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Mössbauer Spectroscopic Investigation of Fe II and Fe III 3,4,5‐Trihydroxybenzoates (Gallates) – Proposed Model Compounds for Iron‐Gall Inks
Author(s) -
Wagner Friedrich E.,
Lerf Anton
Publication year - 2015
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.201500532
Subject(s) - mössbauer spectroscopy , gallate , ferrous , chemistry , gallic acid , metal , analytical chemistry (journal) , spectroscopy , inorganic chemistry , nuclear chemistry , crystallography , organic chemistry , physics , quantum mechanics , antioxidant
Iron gallates with iron in the oxidation states Fe 2+ and Fe 3+ were prepared and studied by Mössbauer spectroscopy, X‐ray diffraction, and IR spectroscopy. Fe III 3,4,5‐trihydroxybenzoate (gallate) Fe(C 7 O 5 H 4 ) · 2H 2 O, whose structure was first determined by Wunderlich , was obtained by the reaction of gallic acid and metallic iron or by oxidation of the Fe II gallate, which was obtained by the reaction of ferrous sulfate with 3,4,5‐trihydroxybezoic acid (gallic acid) under anoxic conditions. Trials to reproduce the hydrothermal preparation method of Feller and Cheetham show that the result depends crucially on the free gas volume in the reaction vessel. If there is no free volume one obtains the same Fe III gallate as in the other preparation methods. With a large free volume another compound was found to form whose composition and structure could not be determined. It could be specified only by Mössbauer spectroscopy. Fe III gallate, the Fe II gallate, and the new phase show magnetic ordering at liquid helium temperature.