Nickel(II) Complexes with Tetra- and Pentadentate Aminopyridine Ligands: Synthesis, Structure, Electrochemistry, and Reduction to Nickel(I) Species
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- 作者：Sergey V. Kryatov ; B. Sharmila Mohanraj ; Vladislav V. Tarasov ; Olga P. Kryatova ; Elena V. Rybak-Akimova ; Bharathi Nuthakki ; James F. Rusling ; Richard J. Staples ; and Alexander Y. Nazarenko
- 刊名：Inorganic Chemistry
- 出版年：2002
- 出版时间：February 25, 2002
- 年：2002
- 卷：41
- 期：4
- 页码：923 - 930
- 全文大小：110K
- 年卷期：v.41,no.4(February 25, 2002)
- ISSN：1520-510X
文摘
A series of nickel(II) complexes with polydentate aminopyridine ligands N,N,N'-tris-[2-(2'-pyridyl)ethyl]ethane-1,2-diamine (L1), N,N,N'-tris-[2-(2'-pyridyl)ethyl]-N'-methylethane-1,2-diamine (L2), and N,N'-bis-[2-(2'-pyridyl)ethyl]-N,N'-dimethylethane-1,2-diamine (L3) were synthesized and characterized by elemental analysis and spectroscopicmethods. Single-crystal X-ray diffraction studies showed that the Ni(II) ions have five-coordinate square-pyramidalgeometry in [NiL2](ClO4)2, similar to that previously found in [NiL1](ClO4)2·CH3NO2 (Hoskins, B. F.; Whillans, F. D.J. Chem. Soc., Dalton Trans. 1975, 657), and square-planar geometry in [NiL3](ClO4)2. All three nickel(II) complexesare reduced by sodium borohydride or sodium amalgam in organic solvents to nickel(I) species, which were identifiedby highly anisotropic EPR spectra at 100 K: g1 = 2.239, g2 = 2.199, and g3 = 2.025 for [NiL1]+; g
par.gif"> = 2.324 andg
= 2.079 for [NiL2]+ and [NiL3]+. Cyclic voltammetry of the nickel(II) complexes in acetonitrile exhibited reversiblereduction waves at -1.01 V for [NiL1]2+, -0.91 V for [NiL2]2+, and -0.83 V for [NiL3]2+ versus SCE, potentialswhich are significantly less negative than those of most previously characterized Ni(II) complexes with nitrogen-only donor atoms. Complexes [NiL1]2+ and [NiL2]2+ showed high catalytic activity in the electroreduction of 1,2-trans-dibromocyclohexane to cyclohexene.
par.gif"> = 2.324 andg = 2.079 for [NiL2]+ and [NiL3]+. Cyclic voltammetry of the nickel(II) complexes in acetonitrile exhibited reversiblereduction waves at -1.01 V for [NiL1]2+, -0.91 V for [NiL2]2+, and -0.83 V for [NiL3]2+ versus SCE, potentialswhich are significantly less negative than those of most previously characterized Ni(II) complexes with nitrogen-only donor atoms. Complexes [NiL1]2+ and [NiL2]2+ showed high catalytic activity in the electroreduction of 1,2-trans-dibromocyclohexane to cyclohexene.