Three-dimensional Metal Complex Structures with Ambident Propylene-diamine Ligands Serving as the Hosts of the Aromatic Guest Molecules. Hofmann-pn and pn-Td Type Clathrates

Abstract

Novel clathrate compounds, Hofmann-pn type Cd(pn)Ni(CN)4·3/2G (G=C4H5N, C4H4S, or C6H6) and pn-Td type Cd(pn)Cd(or Hg)(CN)4·3/2C6H6, have been prepared. Their host structures are analogous to those of the known Hofmann-en type Cd(en)Ni(CN)4·2G and en-Td type Cd(en)Cd(or Hg)(CN)4·2C6H6. The propylenediamine (pn: 1,2-diaminopropane) molecule ambidently bridges six-coordinate Cd atoms, as the en (ethylenediamine) does in the latter types of clathrates. The guest molecules occupy at random three quarters of the cavities in the host structures: every remaining cavity contains two methyl groups of the pn molecules. The crystal structure of Cd(l-pn)Ni(CN)4·3/2C4H5N has been analyzed in order to demonstrate the structural features. The crystal is tetragonal with the space group P422, a=7.575(2) and c=7.742(2) Å, and Z=1. The degree of disorder is extremely high with regard to the arrangement and orientation of the l-pn molecule.