Abstract
In the title compound, {(C4H12N2)(2)[ Li-2(P6O18)]center dot 4H(2)O}(n), the phosphate ring anion, located around an inversion center, adopts a chair conformation. Adjacent (PO18)-O-6 rings are linked via corner-sharing by LiO4 tetrahedra, generating anionic porous {[Li-2(P6O18)](4-)}(n) layers parallel to (101). The piperazine- 1,4-diium cations occupy the pores and develop hydrogen bonds with the inorganic framework. An extensive network of N - H center dot center dot center dot O and O - H center dot center dot center dot O hydrogen-bonding interactions link the components into a three-dimensional network and additional stabilization is provided by weak C - H center dot center dot center dot O hydrogen bonds.