1-Methyl-piperazine-1,4-diium dipicrate

Crystal structure studies of 4-ethyl-piperazin-1-ium 3,5-di-nitro-benzoate, 4-methyl-piperazin-1-ium 3,5-di-nitro-benzoate and 4-methyl-piperazin-1-ium 4-iodo-benzoate

As part of our ongoing investigation on the chemical and biological properties of piperazinium salts, we synthesized three novel compounds: 1-ethyl-piperazinium 3,5-di-nitro-benzoate (I), 1-methyl-piperazinium 3,5-di-nitro-benzoate (II) and 1-methyl-piperazinium 4-iodo-benzoate (III). The crystal structures of these compounds are built up of organic layers formed by the strong connection between the mol-ecules by hydrogen bonds of type N-H⋯O. These layers are linked through N-H⋯O hydrogen bonds and C-H⋯O inter-actions or C-I⋯N halogen bonding, leading to the formation of a three-dimensional network.

Bis(1-methyl-piperazine-1,4-diium) di-μ-bromido-bis-[tetra-bromido-bismuthate(III)] dihydrate

In the title hydrated salt, (C₅H₁₄N₂)₂[Bi₂Br₁₀]·2H₂O, the com­plete [Bi₂Br₁₀]⁴⁻ biocta­hedron is generated by crystallographic inversion symmetry. The diprotonated piperazine ring adopts a chair conformation, with the methyl group occupying an equatorial position. In the crystal, the tetra­anions and water mol­ecules are linked by O—H⋯Br and O—H⋯(Br,Br) hydrogen bonds to generate [100] chains. The chains are crosslinked by N—H⋯Br, N—H⋯O and C—H⋯Br hydrogen bonds originating from the piperazinediium dications, thereby forming a three-dimensional network.

1-Methyl-piperazine-1,4-dium bis-(hydrogen oxalate)

In the crystal structure of the title compound, C5H14N2 (2+)·2HC2O4 (-), the two crystallographically independent hydrogen oxalate anions are linked by strong inter-molecular O-H⋯O hydrogen bonds, forming two independent corrugated chains parallel to the b axis. These chains are further connected by N-H⋯O and C-H⋯O hydrogen bonds originating from the organic cations, forming a three-dimensional network. The diprotonated piperazine ring adopts a chair conformation, with the methyl group occupying an equatorial position.

4-[Bis(4-fluorophenyl)methyl]piperazin-1-ium 2-(2-phenylethyl)benzoate

The asymmetric unit of the title salt, C(17)H(19)F(2)N(2) (+.)C(15)H(13)O(2) (-), derived from a 1,4-diaza-cyclo-hexane derivative and a carb-oxy-lic acid, contains two formula units. The cation is protonated at the secondary amine functionality. The six-membered heterocycles adopt chair conformations. The fluorophenyl rings in the two cations make dihedral angles of 77.21 (19) and 78.8 (2)° while the aromatic rings in the anions enclose angles of 69.5 (2) and 69.9 (2)°. In the crystal, classical N-H⋯O hydrogen bonds as well as C-H⋯F and C-H⋯O contacts connect the entities into layers parallel to ac.

4-[Bis(4-fluorophenyl)methyl]piperazin-1-ium picrate

The title compound {systematic name: 4-[bis(4-fluorophenyl)methyl]piperazin-1-ium 2,4,6-tri-nitro-phenolate}, C(17)H(19)F(2)N(2) (+)·C(6)H(2)N(3)O(7) (-), is the picrate salt of a piperazine-supported amine bearing a benzhydryl substituent on one of its N atoms. During co-crystallisation, protonation took place on the N atom of the secondary amine functionality. The non-aromatic six-membered heterocycle adopts a chair conformation. In the crystal, N-H⋯O hydrogen bonds as well as C-H⋯O contacts connect the components into a three-dimensional network.