São ligações do tipo covalente, formadas pela sobreposição paralela de dois orbitais p. São mais fracas que as ligações sigma.
Meaning
In chemistry, pi bonds (π bonds) are covalent chemical bonds where two lobes of one involved electron orbital overlap two lobes of the other involved electron orbital. Only one of the orbital's nodal planes passes through both of the involved nuclei. (http://en.wikipedia.org...)