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Square-planar N2S2NiII complexes with an extended pi-conjugated system
Tatsuya Kawamoto1, Kazunori Takeda, Masato Nishiwaki
1Department of Chemistry, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. kaw@ch.wani.osaka-u.ac.jp
Inorganic Chemistry
|April 11, 2007
Summary
Researchers synthesized novel square-planar nickel(II) complexes using benzothiazoline ligands. These complexes, featuring non-innocent ligands, exhibit intense near-infrared absorptions, indicating extended pi delocalization and potential for unique electronic properties.
Area of Science:
- Coordination Chemistry
- Materials Science
- Organic Synthesis
Background:
- Benzothiazoline derivatives serve as versatile ligands in coordination chemistry.
- Nickel(II) complexes with non-innocent ligands are of interest due to their unique electronic and optical properties.
Purpose of the Study:
- To synthesize and characterize novel square-planar nickel(II) complexes with innocent and non-innocent benzothiazoline-based ligands.
- To investigate the electronic properties, particularly near-infrared absorptions, of these complexes.
- To explore the structural diversity and electronic behavior influenced by ligand modifications.
Main Methods:
- Reaction of nickel(II) acetate tetrahydrate with 2-(1-naphthyl)benzothiazoline (HL1) and 2,6-diphenylbenzo[1,2-d:4,5-d']bisthiazoline (H3L2).
- Synthesis of a nickel(II) complex with a non-innocent ligand using 2,6-bis(3,5-dichlorophenyl)benzo[1,2-d:4,5-d']bisthiazoline (H3L3).
- Characterization using UV-Vis spectroscopy and X-ray crystallography.
Main Results:
- Three types of square-planar nickel(II) complexes were obtained: [Ni(L1)2] (innocent ligand), [Ni(L1-L1)], [Ni(L1-L2)], and [Ni(L2-L2)] (non-innocent ligands).
- Complexes with non-innocent ligands ([Ni(L1-L1)], [Ni(L1-L2)], [Ni(L2-L2)]) exhibited intense near-infrared absorptions.
- Complex [Ni(L2-L2)] showed a significant red-shifted absorption at 981 nm, indicating extended pi delocalization.
- Complex [Ni(L3-L3)] displayed higher electrical conductivity compared to [Ni(L2-L2)].
- Molecular structures of [Ni(L1-L2)], [Ni(L1)2], [Ni(L2-L2)], and [Ni(L3-L3)] were determined via X-ray crystallography.
Conclusions:
- The study successfully synthesized nickel(II) complexes with both innocent and non-innocent benzothiazoline-based ligands.
- Non-innocent ligands lead to square-planar nickel(II) complexes with characteristic intense near-infrared absorptions.
- Ligand structure significantly influences the electronic properties, such as pi delocalization and absorption wavelengths.
- The findings contribute to the understanding of structure-property relationships in nickel coordination complexes.
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