Estimation of thermodynamic and physicochemical properties of the alkali astatides: On the bond strength of molecular astatine (At2) and the hydration enthalpy of astatide (At−)

• Published in: Journal of mass spectrometry. 2024-04, Vol.59 (4), p.e5010-n/a
• Main Authors: Burgers, Peter C., Zeneyedpour, Lona, Luider, Theo M., Holmes, John L.
• Format: Article
• Language: English
• Subjects: alkali astatides; Alkali halides; Astatine; Bonding strength; Born‐Haber cycle; Charge transfer; Chemical bonds; Dissociation; Electron affinity; Enthalpy; Halides; Heat of formation; Heats (energies); Hydration; Molecular dynamics; Physicochemical processes; Physicochemical properties; solubilities; Sublimation; Thermal properties; Thermodynamic properties; Thermodynamics
• ISSN: 1076-5174; 1096-9888
• DOI: 10.1002/jms.5010

The recent accurate and precise determination of the electron affinity (EA) of the astatine atom At0 warrants a re‐investigation of the estimated thermodynamic properties of At0 and astatine containing molecules as this EA was found to be much lower (by 0.4 eV) than previous estimated values. In this contribution we estimate, from available data sources, the following thermodynamic and physicochemical properties of the alkali astatides (MAt, M = Li, Na, K, Rb, Cs): their solid and gaseous heats of formation, lattice and gas‐phase binding enthalpies, sublimation energies and melting temperatures. Gas‐phase charge‐transfer dissociation energies for the alkali astatides (the energy requirement for M+At− ➔ M0 + At0) have been obtained and are compared with those for the other alkali halides. Use of Born‐Haber cycles together with the new AE (At0) value allows the re‐evaluation of ΔHf (At0)g (=56 ± 5 kJ/mol); it is concluded that (At2)g is a weakly bonded species (bond strength