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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

2009; Wiley; Volume: 2010; Issue: 1 Linguagem: Inglês

10.1002/ejic.200900767

1099-0682

Akira Hashimoto, Hiroshi Yamaguchi, Takayoshi Suzuki, Kazuo Kashiwabara, Masaaki Kojima, Hideo D. Takagi,

Magnetism in coordination complexes

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 ](BF 4 ) 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 .