化学学报 ›› 2018, Vol. 76 ›› Issue (6): 445-452.DOI: 10.6023/A18030095 上一篇    下一篇

研究论文

硼桥联三氮杂环卡宾配位的铁分子氮配合物:合成、表征和反应性质研究

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
  • 收稿日期:2018-03-10 出版日期:2018-06-15 发布日期:2018-04-08
  • 通讯作者: 施敏,E-mail:mshi@mail.sioc.ac.cn;邓亮,E-mail:deng@sioc.ac.cn E-mail:mshi@mail.sioc.ac.cn;deng@sioc.ac.cn
  • 基金资助:

    项目受科技部国家重点研发计划(No.2016YFA0202900)、国家自然科学基金(Nos.21725104,21690062和21432001)、中科院战略先导科技专项(No.XDB20000000)和中央高校基本科研业务费专项资金(No.222201717003)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 Online:2018-06-15 Published:2018-04-08
  • Contact: 10.6023/A18030095 E-mail:mshi@mail.sioc.ac.cn;deng@sioc.ac.cn
  • 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).

研究了氮上取代基为1-金刚烷基的苯基硼桥联三氮杂环卡宾配体在铁促进的氮气活化转化反应中的应用.通过苯基硼桥联三氮杂环卡宾亚铁氯化物[PhB(AdIm)3FeCl](1)在氮气氛下与KC8反应合成了一价铁分子氮配合物[PhB(AdIm)3Fe(N2)](2).进一步通过2与KC8和18-C-6的反应合成了零价铁分子氮配合物[K(18-C-6)(THF)]-[PhB(AdIm)3Fe(N2)](4).这些配合物均通过核磁共振、紫外吸收光谱、红外光谱、元素分析等表征,其中配合物24的结构经单晶X射线衍射表征确定.配合物24的N—N伸缩振动频率分别为1928和1807 cm-1,均为同价态铁末端分子氮配合物最低值.在过量KC8和Me3SiCl存在下,配合物124均可催化N2的还原硅基化反应,生成N(SiMe33.催化体系的TON可达87.

关键词: 氮杂环卡宾, 铁, 分子氮配合物, 氮气活化, 氮气硅基化

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