PMDTA

PMDTA

Identifiers
CAS Number	3030-47-5 Y
3D model (Jmol)	Interactive image
Beilstein Reference	1741396
ChEBI	CHEBI:39475 N
ChemSpider	17187 N
ECHA InfoCard	100.019.275
EC Number	221-201-1
Gmelin Reference	27747
PubChem CID	18196
RTECS number	IE2100000
UN number	2734
InChI InChI=1S/C9H23N3/c1-10(2)6-8-12(5)9-7-11(3)4/h6-9H2,1-5H3 N Key: UKODFQOELJFMII-UHFFFAOYSA-N N
SMILES CN(C)CCN(C)CCN(C)C
Properties
Chemical formula	C9H23N3
Molar mass	173.30 g·mol−1
Appearance	Colorless liquid
Odor	Fishy, ammoniacal
Density	830 mg mL−1
Melting point	−20 °C (−4 °F; 253 K)
Boiling point	198 °C (388 °F; 471 K)
Vapor pressure	31 Pa (at 20 °C)
Refractive index (nD)	1.442
Hazards
Safety data sheet	sigmaaldrich.com
GHS pictograms
GHS signal word	DANGER
GHS hazard statements	H302, H311, H314
GHS precautionary statements	P280, P305+351+338, P310
EU classification (DSD)	T
R-phrases	R22, R24, R34
S-phrases	(S1/2), S26, S36/37/39
Flash point	53 °C (127 °F; 326 K)
Autoignition temperature	155 °C (311 °F; 428 K)
Explosive limits	1.1–5.6%
Lethal dose or concentration (LD, LC):
LD50 (median dose)	232 mg kg−1(dermal, rabbit) 1.351 g kg−1(oral, rat)
Related compounds
Related amines	triethylenetetramine tmeda diethylenetriamine triazacyclononane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

PMDTA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) is an organic compound with the formula [(CH₃)₂NCH₂CH₂]₂NCH₃. PMDTA is a basic, bulky, and flexible, tridentate ligand that is a used in organolithium chemistry. It is a colorless liquid, although impure samples appear yellowish.

PMDTA is prepared from diethylenetriamine by the Eschweiler-Clarke reaction, involving the use of formaldehyde and formic acid.

Unlike diethylenetriamine, all three amines in PMDTA are tertiary. Both PMDTA and diethylenetriamine are tridentate ligands that form two five-membered chelate rings. The σ-donating properties of the amino groups of diethylenetriamine are greater than that of PMDTA in copper(II) complexes. Both ligands can coordinate metal complexes in arrangements where the three nitrogen centers are co-planar or mutually cis.

PMDTA is used to modify the reactivity of organolithium compounds, which deaggregate in the presence of Lewis bases to enhance their reactivity. Commonly, the ditertiary amine TMEDA is used in these applications; it binds to the lithium center as a bidentate ligand. PMDTA behaves analogously, but since it is tridentate, it binds more strongly to lithium. In contrast to TMEDA, PMDTA forms monomeric complexes with organolithium compounds. Both amines affect the regiochemistry of metalation.

In the PMDTA/n-BuLi adducts, the Li-C bonds are highly polarized, thus increasing the basicity of the butyl group.

The effect of PMDTA on lithium anilide is illustrative of PMDTA's complexing power. The complex, [{PhN(H)Li}₃·2PMDTA], is trinuclear, featuring approximately colinear Li⁺ centers that are three-, four-, and five-coordinate. The central three-coordinate lithium atom is not bonded to PMDTA. One of the terminal Li centers is pseudo-tetrahedral in an N₄ coordination sphere. The other terminal lithium atom is five-coordinate and binds to two anilino N centers and the PMDTA.

PMDTA often forms five-coordinate complexes due to steric bulk of the methyl groups. PMDTA stabilize unusual cations. The first cationic derivative of alane, [H₂Al(PMDTA)]⁺[AlH₄]⁻ was prepared by treating H₃AlNMe₃ with PMDTA.