Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract Two clathrate modifications of the title host with 4-methylpyridine (4-CH3C5H4N) as a guest have been determined at −50°C. [Mg(4-CH3C5H4N)4(NCS)2] · 2/3(4-CH3C5H4N) · 1/3H2O is trigonal, space group $$R\bar 3$$ , witha=27.630(7),c=11.219(3) ÅV=7417(4) Å3,Z=9,D calc=1.171 g cm−3,μ(CuK α)=18.506 cm−1, finalR=0.064. [Mg(4-CH3C5H4N)4(NCS)2] · (4-CH3C5H4N) is tetragonal, space group I4l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D calc=1.191 g cm−3, μ(CuK α)=18.200 cm−1, finalR=0.071. The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.
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