12bindning

12bindning is a term used in Swedish chemistry to describe a coordination environment in which a central atom is surrounded by twelve ligands, yielding a coordination number of 12. This high coordination is less common than lower CNs but occurs in certain metal complexes and solid-state materials where space and electronic requirements allow many ligands to donate electron density around the center.

In practice, 12-fold binding is achieved with small, bridging, or bulky ligands that can occupy multiple coordination positions, or in structures where ligands extend into secondary coordination spheres. The geometry around the central atom can be dodecahedral, icosahedral, or other high-symmetry arrangements, and it is often discussed within the frameworks of crystal field theory and ligand-field theory extended to high coordination numbers.

Characterization typically relies on single-crystal X-ray diffraction to determine the coordination environment, complemented by spectroscopy and computational chemistry to interpret bonding, electron count, and stability. The practical significance of 12bindning lies in understanding reactivity, catalysis, and material properties of dense coordination complexes and related frameworks.

The term is mainly used in Swedish scientific literature on inorganic chemistry and crystal engineering. See also coordination number, multicenter bonding, cluster compounds, and solid-state chemistry.