  We describe the synthesis and single molecule electrical transport properties
of a molecular wire containing a ${\pi}$-extended tetrathiafulvalene (exTTF)
group and its charge-transfer complex with F4TCNQ. We form single molecule
junctions using the in-situ break junction technique using a home-built
scanning tunneling microscope with a range of conductance between 10 G$_{0}$
down to 10$^{-7}$ G$_{0}$. Within this range we do not observe a clear
conductance signature of the neutral parent molecule, suggesting either that
its conductance is too low or that it does not form stable junctions.
Conversely, we do find a clear conductance signature in the experiments carried
out on the charge-transfer complex. Due to the fact we expected this species to
have a higher conductance than the neutral molecule, we believe this supports
the idea that the conductance of the neutral molecule is very low, below our
measurement sensitivity. This is further supported by our theoretical
calculations. To the best of our knowledge, these are the first reported single
molecule conductance measurements on a molecular charge-transfer species.
