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10:51
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Ruthenium complexes containing 2-(2-nitrosoaryl)pyridine: structural, spectroscopic, and theoretical studies
Siu-Chung Chan1, Ho-Yuen Cheung, Chun-Yuen Wong
1Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, People's Republic of China.
Inorganic Chemistry
|October 26, 2011
Summary
Ruthenium complexes with 2-(2-nitrosoaryl)pyridine (ON(^)N) ligands were synthesized. These nitrosated complexes exhibit unique electronic properties, acting as superior electron acceptors compared to traditional ligands like 2,2′-bipyridine (bpy).
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Photophysics and Spectroscopy
Background:
- Cyclometalated ruthenium(II) complexes are versatile platforms in coordination chemistry.
- The electronic properties of ligands significantly influence the behavior of metal complexes.
- Nitrosated arylpyridine ligands offer a novel structural motif for tuning electronic characteristics.
Purpose of the Study:
- To synthesize and characterize novel ruthenium complexes featuring 2-(2-nitrosoaryl)pyridine (ON(^)N) ligands.
- To investigate the structural, spectroscopic, and electrochemical properties of these nitrosated ruthenium complexes.
- To compare the electron-accepting capabilities of ON(^)N ligands with established ligands like 2,2′-bipyridine (bpy).
Main Methods:
- Synthesis of ruthenium(II) complexes with ON(^)N and macrocyclic thioether ligands ([14]aneS4 or [9]aneS3).
- X-ray crystallography for determining molecular structures and bond distances (Ru-N(NO), N-O).
- UV-Vis spectroscopy to analyze electronic transitions and time-dependent density functional theory (TD-DFT) for assignment.
- Electrochemical measurements (cyclic voltammetry) to determine reduction potentials.
- Natural population analysis (NPA) to assess charge distribution.
Main Results:
- Successful synthesis of [Ru(ON(^)N)([14]aneS4)](2+) and [Ru(ON(^)N)([9]aneS3)(C≡N(t)Bu)](2+) complexes.
- Structural analysis confirmed the bidentate chelation of ON(^)N ligands and provided key bond distances.
- Spectroscopic data revealed moderate to intense visible absorptions assigned to metal-to-ligand charge transfer (MLCT) and intraligand transitions.
- Electrochemical studies indicated that the ON(^)N ligands are centered in the lowest unoccupied molecular orbitals (LUMOs).
- NPA revealed increased positive charge on ruthenium centers, suggesting enhanced electron deficiency.
Conclusions:
- The coordinated ON(^)N ligands exist as neutral moieties, not anionic radicals or dianions.
- Ruthenium complexes with ON(^)N ligands exhibit significant π-acidic character.
- ON(^)N ligands demonstrate superior electron-accepting properties compared to 2,2′-bipyridine (bpy).
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