Crystal structure of the Hofmann-dma type clathrate

Seven new Hofmann-dma type clathrates Cd(dma)(2)Ni(CN)(4).xG (x = 1, G = an iline, 2,3-xylidine, 2,4-xylidine, 2,5-xylidine, 2,6-xylidine, 3,5-xylidine and x = 2, G = 2,4,6-trimethylanaline) were prepared by replacing the amin e in a Hofmann type clathrate Cd(NH3)(2)Ni(CN)(4). 2G by dimethylamine (dma ). The structure of the Hofmann-dma type clathrate is formed with stacked h ost two-dimensional metal complexes of Cd(dma)(2)Ni(CN)(4) and guest molecu les accommodated in the space between the stacked host complexes. This basi c structure scheme is the same as that of the Hofmann type clathrate. Howev er, the guest species accommodated in the Hofmann-dma type clathrate are mo re various than those of the Hofmann type clathrate, and their crystal stru ctures are classified into four types depending on the geometry of the gues t species. In order to clarify the structure of the Hofmann-dma type clathr ate, single crystal X-ray diffraction experiments were carried out on the s even new clathrates, and the crystal structure of the o-, m- and p-toluidin e clathrates were refined. The X-ray structure analyses showed that the hos t two-dimensional metal complex of the Hofmann-dma type clathrate has struc tural flexibility to form a puckered structure, which results from the angu lar distortion of the bond between Cd and N of the cyanide bridge in the ho st two-dimensional complex. This structural flexibility of the host complex leads to the diversity of crystal structures and guest species in Hofmann- dma type clathrates.