Ligands of this type usually form octahedral complexes which have a coordination number of 6.īidentate ligands are ones which form two dative covalent bonds with the central metal atom. The image below shows water acting as a monodentate ligand. Monodentate ligands are ones which have only one donor atom (aka they form only one dative covalent bond with the central metal atom). Ligands can be classified in a number of ways.

Additionally, all the ligands do not have to be the same. It is important to know that the coordination number may not necessarily be the number of ligands (unless it is a monodentate ligand). The number of atoms bonded to the central metal atom is called the coordination number – the most common coordination numbers are 2,4, and 6. In order to form these dative covalent bonds with the central atom, the ligand must have a lone pair of electrons in the outermost energy level – as such, all ligands are therefore Lewis bases. These molecules (or ions) which surround the central metal atom are called ligands. This central atom is called the coordination centre. These molecules are usually bonded to the central metal atom through dative covalent (co-ordinate) bonds – these are bonds where the shared pair of electrons both come from one atom.

Complexes have very specific naming conventionsĪ complex, sometimes also referred to as a coordination complex, consists of a central metal atom surrounded by other molecules or ions.

Ligands can be classified as monodentate, bidentate, and polydentate.The number of atoms bonded to the central metal atom is called the coordination number.A complex is a central metal atom bonded to other molecules (called ligands) through dative covalent bonds.

Complex ion bonding