polynuclear

Polynuclear is a term used in chemistry to describe species that contain more than one nucleus. In inorganic and organometallic chemistry, polynuclear refers to compounds or clusters that have multiple metal centers within a single molecule, which may be the same element (homonuclear) or different elements (heteronuclear). These centers are often connected by bridging ligands such as oxo, hydroxo, carboxylate, cyanide, sulfide, or by direct metal–metal bonds.

Polynuclear metal complexes are central to cluster chemistry. They range from dinuclear and trinuclear species to larger metal clusters. The properties of polynuclear systems arise from interactions between metal centers, including magnetic coupling, electron transfer, and cooperative catalysis. They are widely studied for applications in catalysis, electrochemistry, magnetic materials, and luminescent devices. Natural polynuclear clusters, such as iron–sulfur clusters in ferredoxins and nitrogenase, illustrate biological relevance.

In organic chemistry, polynuclear can refer to molecules built from multiple fused or connected rings with extensive conjugation. Polynuclear aromatic hydrocarbons (PAHs) are polycyclic systems comprised of fused benzene rings, such as naphthalene (two rings) and pyrene (four rings). The term is sometimes used more broadly to describe any molecule with multiple nuclear centers or cores.