The N-(2-pyridinium)urea cation of the title compound, C6H8N3O+.ReO4-,
is planar to within 0.085(9) Angstrom and adopts an s-cis-s-cis confo
rmation with respect to the imino C-N bonds. The structure consists of
columns of centrosymmetric dimeric plane-to-plane stacked cations and
hydrogen-bonded anions. The distance between the anti-parallel carbon
yl groups in the dimer is 3.16(5) Angstrom. An extensive network of hy
drogen bonds stabilizes the ordering of the ions within the columns, w
hich are held together by weaker hydrogen bonds and van der Waals inte
ractions.