Preparation, Crystal Structures, and Spectroscopic and Redox Properties of Nickel(II) Complexes Containing Phosphane–(Amine or Quinoline)-Type Hybrid Ligands and a Nickel(I) Complex Bearing 8-(Diphenylphosphanyl)quinoline
✍ Scribed by Akira Hashimoto; Hiroshi Yamaguchi; Takayoshi Suzuki; Kazuo Kashiwabara; Masaaki Kojima; Hideo D. Takagi
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 673 KB
- Volume
- 2010
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
Nickel(II) complexes containing P–N‐type bidentate hybrid ligands of 2‐aminoethylphosphanes (RR′Pea; RR′ = Ph~2~ or MePh) or 8‐quinolylphosphanes (RR′Pqn), namely Ni(P–N)~2~~2~ [P–N = Ph~2~Pea (1), MePhPea (2), Ph~2~Pqn (3), or MePhPqn (4)] have been prepared, and their structural, spectroscopic, and electrochemical properties determined. The crystal structure analysis indicates that the 2‐aminoethylphosphane complexes (1 and 2) have a square‐planar coordination geometry around the Ni^II^ center with a cis(P,P) configuration, whereas the 8‐quinolylphosphane complexes (3 and 4) exhibit a severe tetrahedral distortion because of the steric repulsion between the ortho‐H atoms in the mutually cis‐positioned quinolyl rings. Complexes 1 and 2 maintain their diamagnetic square‐planar four‐coordinate structure on acetonitrile solution, whereas complexes 3 and 4 show paramagnetic behavior. Spectroscopic and electrochemical measurements suggest that the ligand‐field strengths of these four P–N‐type ligands increase in the order Ph~2~Pqn (3) < MePhPqn (4) < Ph~2~Pea (1) < MePhPea (2). The Ph~2~Pqn complex 3 is readily reduced by Zn powder to afford the corresponding nickel(I) complex [Ni(Ph~2~Pqn)~2~]BF~4~ (5). The crystal structure of complex 5 reveals that the Ni^I^ ion adopts a distorted tetrahedral coordination geometry with slightly longer (≈ 0.05 Å) Ni–P and Ni–N bond lengths than those in the corresponding Ni^II^ complex 3.