What does a Lewis base do in a chemical reaction?

A Lewis base is defined as a species that donates electron pairs in a chemical reaction. This concept is part of Lewis acid-base theory, which broadens the definition beyond protons (H⁺ ions) to include electron pair interactions. When a Lewis base donates an electron pair, it can form a coordinate covalent bond with a Lewis acid, which is an electron acceptor. This donation of electron pairs is essential for many chemical processes, including complex formation and nucleophilic attacks.

Understanding this fundamental role of Lewis bases highlights their significance in reactions involving nucleophiles, where a nucleophile donates an electron pair to an electrophile, facilitating various organic and inorganic reactions. Thus, the ability of a Lewis base to donate electron pairs establishes its role in many reaction mechanisms.