Inclusion complex formation of diferrocenyldimethylsilane with β-cyclodextrin

An inclusion compound comprising β-cyclodextrin (β-CD) and diferrocenyldimethylsilane, Fc–SiMe2–Fc [Fc = (η5-C5H5)Fe(η5-C5H4)], has been prepared and characterized in the solid state by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and magic angle spinning (MAS) NMR spectroscopy (13C, 29Si). Elemental analysis indicated that the host:guest molar ratio in the product was approximately 1.5. Ab initio calculations in vacuo were carried out in order to investigate the possible inclusion modes. The first structure, designated form 2a, was determined assuming a barrel-type conformation, with parallel head-to-head cyclodextrins. A second V-shaped complex (2b) was also found by allowing variation of the angle between the cyclodextrins. Form 2a was assumed to be the best approximation to the real structure, since this geometrical arrangement favors the formation of a channel-type packing motif.