Tetramethylethylenediamine (TMEDA or TEMED) is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula (CH₃)₂NCH₂CH₂N(CH₃)₂. This species is derived from ethylenediamine by replacement of the four

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen Hydrogen is the chemical element wi ...

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

s with four methyl groups. It is a colorless liquid, although old samples often appear yellow. Its odor is similar to that of rotting fish.

As a reagent in synthesis

TMEDA is widely employed as a

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

for metal ions. It forms stable complexes with many metal halides, e.g.

zinc chloride Zinc chloride is the name of inorganic chemical compounds with the formula ZnCl2 and its hydrates. Zinc chlorides, of which nine crystalline forms are known, are colorless or white, and are highly soluble in water. This salt is hygroscopic and e ...

and

copper(I) iodide Copper(I) iodide is the inorganic compound with the formula CuI. It is also known as cuprous iodide. It is useful in a variety of applications ranging from organic synthesis to cloud seeding. Copper(I) iodide is white, but samples often appe ...

, giving complexes that are soluble in organic solvents. In such complexes, TMEDA serves as a bidentate ligand. TMEDA has an affinity for

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...

ions. When mixed with ''n''-butyllithium, TMEDA's nitrogen atoms coordinate to the lithium, forming a cluster of higher reactivity than the tetramer or hexamer that ''n''-butyllithium normally adopts. BuLi/TMEDA is able to

metallate Metallate or metalate is the name given to any complex anion containing a metal ligated to several atoms or small groups. Typically, the metal will be one of the transition elements and the ligand will be oxygen or another chalcogenide or a cyanid ...

or even doubly metallate many substrates including

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

, furan,

thiophene Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its react ...

, ''N''-alkyl pyrroles, and ferrocene. Many anionic organometallic complexes have been isolated as their i(tmeda)₂sup>+ complexes. In such complexes i(tmeda)₂sup>+ behaves like a

quaternary ammonium salt In chemistry, quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure , R being an alkyl group or an aryl group. Unlike the ammonium ion () and the primary, secondary, or tertiary ammonium cation ...

, such as Et₄sup>+. : LiHMDS-tmeda complex

sec-Butyllithium ''sec''-Butyllithium is an organometallic compound with the formula CH3CHLiCH2CH3, abbreviated ''sec''-BuLi or ''s''-BuLi. This chiral organolithium reagent is used as a source of ''sec''-butyl carbanion in organic synthesis.. Synthesis ''sec'' ...

/TMEDA is a useful combination in organic synthesis where the ''n''-butyl analogue adds to substrate. TMEDA is still capable of forming a metal complex with Li in this case as mentioned above.

Other uses

The complexes (TMEDA)Ni(CH₃)₂ and TMEDA)Ni(''o''-tolyl)Clillustrate the use of tmeda to stabilize homogeneous catalysts.

References

{{reflist Dimethylamino compounds Chelating agents Foul-smelling chemicals