Ammelinium Sulfate Monohydrate and Ammelinium Sulfate Cyanuric Acid – Synthesis and Structural Characterization

Abstract

Two ionic carbon nitride type compounds containing the ammelinium cation, ammelinium sulfate cyanuric acid (6C3N5H6O+·3SO42–·1⅔C3N3H3O3·H2O) (1) and ammelinium sulfate monohydrate (2C3N5H6O+·SO42–·H2O) (2) were synthesized through hydrolysis of melam (C6N11H9) in diluted sulfuric acid. 1 crystallizes in hexagonal space group P63 (no. 173) with lattice parameters of a = 14.642(3), c = 13.113(4), and Z = 2. The structure is comprised of protonated ammelinium ions and neutral cyanuric acid molecules, which form a layered structure, as well as sulfate ions that span through these layers. 2 crystallizes in the triclinic space group P1 with lattice parameters of a = 7.404(3), b = 9.673(4), c = 10.040(4), α = 91.098(15), β = 109.884(10), γ = 92.567(13), and Z = 2. As for 1, the ammelinium rings form layers with the sulfate ions located in between. In both structures, no extended hydrogen bond networks between the respective triazine‐based molecules are formed. Instead, single molecules or small building blocks occur isolated and interact primarily with sulfate anions. Compound 1, which was obtained phase pure, was further investigated by FTIR spectroscopy, solid‐state NMR spectroscopy and powder X‐ray diffractometry.

On Tautomerism and Amphoterism: An In‐Depth Structural and Physicochemical Characterization of Ammeline and Some of Its Salts

“…The ammelinium molecules in 3α and 3β , as in all other reported ammelinium containing structures, occur exclusively in the 2(1 H )‐keto form with protonation at both triazine‐nitrogen atoms adjacent to the carbonyl‐carbon and a near C 2 v molecular symmetry (Figure 7). Moreover, the measured C−O bond lengths of 1.2074(14) Å for 3α and 1.208(3) Å for 3β are consistent with reported values for ammelinium (1.20–1.23 Å) [17,18,25] . Similarly, the length of the two OC−NH bonds in each modification are similar to each other, namely 1.3742(14) and 1.3744(14) Å in 3α 1.377(3) and 1.380(3) Å and in 3β , and to reported values (1.36–1.39 Å).…”

“…Moreover, the measured CÀ O bond lengths of 1.2074( 14) Å for 3α and 1.208(3) Å for 3β are consistent with reported values for ammelinium (1.20-1.23 Å). [17,18,25] Similarly, the length of the two OCÀ NH bonds in each modification are similar to each other, namely 1.3742 (14) All ammelinium molecules in 3α and 3β are aligned parallel to (À 101) and (100), respectively. Furthermore, in both modifications, the ammelinium molecules are arranged into rows with identical orientation.…”

On Tautomerism and Amphoterism: An In‐Depth Structural and Physicochemical Characterization of Ammeline and Some of Its Salts

“…Moreover, the measured CÀ O bond lengths of 1.2074( 14) Å for 3α and 1.208(3) Å for 3β are consistent with reported values for ammelinium (1.20-1.23 Å). [17,18,25] Similarly, the length of the two OCÀ NH bonds in each modification are similar to each other, namely 1.3742 (14) All ammelinium molecules in 3α and 3β are aligned parallel to (À 101) and (100), respectively. Furthermore, in both modifications, the ammelinium molecules are arranged into rows with identical orientation.…”