TMEDA

TMEDA (N,N,N',N'-tetramethylethylenediamine) is a bidentate Lewis base widely used in organic and organometallic chemistry. It consists of two tertiary amine groups attached to an ethylene backbone, giving the structure (CH3)2N-CH2-CH2-N(CH3)2. The molecule acts as a flexible two-donor ligand that readily coordinates to a variety of metal centers, including magnesium, lithium, copper, palladium, nickel, and zinc. In solution, TMEDA forms coordinated adducts such as RMgX(TMEDA) or LiTMEDA, which can modulate reactivity and solubility of the metal species.

TMEDA's primary role is as a ligand and as a non-nucleophilic, strongly basic additive. In Grignard reagent chemistry, TMEDA increases the solubility and reactivity of organomagnesium species, especially in less polar solvents or at low temperatures, enabling more rapid additions to carbonyl compounds and other carbon–carbon bond-forming processes. It is also used as a coordinating ligand in various catalytic systems, including nickel- and palladium-catalyzed cross-coupling and polymerization catalysts, where TMEDA-bound metal centers can enhance activity and selectivity.

Synthesis and handling: TMEDA is prepared by alkylation of ethylenediamine with methylating agents, yielding N,N,N',N'-tetramethylethylenediamine. It is a colorless to pale liquid with a strong amine odor, miscible with water and many organic solvents. It is hygroscopic and should be handled with appropriate precautions; it is corrosive and irritating upon contact.