Hydrogen-Bond Networks of Mellitate Anions ([C6(COO)6H6-n]n-) in Salts with Pyridine Derivatives

Single crystals of mellitate anion ([C6(COO)6H6-n]n-) salts with 3-aminopyridinium, [3-NH2C5H4NH+]3[C6(COO)6H33-] (1), 4-methylpyridinium, [4CH3C5H4NH+]2[CH3C5H4N]2[C6(COO)6H42-] (2), [4-CH3C5H4NH+]2[C6(COO)6H42-]·2CH3OH (3), pyridinium, [C5H5NH+]2[C6(COO)6H42-]·2H2O (4), 3methylpyridinium, [3-CH3C5H4NH+]2[C6(COO)6H42-] (5), [3-CH3C5H4NH+]5[C6(COO)6H33-][C6(COO)6H42-]·CH3OH (6), and isoquinolinium, [C9H7NH+]2 [C6(COO)6H42-]·CH3OH (7), [C9H7NH+]2[C9H7NH0.50.5+][C6(COO)6H3.52.5-]·CH3OH (8) have been structurally characterized. In these crystals, strong hydrogen-bonds between the mellitate anions are formed. Various arrangements that depend on the deprotonation number, n, have been found. All hydrogen-bonds found between the anions are combinations of a carboxy and a carboxylato group. The "triangular hydrogen-bond" unit between the anions, in which three anions are connected by the three hydrogen-bonds to form a triangle, in the salt with n = 3, induces the two dimensional (2-D) sheet self-organizing structure in this crystal. "Dual hydrogen-bond" units between the anions, in which two pairs of the hydrogen-bonds connect the neighboring anions, have been found in the salts with n = 2 or 2.5. The repetition of the co-planer "dual hydrogen-bond" induces the anion one-dimensional (1-D) belt structure, while the combination of the standing and co-planer "dual hydrogen-bond" units induces the 2-D grid structure. These 2-D grids are further linked by hydrogen-bonds to form a channel. In all the salts (n = 3, 2, 2.5), the counter cation molecules are arranged in the space defined by the anion network.