C8H18N2(2+).[Cu3Cl8]2-, M(r) = 616.5, monoclinic, P2(1)/n, a = 7.335 (2), b = 19.499 (8), c = 13.532 (6) angstrom, beta = 100.79 (3)degrees, V = 1901 (1) angstrom 3, Z = 4, D(x) = 2.15 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 4.45 mm-1, F(000) = 1212, T = 295 K, R = 0.0569 for 1436 unique observed [F greater-than-or-equal-to 3-sigma(F)] reflections and 196 parameters. The structure consists of discrete organic cations and stacks of quasiplanar symmetrically bibridged Cu3Cl8(2-) dimers. A pronounced alternation of Cu-Cl distances occurs within the trimeric units: 2.243 (4) angstrom for terminal Cu-Cl, 2.396 (4) angstrom for first Cu-Cl bridge and 2.269 (4) angstrom for inner Cu-Cl bridge distances. The primary coordination geometry is nearly planar for the central Cu(2) atom, while a pronounced folding is exhibited for terminal Cu atoms. Formation of semi-coordinate bonds between oligomeric units leads to the formation of stacks of trimers parallel to the a axis and yields a very elongated octahedral coordination sphere for each Cu(II) ion. When each trimer is represented by an envelope, the semicoordinate bond formation leads to the generation of a stacking pattern illustrated in (I). The Geiser notation for the stacking is 3 (1/2, 1/2) (1/2, -1/2).