Indium(III) chloride
Indium(III) chloride is the chemical compound with the formula InCl. This salt is a white, flaky solid with applications in organic synthesis as a Lewis acid. It is also the most available soluble derivative of indium. Synthesis and structure. Being a relatively electropositive metal, indium reacts quickly with chlorine to give the trichloride. Indium trichloride is very soluble and deliquescent. A synthesis has been reported using an electrochemical cell in a mixed methanol-benzene solution. Like AlCl and TlCl, InCl crystallizes as a layered structure consisting of a close-packed chloride arrangement containing layers of octahedrally coordinated In(III ) centers, a structure akin to that seen in YCl. In contrast, GaCl crystallizes as dimers containing GaCl. Molten InCl conducts electricity, whereas AlCl does not as it converts to the molecular dimer, AlCl. Reactions. InCl is a Lewis acid and forms complexes with donor ligands, L, InClL, InClL, InClL. For example, with the chloride ion it forms tetrahedral InCl, trigonal bipyramidal InCl, and octahedral InCl. In diethyl ether solution, InCl reacts with lithium hydride, LiH, to form . This unstable compound decomposes below 0 °C, and is reacted "in situ" in organic synthesis as a reducing agent and to prepare  tertiary amine and phosphine complexes of InH. Trimethylindium, InMe, can be produced by reacting InCl in diethyl ether solution either with the Grignard reagent or methyllithium, LiMe. Triethylindium can be prepared in a similar fashion but with the grignard reagent EtMgBr. InCl reacts with indium metal at high temperature to form the lower valent indium chlorides InCl, InCl and InCl. Catalyst in chemistry. Indium chloride is a Lewis acid catalyst in organic reactions such as Friedel-Crafts acylations and Diels-Alder reactions. As an example of the latter, the reaction proceeds at room temperature, with 1 mole% catalyst loading in  an acetonitrile-water solvent mixture. The first step is a Knoevenagel condensation between the barbituric acid and the aldehyde; the second step is a reverse electron-demand Diels-Alder reaction, which is a multicomponent reaction of N,N'-dimethyl-barbituric acid, benzaldehyde and ethyl vinyl ether. With the catalyst, the reported chemical yield is 90% and the percentage trans isomer is 70%. Without the catalyst added, the yield drops to 65% with 50% trans product.