes before "flash-freezing". 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.…”

“…The large Ga, In, and Tl hyperfine couplings observed affirm that the radical is overwhelmingly a metal centred radical. Heavier Group 14 radical complexes 9,10,12,47,48 are of particular interest for numerous analogues within carbon chemistry. Previously, several Group 14 radicals generated within solid matrixes through 60 Co γ-irradiation or other means such as E-X halogen abstraction have been characterized by EPR spectroscopy.…”

A Silylene–Germylene Molecule Containing a SiI−GeI Single Bond

“…The alkyne analogues of Sn show varying structures between dimetallyne A and dimetallylene C , whereas the corresponding Pb species exists in the form of C . According to the very recent reports, the distannyne A can dissociate into mono‐substituent Sn I radicals [Ar‐ . Sn:, Ar=C 6 H 3 ‐2,6(C 6 H 3 ‐2,6‐ i Pr 2 ) 2 ] in equilibrium in solution.…”

Synthesis and decarbonylation chemistry of gallium phosphaketenes

“…Recent work by Power and co-workers investigated the nature of the tin-tin bond in ArSnSnAr (Ar = C 6 H 3 -2,6(C 6 H 3 -2,6-i Pr 2 ) 2 ), which undergoes reversible homolytic cleavage in solution to yield radical species as observed by EPR spectroscopy. 15 It could be proposed that upon irradiation of 2a, yielding 3, the steric bulk causes poor overlap of the P-P bonding orbitals resulting in heterolytic dissociation into radicals. Increasing the steric requirement at the gallium centre (2b-c) accelerates the dissociation into monomers, preventing the observation of the diphosphene by NMR spectroscopy.…”