Dimethylaluminium chloride

Dimethylaluminium chloride is an organoaluminium compound with the chemical formula [(CH3)2AlCl]2. It behaves similarly to diethylaluminium chloride but is more expensive. Hence, it is less commonly used.

Like other organoaluminium chlorides, dimethylaluminium chloride is a Lewis acid. This property is exploited by the use of dimethylaluminium chloride to induce some Diels-Alder reactions.

Structure and bonding
Compounds of the empirical formula AlR2Cl (R = alkyl, aryl) usually exist as dimers with the formula (R2Al)2(μ-Cl)2. The bridging ligands, indicated by the prefix "μ-", are halides, not the organic substituents. The aluminium adopts a tetrahedral geometry and follows the octet rule. By contrast, triethylaluminium and trimethylaluminium feature bridging alkyl groups and these compounds violate the octet rule.

Safety
Dimethylaluminium chloride is not only flammable but pyrophoric.