Mass spectrometric determination of the dissociation energies of the molecules CuLi, AgLi and AuLi

Abstract

Equilibria involving gaseous species CuLi, AgLi and AuLi have been investigated using a Knudsen effusion technique combined with mass spectrometric analysis of the vapour composition. The following dissociation energies were derived by the third law procedure from the measured ion intensities, free energy functions and auxiliary data: D^°₀(CuLi)= 189.3 ± 8.8 kJ mol^–1, D^°₀(AgLi)= 173.6 ± 6.3 kJ mol^–1, D^°₀(AuLi)= 280.8 ± 6.5 kJ mol^–1. The measured dissociation energies are considerably lower than those calculated from the Pauling model of the polar bond.