Cobalt tetracarbonyl hydride

• Tetracarbonylhydridocobalt
• Cobaltcarbonylwasserstoff
• Cobalttetracarbonylhydrid
• Cobalthydrocarbonyl

Yellowish liquid

Liquid

-26.2 ° C

Decomposition above -18 ° C

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Cobaltcarbonylhydrid is a chemical compound of cobalt and one of the carbonyl. Carbonyl in addition to a hydrogen atom is also bonded to the cobalt atom. It is a yellowish, air-sensitive, easily decomposed liquid.

Production and representation

Cobaltcarbonylhydrid can be represented from dicobaltoctacarbonyl. Dicobalt octacarbonyl is converted to sodium, which the cobalt -cobalt bond is broken and forms Natriumtetracarbonylcobaltat. By reacting with an acid Cobaltcarbonylhydrid formed.

Technically Cobaltcarbonylhydrid is prepared by reductive carbonylation of cobalt oxides with carbon monoxide and hydrogen. It is initially formed dicobaltoctacarbonyl that is cleaved by the hydrogen.

Properties

The Cobaltcarbonylhydrid complex is trigonal bipyramidal. Here, the hydrogen atom and a carbonyl ligand is axially arranged the other three equatorial carbonyl ligands. The cobalt -hydrogen distance is 114 pm, the cobalt-carbon distance 176 pm for the axial CO ligands and 182 pm for the equatorial CO ligands.

The hydrogen ligand is acidic and can be easily removed. The pKa value of the complex is 8.3, measured in acetonitrile. In water, the compound is a strong acid having a pK a value of 1.

Use

Cobaltcarbonylhydrid is industrially used in the hydroformylation. Here, the complex acts as a catalyst for the production of aldehydes from olefins. It enables the insertion of carbon monoxide in a C -H bond of the alkene.

The synthesis using cobalt catalysts has, however, often replaced by rhodium catalysts, as these milder reaction conditions and a more selective reaction allow.