Do π-dimers of tetrathiafulvalene cation radicals really exist at room temperature?

The longest wave absorption band of the tetramethylthiotetrathiafulvalene cation radical, which is usually interpreted as a pi -dimer band, is shown to be the intrinsic cation radical absorption, all studied cation radicals in solution at room temperature exist as paramagnetic monomers and only tetrathiafulvelene and tetramethyltetrathiafulvalene cation radicals undergo pi -dimerization at low temperatures.