Order-disorder phase transition in the peroxidovanadium complex NH4[VO(O2)2(NH3)]

Peter Schwendt; Róbert Gyepes; Jana Chrappová; Ivan Němec; Přemysl Vaněk

doi:10.1016/j.saa.2018.04.019

Order-disorder phase transition in the peroxidovanadium complex NH₄[VO(O₂)₂(NH₃)]

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Jul 5:200:110-115. doi: 10.1016/j.saa.2018.04.019. Epub 2018 Apr 10.

Authors

Peter Schwendt¹, Róbert Gyepes², Jana Chrappová¹, Ivan Němec³, Přemysl Vaněk⁴

Affiliations

¹ Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovakia.
² Department of Chemistry, Faculty of Education, J. Selye University, Bratislavská 3322, 945 01 Komárno, Slovakia. Electronic address: gyepesr@ujs.sk.
³ Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43 Praha 2, Czech Republic.
⁴ Department of Dielectrics, Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic.

PMID: 29677497
DOI: 10.1016/j.saa.2018.04.019

Abstract

Complex NH₄[VO(O₂)₂(NH₃)] (1) undergoes an order-disorder phase transition at T_c~258K. This transition is accompanied by change in the space group of the orthorhombic lattice and also by significant structural rearrangements of the constituent molecules, which are pertinent mostly to their NH₄⁺ ions and their ammonia ligands. The low-temperature solid state IR and Raman spectra of 1 were corroborated by solid-state computations that employed Gaussian functions as the basis set. Results of these computations yielded excellent agreement with experimental data. On the curves of temperature dependence of vibrational modes, the phase transition is expressed by an abrupt change of the slope above T_c.

Keywords: Crystal structure; Peroxido complex; Phase transition; Solid-state computation; Vibrational spectra.