Quantification of effective polarisability. Applications to studies of X-ray photoelectron spectroscopy and alkylamine protonation

Abstract

Two new empirical methods lead to a quantification of polarisability-derived stabilisation of charge in molecules. These take account of the all-important attentuation of substituent influence as it is further from the charged center. The first is derived from a formula for calculating mean molecular polarisabilities and also takes account of heteroatom substitution. A simple bond-counting procedure is an alternative for unsubstituted alkyl groups. The value of these two models is shown with studies on Cl and Ge ESCA/Auger spectral data, nitrogen 1s binding energy shifts, and with data on the gas phase proton affinities of alkyl substituted amines.