Raman Detection of “Ambiguous” Conjugated Biradicals: Rapid Thermal Singlet‐to‐Triplet Intersystem Crossing in an Extended Viologen

Abstract

Raman marks of the singlet and triplet biradical species of an extended viologen are resolved in spite of the efficient intersystem crossing promoted by the quasi-isoenergetic locations of the lowest singlet and triplet states. Variable-temperature Raman measurements (see spectra) are instrumental for discriminating between the species, which rapidly interconvert their spin states.