1-Butyl-3-methylimidazolium tetrachloroferrate

{{Short description|Magnetic liquid}}

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| CASNo = 359845-21-9

| ChemSpiderID = 9849184

| EC_number = 678-175-3

| PubChem = 11674455

| StdInChI=1S/C8H15N2.4ClH.Fe/c1-3-4-5-10-7-6-9(2)8-10;;;;;/h6-8H,3-5H2,1-2H3;4*1H;/q+1;;;;;+3/p-4

| StdInChIKey = FYHLFBVHUIJIII-UHFFFAOYSA-J

| SMILES = CCCCN1C=C[N+](=C1)C.Cl[Fe-](Cl)(Cl)Cl

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| Section2 = {{Chembox Properties

| C=8|H=15|Cl=4|Fe=1|N=2

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1-Butyl-3-methylimidazolium tetrachloroferrate is a magnetic ionic liquid. It can be obtained from 1-butyl-3-methylimidazolium chloride and ferric chloride. It has quite low water solubility.{{cite journal | title = Discovery of a Magnetic Ionic Liquid [bmim]FeCl₄ |author1=Satoshi Hayashi |author2=Hiro-o Hamaguchi|journal=Chemistry Letters|volume=33|year=2004|issue=18|pages=1590–1591|doi=10.1246/cl.2004.1590}}{{cite journal|title=A new class of magnetic fluids: bmim[FeCl₄] and nbmim[FeCl₄] ionic liquids |author1=Satoshi Hayashi |author2=Satyen Saha |author3=Hiro-o Hamaguchi|journal=IEEE Transactions on Magnetics|volume=42|year=2006|issue=1|pages=12–14|doi=10.1109/TMAG.2005.854875 |bibcode=2006ITM....42...12H |s2cid=42347833 }}

Due to the presence of the high spin FeCl₄ anion, the liquid is paramagnetic and a magnetic susceptibility of 40.6 × 10⁻⁶ emu g⁻¹ is reported. A simple small neodymium magnet suffices to attract the liquid in a test tube.