Synthesis and Characterization of Mononuclear and Dinuclear Ruthenium Complexes with Tris(2-pyridylmethyl)amine and Tris(5-methyl-2-pyridylmethyl)amine

Takahiko Kojima, Takayuki Amano, Youichi Ishii, Masaaki Ohba, Yoshihiro Okaue, Yoshihisa Matsuda

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Abstract

Novel Ru(II) and Ru(III) complexes having TPA (tris(2-pyridylmethyl)amine, L1) and 5-Me3-TPA (tris(5-methyl-2-pyridylmethyl)amine, L2) were prepared to establish their synthetic routes and to elucidate coordination geometry and interactions between tightly bound tripodal tetradentate ligands and RuII/RuIII centers. They include mononuclear Ru(II) complexes [RuCl(DMSO)(L)]ClO4 (1 (L1), 2 (L2)), dinuclear bis-μ-chloro Ru(II) complexes [RuCl(L)]2(ClO4)2 (3 (L1), 4 (L2)), and mononuclear Ru(III) complexes [RuCl2(L)]ClO4 (5 (L1), 6 (L2)). They were characterized by X-ray crystallography (for 2, 3, and 5), 1H NMR spectroscopy, and cyclic voltammetry. For compound 2, the crystal structure was determined to possess S-bound DMSO ligand which was trans to pyridine and Cl- trans to the tertiary amino group of L2, and this isomer was obtained exclusively. Complex 1 was also isolated as a single isomer. Complex 3 was revealed to be a dinuclear bis-μ-chloro Ru(II) species withthe center of symmetry midway between two Cl-. 1H NMR spectra of Ru(II) complexes 1-4, the molecular structure of 2, and comparison of the molecular structure of 3 with 5 suggest that the interaction between the Ru(II) center, pyridyl moieties, and the DMSO ligand is strengthened by π-back-bonding from the Ru(II) center to the ligands in addition to σ-bonding of the tertiary amino group. Electrochemical measurements on 1-6 in CH3CN revealed that the methyl groups on pyridyl rings exert electron-donating effects onto the Ru centers to lower each redox process and such effect strengthens the Ru-S bonding in 2 compared with that in 1, accommodating π-back-bonding from Ru(II) center to other TT-acceptors such as DMSO in 2 enough to prevent isomerization of DMSO binding mode. The dinuclear complexes 3 and 4 showed relatively large comproportionation constants, which suggest mixed-valent RuIIRuIII states would be stabilized.

Original languageEnglish
Pages (from-to)4076-4085
Number of pages10
JournalInorganic chemistry
Volume37
Issue number16
Publication statusPublished - Dec 1 1998

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Ruthenium
Dimethyl Sulfoxide
ruthenium
Amines
amines
Ligands
synthesis
ligands
Isomers
Molecular structure
molecular structure
isomers
X ray crystallography
Isomerization
nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
Cyclic voltammetry
isomerization
Crystal structure
crystallography

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

Synthesis and Characterization of Mononuclear and Dinuclear Ruthenium Complexes with Tris(2-pyridylmethyl)amine and Tris(5-methyl-2-pyridylmethyl)amine. / Kojima, Takahiko; Amano, Takayuki; Ishii, Youichi; Ohba, Masaaki; Okaue, Yoshihiro; Matsuda, Yoshihisa.

In: Inorganic chemistry, Vol. 37, No. 16, 01.12.1998, p. 4076-4085.

Research output: Contribution to journalArticle

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abstract = "Novel Ru(II) and Ru(III) complexes having TPA (tris(2-pyridylmethyl)amine, L1) and 5-Me3-TPA (tris(5-methyl-2-pyridylmethyl)amine, L2) were prepared to establish their synthetic routes and to elucidate coordination geometry and interactions between tightly bound tripodal tetradentate ligands and RuII/RuIII centers. They include mononuclear Ru(II) complexes [RuCl(DMSO)(L)]ClO4 (1 (L1), 2 (L2)), dinuclear bis-μ-chloro Ru(II) complexes [RuCl(L)]2(ClO4)2 (3 (L1), 4 (L2)), and mononuclear Ru(III) complexes [RuCl2(L)]ClO4 (5 (L1), 6 (L2)). They were characterized by X-ray crystallography (for 2, 3, and 5), 1H NMR spectroscopy, and cyclic voltammetry. For compound 2, the crystal structure was determined to possess S-bound DMSO ligand which was trans to pyridine and Cl- trans to the tertiary amino group of L2, and this isomer was obtained exclusively. Complex 1 was also isolated as a single isomer. Complex 3 was revealed to be a dinuclear bis-μ-chloro Ru(II) species withthe center of symmetry midway between two Cl-. 1H NMR spectra of Ru(II) complexes 1-4, the molecular structure of 2, and comparison of the molecular structure of 3 with 5 suggest that the interaction between the Ru(II) center, pyridyl moieties, and the DMSO ligand is strengthened by π-back-bonding from the Ru(II) center to the ligands in addition to σ-bonding of the tertiary amino group. Electrochemical measurements on 1-6 in CH3CN revealed that the methyl groups on pyridyl rings exert electron-donating effects onto the Ru centers to lower each redox process and such effect strengthens the Ru-S bonding in 2 compared with that in 1, accommodating π-back-bonding from Ru(II) center to other TT-acceptors such as DMSO in 2 enough to prevent isomerization of DMSO binding mode. The dinuclear complexes 3 and 4 showed relatively large comproportionation constants, which suggest mixed-valent RuIIRuIII states would be stabilized.",
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T1 - Synthesis and Characterization of Mononuclear and Dinuclear Ruthenium Complexes with Tris(2-pyridylmethyl)amine and Tris(5-methyl-2-pyridylmethyl)amine

