title: Theoretical study of negatively charged Fe(-)-(H2O)(n ≤ 6) clusters.
abstract: Interactions of a singly negatively charged iron atom with water molecules, Fe(-)-(H(2)O)(n≤6), in the gas phase were studied by means of density functional theory. All-electron calculations were performed using the B3LYP functional and the 6-311++G(2d,2p) basis set for the Fe, O, and H atoms. In the lowest total energy states of Fe(-)-(H(2)O)(n), the metal-hydrogen bonding is stronger than the metal-oxygen one, producing low-symmetry structures because the water molecules are directly attached to the metal by basically one of their hydrogen atoms, whereas the other ones are involved in a network of hydrogen bonds, which together with the Fe(δ-)-H(δ+) bonding accounts for the nascent hydration of the Fe(-) anion. For Fe(-)-(H(2)O)(3≤n), three-, four-, five-, and six-membered rings of water molecules are bonded to the metal, which is located at the surface of the cluster in such a way as to reduce the repulsion with the oxygen atoms. Nevertheless, internal isomers appear also, lying less than 3 or 5 kcal/mol for n = 2-3 or n = 4-6. These results are in contrast with those of classical TM(+)-(H(2)O)(n) complexes, where the direct TM(+)-O bonding usually produces high symmetry structures with the metal defining the center of the complex. They show also that the Fe(-) anions, as the TM(+) ions, have great capability for the adsorption of water molecules, forming Fe(-)-(H(2)O)(n) structures stabilized by Fe(δ-)-H(δ+) and H-bond interactions.
authors.affiliation: Departamento de Física y Química Teórica, DEPg. Facultad de Química, Universidad Nacional Autónoma de México, Del. Coyoacán, México D.F., C.P. 04510, México. castro@quetzal.pquim.unam.mx
authors.forename: Miguel
authors.initials: M
authors.lastname: Castro
mesh_terms: D000838:Anions / Q000737:chemistry; D003198:Computer Simulation; D004583:Electrons; D005740:Gases / Q000737:chemistry; D006860:Hydrogen Bonding; D058085:Iron Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry; D011789:Quantum Theory; D014867:Water / Q000737:chemistry*
chemical_list: D000838:Anions; D005740:Gases; D058085:Iron Compounds; D014867:Water; D010100:Oxygen