Issue 18, 2015

Novel pure PnmaP212121 ferroelastic phase transition of 1,4-diisopropyl-1,4-diazonia-bicyclo[2.2.2]octane tetra-chlorobromo-M(ii) (M = Mn and Co)

Abstract

Two novel phase transition compounds Dip-DABCO tetra-chlorobromo-M(II) (M = Mn and Co), (Dip-DABCO = 1,4-diisopropyl-1,4-diazonia-bicyclo[2.2.2]octane) C12H26N2·MnBrCl3 (1) and (C12H26N2)4·(CoBr1.25Cl2.75)4 (2) were synthesized, and their structures have been determined by means of single-crystal X-ray diffraction. The two compounds are isomorphous. Differential scanning calorimetry (DSC) measurements indicated that compounds 1 and 2 underwent a reversible phase transition at ca. 245.2 K with a hysteresis width of 4.4 K and at ca. 222.3 K with a hysteresis width of 5.5 K, respectively. The variable-temperature single-crystal X-ray diffraction data suggests that the phase transition was from high crystallographic symmetry with a space group of Pnma to a low-symmetry state with a space group of P212121. That is, Landau symmetry breaking occurred with a pure GPT (mmm–222). The ordering of twisting motions of the 1,4-diazoniabicylo[2,2,2]octane ring may have driven the phase transition.

Graphical abstract: Novel pure Pnma–P212121 ferroelastic phase transition of 1,4-diisopropyl-1,4-diazonia-bicyclo[2.2.2]octane tetra-chlorobromo-M(ii) (M = Mn and Co)

Supplementary files

Article information

Article type
Paper
Submitted
19 Oct 2014
Accepted
13 Jan 2015
First published
13 Jan 2015

RSC Adv., 2015,5, 13488-13494

Author version available

Novel pure PnmaP212121 ferroelastic phase transition of 1,4-diisopropyl-1,4-diazonia-bicyclo[2.2.2]octane tetra-chlorobromo-M(II) (M = Mn and Co)

L. Chen, D. Huang, Q. Pan and J. Ge, RSC Adv., 2015, 5, 13488 DOI: 10.1039/C4RA12690D

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