Ej. Maclean et al., A three-dimensional hydrogen-bonded framework in piperazine-3,4-dihydroxy3-cyclobutene-1,2-dione-water (1/1/2), ACT CRYST C, 55, 1999, pp. 1896-1899
The title compound, piperazine-1,4-diium 3,4-dihydroxy-3-cyclobutene- 1,2-d
ionate(2-) dihydrate, is a hydrated salt, C4H12N22+. C4O42-. 2H(2)O The wat
er molecules and the centrosymmetric anions are linked by O-H ... O hydroge
n bonds into two-dimensional nets built from a single type of R-8(6)(24) ri
ng. Adjacent nets are linked by the centrosymmetric cations, each of which
forms four N-H ... O hydrogen bonds, with four different anions as accepter
s.