3D model (Jmol)
|Molar mass||221.18 g/mol|
|Melting point||586 °C (1,087 °F; 859 K)|
|Boiling point||800 °C (1,470 °F; 1,070 K)|
|195 g/100 mL, exothermic|
|Solubility in other solvents||THF, Ethanol|
|C12/m1, No. 12|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Indium(III) chloride is the chemical compound with the formula InCl3. This colorless salt finds some use 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 AlCl3 and TlCl3, InCl3 crystallizes as a layered structure consisting of close-packed chloride arrangement containing layers of octahedrally coordinated In(III) centers. The motif is akin to that seen for YCl3. In contrast, GaCl3 crystallizes as dimers containing Ga2Cl6. Molten InCl3 conducts electricity, whereas AlCl3 does not as it converts to the molecular dimer, Al2Cl6.
InCl3 is a Lewis acid and forms complexes with donor ligands, L, InCl3L, InCl3L2, InCl3L3. For example with chloride ion it forms tetrahedral, InCl4−; trigonal bipyramidal, InCl52− and octahedral InCl63−.
In diethyl ether solution InCl3 reacts with lithium hydride, LiH, to form , an unstable compound decomposing below 0 °C, which is reacted "in situ" in organic synthesis as a reducing agent and to prepare tertiary amine and phosphine complexes of InH3.
Trimethylindium, InMe3 can be produced by reacting InCl3 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.
- the ether is removed at 25 °C in vacuo
InCl3 reacts with indium metal at high temperature to form lower valent indium chlorides, In5Cl9, In2Cl3 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 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.
- Araki, S.; Hirashita, T. "Indium trichloride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
- Indium Trichloride
- Habeeb, J. J.; Tuck, D. G. "Electrochemical Synthesis of Indium(III) Complexes" Inorganic Syntheses, 1979, volume XIX, ISBN 0-471-04542-X
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