Synthesis, structures, and properties of bis(μ-oxo)nickel(III) and bis(μ-superoxo)nickel(II) complexes: An unusual conversion of a Ni(III)2(μ- O)2 core into a Ni(II)2(μ-OO)2 core by H2O2 and oxygenation of ligand

Kazushi Shiren, Seiji Ogo, Shuhei Fujinami, Hideki Hayashi, Masatatsu Suzuki, Akira Uehara, Yoshihito Watanabe, Yoshihiko Moro-oka

Research output: Contribution to journalArticle

107 Citations (Scopus)

Abstract

A six-coordinate bis(μ-oxo)nickel(III) complex, [Ni2(μ-O)2(Me3- tpa)2]2+ (1), was synthesized by the reaction of [Ni2(μ-OH)2(Me3- tpa)2]2+ (2) with 1 equiv of hydrogen peroxide in methanol at -90 °C, where Me3-tpa = tris(6-methyl-2-pyridylmethyl)amine. The 6-methyl groups of Me3-tpa have a significant influence on the formation and stabilization of the high-valent bis(μ-oxo)dinickel(III) species. The reaction of 2 with a large excess of hydrogen peroxide (> 10 equiv) afforded a novel bis(μ- superoxo)dinickel(II) complex, [Ni2(μ-O2)2(Me3-tpa)2]2+ (3), thus, the reaction demonstrates a unique conversion of a Ni(III)(μ-O)2Ni(III) core into a Ni(II)(μ-OO)2Ni(II) core upon exposure to hydrogen peroxide. Complexes 1, 2, and 3 have been characterized by X-ray crystallography and various physicochemical techniques. Complex 1 has a Ni(μ-O)2Ni core and the average Ni-O and Ni-N bond distances (1.871 and 2.143 Å, respectively) are significantly shorter than those of 2 (2.018 and 2.185 Å, respectively), suggesting that 1 is a bis(μ-oxo)dinickel(III) complex. Complex 3 consists of a Ni(μ-OO)2Ni core with two μ-1,2-O-O bridges to form a six-membered ring with chair conformation and the O-O bond distance is 1.345(6) Å. The resonance Raman spectrum of a powdered sample of 3 measured at ~110 K showed an isotope-sensitive band at 1096 cm-1 (1044 cm-1 for an 18O-labeled sample), indicating that 3 is a bis(μ-superoxo)dinickel(II) complex. Thermal decomposition of both 1 and 3 in acetone at -20 °C under N2 atmosphere resulted in partial hydroxylation of a methyl group of Me3-tpa in yields of 21-27% for both complexes. For complex 3, a carboxylate complex, [Ni(Me2- tpaCOO)(OH2)]+ (4) where one of the three methyl groups of Me3-tpa is oxidized to carboxylate, was also isolated as a decomposed product under N2 atmosphere. During the decomposition process of 3, dioxygen evolution was simultaneously observed. The electrospray ionization mass spectrometry (ESI- MS) of 3 revealed the formation of 1 during the decomposition process. These results suggest that one possible decomposition pathway of 3 is disproportionation of two coordinated superoxides to dioxygen and peroxide followed by the O-O bond scission of peroxide to regenerate 1, which is responsible for the hydroxylation and the oxidation of the 6-methyl group of Me3-tpa.

Original languageEnglish
Pages (from-to)254-262
Number of pages9
JournalJournal of the American Chemical Society
Volume122
Issue number2
DOIs
Publication statusPublished - Jan 19 2000
Externally publishedYes

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Oxygenation
Nickel
Hydrogen peroxide
Hydrogen Peroxide
Hydroxylation
Ligands
Peroxides
Decomposition
Atmosphere
Oxygen
Electrospray ionization
Electrospray Ionization Mass Spectrometry
X ray crystallography
X Ray Crystallography
Acetone
Superoxides
Isotopes
Amines
Mass spectrometry
Methanol

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Synthesis, structures, and properties of bis(μ-oxo)nickel(III) and bis(μ-superoxo)nickel(II) complexes : An unusual conversion of a Ni(III)2(μ- O)2 core into a Ni(II)2(μ-OO)2 core by H2O2 and oxygenation of ligand. / Shiren, Kazushi; Ogo, Seiji; Fujinami, Shuhei; Hayashi, Hideki; Suzuki, Masatatsu; Uehara, Akira; Watanabe, Yoshihito; Moro-oka, Yoshihiko.

In: Journal of the American Chemical Society, Vol. 122, No. 2, 19.01.2000, p. 254-262.

