The infra-red spectrum and structure of melamine

Abstract

The infra-red spectra of melamine and of melamine-& have been studied from 450 to 5000 cm-1 in the solid state. The spectral studies support the view that the molecule has the almost all-planar cyanuric triamide structure in the crystal state.A complete frequency assignment is attempted for the class Ai, class A: and class E' vibrations. The splitting of the absorption bands arising from the doubly-degenerate class E' modes and the appearance of the infra-red forbidden class Ai absorptions is interpreted as evidence that the molecule is distorted in the crystal thus losing to some extent its D3h symmetry.

Melem (2,5,8-Triamino-tri-s-triazine), an Important Intermediate during Condensation of Melamine Rings to Graphitic Carbon Nitride: Synthesis, Structure Determination by X-ray Powder Diffractometry, Solid-State NMR, and Theoretical Studies

“…These can be divided into two parts: 21 vibrations are associated with the three NH 2 groups of melem, which is comparable to the situation found for melamine with its three amino groups. 55,56 Each NH 2 group has six vibrational modes: the stretching vibrations ν as -NH 2 and ν s NH 2 , the bending and rocking vibrations δNH 2 and FNH 2 which are in-plane, as well as the out-of-plane twisting and wagging vibrations τNH 2 and ωNH 2 . The remaining 39 modes are skeletal vibrations belonging to the C 6 N 7 nucleus which are found in trichloro-tri-s-triazine, too.…”

Supramolecular systems based on the melamine salt of bis(hydroxymethyl)phosphinic acid (melafen) dihydrate and surfactants

“…The IR spectra of BPA and M were analyzed by analogy to those described previously. [15][16][17][18] The discussed parameters of M and BPA and their possible changes were also com mented earlier. [19][20][21][22] A comparison of the spectrum of compound 1 with the spectra of compounds M and BPA shows that the IR spectrum of compound 1 retains a complicated system of intense bands in the ν(NH) region at 3000-3500 cm -1 , multiple bonds in the ν(СN) and δ(NH) region at ~1400-1700 cm -1 , and the phosphorus framework in the interval 950-1200 cm -1 .…”

“…Along with the observed disappearance of the absorption at ~1550 cm -1 , this spectral pattern is a property of sym metry loss. 16,20,21 In the spectra of compound 1 com pared to those of BPA, the multiplet of strong peaks of the phosphorus framework also somewhat changes in the indicated above characteristic interval. The high frequen cy peak (1163 cm -1 , ν(Р=О) of BPA) shifts in the spec trum of compound 1 to the low frequency region to 1136 cm -1 (Δ = 27 cm -1 ), which is characteristic of the phosphate anion 18,19 РО 2 -(ν as (РО 2 -)).…”

2,4,6-Triamino-1,3,5-triazin-1-ium Acetate Acetic Acid Solvate Monohydrate. Infrared and Raman Spectra

“…Few papers concerning the melamine molecule vibrations were already published [29][30][31][32][33]39 and constitute a good source for the assignment of vibrational bands.…”

“…The frequency of the band originating from this type of coupling rises from 3328 cm . 30 Thus, the intermolecular interactions through the NH 2 groups of melamine molecule cause the rising of their frequencies for bending type of motion, also.…”