Cation−Ether Complexes in the Gas Phase: Bond Dissociation Energies and Equilibrium Structures of Li+[O(CH3)2]x, x = 1−4

Abstract

Bond dissociation energies, equilibrium structures, and harmonic vibrational frequencies of Li+[O(CH3)2]x, x = 1−4, are reported. The bond dissociation energies are determined experimentally by analysis of the thresholds for collision-induced dissociation of the cation−ether complexes by xenon (measured using guided ion beam mass spectrometry) and computationally by ab initio electronic structure calculations at the RHF and MP2 levels of theory. In all cases, the primary and lowest energy dissociation channel observed experimentally is endothermic loss of one ether molecule. The cross-section thresholds are interpreted to yield 0 and 298 K bond energies after accounting for the effects of multiple ion−molecule collisions, internal energy of the complexes, and unimolecular decay rates. The experimental and theoretical bond energies are in good agreement with previous experimental results for Li+[O(CH3)2]. Agreement between experiment and theory is also good for x = 2−4, where the bond energies calculated w...