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Bond Strength and Reactivity Scales for Lewis Superacid Adducts: A Comparative Study with In(OTf) 3 and Al(OTf) 3
Author(s) -
Compain Guillaume,
Sikk Lauri,
Massi Lionel,
Gal JeanFrançois,
Duñach Elisabet
Publication year - 2017
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.201601389
Subject(s) - chemistry , superacid , lewis acids and bases , reactivity (psychology) , adduct , denticity , trifluoromethanesulfonate , bond dissociation energy , deprotonation , dissociation (chemistry) , organometallic chemistry , electrophile , catalysis , bond energy , collision induced dissociation , medicinal chemistry , mass spectrometry , computational chemistry , organic chemistry , tandem mass spectrometry , metal , molecule , ion , medicine , alternative medicine , pathology , chromatography
Metal triflates, often called Lewis superacids, are potent catalysts for organic synthesis. However, the reactivity of a given Lewis superacid toward a given base is difficult to anticipate. A systematic screening of catalysts is often necessary when developing synthetic methodologies. Presented herein is the development of quantitative reactivity and bond strength scales by using mass spectrometry (MS). By applying a collision‐induced dissociation (CID) technique to the adducts formed between Lewis superacids Al(OTf) 3 or In(OTf) 3 with a series of amides bases, including monodentate and bidentate ligands, different dissociation pathways were observed. Quantitative relative energy scales were established by performing energy‐resolved mass spectrometry (ERMS) analysis on the adducts. ERMS of the adducts affords a bond strength scale when the fragmentation leads to the loss of a ligand, and reactivity scales when the dissociation leads to the C−F bond activation of one triflate anion or the deprotonation of the ligand. Al(OTf) 3 was found to bind stronger to amides than In(OTf) 3 and to provide the most reactive adducts.