Aromatic Guest Molecules Enclathrated in Hofmann‐Type and Analogous Clathrates

Abstract

AbstractThe structural features of the clathrate compounds with a general formula M(diam)M'(CN)4. 2G (M = a divalent metal in six‐coordination, diam = (NH3)2 or a diamine, M'(CN)4 = a square‐planar or tetrahedral teracyanometallate(II), G = an aromatic guest such as C4H5N, C4H4S, C6H6, C6H5NH2, etc.) are discussed from the viewpoint of the arrangement and orientation of the guest molecules in relation to the structure of the metal complex hosts. The layer structure of the Hofmann‐type host M(NH3)2M'(CN)4 (M'(CN)4 = a square‐planar moiety) enclathrates the guest molecules with a fixed orientation, but the three‐dimensional host structures built up of tetrahedral M'(CN)4 moieties provide considerably flexible and expanded cavities for guest molecules. The cavity in the three‐dimensional host may be seen as a container of a guest molecule with a chemically inactive wall and with a volume slightly larger than that of the molecule; in the container the guest molecule has freedom of motion to a certain extent. It can be expected that appropriate selection of the host constituents will afford the host lattice a stereospecific function and/or a function of keeping chemically‐active species stable in the cavity of the clathrate structure.