A single oxygen atom can bridge to two metal centers.

This trend can continue until only one ligand is left coordinated to the metal center.

In the closed state, the metal center is fully chelated to both ligands.

Other violations can be classified according to the kinds of ligands on the metal center.

They generally do not participate in reactions, except to dissociate from the metal center.

In order to satisfy the zero charge criteria the metal center must be changed.

This trend can continue until only one ligand is left coordinated to the metal center, as shown in Figure 3.

The metal centre will open in the end of 2011.

For example many alkoxides use one of their three lone pairs to make a single bond to a metal center.

These species are now known to bind well to electrophilic metal centers.