Hydrogen-bonded bilayers in piperazinium(2+) bis(mandelate) bis(methanol) solvate

In the title compound, C4H12N22+. 2C(8)H(7)O(3)(-). 2CH(4)O, the cations lie across centres of inversion and are disordered over two orientations with equal occupancy; there are equal numbers of (R)- and (S)-mandelate anions present (mandelate is alpha -hydroxybenzeneacetate). The anions and the neutral water molecules are linked by O-H . . .O hydrogen bonds [O . . .O 2.658 (3) and 2.682 (3) Angstrom, and O-H . . .O 176 and 166 degrees] into deeply folded zigzag chains. Each orientation of the cation forms two symmetry-related two-centre N-H . . .O hydrogen bonds [N . . .O 2.588 (4) and 2.678 (4) Angstrom, and N- H . . .O 177 and 171 degrees] and two asymmetric, but planar, three-centre N-H . . . (O)(2) hydrogen bonds [N . . .O 2.686 (4)- 3.137 (4) Angstrom and N-H . . .O 137-147 degrees], and by means of these the cations link the anion/water chains into bilayers.