The ordering of the anion in the molecular conductor salt (TMTSF)(2)NO3 at
low temperature depends on the rate of cooling and corresponds to the doubl
ing of the a cell parameter. This order-disorder transition does not affect
the crystal packing as the TMTSF chains in the ordered and in the disorder
ed crystal structures at 12K can not be distinguished. This salt is strongl
y 1D at low temperature.