Very pure trialkylindium compounds were prepared by E. Todt and R . DStzer. They fused technical In (containing up to 5 %, impurities) with technical Mg in an atmosphere of hydrogen. Fine turnings of this alloy (or niixtures of In and Mg) were covered with ether and treated with alkyl halides under a blanket of specially purified nitrogen or argon. After the reaction, the trialkylindium compounds can be distilled off as etherates; a second distillation is usually sufficient to remove the ether. The etherate of trimethylindium can be decomposed by distillation with a little benzene. Trimethylindium (1) forms colorless crystals (b.p. 66-67 OC/12 mm; m.p. 88.4 "C) and is complelcly stable to light and heat, even at 250 "C. The triethyl, tri-n-propyl, tri-isopropyl (2), tri-nbutyl, tri-isobutyl, and tri-s-butyl (3) derivatives of I n are faintly viscous, colorless liquids; (2) and (3) are yellow. All these compounds ignite spontaneously in air and react violently with water. With the exception of 1/), they are decomposed by light and by heating to 200"C, or less, the metal being deposited. Indium purified in this manner is suitable