Coordination complex

A chemical species in which a central atom or ion is bonded to surrounding molecules or ions called ligands. Its structure and properties depend on the central atom, ligand identities, and bonding arrangement.

Ligand: An atom, ion, or molecule that donates electron density to a central atom in a coordination complex. Ligands are the surrounding species bound to the complex’s central atom.
Coordinate covalent bond: A covalent bond in which both shared electrons are supplied by one bonding partner. Ligand donor atoms form this kind of bond to the central atom.
Hemoglobin: An oxygen-binding protein whose heme groups contain iron coordination complexes. Its iron center binds oxygen reversibly within a protein-bound coordination site.
Organometallic compound: A compound containing at least one direct bond between a metal and a carbon atom of an organic group. Organometallic compounds are defined by metal–carbon bonds, unlike coordination complexes generally.
Coordination number: The number of donor atoms directly bonded to a central atom in a coordination entity. It counts the bonds that organize a complex’s immediate coordination environment.
Crystal field theory: A model describing how surrounding charges split the energies of a metal ion’s d orbitals. It explains how ligand arrangement changes the metal’s d-orbital energies.
Cisplatin: A platinum-based chemotherapy drug with two ammine and two chloride ligands in a square-planar complex. This coordination complex damages cancer-cell DNA after ligand substitution.
Double salt: A crystalline salt containing two different cations or anions that dissociates into its constituent ions in solution. A double salt loses its combined identity on dissolution, unlike a persistent complex ion.
Chelation: The binding of a multidentate ligand to one central atom through multiple donor atoms. Chelating ligands can occupy several coordination sites at once.
Ligand field theory: A bonding model combining molecular orbital theory with the effects of ligands on metal orbitals. It extends crystal-field ideas by treating metal–ligand bonding more explicitly.

Linked from 59 pages