ElektronenpaarDonorstelle

ElektronenpaarDonorstelle, also known as an electron-pair donor site, is a structural motif in a molecule that possesses a lone pair of electrons capable of forming a coordinate covalent bond with an electron-accepting species. The concept is an application of Lewis acid–base theory, where the donor site acts as a Lewis base and the acceptor as a Lewis acid. In coordination chemistry, these donor sites are often referred to as ligands and can bind to transition metal centers, influencing the geometry and electronic properties of the metal complex.

Typical examples of ElektronenpaarDonorstellen include nitrogen atoms in amines or amides, oxygen atoms in alcohols or carboxylates, sulfur atoms in thiols, and phosphorus atoms in phosphines or phosphites. The strength of a donor site is quantified by parameters such as donor number, hard–soft acid–base (HSAB) classification, and spectrochemical series values. Strong donor sites are called "hard" bases, while weak donors are "soft" bases, with applications in selective catalysis and the stabilization of high-index oxidation states.

In supramolecular chemistry, electron‑pair donors participate in hydrogen bonding, halogen bonding, and other non-covalent interactions, contributing to the assembly and function of larger systems. Computational methods, such as electron density analysis and molecular orbital calculations, are routinely employed to predict donor capability and to design ligands with desired binding properties. Overall, understanding electron‑pair donor sites is essential for elucidating reaction mechanisms, designing catalysts, and engineering functional materials.