Stegner Philipp, Färber Christian, Oetzel Jan, Siemeling Ulrich, Wiesinger Michael, Langer Jens, Pan Sudip, Holzmann Nicole, Frenking Gernot, Albold Uta, Sarkar Biprajit, Harder Sjoerd
Chair of Inorganic and Organometallic Chemistry, Universität Erlangen-Nürnberg, Egerlandstrasse 1, 91058, Erlangen, Germany.
Institute of Chemistry, University of Kassel, Heinrich-Plett-Str. 40, 34132, Kassel, Germany.
Angew Chem Int Ed Engl. 2020 Aug 17;59(34):14615-14620. doi: 10.1002/anie.202005774. Epub 2020 Jul 2.
Double deprotonation of the diamine 1,1'-(tBuCH NH)-ferrocene (1-H ) by alkaline-earth (Ae) or Eu metal reagents gave the complexes 1-Ae (Ae=Mg, Ca, Sr, Ba) and 1-Eu. 1-Mg crystallized as a monomer while the heavier complexes crystallized as dimers. The Fe⋅⋅⋅Mg distance in 1-Mg is too long for a bonding interaction, but short Fe⋅⋅⋅Ae distances in 1-Ca, 1-Sr, and 1-Ba clearly support intramolecular Fe⋅⋅⋅Ae bonding. Further evidence for interactions is provided by a tilting of the Cp rings and the related H NMR chemical-shift difference between the Cp α and β protons. While electrochemical studies are complicated by complex decomposition, UV/Vis spectral features of the complexes support Fe→Ae dative bonding. A comprehensive bonding analysis of all 1-Ae complexes shows that the heavier species 1-Ca, 1-Sr, and 1-Ba possess genuine Fe→Ae bonds which involve vacant d-orbitals of the alkaline-earth atoms and partially filled d-orbitals on Fe. In 1-Mg, a weak Fe→Mg donation into vacant p-orbitals of the Mg atom is observed.
通过碱土（Ae）或铕金属试剂对二胺1,1'-（叔丁基甲基亚氨基）-二茂铁（1-H₂）进行双去质子化反应，得到配合物1-Ae（Ae = Mg、Ca、Sr、Ba）和1-Eu。1-Mg以单体形式结晶，而较重的配合物以二聚体形式结晶。1-Mg中Fe⋅⋅⋅Mg的距离过长，无法形成键合相互作用，但1-Ca、1-Sr和1-Ba中较短的Fe⋅⋅⋅Ae距离明确支持分子内Fe⋅⋅⋅Ae键合。Cp环的倾斜以及Cp α和β质子之间相关的¹H NMR化学位移差异为相互作用提供了进一步的证据。虽然电化学研究因配合物分解而变得复杂，但配合物的紫外/可见光谱特征支持Fe→Ae配位键合。对所有1-Ae配合物的全面键合分析表明，较重的物种1-Ca、1-Sr和1-Ba具有真正的Fe→Ae键，这些键涉及碱土原子的空d轨道和Fe上部分填充的d轨道。在1-Mg中，观察到Fe向Mg原子的空p轨道有微弱的电子给予作用。
