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γ‐FOX‐7: Structure of a High Energy Density Material Immediately Prior to Decomposition
Author(s) -
Crawford MargaretJane,
Evers Jürgen,
Göbel Michael,
Klapötke Thomas M.,
Mayer Peter,
Oehlinger Gilbert,
Welch Jan M.
Publication year - 2007
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.200700240
Subject(s) - crystal structure , crystallography , crystal (programming language) , detonation , molecule , materials science , decomposition , chemistry , explosive material , organic chemistry , computer science , programming language
1,1‐Diamino‐2,2‐dinitroethene, C 2 H 4 N 4 O 4 (FOX‐7), is a novel high energy density material with low friction and impact sensitivity and a high activation barrier to detonation. In this study, the previously unknown crystal structure of the γ‐polymorph of trimorphic FOX‐7 is reported. γ‐FOX‐7 is stable from ∼435 K until the compound decomposes just above 504 K. A single crystal of α‐FOX‐7 ( P 2 1 /n, Z =4, a =694.67(7) pm, b =668.87(9) pm, c =1135.1(1) pm, β=90.14(1)°, T =373 K) was first transformed into a single crystal of β‐FOX‐7 ( P 2 1 2 1 2 1 , Z =4, a =698.6(1) pm, b =668.6(2) pm, c =1168.7(3) pm, T =423 K) and then into a single crystal of γ‐FOX‐7 at 450 K. The γ‐FOX‐7 crystal was then subsequently quenched to 200 K. The structure of γ‐FOX‐7 ( P 2 1 / n, Z =8, a =1335.4(3) pm, b =689.5(1) pm, c =1205.0(2) pm, β=111.102(8)°, T =200 K) consists of four planar layers, each containing two crystallographically independent FOX‐7 molecules found in the asymmetric unit.