Indium(III) chloride

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Indium(III) chloride
Indium(III) chloride
Identifiers
CAS number 10025-82-8 YesY
PubChem 24812
ChemSpider 23197 YesY
UNII 58TD96H03I YesY
Jmol-3D images Image 1
Properties
Molecular formula InCl3
Molar mass 221.18 g/mol
Appearance white flakes
Density 3.46 g/cm3
Melting point 586 °C
Boiling point 800 °C
Solubility in water soluble, exothermic
Solubility in other solvents THF
Structure
Crystal structure Monoclinic, mS16
Space group C12/m1, No. 12
Hazards
EU Index Not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Related compounds
Other anions Indium(III) fluoride
Indium(III) bromide
Indium(III) iodide
Other cations Aluminium chloride
Gallium trichloride
Thallium(III) chloride
Except where noted otherwise, 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[edit]

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[edit]

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 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, MeMgI, or methyllithium, LiMe. Triethylindium can be prepared in a similar fashion but with the grignard reagent, EtMgBr.[10]

InCl3 + 3LiMe → Me3In.OEt2 + 3LiCl
InCl3 + 3MeMgI → Me3In.OEt2 + 3MgClI
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[edit]

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.

Indium chloride application, reaction product is mixture of cis-trans isomers

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[edit]

  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. ^ a b c d Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
  5. ^ a b 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 0080379419. 
  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