One-dimensional anionic radical chains based on M₂P₂ rings (M = Ti, Zr, Hf)
AuthorsX. Sun, R. Yadav, A. Hinz, J. Göttlicher, T. Vitova, S. Dinauer, M. Scheer, P. RoeskyYear of publicationPublished in:Chemical Science
This work deals with the synthesis of metallocene-phosphorus based radical coordination polymers. The radical polymeric chains were synthesized by a single step reaction between commercially available group 4 metallocene dichlorides [Cp ₂ MCl ₂ ] (M = Ti, Zr, Hf; Cp = η ⁵ -C ₅ H ₅ ), pentaphosphaferrocene [Cp*Fe(η ⁵ -P ₅ )] (Cp* = η ⁵ -C ₅ Me ₅ ) and potassium metal. These reactions selectively gave polymeric chains of radical, [K{Cp ₂ M} ₂ {(η ⁴ -P ₅ )FeCp*} ₂ ] n (M = Ti, Zr, Hf). The four membered P ₂ M ₂ core is the first example of such a phosphorus-based ring with a radical anionic nature. Moreover, it is also a rare example of a main group element based radical polymeric chain. The radical nature of the metallopolymer is further established by EPR, XANES and quantum chemical calculations. The potassium ion acts as a linker ion between two [{Cp ₂ M}{(η ⁴ -P ₅ )FeCp*}] fragments. The reaction of [K{Cp ₂ M} ₂ {(η ⁴ -P ₅ )FeCp*} ₂ ] n with [2.2.2]-cryptand in THF resulted in chain cleavage into charge separated monomeric complexes [(K[2.2.2]-cryptand){Cp ₂ M} ₂ {(η ⁴ -P ₅ )FeCp*} ₂ ] (M = Ti, Zr, Hf).