Prediction of singlet-triplet splittings for aryne biradicals from H-1 hyperfine interactions in aryl radicals

Density functional calculations with a polarized double-xi basis set on simple aryl radicals have predictive utility in the estimation of singlet-triplet energy splittings of corresponding aryne biradicals through a proportionality between isotropic hyperfine couplings for the former species and the splittings for the latter species. This allows rapid estimation of singlet-tripler splittings in large hydrocarbon systems, where direct calculation would be prohibitively costly, and should simplify the design of aryne systems having controlled reactivities as a function of their singlet-triplet state energy splittings.