Synthesis, characterization and antioxidant activity of a novel organic–inorganic hybrid material trans-2,5-dimethylpiperazine-1,4-diium pentachlorobismuthate(III): [C6H16N2]BiCl5

• A new bismuthate(III) complex, [C6H16N2]BiCl5, was synthesized at room temperature.
• The atomic arrangement shows three-dimensional network.
• The crystal packing is ensured by hydrogen bonds and stabilized by Cl … Cl interactions.
• This compound was investigated by IR and CP-MAS NMR spectroscopies.

A novel organic-inorganic hybrid compound, trans-2,5-dimethylpiperazine-1,4-diium pentachlorobismuthate(III), [C6H16N2]BiCl5, was synthesized and its structure determined by means of single crystal X-ray diffraction studies. It crystallizes in the monoclinic space group C2/c, with the following parameters: a = 15.365(5), b = 12.634(3), c = 8.313(3) Å, β = 120.59(3)°, Z = 4 and V = 1389.1(7) Å3. Its crystal structure consists of [BiCl5]2− anions surrounded by [C6H16N2]2+ cations. Complex hydrogen bonding interactions between [BiCl5]2− and organic cations through N(C)–H … Cl hydrogen bonds to form a three-dimensional network. The crystal packing is stabilized by Cl … Cl interactions. The structure reveals that the piperazine ring is in a chair conformation. The vibrational spectrum has been measured at room temperature by FT-infrared spectroscopy (4000–400 cm−1) on polycrystalline samples. The number of the NMR components in the 13C CP-MAS NMR spectrum proves the presence of three crystallographically independent carbons as revealed by X-ray structure determination. Investigation of antioxidant activity of compound was carried out by 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical, Ferric Reducing Power (FRP) and Ferrous ion chelating (FIC) methods. The synthesized compound exhibited significant antioxidant activities.