A Systematic Approach to Alkali Biuretooxophosphates

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Melamium salts are a group of ionic carbon nitride type compounds that has been investigated only scarcely. We herein present a novel representative of this group. A melamium thiocyanate melam (1:1) adduct was synthesized from dicyandiamide and ammonium thiocyanate in sealed glass ampoules. The structure of the adduct was determined from single‐crystal X‐ray diffraction. Melamium thiocyanate melam crystallizes in monoclinic space group P21/c (no. 14) with lattice parameters of a = 3.6041(11), b = 28.532(7), c = 10.937(4) Å, β = 99.051(14)°, and Z = 4. While the melamium ions form 2D extended hydrogen bridged networks, the thiocyanate ions are disordered and no distinct structural sites could be assigned to the respective atoms. Instead, continuous columns of electron density located in channels in the porous structure were identified as potential space for anion locations. The compound was further characterized by elemental analysis, FTIR spectroscopy and solid‐state MAS‐NMR spectroscopy of the nuclei 1H, 13C and 15N. Rietveld refinement of powder samples was performed for phase analysis. Furthermore, DSC‐TG was used to investigate the thermal behavior of the compound.

Section: Resultscontrasting

confidence: 94%

Melamium Thiocyanate Melam, a Melamium Salt with Disordered Anion Sites

Kessler¹,

Schuhbeck²,

Schnick³

2019

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“…There are indications for a direct conversion of melamine to melem as well as for a route that contains melam as an intermediate in the form of adduct compounds of melamine and melem on the one and melam and melem on the other hand. [29,30] At least for syntheses in salt melts our results seem to favor the latter route.…”

Section: Resultsmentioning

confidence: 70%

From Heptazines to Triazines – On the Formation of Poly(triazine imide)

Kessler¹,

Schnick²

2019

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Poly(triazine imide), a 2D extended carbon nitride network compound that is obtained from ionothermal synthesis in LiCl/KCl or LiBr/KBr salt melt has been known for over a decade. We now have investigated the formation process of this material starting from various triazine‐ and heptazine‐based precursors as well as the differences between ionothermal and conventional synthesis via thermal condensation. Independent of chosen starting material, melem (triamino‐s‐heptazine) is initially formed from the starting material as the imminent precursor to poly(triazine imide). We elucidate the impact of various different carbon nitride precursor compounds on the formation process, propose a mechanism for the back reaction of heptazines to triazines, and rationalize the occurring processes.

“…The latter of those is unknown from previously described melamium salts [7,27] , however can be found in melam hydrate. [18]…”

Section: Articlementioning

confidence: 99%

“…[15] Certain synthesis routes starting from melamine or its chloro-substituted derivatives in the presence of Lewis acidic salts have been proposed, [16,17] however, a route to obtain larger quantities of phase pure melam has first been published in 2013. [18] In this, melam could be obtained from dicyandiamide in autoclaves under ammonia pressure, ARTICLE thus preventing further condensation towards melem by impeding ammonia eliminating reactions through an already high ammonia partial pressure.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structure of Melamium Bromide C₆N₁₁H₁₀Br and Melamium Iodide C₆N₁₁H₁₀I

Kessler

Koller

Schnick

2018

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Melamium bromide and melamium iodide were synthesized from dicyandiamide in the presence of ammonium halides in evacuated Duran glass ampoules at temperatures of 450 °C. The crystal structures of both compounds were obtained from single‐crystal X‐ray diffraction. Melamium bromide C6N11H10Br crystallizes in space group P21/n [no. 14, a = 7.0500(5), b = 28.7096(18), c = 10.8783(8) Å, β = 96.060(2)°, Z = 8, wR2 = 0.2231] and exhibits a layer‐like arrangement of melamium ions, wherein both planar as well as twisted molecular structures of the cations occur. Melamium iodide C6N11H10I crystallizes in space group P21/c [no. 14, a = 6.8569(3), b = 11.9949(6), c = 14.0932(6) Å, β = 97.613(2)°, Z = 4, wR2 = 0.0654], however in a structure completely different from the one of melamium bromide. The melamium iodide structure is comprised of stacks of planar melamium ions that form complex, hydrogen‐bonded network layers with iodide ions within the layers. Both compounds were further characterized by FTIR spectroscopy, mass spectrometry, and elemental analyses. Melamium bromide and melamium iodide could be obtained as air stable and colorless crystals. Samples are crystallographically phase pure as shown by Rietveld refinement.