Isomorphic relationship between 1,2,4,5-tetrachlorobenzene and 1,2,4,5-tetrabromobenzene
Journal of Applied Crystallography
Volume 30, Issue 6, pages 1152–1155, December 1997
How to Cite
Michaud, F., Negrier, P., Haget, Y., Leger, J.-M., Courseille, C., Cuevas Diarte, M. A. and Oonk, H. A. J. (1997), Isomorphic relationship between 1,2,4,5-tetrachlorobenzene and 1,2,4,5-tetrabromobenzene. Jnl Applied Crystallography, 30: 1152–1155. doi: 10.1107/S0021889897002215
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1,2,4,5-Tetrachlorobenzene (TeCB) exhibits a phase transition αβ at 185 K whereas 1,2,4,5-tetrabromobenzene (TeBB) exhibits a phase transition βγ at 307 K, the `room temperature' form being β for the two compounds. This work establishes which are the isomorphous forms. Quenching the molten mixtures into liquid nitrogen produced molecular alloys (TeCB)1 −x(TeBB)x at 295 K with any value of x, even in the 0.20 ≤x≤ 0.75 and 0.81 ≤x≤ 0.97 ranges where these molecular alloys are only metastable because of demixing phenomena. Powder diffraction analysis on the whole range of molecular alloys proved that βTeCB is isomorphous in the strictest sense (i.e. capable of giving a continuous series of mixed crystals) with the γ form of TeBB.