Indium(III) chloride is the
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the formula
In Cl3. This
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
is a white, flaky solid with applications in
organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
as a
Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
. It is also the most available soluble derivative of indium.
Synthesis and structure
Being a relatively electropositive metal,
indium
Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts p ...
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
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
-
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
solution.
Like
AlCl3 and
TlCl3, InCl
3 crystallizes as a layered structure consisting of a close-packed chloride arrangement containing layers of
octahedrally coordinated In(III) centers,
[Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier ] a structure akin to that seen in
YCl3.
[Wells, A.F. Structural Inorganic Chemistry, Oxford: Clarendon Press, 1984. .] In contrast,
GaCl3 crystallizes as dimers containing Ga
2Cl
6.
Molten InCl
3 conducts electricity,
whereas AlCl
3 does not as it converts to the molecular dimer, Al
2Cl
6.
Reactions
InCl
3 is a Lewis acid and forms complexes with donor
ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...
s, L, InCl
3L, InCl
3L
2, InCl
3L
3. For example, with the chloride ion it forms tetrahedral InCl
4−, trigonal bipyramidal InCl
52−, and octahedral InCl
63−.
In
diethyl ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liq ...
solution, InCl
3 reacts with
lithium hydride
Lithium hydride is an inorganic compound with the formula Li H. This alkali metal hydride is a colorless solid, although commercial samples are grey. Characteristic of a salt-like (ionic) hydride, it has a high melting point, and it is not solub ...
, LiH, to form
LiInH4. 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
InH3.
Trimethylindium
Trimethylindium, often abbreviated to TMI or TMIn, is the organoindium compound with the formula In(CH3)3. It is a colorless, pyrophoric solid. Unlike trimethylaluminium, but akin to trimethylgallium, TMI is monomeric.
Preparation
TMI is prepared ...
, InMe
3, can be produced by reacting InCl
3 in
diethyl ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liq ...
solution either with the
Grignard reagent
A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide ...
MeMgI or
methyllithium
Methyllithium is the simplest organolithium reagent with the empirical formula CH3Li. This s-block organometallic compound adopts an oligomeric structure both in solution and in the solid state. This highly reactive compound, invariably used in so ...
, LiMe.
Triethylindium
Triethylindium is an
organometallic compound. Its chemical formula is .
Synthesis
This compound can be obtained by reacting indium(III) chloride with a diethyl ether solution of ethyl magnesium chloride:
: + 3 → In(C2H5)3 + 3
Other routes ...
can be prepared in a similar fashion but with the grignard reagent EtMgBr.
:
+ 3LiMe -> + 3LiCl
:
+ 3MeMgI -> + 3MgClI
:
+ 3EtMgBr -> + 3MgBr2
InCl
3 reacts with indium metal at high temperature to form the lower valent indium chlorides In
5Cl
9, In
2Cl
3 and InCl.
Catalyst in chemistry
Indium chloride is a Lewis acid
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
in
organic reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, Mechanistic Organ ...
s such as
Friedel-Crafts acylations and
Diels-Alder reactions. As an example of the latter,
[''An efficient synthesis of novel pyrano ,3-d and furopyrano ,3-dyrimidines via Indium-Catalyzed Multicomponent Domino Reaction'' Prajapati, D. Mukut Gohain, M. ]Beilstein Journal of Organic Chemistry
The ''Beilstein Journal of Organic Chemistry'' is a peer-reviewed open-access scientific journal established in 2005. It is published by the Beilstein Institute for the Advancement of Chemical Sciences, a German non-profit foundation. The editor-in ...
2006, 2:11 the reaction proceeds at
room temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
, with 1 mole% catalyst loading in an
acetonitrile
Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...
-water solvent mixture. The first step is a
Knoevenagel condensation
In organic chemistry, the Knoevenagel condensation () reaction is a type of chemical reaction named after German chemist Emil Knoevenagel. It is a modification of the aldol condensation.
A Knoevenagel condensation is a nucleophilic addition o ...
between the barbituric acid and the aldehyde; the second step is a reverse electron-demand
Diels-Alder reaction, which is a
multicomponent reaction In chemistry, a multi-component reaction (or MCR), sometimes referred to as a "Multi-component Assembly Process" (or MCAP), is a chemical reaction where three or more compounds
react to form a single product. By definition, multicomponent reaction ...
of N,N'-dimethyl-
barbituric acid
Barbituric acid or malonylurea or 6-hydroxyuracil is an organic compound based on a pyrimidine heterocyclic skeleton. It is an odorless powder soluble in water. Barbituric acid is the parent compound of barbiturate drugs, although barbituric acid ...
,
benzaldehyde
Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful.
It is a colorless liquid with a characteristic almond-like odor. ...
and
ethyl vinyl ether
Ethyl vinyl ether is an organic compound with the chemical formula CH3CH2OCH=CH2. It is the simplest enol ether that is liquid at room temperature. It is used as a synthetic building block and a monomer.
Preparation and reactions
Ethyl vinyl e ...
. With the catalyst, the reported
chemical yield
In chemistry, yield, also referred to as reaction yield, is a measure of the quantity of moles of a product formed in relation to the reactant consumed, obtained in a chemical reaction, usually expressed as a percentage. Yield is one of the pr ...
is 90% and the percentage
trans isomer
Trans- is a Latin prefix meaning "across", "beyond", or "on the other side of".
Used alone, trans may refer to:
Arts, entertainment, and media
* Trans (festival), a former festival in Belfast, Northern Ireland, United Kingdom
* ''Trans'' (film ...
is 70%. Without the catalyst added, the yield drops to 65% with 50% trans product.
:
References
{{Chlorides
Chlorides
Metal halides
Indium compounds