Fifteen 4-(2-methoxyphenyl)piperazin-1-ium salts containing organic anions: supramolecular assembly in zero, one, two and three dimensions

Abstract

Fifteen 4-(2-methoxyphenyl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. In the isostructural 4-chlorobenzoate and 4-bromobenzoate salts, C11H17N2O+·C7H4ClO2− (I) and C11H17N2O+·C7H4BrO2− (II), and the 4-iodobenzoate salt C11H17N2O+·C7H4IO2− (III), the ions are linked by N—H...O hydrogen bonds, forming centrosymmetric R44(12) four-ion aggregates; a similar aggregate is formed in the 2-chlorobenzoate salt (V), isomeric with (I). In the 2-fluorobenzoate salt C11H17N2O+·C7H4FO2− (IV), and the isomorphous pair of salts, the 2-bromobenzoate (VI), isomeric with (II) and 2-iodobenzoate (VII), isomeric with (III), N—H...O and C—H...π(arene) interactions link the components into three-dimensional arrays. Four-ion R44(12) aggregates are also found in the 2-methylbenzoate, 4-aminobenzoate and 4-nitrobenzoate salts, C11H17N2O+·C8H7O2− (VIII), C11H17N2O+·C7H6NO2− (IX) and C11H17N2O+·C7H4NO4− (X), but those in (IX) are linked into complex sheets by an additional N—H...O hydrogen bond. In the 3,5-dinitrobenzoate salt, C11H17N2O+·C7H3N2O6−·2H2O (XI), N—H...O and O—H...O hydrogen bonds link the components into a complex ribbon structure. In the picrate salt, C11H17N2O+·C6H2N3O7− (XII), the four-ion aggregates are linked into chains of rings by C—H...O hydrogen bonds. In the hydrogen maleate salt, C11H17N2O+·C4H3O4− (XIII), two- and three-centre hydrogen bonds link the ions into a ribbon structure while both anions contain very short but asymmetric O—H...O hydrogen bonds, having O...O distances of 2.4447 (16) and 2.4707 (17) Å. O—H...O Hydrogen bonds link the anions in the hydrogen fumarate salt (XIV), isomeric with (XIII), into chains that are linked into sheets via N—H...O hydrogen bonds. In the hydrogen (2R,3R)-tartrate salt, C11H17N2O+·C4H5O6−·1.698H2O (XV), the anions are linked into sheets by O—H...O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Keywords

• synthesis
• piperazines
• crystal structure
• molecular conformation
• absolute configuration
• disorder
• hydrogen bonding
• supramolecular assembly