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Chemical Reactivity of Tetrasulfur Tetranitride: Synthesis, Physical Properties, and Structural Characterization of the Amorphous Phase Cu 7 S 4 N 4
Author(s) -
Irsen Stephan H.,
Kroll Peter,
Dronskowski Richard,
Weirich Thomas E.,
Epple Matthias
Publication year - 2003
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200300123
Subject(s) - amorphous solid , metastability , reactivity (psychology) , materials science , phase (matter) , characterization (materials science) , crystallography , chemistry , nanotechnology , medicine , alternative medicine , organic chemistry , pathology
Abstract Tetrasulfur tetranitride, S 4 N 4 , reacts with elemental Cu within inert solvents to a black‐blue material of approximate composition Cu 7 S 4 N 4 which is totally amorphous to X‐rays and which cannot be made crystalline by either thermal treatment or electron radiation. Cu 7 S 4 N 4 explodes if heated above 234 °C or when subjected to mechanical shock to eventually yield copper(I) sulfide; this together with the characteristic infrared spectrum of Cu 7 S 4 N 4 indicates the presence of molecular S 4 N 4 units inside the amorphous phase. The metastable nature of Cu 7 S 4 N 4 is also mirrored by electron microscopy which furthermore allows the structural characterization of its degradation products. Based on experimental EXAFS data offering characteristic Cu—N and Cu—S distances, a theoretical crystalline approximant of Cu 7 S 4 N 4 was suggested and structurally optimized by density‐functional total‐energy calculations including periodic boundary conditions. This model incorporates a central S 4 N 4 unit bonded to three shells of Cu atoms of different functionalities; in addition, a partial rupture of the S 4 N 4 unit is likely to allow for a lowering of the total energy of the metastable phase. The latter observation supports the impossibility to make Cu 7 S 4 N 4 crystallize using 4 N 4 crystallize using whatever kind of measures.