Melem

Names
IUPAC name

11-imino-2,4,6,8,10,12,13-heptazatricyclo[7.3.1.05,13]trideca-1(12),2,4,7,9-pentaene-3,7-diamine

Other names

2,5,8-triamino-heptazine; 2,5,8-triamino-tri-s-triazine; cyamelurotriamide; triamino-s-heptazine; 1,3,4,6,7,9,9b-Heptaazaphenalene-2,5,8-triamine

Identifiers

CAS Number

* 1502-47-2 Y

3D model (JSmol)

* Interactive image

Beilstein Reference

| 27284
ChEBI |

* CHEBI:38055 Y

ChemSpider |

* 4575652 N

ECHA InfoCard | 100.014.657
EC Number |

* 216-122-4

Gmelin Reference

| 241276

PubChem CID

* 73919

UNII |

* WP6U3U42XL Y

CompTox Dashboard (EPA)

* DTXSID40164493

InChI

* InChI=1S/C6H6N10/c7-1-10-4-12-2(8)14-6-15-3(9)13-5(11-1)16(4)6/h(H6,7,8,9,10,11,12,13,14,15) N

Key: YSRVJVDFHZYRPA-UHFFFAOYSA-N

SMILES

* C1(=NC2=NC(=N)N=C3N2C(=NC(=N3)N)N1)N

Properties

Chemical formula

| C6H6N10
Molar mass | 218.18 g/mol
Appearance  | white solid

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Chemical compound

In chemistry, melem is a compound with formula C

10H
6; specifically, 2,5,8-triamino-heptazine or 2,5,8-triamino-tri-s-triazine, whose molecule can be described as that of heptazine with the three hydrogen atoms replaced by amino groups. It is a white crystalline solid.[1]

## Preparation

[edit]

Melem can be prepared by thermal decomposition of various C−N−H compounds, such as melamine C3N3(NH2)3, dicyandiamide H4C2N4, ammonium dicyanamide NH4[N(CN)2], cyanamide H2CN2, at 400 to 450 °C.[1][2]

## Structure and properties

[edit]

### Crystal structure

[edit]

Melem crystallizes in the group P21/c (No. 14), with parameters a = 739.92(1) pm, b = 865.28(3) pm, c = 1338.16(4) pm, β = 99.912(2)°, and Z = 4. The almost-planar molecules are arranged in parallel layers spaced 327 pm apart. The molecule is in the triamino form, rather than one of the possible tautomers.[1]

### Thermal decomposition

[edit]

When heated above 560°, melem transforms into a graphite-like C−N material.[1]

### Melemium cations

[edit]

Melem accepts up to three protons yielding cations called melemium [(NH2)3(C6N7Hx)]x+. Some salts described in the literature are melemium sulfate, [(NH

3(C

2)]SO
4 • 2H
2O, melemium perchlorate, [(NH

3(C

7H)]ClO
4 • H
2O, melemium hydrogensulfate [(NH

3(C

3)](HSO

3 and two melemium methylsulfonates [(NH

3(C

2)](SO
3CH

2 • H
2O and [(NH

3(C

7H)][(NH

3(C

2)](SO
3CH

3 • H
2O. The protons can be inserted in any of the six outer nitrogen atoms of the heptazine core, yielding many tautomers of apparently similar energies.[3]

## See also

[edit]

* Triazine H

3, with a single C-N ring
* Melamine (NH

3(C

3), triamino triazine
* Melaminium [H(NH

3(C

3)]+
, a cation derived from melamine
* Melam ((NH

2(C

3))
2NH, a condensation dimer of melamine
* Melamium [H((NH

2(C

3))
2NH]+
, a cation derived from melam
* Melon (NH
2)(NH(C

7H)NH)
nH, a condensation oligomer of melem

## References

[edit]

1. ^ a b c d Jürgens, Barbara; Irran, Elisabeth; Senker, Jürgen; Kroll, Peter; Müller, Helen; Schnick, Wolfgang (2003-08-01). "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". Journal of the American Chemical Society. 125 (34): 10288–10300\. doi:10.1021/ja0357689. ISSN 0002-7863.
2. ^ Tamikuni Komatsu (2001)> Komatsu, Tamikuni (2001-01-01). "The First Synthesis and Characterization of Cyameluric High Polymers". Macromolecular Chemistry and Physics. 202 (1): 19–25\. doi:10.1002/1521-3935(20010101)202:1<19::AID-MACP19>3.0.CO;2-G. ISSN 1022-1352.
3. ^ Fabian Karl Keßler (2019), Structure and Reactivity of s-Triazine-Based Compounds in C/N/H Chemistry. Doctoral thesis, Fakultät für Chemie und Pharmazie, Ludwig-Maximilians-Universität München

*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency