SPECTROSCOPIC CHARACTERIZATION AND ROOM-TEMPERATURE STRUCTURE OF BIS(4-AMINOPYRIDINIUM) DICHROMATE
R. Ben Smail1,2, H. Chebbi3,2, B.R. Srinivasan4, M.F. Zid2
1University of Carthage, Nabeul, Tunisia
2University of Tunis El Manar, Tunis, Tunisia
3University of Tunis, Montfleury, Tunis, Tunisia
4Goa University, Goa, India
Keywords: crystal structure, infrared spectroscopy, bis(4-aminopyridinium) dichromate
Abstract
Crystals of bis(4-aminopyridinium) dichromate (C5H7N2)2[Cr2O7] (1) were isolated via slow solvent evaporation and characterized by energy dispersive spectroscopy (EDS), infrared (IR) and ultratviolet-visible (UV-Vis) spectroscopy, and single crystal X-ray diffraction. The room-temperature (RT; 298 K) phase of 1 crystallizes in the monoclinic space group P21/m. Its asymmetric unit consists of two crystallographically independent 4-aminopyridinium cations (A and B) and two halves of symmetry-independent dichromate anions (A and B). Cations and anions are linked with the aid of several moderate N-H⋯O hydrogen bonds and weak C-H⋯O interactions resulting in a three-dimensional supramolecular network. The crystal structure is further stabilized by extensive p-p stacking interactions between adjacent pyridine rings. A comparison of the structure of the RT phase of 1 and that of the low temperature (LT; 150 K) phase is described.
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