Organometallics are organic compounds that have at least one metal atom bonded to a carbon atom. Usually the metals that form this type of substance are: magnesium (Mg), zinc (Zn), lead (Pb) and mercury (Hg).
Among the most common organometallics are organomagnesiumbetter known as compounds or Grignard reagentswhose metal bonded to carbon is magnesium, and it, in turn, is bonded to a halogen, which can be one of the following elements from family 17 of the Periodic Table: fluorine (F), chlorine (Cl), bromine (Br ) and iodine (I).
Organometallic compounds are usually toxic, as they have metals that accumulate in the body and are more soluble in organic compounds than other inorganic compounds that have the presence of these metals. An example where this can be seen is when miners or industries throw organometallic compounds into lakes and rivers. The results are serious problems for the health of the users of these waters (both humans and animals), as well as other ecological problems.
Below are three examples of organometallic compounds present in our daily lives:
• Ethyl mercury chloride (H3C ─ CH2 ─ HgCl): this compound can be used as a fungicide in seed preservation. However, its use is very dangerous, because it contains mercury and is highly toxic, especially for the nervous system;
• Butyllithium (H3C ─ CH2 ─ CH2 ─ CH2 ─ Li): this compound is used as a polymerization initiator for the production of elastomers, that is, polymers with elastic properties;
• Tetraethyl lead (or tetraethyl lead): for a long time this compound was used as an antiknock in gasoline, as it increased its octane number and engine performance. However, along with the burning of gasoline, this compound released lead into the environment, causing air pollution. This lead is toxic, pollutes the environment and is especially dangerous because it affects the brain, causing effects on motor coordination.
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Structure of tetraethyl lead.
Thus, in its place another organometallic is being used: ferrocene, which has in its structure two cyclopentadienyl rings on each side of an iron, as shown in the chemical structures below:
Ferrocene structure.
The nomenclature of organometallics follows the following scheme:
Examples:
CH3
│
CH2
│
H3C ─ CH2 ─Al : triethylaluminium
│
CH2
│
CH3
H3C ─ CH2 ─ CH2 ─ Li : propyl lithium
If it is a Grignard composite, we have:
Examples:
H3C ─ CH2 ─ MgCl : Ethyl Magnesium Chloride
H2C ═ CH ─ MgBr : Vinyl magnesium bromide
By Jennifer Fogaça
Graduated in Chemistry