The structure - properties relations in the clathrates of N1 (NCS)2 (4-methylpyridine)4

The Ni(NCS)₂(4-methylpyridine)₄ molecule shows significant confomational flexibility of the four piooline and the two isothiocyanate ligands. Both intramolecular non-bonded energy calculations and x-ray crystal structures support the idea that the host molecule may adopt different conformations (molecular shape) in order to bind, in clathrate formation, guest molecules of different shape and size. This versatility enables the Ni(NCS)₂(4-methylpyridine)₄ complex to form many different crystal structures able to absorb both small molecules, e.g. noble gases, and relatively large condensed aromatic hydrocarbons. The type of the crystalline structure formed defines “primary” properties of the clathrate. Secondary effects are observed when varying lattice parameters of the host structure (dilatation - contraction) by introducing guest component of suitable composition.