Molecular encapsulation of transition metal complexes in cyclodextrins. Part 3. Structural consequences of varying the guest geometry in channel-type inclusion compounds

Inclusion compounds of a range of cyclopentadienyl (arene)iron(II) sandwich complexes, structurally related ferrocenes and (tetramethylcyclobutadiene) cobalt complexes with α-, β- or γ-cyclodextrin (α-, β-, γ-cd) have been prepared. Complexes bearing sterically demanding ring ligands were selectively included in β- or γ-cd. X-Ray crystallographic studies of seven new α-cd adducts demonstrate that the molecular packing of the α-cd macrocycles in channel-type structures depends on the size and shape of the guest complexes. Crystal structure determinations of two of the β-cd adducts reveal a channel type structure similar to that of the corresponding α-cd adducts, although in these cases the exact orientation of the guest molecules could not be determined due to disorder.