Radicals Containing a Selenopyran Ring

9-Phenylselenoxanthenyl (194) was studied along with its oxygen and sulfur counterparts as in the other cases, the phenyl ring was found to be twisted by about 70° from the plane of the heterocycle (cf. Sections, 

a and 3) Japanese workers observed ESR spectra of 194 when selenoxanthylium salts were treated with organometallic reagents however, their conclusions drawn in this work have been refuted. Hyper-fine splittings for 194 are indicated in gauss. 

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