Komplexeket

Komplexeket (singular: komplex) is Hungarian for coordination complexes; the accusative plural form is komplexeket. In chemistry, a coordination complex consists of a central metal atom or ion surrounded by molecules or anions called ligands that donate electron pairs and form coordinate covalent bonds to the metal. The ligands may be neutral or negatively charged; typical metals are transition metals, lanthanides, and actinides. The number of ligands and their arrangement define the coordination number and geometry, commonly 4- or 6-coordinate, with square planar, tetrahedral, and octahedral geometries among the most common.

The bonds arise from donor-acceptor interactions between ligand lone pairs and metal orbitals. The resulting complex is often described by its stability constant (formation constant, Kf). Complexes can be labile or inert in solution, influencing reactivity and exchange of ligands.

Properties of komplekset include vivid colors due to electronic transitions, notably d–d transitions in transition metals, and sometimes strong magnetic behavior. They can be colorimetric indicators, catalysts, or materials with interesting optical or magnetic properties.

Examples of well-known komplekset include [Cu(NH3)4]2+ (tetrammine copper(II)) and [Fe(CN)6]3-/4- (ferricyanide and ferrocyanide), as well as octahedral [Co(NH3)6]3+. In medicine, metal complexes such as cisplatin-type compounds play roles in chemotherapy. In Hungarian texts, the plural is komplexek and the accusative plural is komplexeket, used when the complexes themselves are the object of discussion or action.

See also coordination chemistry, ligands, chelate effect, coordination number, Werner's theory.