Ligandenort

Ligandenort is a term in coordination chemistry denoting the spatial position a ligand occupies in a metal complex. The word blends the German liganden (ligand) and Ort (place), highlighting that a complex has several binding sites around the central atom. It is a descriptive concept; the exact labeling depends on geometry, ligand set, and convention.

Ligand sites are described by the arrangement around the metal. In octahedral complexes, six positions can be related as cis or trans, and in some cases mer and fac when three identical ligands are present. In square planar complexes, sites are cis or trans. Other geometries use axial versus equatorial positions, or treat sites as equivalent. Multidentate ligands occupy multiple adjacent sites, defining bite angles and constraining donor atoms.

The ligandenort is important for understanding reactivity, selectivity, and stereochemistry. It can be determined by X-ray crystallography or inferred from spectroscopy and comparisons with model compounds. Different ligand sites lead to geometric isomers (cis/trans) and, in some cases, optical isomers. The concept also helps describe catalytic intermediates where substrates bind at specific metal sites.

The term is widely used descriptively; labeling varies with convention and serves as a practical guide to binding patterns, steric effects, and electronic influences around the metal.