RECHECKING OF THE EQUILIBRIUM GAS-PHASE BASICITY SCALE FOR LOW-BASICITY COMPOUNDS USING FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE SPECTROMETRY

Fourier transform ion cyclotron resonance (FT-ICR) spectrometry was us ed to study and recheck the proton transfer equilibria for a large num ber of low basicity compounds, particularly those which are less basic than H2O. The data obtained were used for the construction of a conti nuous scale of the relative gas-phase basicities between H2S and SO2F2 . The present results are compared with the results obtained by McMaho n and coworkers using ICR spectrometry and high-pressure mass spectrom etric (HPMS) techniques, Satisfactory agreement is found with the exis ting ICR spectrometric data, The results, however, show unexplained va riances with earlier and recent HPMS results that are also not interna lly self consistent. The substituent effects for some families of low- basicity compounds (nitriles, carbonyl compounds, ethers and some othe rs) are discussed.