Ball-and-stick schematic of the mechanism of hydroformylation. This is a catalytic cycle in which CO and H₂ are added across the C=C bond of an alkene to form an aldehyde, catalysed by HCo(CO)₄. In this example the alkene is propylene and the aldehyde is butyraldehyde.

For further discussion, see:

• (1997) Chemistry of the Elements (2nd ed.), Butterworth-Heinemann, pp. 1,134−1,136, 1,140 ISBN: 978-0-08-037941-8.
• (2008) Inorganic Chemistry (3rd ed.), Prentice Hall, pp. 917−919 ISBN: 978-0-13-175553-6.
• (2009) The Organometallic Chemistry of the Transition Metals (5th ed.), Wiley, pp. 244−247 ISBN: 978-0-470-25762-3.

Colour code:

  Cobalt, Co: blue-grey

  Carbon, C: grey-black

  Hydrogen, H: white

  Oxygen, O: red