Owing to the importance of metal triflates in catalysis, the affinity of the cationic center for a selection of organic ligands was explored for InIII and ZnII 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.

Quantitative Ligand Affinity Scales for Metal Triflate Salts: Application to Isomer Differentiation

Iacobucci C.;De Angelis F.;
2017

Abstract

Owing to the importance of metal triflates in catalysis, the affinity of the cationic center for a selection of organic ligands was explored for InIII and ZnII 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.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11697/182214
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