Theoretical Study of Nascent
Hydration in the Fe<sup>+</sup>(H<sub>2</sub>O)<sub><i>n</i></sub> System
- Publication date
- Publisher
Abstract
The interactions of the iron monocation with water molecules
and argon atoms in the gas phase were studied computationally to elucidate
recent infrared vibrational spectroscopy on this system. These calculations
employ first-principles all-electron methods performed with B3LYP/DZVP
density functional theory. The ground state of Fe<sup>+</sup>(H<sub>2</sub>O) is found to be a quartet (<i>M</i> = 2<i>S</i> + 1 = 4, <i>S</i> is the total spin). Different
binding sites for the addition of one or two argon atoms produce several
low-lying states of different geometry and multiplicity in a relatively
small energy range for Fe<sup>+</sup>(H<sub>2</sub>O)–Ar<sub>2</sub> and Fe<sup>+</sup>(H<sub>2</sub>O)<sub>2</sub>–Ar.
In both species, quartet states are lowest in energy, and sextets
and doublets lie at higher energies from the respective ground states.
These results are consistent with the conclusion that the experimentally
determined infrared photodissociation spectra (IRPD) of Fe<sup>+</sup>(H<sub>2</sub>O)–Ar<sub>2</sub> and Fe<sup>+</sup>(H<sub>2</sub>O)<sub>2</sub>–Ar are complicated because of the presence
of multiple isomeric structures. The estimated IR bands for the symmetric
and asymmetric O–H stretches from different isomers provide
new insight into the observed IRPD spectra