Crystal structure, vibrational studies, optical properties, and Hirshfeld surface analysis of (C5H6N5)2[Cr2O7]

Single crystals of a new organic–inorganic compound, (C5H6N5)2Cr2O7 (1), adeninium dichromate, were grown by the slow evaporation technique and characterized by X-ray diffraction, infrared absorption, and the optical properties were also investigated by UV-vis absorption spectroscopy. The compound crystallizes in the triclinic system and P-1 space group with a = 11.6850(2) Å, b = 11.7531(5) Å, c = 14.5603(7) Å, α = 83.956(3)°, β = 70.481(4)°, γ = 61.863(2)°, V = 1658.70(12) Å3. The structure of the compound consists of four adeninium, (C5H5N2)+, cations, and two dichromate dianions with all the atoms situated in general positions. Each dichromate anion is formed by two tetrahedral CrO4 joined through shared O atoms and are linked to the cations with several weak hydrogen bonding interactions resulting in an extended network. 3-D Hirshfeld surface analysis and 2-D fingerprint plots indicate that the packing is dominated by H⋯O/O⋯H and H⋯N/N⋯H contacts.