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Structural aspects of phase transition in pyrrole‐2,5‐dithioamide single crystals
Author(s) -
Dobrzycki Lukasz,
Zielinski Tomasz,
Jurczak Janusz,
Wozniak Krzysztof
Publication year - 2005
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.955
Subject(s) - chemistry , thioamide , phase transition , crystallography , phase (matter) , symmetry (geometry) , pyrrole , volume (thermodynamics) , molecule , ferroics , thermodynamics , stereochemistry , quantum phase transition , organic chemistry , quantum critical point , physics , geometry , mathematics
The new pyrrole thioamide derivative 1 H ‐pyrrole‐2,5‐dithiocarboxylic acid bis( n ‐butylamide) exists in two different phases with the first‐order phase transition at ∼195.8 K on heating up. We describe details of the lower and higher temperature phases and the nature of the phase transition. The high‐temperature phase is centrosymmetric, with the molecule having one statically disordered aliphatic chain, whereas the low‐temperature crystals are characterized by chiral P 2 1 space group symmetry with the unit cell volume six times bigger than the volume of the high‐temperature phase. Although the unit cell volume changes continuously with temperature, all other geometric parameters of the unit cell ( a , b , c , β) change in a discrete manner during the phase transition. We propose a model explaining the structural disorder observed at high temperature and discuss the variation of properties of weak interactions on decrease of symmetry. Copyright © 2005 John Wiley & Sons, Ltd.