Supramolecular Organization of Organoammonium Squarates

Abstract

Syntheses, thermal behavior, and IR data of three hydrogen squarates, Hsq-, with 2-(acetyl-amino)-4-methylpyridinium, [(C<inf>8</inf>H <inf>11</inf>N<inf>2</inf>O)(HC<inf>4</inf>O<inf>4</inf>)] (1), 2-carboxamido-pyridinium, [(C<inf>6</inf>H<inf>7</inf>N<inf>2</inf>O)-(HC <inf>4</inf>O<inf>4</inf>)] (2), and 2-methylpyridinium cations, [(C <inf>6</inf>H<inf>8</inf>N)(HC<inf>4</inf>O<inf>4</inf>)(H<inf>2</inf>O)] (3), and one squarate, sq2-, with 2-amino-4-methyl-pyrimidinium cations, [(C<inf>6</inf>H<inf>9</inf>N<inf>2</inf>)<inf>2</inf>(C<inf>4</inf>O <inf>4</inf>)] (4) are reported. The crystal structures of 1 and 4 have been studied. The compounds decompose in two thermal stages: (i) release of organic base, (ii) decomposition of squarate. Crystallographic analyses show that 1 and 4 have S6, R<inf>2</inf>2(10) R<inf>2</inf>2(9) R <inf>2</inf>2(7) rings. The hydrogen bonding motifs formed by the hydrogensquarate anions interact with the ammonium cations through N-H ⋯ O hydrogen bonds and give rise to predominantly layered structures, which also exhibit three-dimensional connectivity. © 2006 Verlag der Zeitschrift für Naturforschung.