A unique tetramer of 4 : 5 (beta)-cyclodextrin-ferrocene in the solid state

A single crystal of a unique 4 : 5 inclusion complex between (beta)-cyclodextrin and ferrocene was prepared and the structure was determined by X-ray crystallographic analysis, showing that four of the five ferrocenes were included in the cavities of four (beta)cyclodextrins along the axial orientation of the tetramer, while another was co-included between two (beta)-cyclodextrins from the equatorial orientation.