Acta Chimica Sinica ›› 2022, Vol. 80 ›› Issue (3): 272-276.DOI: 10.6023/A22010038 Previous Articles     Next Articles

Article

氮杂环卡宾配位的单核型一价铁硫酚基配合物

李尚钊a, 欧阳振武b, 邹俊杰b, 王东阳b, 许斌a,*(), 邓亮b,*()   

  1. a 上海大学 化学系 上海 200444
    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 上海 200032
  • 投稿日期:2022-01-21 发布日期:2022-02-15
  • 通讯作者: 许斌, 邓亮
  • 基金资助:
    国家自然科学基金(21725104); 国家自然科学基金(22061160464); 国家自然科学基金(21821002); 上海市科学技术委员会(19XD1424800); 王宽诚基金会

A Mononuclear Iron Thiolate Complex with N-Heterocyclic Carbene Ligation

Shangzhao Lia, Zhenwu Ouyangb, Junjie Zoub, Dongyang Wangb, Bin Xua(), Liang Dengb()   

  1. a Department of Chemistry, Shanghai University, Shanghai 200444
    b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, CAS, Shanghai 200032
  • Received:2022-01-21 Published:2022-02-15
  • Contact: Bin Xu, Liang Deng
  • Supported by:
    National Natural Science Foundation of China(21725104); National Natural Science Foundation of China(22061160464); National Natural Science Foundation of China(21821002); Program of Shanghai Academic Research Leader(19XD1424800); K. C. Wong Education Foundation

The relevance of low-valent iron complexes bearing sulfur-containing ligands with the reactive iron intermediates in enzymatic dinitrogen fixation has stimulated great synthetic efforts toward them. Low-valent iron thiolate complexes have been mostly known for the thiolate-bridged diiron(I) carbonyl compounds. In contrast, isolable mononuclear iron(I) thiolate complexes are exceedingly rare. Herein, we report the synthesis and characterization of a mononuclear iron(I) complex [(IMes)Fe(SAr*)] (1, IMes=1,3-bis(mesityl)imidazole-2-ylidene, Ar*=2,6-(2',4',6'-Pri3C6H2)2C6H3) as well as its catalytic performance in dinitrogen silylation reaction. Complex 1 was synthesized from the reaction of (IMes)2FeBr with KSAr* in Et2O in 81% isolated yield. Single-crystal X-ray diffraction studies revealed that the thiolate ligand in 1 is coordinating to the iron center in an σ:η6-fashion via the sulfur atom and one of the flanking Pri3C6H2 ring with the Fe—S distance of 0.2228(1) nm and the Fe—C(Trip) distances ranging from 0.2076(2) to 0.2205(2) nm. Zero-field 57Fe Mössbauer spectrum at 80 K (δ=0.56 mm•s-1; ΔEQ=0.98 mm•s-1) and X-band electron paramagnetic resonance data (g=[2.20, 2.03, 1.99]) at 103 K of 1 point to its low-spin iron(I) nature (S=1/2). These data are comparable with those of Holland's iron(I) thiolate complex K[(2-S-1,3-(6-F-3-(2,4,6-Pri3C6H2)C6H2)2C6H4)Fe] (Nature 2015, 526, 96). Density functional theory studies support the S=1/2 ground spin-state for 1 and reveal that the interaction between the iron atom and the sulfur atom is essentially σ-bonding in character. In addition, π- and δ-type interactions between the iron atom and the η6-Pri3C6H2 ring in 1 also exist. Complex 1 can catalyze the reaction of N2 with KC8 and Me3SiCl in Et2O at room temperature, affording N(SiMe3)3 with a turn-over number up to 73 in 24 h and 87 in 48 h. The reaction employing (IMes)2FeBr as catalyst has a turn-over number up to 73 in 24 h and elongating the reaction time to 48 h does not lead to further increase of the turn-over number. The fine catalytic performance with 1 over (IMes)2FeBr implies that the thiolate ligand in 1 might render the catalytically active intermediate a relatively long lifetime.

Key words: N-heterocyclic carbene, iron, sulfur ligand, N2 activation, low valent