Isolated free-radical pairs in Rb+ 18-crown-6 TCNQ– single crystals (TCNQ = tetracyanoquinodimethane)
Abstract
An X-ray crystallographic study of Rb+ 18-crown-6 TCNQ– reveals the presence of localised pairs of radical anions rather than the stacks commonly encountered in salts of TCNQ–; the spin–spin tensor of the excited triplet observed and measured by EPR spectroscopy of a single crystal has principal values and directions appropriate for the location of the intrinsic pair within the crystal structure.