Encapsulation of cyano(cyclopentadienyl) complexes of iron with β-cyclodextrin

Inclusion compounds have been prepared comprising beta-cyclodextrin (CD) molecules as the host and half-sandwich cyano complexes of iron as the guests. High yields of crystalline one-to-one adducts were obtained by treatment of CpFe(CO)(2)CN and K[CpFe(CO)(CN)(2]) with beta-CD. In the case of CpFe(dppe)CN [dppe = bis(diphenylphosphine)ethane], a non-stoichiometric product is obtained and it is evident that the organometallic guests are easily liberated from the host cavities. The products were characterized in the solid-state by elemental analysis, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), FTIR and CP MAS NMR (C-13, P-31) spectroscopy. Additional information concerning the possible structure of the inclusion compounds was obtained from ab initio calculations using a two-layer approximation. The best organometallic-beta-CD interaction is obtained with deep inclusion of the cyclopentadienyl ring, a geometry that is not possible in the case of the CpFe(dppe)CN system due to the size and orientation of the dppe ligand.