Wydział Chemii

Magdalena Węcławik

Jan Baran

Piotr Durlak

Łukasz Marciniak

Anna Piecha-Bisiorek

Ryszard Jakubas

2017

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy

179

83-94

10.1016/j.saa.2017.02.029

Naukowa

Angielski

Artykuł

The paper presents the Infrared and Raman spectra of the powdered [C3N2H5+]2[I−∙I3−] crystal at the temperatureintervals of 11–270 K, covering two low-temperature phase transitions: discontinuous at 182/188 K (cooling/heating) and continuous at 254 K. The research shows that the vibrational states of the pyrazolium cationschange significantly during discontinuous phase transition (III→II), while the continuous nature of successivestructuraltransformation ismoresubtleand displaysaninsignificant change inthetemperaturecoefficient ofnu-merous vibrations during the II→I PT at 254 K. The spectacular changes at Raman spectra above 188 K confirm ahuge rebuilding of inorganic network from [I−∙I3−]to[I42−]. Additionally, a complete geometry optimization wascarried out in the solid state in order to obtain minimum structures and bonding properties. The theoretical re-sults correspond well with the experimental data. Moreover, the infrared spectrum in harmonic approximationwas calculated, and a comparative vibrational analysis was performed. CRYSTAL09 vibrational results appear tobe in a good agreement with the experimental ones

Polyhalides, phase transition, Infrared, Raman

http://dx.doi.org/10.1016/j.saa.2017.02.029

http://www.elsevier.com