AU - Kojima, Takahiko

AU - Amano, Takayuki

AU - Ishii, Youichi

AU - Ohba, Masaaki

AU - Okaue, Yoshihiro

AU - Matsuda, Yoshihisa

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N2 - Novel Ru(II) and Ru(III) complexes having TPA (tris(2-pyridylmethyl)amine, L1) and 5-Me3-TPA (tris(5-methyl-2-pyridylmethyl)amine, L2) were prepared to establish their synthetic routes and to elucidate coordination geometry and interactions between tightly bound tripodal tetradentate ligands and RuII/RuIII centers. They include mononuclear Ru(II) complexes [RuCl(DMSO)(L)]ClO4 (1 (L1), 2 (L2)), dinuclear bis-μ-chloro Ru(II) complexes [RuCl(L)]2(ClO4)2 (3 (L1), 4 (L2)), and mononuclear Ru(III) complexes [RuCl2(L)]ClO4 (5 (L1), 6 (L2)). They were characterized by X-ray crystallography (for 2, 3, and 5), 1H NMR spectroscopy, and cyclic voltammetry. For compound 2, the crystal structure was determined to possess S-bound DMSO ligand which was trans to pyridine and Cl- trans to the tertiary amino group of L2, and this isomer was obtained exclusively. Complex 1 was also isolated as a single isomer. Complex 3 was revealed to be a dinuclear bis-μ-chloro Ru(II) species withthe center of symmetry midway between two Cl-. 1H NMR spectra of Ru(II) complexes 1-4, the molecular structure of 2, and comparison of the molecular structure of 3 with 5 suggest that the interaction between the Ru(II) center, pyridyl moieties, and the DMSO ligand is strengthened by π-back-bonding from the Ru(II) center to the ligands in addition to σ-bonding of the tertiary amino group. Electrochemical measurements on 1-6 in CH3CN revealed that the methyl groups on pyridyl rings exert electron-donating effects onto the Ru centers to lower each redox process and such effect strengthens the Ru-S bonding in 2 compared with that in 1, accommodating π-back-bonding from Ru(II) center to other TT-acceptors such as DMSO in 2 enough to prevent isomerization of DMSO binding mode. The dinuclear complexes 3 and 4 showed relatively large comproportionation constants, which suggest mixed-valent RuIIRuIII states would be stabilized.

AB - Novel Ru(II) and Ru(III) complexes having TPA (tris(2-pyridylmethyl)amine, L1) and 5-Me3-TPA (tris(5-methyl-2-pyridylmethyl)amine, L2) were prepared to establish their synthetic routes and to elucidate coordination geometry and interactions between tightly bound tripodal tetradentate ligands and RuII/RuIII centers. They include mononuclear Ru(II) complexes [RuCl(DMSO)(L)]ClO4 (1 (L1), 2 (L2)), dinuclear bis-μ-chloro Ru(II) complexes [RuCl(L)]2(ClO4)2 (3 (L1), 4 (L2)), and mononuclear Ru(III) complexes [RuCl2(L)]ClO4 (5 (L1), 6 (L2)). They were characterized by X-ray crystallography (for 2, 3, and 5), 1H NMR spectroscopy, and cyclic voltammetry. For compound 2, the crystal structure was determined to possess S-bound DMSO ligand which was trans to pyridine and Cl- trans to the tertiary amino group of L2, and this isomer was obtained exclusively. Complex 1 was also isolated as a single isomer. Complex 3 was revealed to be a dinuclear bis-μ-chloro Ru(II) species withthe center of symmetry midway between two Cl-. 1H NMR spectra of Ru(II) complexes 1-4, the molecular structure of 2, and comparison of the molecular structure of 3 with 5 suggest that the interaction between the Ru(II) center, pyridyl moieties, and the DMSO ligand is strengthened by π-back-bonding from the Ru(II) center to the ligands in addition to σ-bonding of the tertiary amino group. Electrochemical measurements on 1-6 in CH3CN revealed that the methyl groups on pyridyl rings exert electron-donating effects onto the Ru centers to lower each redox process and such effect strengthens the Ru-S bonding in 2 compared with that in 1, accommodating π-back-bonding from Ru(II) center to other TT-acceptors such as DMSO in 2 enough to prevent isomerization of DMSO binding mode. The dinuclear complexes 3 and 4 showed relatively large comproportionation constants, which suggest mixed-valent RuIIRuIII states would be stabilized.

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