Vanadiumhexacarbonyl

Vanadiumcarbonyl

Bluish- green crystals

Fixed

Decomposition above 70 ° C

• Insoluble in water and ethanol
• Slightly soluble in hexane
• Soluble in other organic solvents

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Vanadiumhexarbonyl is a metal carbonyl having the chemical formula V (CO ) 6 These highly reactive species is noteworthy from a theoretical and scientific perspective. It is a rare example of an isolable homoleptic metal carbonyl, which is paramagnetic. Most metal carbonyls with the formula Mex (CO ) y follow the 18- electron rule, while V (CO) 6 has only 17 valence electrons.

Synthesis

Traditional V ( CO) 6 in two steps via intermediate [ HV ( CO) 6 ] was prepared. In a first step is reduced with metallic sodium VCl3 below 200 atm CO at 160 ° C. The solvent for this reduction is generally diglyme, CH3OCH2CH2OCH2CH2OCH3. This solves triether sodium salts in a similar manner as a crown ether:

Meanwhile, an improved low-pressure synthesis has been developed by Ellis and Liu.

Properties

Physical Properties

Vanadiumhexacarbonyl is a solid at room temperature, a crystalline substance of a bluish - green color. It does not dissolve in water or ethanol, little in saturated hydrocarbons such as hexane but good in other organic solvents with yellow coloration of the solution. The wavenumber of the CO stretching vibration of the free νCO carbon monoxide is at 1976 cm -1.

V ( CO) 6 has an octahedral coordination geometry ( Oh). High-resolution X-ray crystallography shows that the molecule is slightly distorted with two shorter V -C bonds of 199.3 pm and four equatorial of 200.5 pm. Such a distortion could have arisen due to the Jahn- Teller effect.

Chemical Properties

V (CO) 6 reacts with the cyclopentadienyl anion to an orange complex ( C5H5) V (CO ) 4 ( melting point 136 ° C). How many charge-neutral organometallic compounds is this half -sandwich complex volatile.

V (CO) 6 is a thermally sensitive material. Its primary reaction is the reduction to the monoanion [V (CO ) 6] - and the substitution by phosphines, often with disproportionation. Vanadiumhexacarbonyl can release toxic compounds such as carbon monoxide and vanadium oxides in the decomposition. The substance is a pyrophoric compound, which may explode when heated.

Use

Vanadiumhexacarbonyl is used as a catalyst in isomerization and hydrogenation reactions.