Indium(III) chloride is the chemical compound with the formula which forms a tetrahydrate. 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. This is one of three known indium chlorides.
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 and , 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 . In contrast, crystallizes as dimers containing . Molten conducts electricity, whereas does not as it converts to the molecular dimer, .
The tetrahydrate, InCl<sub>3</sub>÷4H<sub>2</sub>O, crystallises in the orthorhombic crystal system. It consists of a unit of [InCl<sub>3</sub>(H<sub>2</sub>O)<sub>2</sub>] interconnected by two water of crystallizations. It is produced by the evaporation of a solution of indium(III) chloride.
is a Lewis acid and forms complexes with donor ligands, L, , , . For example, with the chloride ion it forms tetrahedral , trigonal bipyramidal , and octahedral .
In diethyl ether solution, reacts with lithium hydride, LiH, to form lithium tetrahydroindate(III) . This unstable compound decomposes below 0 ðC, and is reacted in situ in organic synthesis as a reducing agent and to prepare tertiary amine and phosphine complexes of .
Trimethylindium, , can be produced by reacting in diethyl ether solution either with the Grignard reagent methylmagnesium iodide or methyllithium . Triethylindium can be prepared in a similar fashion but with the grignard reagent EtMgBr.
reacts with indium metal at high temperature to form the lower valent indium chlorides , and InCl.
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.