PNNL

Abstract

Negative ion photoelectron spectra at 20 K along with ab initio (CCSD(T)) and M06-2X density function theory calculations are reported for a series of six basic and nucleophilic pyridine derivatives with an anionic substituent (i.e., 3- and 4-PyrBX3–, where X = F, 4-t-BuC6H4, 4- MeOC6H4, and 3,5-(MeO)2C6H3). Vertical detachment energies spanning from 4.50 – 5.85 eV are observed and well reproduced by M06-2X/aug-cc-pVTZ and CCSD(T)/maug-cc-pVTZ computations. Surprisingly, the VDEs are found to correlate with the SN2 reactivity of the PPh4+ salts of the anions with 1-iodooctane. Spin densities of the neutral structures formed from the anionic species are also reported and indicate where the excess electron density in the anions resides and likely cation-interaction sites in their corresponding salts.