Experimental and Theoretical Studies of Hybrid (C3N2H5)2SbF5 Crystal with the Phase Transition

D. Podsiadłaa, M. Drozdb, B. Andriyevskyyc aInstitute of Experimental Physics, University of Wrocław, M. Born Sq. 9, 50-204 Wrocław, Poland bWłodzimierz Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Science, Okólna 2, 50-422 Wrocław, Poland cFaculty of Electronics and Computer Sciences, Koszalin University of Technology, Śniadeckich 2, 75-453 Koszalin, Poland

Full Text PDF

An organic-inorganic compound (C3N2H5)2SbF5 - bis(imidazolium)pentafluoroantimanate - was investigated. This crystal undergoes a structural phase transition. The phase transition was studied with the use of the infrared spectra of powdered crystal suspended in Nujol and Fluorolube oil in a wide range of internal vibration of the (C3N2H5)2+ and SbF52- ions (i.e., from 4000 to 400 cm-1) in the temperature range from 183 K (154 K in Fluorolube) to 300 K. The room temperature infrared spectrum in KBr and the Raman spectrum were achieved. The infrared measurement results showed a phase transition at 223 K (upon cooling). Temperature-depended changes of wavenumber, half-width, a center of gravity, and bands intensity were analysed in order to describe the contribution of cationic and anionic dynamics to the phase-transition mechanisms. Density functional theory formalism was applied to theoretical studies of normal vibration wavenumbers. For the optimized structure, harmonic frequencies and infrared intensities with Raman activities were calculated by the hybrid tree-parameter density functional model. Hydrogen bonds for the theoretical moiety were found. The results were compared with the experimental data. Electrostatic charges for the investigated molecules were calculated using the natural bond orbital method and Mulliken methods.

DOI:10.12693/APhysPolA.148.240 topics: bis(imidazolium)pentafluoroantimanate, infrared (IR) and Raman spectra, phase transitions, density functional theory (DFT) calculations