At the beginning of your organic chemistry journey, you’re told a golden rule: carbon likes to have four bonds. This is true almost all the time. Why almost? Because you should never draw a carbon with more than four bonds. That rule is absolute.

In neutral molecules, carbon always has four bonds, and these can be either four single bonds or a multiple bond such as a double or triple bond. The image below summarizes the common bonding patterns of carbon, nitrogen, oxygen, and halogens in neutral molecules:

Check the article “Bonding Patterns in Organic Chemistry” for more details and how lone pairs and formal charges come to the rescue when these atoms do not follow their standard bonding pattern.

Now, the question you were searching:

Can carbon have three bonds?

The answer is yes, carbon can have three bonds, but we need to know when and how that happens. In short, this is possible with the right combination of bonds, lone pair, and a formal charge. There are two possibilities for carbon having three bonds, and that is either in carbocations or carbanions.

In carbocations, there is a carbon that is positively charged because it only has three bonds and no lone pair. Carbocations do not satisfy the octet rule, making them very unstable and reactive. They’ll quickly seek electrons from nearby atoms or molecules and react with them to form new molecules.

Carbanions contain a carbon with three bonds and a lone pair which makes them negatively charged. Unlike carbocations, carbanions do satisfy the octet rule, but they are still unstable because they carry excess electron density. They’ll look to react with electron-poor species (electrophiles).

Here are some examples of molecules containing carbon atoms with three bonds. Pay attention to the number of lone pairs and formal charges:

Check the mentioned article for bonding patterns and examples that include second-row elements nitrogen, oxygen, fluorine, and the rest of the halogens.

Check Also

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