Transfer of polyantimony units

Abstract

Transfer reagents are useful tools in chemistry to access metastable compounds. The reaction of [Cp′′₂ZrCl₂] with KSb(SiMe₃)₂ leads to the formation of the novel polyantimony triple decker complex [(Cp′′Zr)₂(μ,η^1:1:1:1:1:1-Sb₆)] (1, Cp′′ = 1,3-di-tertbutyl-cyclopentadienyl), containing a chair-like Sb₆⁶⁻ ligand. Compound 1 represents a valuable transfer reagent to form novel antimony ligand complexes. Thus, the reaction of 1 with Cp^R-substituted transition metal halides of nickel, cobalt and iron leads to the formation of a variety of novel Sb_n ligand complexes, such as the cubane-like compounds [(Cp′′′Ni)₄(μ₃-Sb)₄] (2) and [(Cp′′′Co)₄(μ₃-Sb₄)] (3a) or the complexes [(Cp^BnCo)₃(μ₃-Sb)₂] (4) and [(Cp′′′Fe)₃(μ₃-Sb)₂] (5), representing a trigonal bipyramidal structure. Moreover, beside the transfer of Sb₁ units, also the complete entity can be transferred as seen in the iron complex [(Cp′′′Fe)₃(μ_3,η^4:4:4-Sb₆)] (6). DFT calculations shed light on the bonding situation of the products.