How are atoms usually coordinated in transition-metal oxides with lower oxidation states?

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In transition-metal oxides, the coordination of atoms is closely linked to the oxidation state of the metal.

In oxides formed with lower oxidation states, the atoms are typically octahedrally coordinated. These lower-oxidation-state oxides (generally those with oxidation numbers of +1, +2, and +3) are characterized as ionic compounds consisting of metal cations and oxide anions.12

In contrast, transition-metal oxides with higher oxidation numbers (+4, +5, +6, and +7) behave as covalent compounds, and in the specific case of oxo anions associated with higher oxidation states, the metal atom is typically tetrahedrally surrounded by oxygen atoms.12