In:
Acta Crystallographica Section B Structural Science, International Union of Crystallography (IUCr), Vol. 62, No. 6 ( 2006-12-01), p. 1090-1098
Abstract:
Dibromomethane, CH 2 Br 2 , and diiodomethane, CH 2 I 2 , have been in situ pressure-crystallized in a diamond–anvil cell and their structures determined by single-crystal X-ray diffraction at 0.61 and 0.16 GPa, respectively. The pressure-frozen CH 2 Br 2 crystal is isostructural with its C 2/ c phase obtained by cooling. CH 2 I 2 is known to form several phases at low temperature, one of which is isostructural with CH 2 Br 2 . However, pressure freezing leads to the polar Fmm 2 phase. The formation of the polar CH 2 I 2 structure at 0.16 GPa has been rationalized by the electrostatic and anisotropic van der Waals interactions of the I atoms. No ferroelectric behaviour of the Fmm 2 polar phase II of CH 2 I 2 has been determined. The diffraction, calorimetric and dielectric constant studies reveal considerable temperature hysteresis of transformations between the CH 2 I 2 phases, as well as metastable regions strongly dependent on the sample shape and history.
Type of Medium:
Online Resource
ISSN:
0108-7681
DOI:
10.1107/S0108768106034963
DOI:
10.1107/S0108768106034963/bk5037sup1.cif
DOI:
10.1107/S0108768106034963/bk50371dbm7sup2.hkl
DOI:
10.1107/S0108768106034963/bk50371djmsup3.hkl
DOI:
10.1107/S0108768106034963/bk50371djm_nissup4.hkl
Language:
Unknown
Publisher:
International Union of Crystallography (IUCr)
Publication Date:
2006
detail.hit.zdb_id:
2020841-8
SSG:
13
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