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Correlation between the Stoichiometry and the Bistability of Electronic States in Valence‐Tautomeric Rb x Mn[Fe(CN) 6 ] y · z H 2 O Complexes
Author(s) -
Cobo Saioa,
Fernández Raquel,
Salmon Lionel,
Molnár Gábor,
Bousseksou Azzedine
Publication year - 2007
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200601023
Subject(s) - chemistry , stoichiometry , raman spectroscopy , valence (chemistry) , phase transition , prussian blue , analytical chemistry (journal) , thermal hysteresis , crystallography , condensed matter physics , electrochemistry , physics , organic chemistry , electrode , optics , chromatography
A series of Prussian blue analogues, Rb x Mn[Fe(CN) 6 ] y · z H 2 O with different stoichiometries have been synthesized. Elemental analyses reveal a quasilinear decrease in x and y when z increases. Some of these samples present a first‐order phase transition between the Mn II –Fe III and Mn III –Fe II electronic states with large thermal hysteresis loops observed in the magnetic susceptibility. The phase‐transition temperatures correlate with the stoichiometry, but quantitative predictions cannot be made because of the disordered nature of the compounds. Contrary to previous literature reports, calorimetric and Raman spectroscopic measurements reveal that the charge‐transfer phase transition is accompanied by a significant entropy change, Δ S = 48–59 J K –1 mol –1 , of mainly vibrational origin. In addition to the thermal phase transition, Raman spectra also show that below ca. 120 K a photoinduced Mn III –Fe II to Mn II –Fe III conversion occurs in certain stoichiometries.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)