Electron counting

It is used for classifying compounds and for explaining or predicting their electronic structure and bonding.

It is important, though, to be aware that most chemical species exist between the purely covalent and ionic extremes.

The numbers of electrons "donated" by some ligands depends on the geometry of the metal-ligand ensemble.

When the M–NO subunit is strongly bent at N, the NO is treated as a pseudohalide and is thus a one electron (in the neutral counting approach).

With the ionic counting method, the more electronegative oxygen will gain electrons donated by the two hydrogen atoms in the two OH bonds to become O2-.

In the ionic counting method, the Ruthenium of the complex is treated as Ru(II).

This figure of the water molecule shows how the electrons are distributed with the covalent counting method. The red ones are the oxygen electrons, and the blue ones are electrons from the hydrogen atoms.
This figure of the water molecule shows how the electrons are distributed with the ionic counting method. The red ones are the oxygen electrons, and the blue ones are electrons from hydrogen. All electrons in the OH bonds belong to the more electronegative oxygen.
The geometry of cis -Dichlorobis(bipyridine)ruthenium(II).