HEXAPYRIDINE ADDITION-COMPOUNDS OF METAL(II) SALTS (NICKEL AND MAGNESIUM PERCHLORATES, MAGNESIUM-NITRATE) - THEIR SUPRAMOLECULAR NATURE, AND ANION COORDINATION OF THE METAL CATION

X-ray structures of [NiPy4(ClO4)(2)]2Py (1), [MgPy4(ClO4)(2)]*2Py (2) , and [MgPy4(NO3)(2)]2Py (3) are presented. All three compounds are i sostructural crystallizing in orthorhombic Ccca space group with 4 for mula units per unit cell. For (1) a = 12.344(1) b = 16.104(1), c = 16. 932(1) Angstrom; V = 3366 Angstrom(3); D-calc = 1.445 g cm(-1); final R = 0.074 for 1418 observed data. For (2) a = 12.084(1), b = 16.465(1) , c = 17.379(1) Angstrom; V = 3458 Angstrom(3); D-calc =1.340 g cm(-1) ; final R = 0.053 for 1782 observed data. For (3) a = 12.081(1) b = 15 .146(1), c = 17.222(1) Angstrom; V = 3151 Angstrom(3); D-calc = 1.313 g cm(-1); final R = 0.063 for 1153 observed data. The compounds consis t of host complex molecules with two acido-groups and four pyridine li gands coordinated, and of guest pyridine species included in channels of molecular crystal framework. Coordination of poor acido-ligands in presence of non-bonded pyridine molecules is discussed and possible su pramolecular nature of other 'M(ClO4)(2)6Py' compounds is suggested.