Tris(2-aminoethyl)amine

Tris(2-aminoethyl)amine
IUPAC name Tris(2-aminoethyl)amine
Other names 2,2',2-Nitrilotriethylamine 2,2',2-Triaminotriethylamine TAEA 4-(2-aminoethyl)diethylenetriamine nitrilotris(ethylamine) tris(aminoethyl)amine tris(beta-aminoethyl)amine Tren
Identifiers
CAS number	4097-89-6 Y
PubChem	77731
RTECS number	KH8587082
Properties
Molecular formula	(NH2CH2CH2)3N
Molar mass	146.236 g/mol
Appearance	colourless
Density	0.977  g/cm3
Melting point	−16 °C
Boiling point	265 °C
Solubility in water	miscible
Solubility	polar organic solvents
Hazards
MSDS	Fisher Scientifc MSDS
R-phrases	22-24-34
S-phrases	26-36/37/39-45
Main hazards	Corrosive
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tris(2-aminoethyl)amine is the organic compound with the formula N(CH₂CH₂NH₂)₃. This colourless liquid is soluble in water and is highly basic, consisting of a tertiary amine center and three pendant primary amine groups. Abbreviated "tren," it is the archetypal tripodal ligand of interest in coordination chemistry.

Coordination chemistry

Tren is a tripodal, tetradentate chelating ligand that forms stable complexes with transition metals, especially those in the 2+ and 3+ oxidation states. Tren complexes exist with relatively few isomers, reflecting the constrained connectivity of this tetramine. Thus, only a single achiral stereoisomer exists for [Co(tren)X₂]⁺, where X is halide or pseudohalide.^[1] In contrast, for [Co(trien)X₂]⁺ five diastereoiomers are possible, four of which are chiral. In a few cases, tren serves as a tridentate ligand with one of the primary amine groups non-coordinated.

Structures of trigonal bipyramidal and octahedral complexes of the formulae M(tren)X (left, C_3v symmetry) and M(tren)X₂ (right, C_s symmetry).

Related tripodal ligands

The permethylated derivative of tren is also well known. With the formula N(CH₂CH₂NMe₂)₃, "Me₆tren," forms a variety of complexes but, unlike tren, does not stabilize Co(III). Related amino-triphosphines are also well developed, such as N(CH₂CH₂PPh₂)₃ (m.p. 101-102 °C). This species is prepared from the nitrogen mustard N(CH₂CH₂Cl)₃.^[2]

The tripodal ligand of greatest commercial significance is nitrilotriacetate, N(CH₂CO₂^-)₃.

Organic chemistry

Tren is a common impurity in the more common triethylenetetramine ("trien"). As a trifunctional amine, tren forms a triisocyanate when derivatized with COCl₂.^[3]

Safety considerations

(NH₂CH₂CH₂)₃N, like other polyamines, is corrosive.^[4]

References

1. ^ Donald A. House “Ammonia & N-donor Ligands” in Encyclopedia of Inorganic Chemistry John Wiley & Sons, 2006. doi:10.1002/0470862106.ia009.
2. ^ R. Morassi, L. Sacconi "Tetradentate Tripod Ligands Containing Nitrogen, Sulfur, Phosphorus, and Arsenic as Donor Atoms" Inorganic Syntheses, 1976, vol. 16 p. 174-180. doi:10.1002/9780470132470.ch47
3. ^ Pressure Chemical
4. ^ The Physical and Theoretical Chemistry Laboratory Oxford University MSDS

• Sigma Aldrich