Highercoordination

Highercoordination is a term used in chemistry to describe the arrangement of atoms or molecules around a central atom where the central atom is bonded to more than four other atoms or groups. This is in contrast to lower coordination numbers, such as four, which is common in many organic molecules. Elements in the third period and beyond are more capable of exhibiting higher coordination due to the availability of d orbitals for bonding.

A classic example of higher coordination is found in transition metal complexes. For instance, certain metal ions can form complexes with six ligands, a situation known as octahedral coordination. In these cases, the central metal atom is surrounded by six ligands positioned at the vertices of an octahedron. Other examples of higher coordination include hepta- and octacoordination, where the central atom is bonded to seven or eight other atoms, respectively.

The geometry of higher coordination complexes can be quite varied and is influenced by factors such as the size of the central atom, the steric bulk of the ligands, and electronic repulsion between the ligands. Understanding highercoordination is crucial for comprehending the structure, reactivity, and properties of a wide range of chemical compounds, including catalysts, coordination polymers, and materials with specific electronic or magnetic characteristics.