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Imidazolium salts with varying anions as charge carriers for detection of neutral bis(triphenylphosphine)palladium(II) dichloride in electrospray ionization mass spectrometry
Author(s) -
Walton Barbara L.,
Joshi Ubisha,
Dzyuba Sergei V.,
Youngblood W. Justin,
Verbeck Guido F.
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6653
Subject(s) - chemistry , electrospray ionization , palladium , mass spectrometry , ion , ionic liquid , ionic bonding , electrospray , adduct , inorganic chemistry , ionization , analytical chemistry (journal) , chromatography , organic chemistry , catalysis
RATIONALE While electrospray ionization is a popular technique for mass analysis, without a charged species it is ineffective. This coupled with solvent restrictions hinders the analysis of organometallic complexes. Detecting neutral species whose solubility is limited to nonconventional solvents is a problemthat can be overcome with the right charge carrier, which is described in this study. METHODS Ionic liquids were synthesized and analyzed by electrospray ionization quadrupole ion trap mass spectrometry. The neutral palladium complex was also analyzed using different imidazolium salts as the charge carrier with the same method and instrumentation. Theoretical complementswere also performed using Gaussian 09 at the density functional theory levels, using B3LYP functionals and the 6‐31 g (d,p) basis set for geometry optimizations. RESULTS Low concentration imidazolium salts in methanol showed aggregation behavior of the ionic liquid, where the cation peak and [cation] n+1 [anion] n peaks were observed in positive mode, while the [cation] n [anion] n+1 peaks were seen in negative mode. The unbound anion was observed in all the negative mode spectra except for the salt with the SCN anion when in THF. Solutions of PdCl 2 (PPh 3 ) 2 and a small amount of ionic liquid in THF showed the palladium complex adducted with the imidazolium cation for each of the ionic liquids studied. CONCLUSIONS A charge carrier for a neutral organometallic complex was found in imidazolium salts, where the cation was observed as the ionizing agent. Differing ion intensities of the complex‐adduct peak resulted from the anions ability to dissociate from the cation. Copyright © 2013 John Wiley & Sons, Ltd.