Organovanadium chemistry is the
chemistry of
organometallic compounds
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...
containing a
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
(C) to
vanadium (V)
chemical bond
A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules and crystals. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of ...
. Organovanadium compounds find only minor use as reagents in
organic synthesis but are significant for
polymer chemistry
Polymer chemistry is a sub-discipline of chemistry that focuses on the structures of chemicals, chemical synthesis, and chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry are a ...
as
catalysts
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 ...
.
Oxidation states
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
for vanadium are +2, +3, +4 and +5. Low valency vanadium is usually stabilized with
carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containi ...
ligands. Oxo derivatives are relatively common, unlike the organic complexes of neighboring elements.
Compound classes
Carbonyls
Vanadium carbonyl can be prepared by reductive
carbonylation
Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbony ...
of vanadium salts:
:4 Na + VCl
3 + 6 CO → Na
(CO)6+ 3 NaCl
The salt can be oxidized to the 17e binary carbonyl V(CO)
6.
Cyclopentadienyl derivatives
130px, (Cycloheptatrienyl)(cyclopentadienyl)vanadium is one of many organovanadium compounds that is paramagnetic.
Vanadocene dichloride
Vanadocene dichloride is an organometallic complex with formula (hapticity, ''η''5-cyclopentadienyl, C5H5)2VCl2 (commonly abbreviated as Cp2VCl2). It is a structural analogue of titanocene dichloride but with vanadium(IV) instead of titanium(IV). ...
, the first organovanadium complexes to be reported,
is prepared from
sodium cyclopentadienyl and
vanadium tetrachloride
Vanadium tetrachloride is the inorganic compound with the formula V Cl4. This bright red liquid serves as a useful reagent for the preparation of other vanadium compounds.
Synthesis, bonding, basic properties
With one more valence electron than ...
:
:2 NaC
5H
5 + VCl
4 → VCp
2Cl
2 + 2NaCl
Reduction of this compound gives the parent
vanadocene
Vanadocene, bis(η5-cyclopentadienyl) vanadium, is the organometallic compound with the formula V(C5H5)2, commonly abbreviated Cp2V. It is a violet crystalline, paramagnetic solid. Vanadocene has relatively limited practical use, but it has been ex ...
(Cp
2V):
:VCp
2Cl
2 + LiAlH
4 → VCp
2
Vanadocene
Vanadocene, bis(η5-cyclopentadienyl) vanadium, is the organometallic compound with the formula V(C5H5)2, commonly abbreviated Cp2V. It is a violet crystalline, paramagnetic solid. Vanadocene has relatively limited practical use, but it has been ex ...
is the lightest
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that ca ...
metallocene
A metallocene is a compound typically consisting of two cyclopentadienyl anions (, abbreviated Cp) bound to a metal center (M) in the oxidation state II, with the resulting general formula Closely related to the metallocenes are the metallocene d ...
that is isolable at room temperature. Vanadocene reacts with high pressures of carbon monoxide to give
CpV(CO)4.
of the tetracarbonyl gives Cp
2V
2(CO)
5. Several analogous
indenyl complexes are known.
Monocyclopentadienyl vanadium chlorides include CpVCl
3 and the diamagnetic CpVOCl
2.
Arene complexes
Vanadium forms a variety of
arene
Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past groupin ...
complexes, e.g. with
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 ...
:
:VCl
4 + Al + 2C
6H
6 →
(η6-C6H6)2lCl
4
:
(η6-C6H6)2lCl
4 + H
2O → V(η
6-C
6H
6)
2 + ...
Alkyl and aryl derivatives
A handful of
alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term ''alkyl'' is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
and
aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
complexes exist. The reactive species V(
mesityl
Mesitylene or 1,3,5-trimethylbenzene is a derivative of benzene with three methyl substituents positioned symmetrically around the ring. The other two isomeric trimethylbenzenes are 1,2,4-trimethylbenzene (pseudocumene) and 1,2,3-trimethylbenzene ...
)
3 forms from VCl
3:
:VCl
3(THF)
3 + 3 LiC
6H
2-2,4,6-Me
3 → V(C
6H
2-2,4,6-Me
3)
3(THF) + 3 LiCl
This species binds CO and, under appropriate conditions, N
2. V(
mesityl
Mesitylene or 1,3,5-trimethylbenzene is a derivative of benzene with three methyl substituents positioned symmetrically around the ring. The other two isomeric trimethylbenzenes are 1,2,4-trimethylbenzene (pseudocumene) and 1,2,3-trimethylbenzene ...
)
3 adds a fourth mesityl group and the resulting "ate complex" can be oxidized to the vanadium(IV) derivative:
: V(mes)
3(THF) + LiMes → Li
(mes)4: Li
(mes)4 + air → V(mes)
4(THF)
The tetrakis(norbornyl) complex is also known.
Vanadium oxytrichloride is a starting material for organovanadium(IV) and organovanadium(V) compounds:
: VOCl
3 + Li(mes) → Li
O(mes)3: Li
O(mes)3+
chloranil
Chloranil is a quinone with the molecular formula C6Cl4O2. Also known as tetrachloro-1,4-benzoquinone, it is a yellow solid. Like the parent benzoquinone, chloranil is a planar molecule J.-M. Lü, S. V. Rosokha, I. S. Neretin and J. K. Kochi, "Qui ...
→ VO(mes)
3
: VOCl
3 + ZnPh
2 → VOPhCl
2 + "ZnPh(Cl)"
Catalysts and reagents
Well-defined vanadium compounds do not appear as catalysts in any commercial process. However organovanadium species are clearly implicated as catalysts for the production of butadiene-based rubbers. These catalysts are generated in situ by treating soluble coordination complexes such as
vanadium(III) acetylacetonate with
organoaluminium activators.
References
{{ChemicalBondsToCarbon
