8coördinatie

8coördinatie refers to a specific type of molecular coordination where a central atom is bonded to eight surrounding ligands. This coordination number is less common than others like four or six, but it is observed in certain chemical compounds. The arrangement of these eight ligands around the central atom can take on various geometries, the most prevalent being the square antiprismatic and the dodecahedral geometries.

In a square antiprismatic arrangement, the eight ligands are positioned at the vertices of two parallel, staggered squares. This geometry is often found in transition metal complexes and some organometallic compounds. The dodecahedral geometry, on the other hand, involves ligands arranged in a more complex, eight-faced polyhedron. This arrangement is more typical for larger central atoms and can be seen in some lanthanide and actinide complexes.

The nature of the ligands and the electronic configuration of the central atom play crucial roles in determining whether an 8-coordinate complex will form and which geometry it will adopt. Steric hindrance, the spatial bulk of the ligands, is also a significant factor. While 8-coordination is not as frequently encountered as lower coordination numbers, its study provides valuable insights into the principles of chemical bonding, molecular structure, and the factors influencing coordination preferences in chemistry.