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Quantitative Ligand Affinity Scales for Metal Triflate Salts: Application to Isomer Differentiation
Author(s) -
Iacobucci Claudio,
Jouini Nédra,
Massi Lionel,
Olivero Sandra,
De Angelis Francesco,
Duñach Elisabet,
Gal JeanFrançois
Publication year - 2017
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201700124
Subject(s) - chemistry , trifluoromethanesulfonate , cationic polymerization , mass spectrometry , proton affinity , ligand (biochemistry) , electrospray ionization , lewis acids and bases , catalysis , metal , combinatorial chemistry , ion , organic chemistry , chromatography , biochemistry , receptor , protonation
Owing to the importance of metal triflates in catalysis, the affinity of the cationic center for a selection of organic ligands was explored for In III and Zn II triflates. The organic Lewis bases include a variety of carbonyls (amides, unsaturated ketones, a lactone) and cyclic 1,2‐diols. The relative affinity of the ligands for the cationic center in triflates was quantitatively determined on the basis of relative ion concentrations determined by electrospray‐ionization mass spectrometry. The affinity scales were discussed with reference to gas‐phase proton basicity and Lewis basicity scales. Structural isomers and stereoisomers display significant affinity differences in several cases. In the case of isomer mixtures, a model describing the relative peak intensities in the mass spectra was developed. On this basis, an isomer titration method was set up. Remarkably, this MS‐based method overcame the blindness of mass spectrometry to isomers without the need for isotope labeling or MS/MS experiments. This model may prove to have applications in analytical chemistry and catalysis.