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X‐Ray Photoelectron Spectroscopy of Ferrocenyl‐ and Ferrocenium‐Based Ionic Liquids
Author(s) -
Taylor Alasdair W.,
Licence Peter
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100829
Subject(s) - x ray photoelectron spectroscopy , moiety , ionic liquid , hexafluorophosphate , ferrocene , chemistry , cyclopentadienyl complex , ionic bonding , ion , analytical chemistry (journal) , inorganic chemistry , nuclear magnetic resonance , organic chemistry , electrochemistry , catalysis , electrode , physics
X‐ray photoelectron spectroscopy (XPS) is used to study a series of five 1‐(ferrocenylmethyl)‐3‐methylimidazolium‐ and 1‐(ferroceniummethyl)‐3‐methylimidazolium‐based salts. All samples emit good photoelectron fluxes with sharp, well‐resolved photoelectron peaks. Due to the low volatility of imidazolium‐salts at ambient temperature, no modification of the XP spectrometer was required. Two of the salts exhibit supercooling behaviour, allowing XPS to be recorded at room temperature on liquid samples without the need for charge neutralisation. The photoelectron peaks can be assigned to the component atoms of the salts, based on previous studies on ferrocene, ferrocenium‐compounds and ionic liquids. Oxidation of the ferrocenyl moiety to ferrocenium shiftsthe Fe 2p and cyclopentadienyl C 1s photoelectron peaks to higher binding energy but does not affect the imidazolium and anion peaks. Under charge‐neutralisation conditions, in which the sample is flooded with low‐energy electrons, the ferrocenium moiety of the salt 1‐(ferroceniummethyl)‐3‐methylimidazolium di(hexafluorophosphate) is partially reduced.