Acta Chim. Sinica ›› 2018, Vol. 76 ›› Issue (6): 445-452.DOI: 10.6023/A18030095 Previous Articles     Next Articles



凡一明a, 程骏b, 高亚飞b, 施敏a,b, 邓亮b   

  1. a 华东理工大学 化学与分子工程学院 结构可控先进功能材料及其制备教育部重点实验室 上海 200237;
    b 中国科学院上海有机化学研究所 金属有机化学国家重点实验室 分子合成科学卓越中心 上海 200032
  • 投稿日期:2018-03-10 发布日期:2018-04-08
  • 通讯作者: 施敏,;邓亮,;
  • 基金资助:


Iron Dinitrogen Complexes Supported by Tris(NHC)borate Ligand: Synthesis, Characterization, and Reactivity Study

Fan Yiminga, Cheng Junb, Gao Yafeib, Shi Mina,b, Deng Liangb   

  1. a School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237;
    b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
  • Received:2018-03-10 Published:2018-04-08
  • Contact: 10.6023/A18030095;
  • Supported by:

    Project supported by the National Key Research and Development Program (No. 2016YFA0202900), the National Natural Science Foundation of China (Nos. 21725104, 21690062, 21432001), the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB20000000) and the Fundamental Research Funds for the Central Universities (No. 222201717003).

The use of the N-adamantyl-substituted tris(NHC)borate ligand phenyltris(3-(1-adamantylimidazol-2-ylidene))borate (PhB(AdIm)3-) has enabled the preparation of the high-spin tetrahedral iron(I)-and iron(0)-N2 complexes[PhB(AdIm)3Fe(N2)] (2) and[K(18-C-6)(THF)] [PhB(AdIm)3Fe(N2)] (4), from the reduction of the ferrous precursor[PhB(AdIm)3FeCl] (1) and the iron(I) complex 2 with KC8 under N2, respectively. Single-crystal X-ray diffraction studies revealed a distorted tetrahedral coordination geometry for the iron centers in 2 and 4 with the terminally bonded N2 ligand sitting in the cavity composed by the three adamantyl groups of the borate ligand. The frequencies of the N-N stretching resonance (1928 and 1807 cm-1) of 2 and 4 are the lowest among the reported terminal N2complexes of iron(I) and iron(0), respectively. 57Fe Mössbauer spectrum (δ=0.59 mms-1; ΔEQ=1.31 mms-1) and solution magnetic susceptibility measurement (μeff=5.2(1) μB) of 2 supported its high-spin iron(I) nature. The cyclic voltammogram of 2 measured in THF shows a quasi-reversible redox waves with E1/2=-2.11 V (vs SCE), which is assignable to the corresponding redox process of[PhB(AdIm)3Fe(N2)]1-/0. In addition, the reaction of 2 with an excess amount of CO led to the formation of the bis(carbonyl)iron(I) complex,[PhB(AdIm)3Fe(CO)2] (3), that was characterized by IR spectrum, solution magnetic susceptibility measurement, 1H NMR, as well as elemental analysis. The protonation of 2 and 4 with HCl or HOTf at -78℃ only led to the formation of NH2NH2 and NH3 in low yields[less than 9(3)% and 5(3)% (per mol Fe), respectively]. However, 1, 2, and 4 proved effective catalysts for the reductive silylation of N2by KC8 and Me3SiCl to afford N(SiMe3)3 with comparable catalytic activity. The TON of these catalytic systems could reach 87 using 0.005 mmol of the catalyst, 2000 equiv. of KC8, and 2000 equiv. of Me3SiCl in 10 mL Et2O at room temperature after 24 h.

Key words: N-heterocyclic carbene, iron, dinitrogencomplex, N2 activation, reductive silylation of N2