Steric Bulkiness-Dependent Structural Diversity in Nickel(II) Complexes of N-Heterocyclic Carbenes: Synthesis and Structural Characterization of Tetra-, Penta-, and Hexacoordinate Nickel Complexes
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- 作者：Xiaoming Zhang† ; ; Bin Liu† ; ; Ailing Liu† ; ; Weilong Xie† ; ; Wanzhi Chen*† ; ‡ ;
- 刊名：Organometallics
- 出版年：2009
- 出版时间：March 9, 2009
- 年：2009
- 卷：28
- 期：5
- 页码：1336-1349
- 全文大小：472K
- 年卷期：v.28,no.5(March 9, 2009)
- ISSN：1520-6041
文摘
A family of tetra-, penta-, and hexacoordinate nickel complexes of functionalized N-heterocyclic carbene (NHC) ligands have been prepared via carbene transfer reactions of Ni(PPh3)2Cl2 and silver-NHC complexes in situ generated from corresponding imidazolium salts and Ag2O. These nickel(II) complexes have been characterized by 1H NMR, 13CNMR, and ESI spectroscopy and X-ray diffraction analysis. Structural analysis revealed that [Ni(L1)3](PF6)2 (L1 = 3-butyl-1-(5,7-dimethyl-1,8-naphthyridin-2-yl)imidazolylidene, 3) is a rare example of a nickel complex with trigonal-bipyramidal geometry. [Ni(L4)2](PF6)2 (L4 = 1-butyl-3-((7-methyl-1,8-naphthyridin-2-yl)methyl)imidazolylidene, 5) and [Ni(L20)2](PF6)2 (L20 = 3-(pyridin-2-ylmethyl)-1-(pyrimidin-2-yl)imidazolylidene, 21) are normal square-planar. [Ni(L8)3](PF6)2 (L8 = 3-methyl-1-(pyrimidin-2-yl)imidazolylidene, 9), [Ni(L10)2(CH3CN)](PF6)2 (L10 = 3-ethyl-1-(pyrimidin-2-yl)imidazol-ylidene, 11), [Ni(L12)2(CH3CN)](PF6)2 (L12 = 3-butyl-1-(pyrimidin-2-yl)imidazolylidene, 13), [Ni(L14)2(CH3CN)](PF6)2 (L14 = 3-benzyl-1-(pyrimidin-2-yl)imidazolylidene, 15), and [Ni(L16)2(CH3CN)](PF6)2 (L16 = 3-isopropyl-1-(pyrimidin-2-yl)imidazolylidene, 17) are pentacoordinate, displaying unusual square-pyramidal geometry. [Ni(L12)3](PF6)2 (L9 = 3-butyl-1-(pyrimidin-2-yl)imidazolylid-ene, 19), [Ni(L22)2(CH3CN)2](PF6)2 (L22 = 3-(2,6-diisopropylphenyl)-1-(pyrimidin-2-yl)imidazolylidene, 23), and [Ni(L24)(CH3CN)(H2O)] (L22 = 3-(2,4,6-trimethylphenyl)-1-(pyrimidin-2-yl)imidazolylidene, 25) are octahedral complexes. The structural diversity of these nickel(II) complexes originating from steric pressure of the ligands is discussed.