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Zu Grundfragen Anorganischer Festkörperchemie: Sind NaFeF 3 [1] und CsFeF 3 [2] ‚Perowskite’︁?
Author(s) -
Hoppe Rudolf
Publication year - 2006
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.200500425
Subject(s) - steric effects , crystallography , chemistry , crystal structure , solid state , stereochemistry , physics
On fundametal Questions of Inorganic Solid State Chemistry: Are NaFeF 3 [1] and CsFeF 3 [2] ‘Perovskites’? Even with simple molecules like C 6 H 6 or C 6 H 5 CH 3 ‘gross formulas’ like CH or C 7 H 8 are nonsense. In the case of inorganic solids such procedures are even worse. For example by writing ‘K 2 Si 4 O 9 ’ no hint is given concerning the specific characteristics of the structure. ‘CsFeF 3 ’ hides the true composition, which in fact corresponds to 1 Cs 2i Cs 2 1i Fe 2 2 Fe 1i F 3 2i F 6 . Therefore, it is essential that the correct formulas have to be added, which are based on point groups (PGr) of particles with exactly the same magnitude of infinitude of the partial lattice (PL). In addition, the connectivity of the PL must be indicated, e.g. [PtCl 6 ]K 2 or K 2 [Cl 6 Pt] instead of K 2 [PtCl 6 ]. Therefore, the values of d(X‐M), C.P.(X/M), n ECoN(X/M) (with n = 0, 1, n) of the anions have to be added to those of the cations M in the description of crystal structures. The ‘emancipation’ of the anions is urgent, since in most cases their connectivity reigns the utmost important structural features! Sometimes ‘on‐line‐formulas’ could be used indicating steric arrangements as shown here.