Infrared photodissociation spectroscopy of Co+(NH3)n and Ni+(NH3)n: Preference for tetrahedral or square-planar coordination

Toshitaka Imamura, Kazuhiko Ohashi, Jun Sasaki, Kazuya Inoue, Kazuki Furukawa, Ken Judai, Nobuyuki Nishi, Hiroshi Sekiya

Research output: Contribution to journalArticle

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Abstract

Coordination structures of the Co+(NH3)n and Ni+(NH3)n ions are probed by infrared (IR) photodissociation spectroscopy with the aid of density functional theory (DFT) calculations. The IR spectra of N2-tagged Co+(NH3)n (n = 1-4) exhibit two distinct bands assignable to the symmetric and antisymmetric NH stretches of the NH3 molecules binding directly to Co+. Size-dependent changes in the spectra of Co+(NH3)n (n = 4-8) indicate that the first shell of Co+ is filled with four NH3 molecules and the resulting 4-coordinated structure forms the central core of further solvation. The spectra of Ni+(NH3)n (n = 3-8) suggest that the coordination number of Ni+ is also four, although a minor 3-coordinated isomer is identified for Ni+(NH3)4. Despite the same coordination number, the DFT calculations predict a distorted square-planar coordination for Ni+(NH3)4 and a distorted tetrahedral coordination for Co+(NH3)4. The coordination of Ni+(NH3)4 is explainable by using a simple model based on the geometry of a half-filled 3d orbital in Ni+. This suggests that the Ni+ ion gives priority to the minimization of the metal-ligand repulsion in accommodating four ligands in the first shell. On the other hand, the same model fails to explain the coordination of Co+(NH3)4. An interpretation for this is that the Co+ ion gives priority to the minimization of the ligand-ligand repulsion.

Original languageEnglish
Pages (from-to)11647-11656
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume12
Issue number37
DOIs
Publication statusPublished - Jan 1 2010

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Photodissociation
photodissociation
Spectroscopy
Ligands
Infrared radiation
Ions
ligands
spectroscopy
Density functional theory
coordination number
Molecules
Solvation
density functional theory
ions
optimization
Isomers
Metals
solvation
molecules
infrared spectra

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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Infrared photodissociation spectroscopy of Co+(NH3)n and Ni+(NH3)n : Preference for tetrahedral or square-planar coordination. / Imamura, Toshitaka; Ohashi, Kazuhiko; Sasaki, Jun; Inoue, Kazuya; Furukawa, Kazuki; Judai, Ken; Nishi, Nobuyuki; Sekiya, Hiroshi.

In: Physical Chemistry Chemical Physics, Vol. 12, No. 37, 01.01.2010, p. 11647-11656.

Research output: Contribution to journalArticle

Imamura, Toshitaka ; Ohashi, Kazuhiko ; Sasaki, Jun ; Inoue, Kazuya ; Furukawa, Kazuki ; Judai, Ken ; Nishi, Nobuyuki ; Sekiya, Hiroshi. / Infrared photodissociation spectroscopy of Co+(NH3)n and Ni+(NH3)n : Preference for tetrahedral or square-planar coordination. In: Physical Chemistry Chemical Physics. 2010 ; Vol. 12, No. 37. pp. 11647-11656.
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abstract = "Coordination structures of the Co+(NH3)n and Ni+(NH3)n ions are probed by infrared (IR) photodissociation spectroscopy with the aid of density functional theory (DFT) calculations. The IR spectra of N2-tagged Co+(NH3)n (n = 1-4) exhibit two distinct bands assignable to the symmetric and antisymmetric NH stretches of the NH3 molecules binding directly to Co+. Size-dependent changes in the spectra of Co+(NH3)n (n = 4-8) indicate that the first shell of Co+ is filled with four NH3 molecules and the resulting 4-coordinated structure forms the central core of further solvation. The spectra of Ni+(NH3)n (n = 3-8) suggest that the coordination number of Ni+ is also four, although a minor 3-coordinated isomer is identified for Ni+(NH3)4. Despite the same coordination number, the DFT calculations predict a distorted square-planar coordination for Ni+(NH3)4 and a distorted tetrahedral coordination for Co+(NH3)4. The coordination of Ni+(NH3)4 is explainable by using a simple model based on the geometry of a half-filled 3d orbital in Ni+. This suggests that the Ni+ ion gives priority to the minimization of the metal-ligand repulsion in accommodating four ligands in the first shell. On the other hand, the same model fails to explain the coordination of Co+(NH3)4. An interpretation for this is that the Co+ ion gives priority to the minimization of the ligand-ligand repulsion.",
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AU - Ohashi, Kazuhiko

AU - Sasaki, Jun

AU - Inoue, Kazuya

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