Research output: Contribution to journalArticle

Shiren, Kazushi ; Ogo, Seiji ; Fujinami, Shuhei ; Hayashi, Hideki ; Suzuki, Masatatsu ; Uehara, Akira ; Watanabe, Yoshihito ; Moro-oka, Yoshihiko. / Synthesis, structures, and properties of bis(μ-oxo)nickel(III) and bis(μ-superoxo)nickel(II) complexes : An unusual conversion of a Ni(III)2(μ- O)2 core into a Ni(II)2(μ-OO)2 core by H2O2 and oxygenation of ligand. In: Journal of the American Chemical Society. 2000 ; Vol. 122, No. 2. pp. 254-262.
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title = "Synthesis, structures, and properties of bis(μ-oxo)nickel(III) and bis(μ-superoxo)nickel(II) complexes: An unusual conversion of a Ni(III)2(μ- O)2 core into a Ni(II)2(μ-OO)2 core by H2O2 and oxygenation of ligand",
abstract = "A six-coordinate bis(μ-oxo)nickel(III) complex, [Ni2(μ-O)2(Me3- tpa)2]2+ (1), was synthesized by the reaction of [Ni2(μ-OH)2(Me3- tpa)2]2+ (2) with 1 equiv of hydrogen peroxide in methanol at -90 °C, where Me3-tpa = tris(6-methyl-2-pyridylmethyl)amine. The 6-methyl groups of Me3-tpa have a significant influence on the formation and stabilization of the high-valent bis(μ-oxo)dinickel(III) species. The reaction of 2 with a large excess of hydrogen peroxide (> 10 equiv) afforded a novel bis(μ- superoxo)dinickel(II) complex, [Ni2(μ-O2)2(Me3-tpa)2]2+ (3), thus, the reaction demonstrates a unique conversion of a Ni(III)(μ-O)2Ni(III) core into a Ni(II)(μ-OO)2Ni(II) core upon exposure to hydrogen peroxide. Complexes 1, 2, and 3 have been characterized by X-ray crystallography and various physicochemical techniques. Complex 1 has a Ni(μ-O)2Ni core and the average Ni-O and Ni-N bond distances (1.871 and 2.143 {\AA}, respectively) are significantly shorter than those of 2 (2.018 and 2.185 {\AA}, respectively), suggesting that 1 is a bis(μ-oxo)dinickel(III) complex. Complex 3 consists of a Ni(μ-OO)2Ni core with two μ-1,2-O-O bridges to form a six-membered ring with chair conformation and the O-O bond distance is 1.345(6) {\AA}. The resonance Raman spectrum of a powdered sample of 3 measured at ~110 K showed an isotope-sensitive band at 1096 cm-1 (1044 cm-1 for an 18O-labeled sample), indicating that 3 is a bis(μ-superoxo)dinickel(II) complex. Thermal decomposition of both 1 and 3 in acetone at -20 °C under N2 atmosphere resulted in partial hydroxylation of a methyl group of Me3-tpa in yields of 21-27{\%} for both complexes. For complex 3, a carboxylate complex, [Ni(Me2- tpaCOO)(OH2)]+ (4) where one of the three methyl groups of Me3-tpa is oxidized to carboxylate, was also isolated as a decomposed product under N2 atmosphere. During the decomposition process of 3, dioxygen evolution was simultaneously observed. The electrospray ionization mass spectrometry (ESI- MS) of 3 revealed the formation of 1 during the decomposition process. These results suggest that one possible decomposition pathway of 3 is disproportionation of two coordinated superoxides to dioxygen and peroxide followed by the O-O bond scission of peroxide to regenerate 1, which is responsible for the hydroxylation and the oxidation of the 6-methyl group of Me3-tpa.",
author = "Kazushi Shiren and Seiji Ogo and Shuhei Fujinami and Hideki Hayashi and Masatatsu Suzuki and Akira Uehara and Yoshihito Watanabe and Yoshihiko Moro-oka",
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TY - JOUR

T1 - Synthesis, structures, and properties of bis(μ-oxo)nickel(III) and bis(μ-superoxo)nickel(II) complexes

T2 - An unusual conversion of a Ni(III)2(μ- O)2 core into a Ni(II)2(μ-OO)2 core by H2O2 and oxygenation of ligand

