Indium(III) chloride

Indium(III) chloride

Names
Other names Indium chloride
Identifiers
CAS Number	10025-82-8
3D model (Jmol)	Interactive image
ChemSpider	23197
ECHA InfoCard	100.030.027
PubChem	24812
UNII	58TD96H03I
InChI InChI=1S/3ClH.In/h3*1H;/q;;;+3/p-3 Key: PSCMQHVBLHHWTO-UHFFFAOYSA-K InChI=1/3ClH.In/h3*1H;/q;;;+3/p-3 Key: PSCMQHVBLHHWTO-DFZHHIFOAF
SMILES Cl[In](Cl)Cl
Properties
Chemical formula	InCl3
Molar mass	221.18 g/mol
Appearance	white flakes
Density	3.46 g/cm^3
Melting point	586 °C (1,087 °F; 859 K)
Boiling point	800 °C (1,470 °F; 1,070 K)
Solubility in water	soluble, exothermic
Solubility in other solvents	THF
Structure
Crystal structure	Monoclinic, mS16
Space group	C12/m1, No. 12
Hazards
NFPA 704	0 2 0
Related compounds
Other anions	Indium(III) fluoride Indium(III) bromide Indium(III) iodide
Other cations	Aluminium chloride Gallium trichloride Thallium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.^[1]

Synthesis and structure

Being a relatively electropositive metal, indium reacts quickly with chlorine to give the trichloride. Indium trichloride is very soluble and deliquescent.^[2] A synthesis has been reported using an electrochemical cell in a mixed methanol-benzene solution.^[3]

Like AlCl₃ and TlCl₃, InCl₃ crystallizes as a layered structure consisting of close-packed chloride arrangement containing layers of octahedrally coordinated In(III) centers.^[4] The motif is akin to that seen for YCl₃.^[5] In contrast, GaCl₃ crystallizes as dimers containing Ga₂Cl₆.^[5] Molten InCl₃ conducts electricity,^[4] whereas AlCl₃ does not as it converts to the molecular dimer, Al₂Cl₆.^[6]

Reactions

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⁻.^[4]

In diethyl ether solution InCl₃ reacts with lithium hydride, LiH, to form ${\displaystyle {\ce {LiInH4}}}$, an unstable compound decomposing below 0 °C,^[7] which is reacted "in situ" in organic synthesis as a reducing agent^[8] and to prepare tertiary amine and phosphine complexes of InH₃.^[9]

Trimethylindium, InMe₃ can be produced by reacting InCl₃ in diethyl ether solution either with the grignard reagent, ${\displaystyle {\ce {MeMgI}}}$, or methyllithium, LiMe. Triethylindium can be prepared in a similar fashion but with the grignard reagent, EtMgBr.^[10]

${\displaystyle {\ce {{InCl3}+3LiMe->{Me3In.OEt2}+3LiCl}}}$

${\displaystyle {\ce {{InCl3}+3MeMgI->{Me3In.OEt2}+3MgClI}}}$

${\displaystyle {\ce {{InCl3}+3EtMgBr->{Et3In.OEt2}+3MgBr2}}}$

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.^[4]

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^[11] 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.

References

1. 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.
2. Indium Trichloride
3. Habeeb, J. J.; Tuck, D. G. "Electrochemical Synthesis of Indium(III) Complexes" Inorganic Syntheses, 1979, volume XIX, ISBN 0-471-04542-X
4. Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
5. Wells, A.F. Structural Inorganic Chemistry, Oxford: Clarendon Press, 1984. ISBN 0-19-855370-6.
6. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
7. Anthony John Downs (1993). Chemistry of aluminium, gallium, indium, and thallium. Springer. ISBN 0-7514-0103-X.
8. Main Group Metals in Organic Synthesis vol 1, ed. Hisashi Yamamoto, Koichiro Oshima, Wiley VCH, 2004, ISBN 3527305084
9. The Group 13 Metals Aluminium, Gallium, Indium and Thallium: Chemical Patterns and Peculiarities, Simon Aldridge, Anthony J. Downs, wiley, 2011, ISBN 978-0-470-68191-6
10. Main Group compounds in Inorganic Syntheses, vol 31, , By Schultz, Neumayer, Marks; Ed., Alan H. Cowley, John Wiley & Sons, Inc., 1997, ISBN 0471152889
11. An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via Indium-Catalyzed Multicomponent Domino Reaction Prajapati, D. Mukut Gohain, M. Beilstein Journal of Organic Chemistry 2006, 2:11 doi:10.1186/1860-5397-2-11