Organoantimony chemistry is the
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
of
compounds containing a
carbon to
antimony (Sb)
chemical bond. Relevant
oxidation states are Sb(V) and Sb(III). The toxicity of antimony limits practical application in
organic chemistry.
Organoantimony(V) chemistry
Antimony compounds of the type R
5Sb (stiboranes) can be synthesised from trivalent Sb precursors:
:Ph
3Sb + Cl
2 → Ph
3SbCl
2
:Ph
3SbCl
2 + 2
PhLi →
Ph5Sb
Asymmetric compounds can also be obtained through the stibonium ion:
:R
5Sb + X
2 →
4Sbsup>+
:
4Sbsup>+
+ R'MgX → R
4R'Sb
Just as in the related
organobismuth compounds (same
group 15), organoantimony(V) compounds form
onium compounds and
ate complexes.
Pentaphenylantimony decomposes at 200 °C to
triphenylstibine and
biphenyl
Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one ...
. It forms a
trigonal bipyramidal molecular geometry. In the related
Me5Sb all
methyl
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...
protons are equivalent at -100 °C in
proton NMR. Compounds of the type R
4SbX tend to form dimers.
Organoantimony(III) chemistry
Compounds of the type R
3Sb (stibines) can be accessed by reaction of
antimony trichloride with
organolithium or
Grignard reagents.
:SbCl
3 + 3 RLi (or RMgCl) → R
3Sb
Typical reactions are:
:R
3Sb + Br
2 → R
3SbBr
2
:R
3Sb + O
2 → R
3SbO
:R
3Sb + Na + NH
3 → R
2SbNa
:R
3Sb + B
2H
6 → R
3Sb·BH
3
Stibanes are weak
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 ...
s and therefore ate complexes are not encountered. On the other hand, they have good donor properties and are therefore widely used in
coordination chemistry
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...
. R
3Sb compounds are more air-sensitive than the R
5Sb counterparts.
Antimony
Metallocenes are known as well:
:14SbI
3 + 3 (
Cp*Al)
4 →
Cp*Sbsup>+
lI4sup>− + 8Sb + 6 AlI
3
The Cp*-Sb-Cp* angle is 154°.
The cyclic compound
stibole, a
structural analog of
pyrrole
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4 H4 NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., ''N''-meth ...
, has not been isolated, but substituted derivatives known as stiboles are known.
Organoantimony(II) chemistry
Distibines have a Sb-Sb single bond and are of some interest as
thermochromic materials. For example, tetramethyldistibine is colorless as a gas, yellow as a liquid, red as solid just below the melting point of 18.5 °C and again yellow well below the melting point.
[''Organoantimony compounds with element-element bonds'' H.J. Breunig, R. Rosler Coordination Chemistry Reviews 163 (1997) 33-53]
See also
*
Lewis acidic antimony compounds Among pnictogen group Lewis acids and bases, Lewis acidic compounds, unusual lewis acidity of Lewis acidic antimony compounds have long been exploited as both stable conjugate acids of non-coordinating anions ( and ), and strong Lewis acid counterpa ...
References
{{ChemicalBondsToCarbon
*