Molybdenum(V) chloride is the
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
with the
empirical formula
In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, is simply SO, as is the empir ...
. This dark volatile solid is used in research to prepare other molybdenum compounds. It is moisture-sensitive and soluble in chlorinated solvents.
Structure
Usually called molybdenum pentachloride, it is in fact partly a
dimer with the
molecular formula
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as paren ...
. In the dimer, each molybdenum has local octahedral symmetry and two chlorides
bridge
A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...
between the molybdenum centers. A similar structure is also found for the pentachlorides of W, Nb and Ta. In the gas phase and partly in solution, the
dimers partially dissociate to give a monomeric . The monomer is paramagnetic, with one unpaired electron per Mo center, reflecting the fact that the formal oxidation state is +5, leaving one valence electron on the metal center.
Preparation and properties
is prepared by chlorination of Mo metal but also chlorination of . The unstable hexachloride is not produced in this way.
is reduced by acetonitrile to afford an orange
acetonitrile complex, . This complex in turn reacts with
THF to give , a precursor to other molybdenum-containing complexes.
Molybdenum(IV) bromide is prepared by treatment of with
hydrogen bromide
Hydrogen bromide is the inorganic compound with the formula . It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temper ...
:
:
The reaction proceeds via the unstable molybdenum(V) bromide, which releases bromine at room temperature.
is a good
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 ...
toward non-oxidizable ligands. It forms an adduct with chloride to form . In
organic synthesis
Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...
, the compound finds occasional use in
chlorinations,
deoxygenation, and oxidative coupling reactions.
Reactions
is reduced by
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 class ...
:
:
Although it polymerizes
tetrahydrofuran
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
, is stable in
diethyl ether
Diethyl ether, or simply ether, is an organic compound with the chemical formula , sometimes abbreviated as . It is a colourless, highly Volatility (chemistry), volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It belongs ...
. Reduction of such solutions with tin gives and , depending on conditions.
Safety considerations
is an aggressive oxidant and readily hydrolyzes to release HCl.
See also
*
Molybdenum(IV) chloride
*
Molybdenum(VI) chloride
*
Molybdenum(V) fluoride
*
Tungsten(V) chloride
Tungsten(V) chloride is an inorganic compound with the formula W2 Cl10. This compound is analogous in many ways to the more familiar molybdenum pentachloride.
Synthesis
The material is prepared by reduction of tungsten hexachloride. One metho ...
References
{{Chlorides
Chlorides
Molybdenum halides
Inorganic compounds
Oxidizing agents
Molybdenum(V) compounds