Prediction of Singlet−Triplet Splittings for Aryne Biradicals from 1H Hyperfine Interactions in Aryl Radicals

Density functional calculations with a polarized double-ζ 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−triplet 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.