title: 1,4-Dimethyl-piperazine-1,4-diium bis-(hexa-fluoro-phosphate) dihydrate.
abstract: In the title hydrated mol-ecular salt, C(6)H(16)N(2) (+)·2PF(6) (-)·2H(2)O, the complete 1,4-dimethyl-piperazine-1,4-diium dication is generated by crystallographic inversion symmetry and both C-N bonds are in equatorial orientations. In the crystal, the components are linked by O-H⋯F and N-H⋯O hydrogen bonds but there are no direct links between cations and anions.
authors.affiliation: College of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189,  People's Republic of China.
authors.forename: Su-Wen
authors.initials: SW
authors.lastname: Sun