Vanadium hexacarbonyl 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

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

V(CO)₆. It is a blue-black volatile solid. This highly reactive species is noteworthy from theoretical perspectives as a rare isolable homoleptic

metal carbonyl A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. These properties are all associated with having electrons available at the Fermi level, as against n ...

that is paramagnetic. Most species with the formula M_''x''(CO)_''y'' follow the 18-electron rule, whereas V(CO)₆ has 17 valence electrons.

Synthesis

According to the original synthesis by Calderazzo, V(CO)₆ is prepared in two-steps via the intermediacy of . In the first step, VCl₃ is reduced with metallic

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

under 200 atm CO at 160 °C. The solvent for this reduction is typically

diglyme Diglyme, or bis(2-methoxyethyl) ether, is an organic compound with the chemical formula . It is a colorless liquid with a slight ether-like odor. It is a solvent with a high boiling point. It is the dimethyl ether of diethylene glycol. The name '' ...

, CH₃OCH₂CH₂OCH₂CH₂OCH₃. This tri

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

solubilizes sodium salts, akin to the behavior of a

crown ether In organic chemistry, crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups (). The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., . Impor ...

: :4 Na + VCl₃ + 6 CO + 2 diglyme → a(diglyme)₂V(CO)₆] + 3 NaCl The resulting anion is oxidized with acid: :2 + 2 H₃PO₄ → 2 V(CO)₆ + H₂ + 2

Reactions

Vanadium hexacarbonyl is thermally unstable. Its primary reaction is reduction to the monoanion , salts of which are well studied. It is also susceptible to substitution by tertiary

phosphine ligand A metal-phosphine complex is a coordination complex containing one or more phosphine ligands. Almost always, the phosphine is an organophosphine of the type R3P (R = alkyl, aryl). Metal phosphine complexes are useful in homogeneous catalysis. Prom ...

s, often leading to

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation state. The reverse of disproportionatio ...

. V(CO)₆ reacts with sources of the

cyclopentadienyl Cyclopentadienyl can refer to * Cyclopentadienyl anion, or cyclopentadienide, ** Cyclopentadienyl ligand * Cyclopentadienyl radical, • * Cyclopentadienyl cation, See also * Pentadienyl {{Chemistry index ...

anion to give the orange four-legged piano stool complex (C₅H₅)V(CO)₄ (m.p. 136 °C). Like many charge-neutral organometallic compounds, this half-sandwich species is volatile. In the original preparation of this species, C₅H₅HgCl was employed as the source of .

Structure

V(CO)₆ adopts an

octahedral In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...

coordination geometry and is isostructural with chromium hexacarbonyl, even though they have differing valence electron counts. High resolution X-ray crystallography indicates that the molecule is slightly distorted with two (''axial'') shorter V–C distances of 1.993(2) Å vs. four (equatorial) 2.005(2) Å. Even though V(−I) is a larger ion than V(0), the V–C distances in are 0.07 Å shorter than in the neutral precursor.

Synthesis

Reactions

Structure

References

Further reading