AU - Shiren, Kazushi

AU - Ogo, Seiji

AU - Fujinami, Shuhei

AU - Hayashi, Hideki

AU - Suzuki, Masatatsu

AU - Uehara, Akira

AU - Watanabe, Yoshihito

AU - Moro-oka, Yoshihiko

PY - 2000/1/19

Y1 - 2000/1/19

N2 - A six-coordinate bis(μ-oxo)nickel(III) complex, [Ni2(μ-O)2(Me3- tpa)2]2+ (1), was synthesized by the reaction of [Ni2(μ-OH)2(Me3- tpa)2]2+ (2) with 1 equiv of hydrogen peroxide in methanol at -90 °C, where Me3-tpa = tris(6-methyl-2-pyridylmethyl)amine. The 6-methyl groups of Me3-tpa have a significant influence on the formation and stabilization of the high-valent bis(μ-oxo)dinickel(III) species. The reaction of 2 with a large excess of hydrogen peroxide (> 10 equiv) afforded a novel bis(μ- superoxo)dinickel(II) complex, [Ni2(μ-O2)2(Me3-tpa)2]2+ (3), thus, the reaction demonstrates a unique conversion of a Ni(III)(μ-O)2Ni(III) core into a Ni(II)(μ-OO)2Ni(II) core upon exposure to hydrogen peroxide. Complexes 1, 2, and 3 have been characterized by X-ray crystallography and various physicochemical techniques. Complex 1 has a Ni(μ-O)2Ni core and the average Ni-O and Ni-N bond distances (1.871 and 2.143 Å, respectively) are significantly shorter than those of 2 (2.018 and 2.185 Å, respectively), suggesting that 1 is a bis(μ-oxo)dinickel(III) complex. Complex 3 consists of a Ni(μ-OO)2Ni core with two μ-1,2-O-O bridges to form a six-membered ring with chair conformation and the O-O bond distance is 1.345(6) Å. The resonance Raman spectrum of a powdered sample of 3 measured at ~110 K showed an isotope-sensitive band at 1096 cm-1 (1044 cm-1 for an 18O-labeled sample), indicating that 3 is a bis(μ-superoxo)dinickel(II) complex. Thermal decomposition of both 1 and 3 in acetone at -20 °C under N2 atmosphere resulted in partial hydroxylation of a methyl group of Me3-tpa in yields of 21-27% for both complexes. For complex 3, a carboxylate complex, [Ni(Me2- tpaCOO)(OH2)]+ (4) where one of the three methyl groups of Me3-tpa is oxidized to carboxylate, was also isolated as a decomposed product under N2 atmosphere. During the decomposition process of 3, dioxygen evolution was simultaneously observed. The electrospray ionization mass spectrometry (ESI- MS) of 3 revealed the formation of 1 during the decomposition process. These results suggest that one possible decomposition pathway of 3 is disproportionation of two coordinated superoxides to dioxygen and peroxide followed by the O-O bond scission of peroxide to regenerate 1, which is responsible for the hydroxylation and the oxidation of the 6-methyl group of Me3-tpa.

AB - A six-coordinate bis(μ-oxo)nickel(III) complex, [Ni2(μ-O)2(Me3- tpa)2]2+ (1), was synthesized by the reaction of [Ni2(μ-OH)2(Me3- tpa)2]2+ (2) with 1 equiv of hydrogen peroxide in methanol at -90 °C, where Me3-tpa = tris(6-methyl-2-pyridylmethyl)amine. The 6-methyl groups of Me3-tpa have a significant influence on the formation and stabilization of the high-valent bis(μ-oxo)dinickel(III) species. The reaction of 2 with a large excess of hydrogen peroxide (> 10 equiv) afforded a novel bis(μ- superoxo)dinickel(II) complex, [Ni2(μ-O2)2(Me3-tpa)2]2+ (3), thus, the reaction demonstrates a unique conversion of a Ni(III)(μ-O)2Ni(III) core into a Ni(II)(μ-OO)2Ni(II) core upon exposure to hydrogen peroxide. Complexes 1, 2, and 3 have been characterized by X-ray crystallography and various physicochemical techniques. Complex 1 has a Ni(μ-O)2Ni core and the average Ni-O and Ni-N bond distances (1.871 and 2.143 Å, respectively) are significantly shorter than those of 2 (2.018 and 2.185 Å, respectively), suggesting that 1 is a bis(μ-oxo)dinickel(III) complex. Complex 3 consists of a Ni(μ-OO)2Ni core with two μ-1,2-O-O bridges to form a six-membered ring with chair conformation and the O-O bond distance is 1.345(6) Å. The resonance Raman spectrum of a powdered sample of 3 measured at ~110 K showed an isotope-sensitive band at 1096 cm-1 (1044 cm-1 for an 18O-labeled sample), indicating that 3 is a bis(μ-superoxo)dinickel(II) complex. Thermal decomposition of both 1 and 3 in acetone at -20 °C under N2 atmosphere resulted in partial hydroxylation of a methyl group of Me3-tpa in yields of 21-27% for both complexes. For complex 3, a carboxylate complex, [Ni(Me2- tpaCOO)(OH2)]+ (4) where one of the three methyl groups of Me3-tpa is oxidized to carboxylate, was also isolated as a decomposed product under N2 atmosphere. During the decomposition process of 3, dioxygen evolution was simultaneously observed. The electrospray ionization mass spectrometry (ESI- MS) of 3 revealed the formation of 1 during the decomposition process. These results suggest that one possible decomposition pathway of 3 is disproportionation of two coordinated superoxides to dioxygen and peroxide followed by the O-O bond scission of peroxide to regenerate 1, which is responsible for the hydroxylation and the oxidation of the 6-methyl group of Me3-tpa.

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