Tris(Pyridinium)Triazine in Crystal Synthesis of 3-Fold Symmetric Structures

A series of perchlorometalate salts of the [1,3,5-tris(R)-2,4,6-triazine]3+ trications, where R = 4-, 3-,
or 2-pyridinium, have been prepared and structurally characterized. The supramolecular motifs in these salts show
striking similarities despite differences in the local position of the pyridinium NH group, the metal atom used, and
the incorporation of water molecules in the structure. A supramolecular motif in which the near-planar cations are
surrounded by an octahedral array of six octahedral trianions is observed in the majority of the new salts. The
crystal structures of [1,3,5-tris(4-pyridinium)-2,4,6-triazine][SbCl6] (4), [1,3,5-tris(4-pyridinium)-2,4,6-triazine][BiCl6]
(5), [1,3,5-tris(3-pyridinium)-2,4,6-triazine][SbCl6] (8), [1,3,5-tris(3-pyridinium)-2,4,6-triazine][BiCl6] (9), and [1,3,5-tris(3-pyridinium)-2,4,6-triazine][FeCl6] (10) are essentially isostructural; [1,3,5-tris(4-pyridinium)-2,4,6-triazine]2[FeCl6][FeCl4]3 (6), [1,3,5-tris(2-pyridinium)-2,4,6-triazine][SbCl6]·3H2O (11), and [1,3,5-tris(2-pyridinium)-2,4,6-triazine][BiCl6]·3H2O (12) show related supramolecular structural motifs. The crystal structures of all of 4, 5, 8, 9,
10, and 12 are of R3c or R3̄c symmetry and have similar cell dimensions (a = b = 14.6−15.2 Å, c = 18.5−19.2 Å)
reflecting the planarity and 3-fold symmetry of the cations. The structures appear to be stabilized by complementary
Cl···HN, Cl···HO, Cl···HC, and NH···O hydrogen bonding, shape, and electrostatic interactions and unanticipated
triazine C···Cl interactions.