D-d Dative Bonding Between Iron and the Alkaline-Earth Metals Calcium, Strontium, and Barium.

ABSTRACT: Double deprotonation of the diamine 1,1'-(tBuCH₂ NH)-ferrocene (1-H₂ ) by alkaline-earth (Ae) or Eu^II 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 ¹ 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

SUBMITTER: Stegner P 

PROVIDER: S-EPMC7496664 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature