Effect of Freon matrices on the intermediates stabilized in X-ray irradiated 1,7-dioxaspiro[5,5]undecane solutions at 77 K

Abstract

Freon matrices affected the nature of species stabilized upon the X-ray irradiation of frozen 1,7-dioxaspiro[5,5]undecane (DOSU)/CF3CCl3 or DOSU/CFCl3 solutions at 77 K. This manifested in the stabilization of a ring-closed DOSU radical cation (RC) with an absorption maximum at ∼440 nm in CF3CCl3 versus a paramagnetic intermediate with no absorption in this spectral region and a notably different EPR spectrum in CFCl3. Interestingly, the ultimate product in a sequence of photochemical and thermally induced transformations was the same in both matrices: a distonic DOSU RC with a terminal alkyl fragment afforded upon C–C bond cleavage at the spiro carbon atom.