Organic-inorganic hybrid materials based on iron(III)-polyoxotungstates and 1-butyl-3-methylimidazolium cations

authors	Santos, FM; Brandao, P; Felix, V; Domingues, MRM; Amaral, JS; Amaral, VS; Nogueira, HIS; Cavaleiro, AMV
nationality	International
journal	DALTON TRANSACTIONS
keywords	BRIDGED IRON(III) DIMERS; TEMPERATURE IONIC LIQUID; ELECTROCHEMICAL-BEHAVIOR; HYDROGEN-PEROXIDE; HETEROPOLYTUNGSTATE DIMER; ELECTROCATALYTIC ACTIVITY; PHOSPHOTUNGSTIC ACID; CATALYTIC-PROPERTIES; BENZENE OXIDATION; CRYSTAL-STRUCTURE
abstract	The iron(III) mu-oxo bridged dimeric polyoxometalate [(PW11O39Fe)(2)O](10-) was isolated by reacting the transition metal monosubstituted Keggin anion [PW11O39Fe(H2O)](4-) and the ionic liquid 1-butyl-3-methylimidazolium bromide, (Bmim) Br, at pH 5.5. The crystal structure of (Bmim)(10)[(PW11O39Fe)(2)O]center dot 0.5H(2)O (1) (monoclinic, space group P2(1)/n, Z = 4) was determined by single crystal X-ray diffraction. By changing the reaction conditions, (Bmim)(4)[PW11O39Fe(H2O)]center dot H2O (2) was obtained, whilst the reaction between the Bmim(+) cation and the heteropolyanion [SiW11O39Fe(H2O](5-), in the pH conditions used for 1, afforded (Bmim)(5)[SiW11O39Fe(H2O)]center dot 4H(2)O (3). The compounds were characterized by spectroscopic techniques, thermal analysis, cyclic voltammetry, magnetic measurements and mass spectrometry. This study contributes to the understanding of iron mu-oxo dimer formation in polyoxometalate chemistry and calls attention to the influence of the counter-cations on the stability and formation of compound 1. The combination of the cationic part of ionic liquids and iron-substituted polyoxotungstates is predicted to lead to new materials with interest to catalysis, electrocatalysis and ionic liquid based nanocomposites.
publisher	ROYAL SOC CHEMISTRY
issn	1477-9226
year published	2012
volume	41
issue	39
beginning page	12145
ending page	12155
digital object identifier (doi)	10.1039/c2dt31206a
web of science category	Chemistry, Inorganic & Nuclear
subject category	Chemistry
unique article identifier	WOS:000308889300027