CoO6

CoO6 refers to a coordination or structural unit in which a cobalt center is surrounded by six oxide ligands, forming an octahedral arrangement. This coordination environment is common in cobalt-containing oxide materials, especially cobalt perovskites and related oxides, where the cobalt site sits in an octahedral MO6 cage that shares corners or edges with neighbouring octahedra to build a three-dimensional lattice.

In such oxides, the oxidation state of cobalt in CoO6 octahedra is typically +3, though mixed-valence state arrangements such as Co2+/Co3+ or Co3+/Co4+ can occur in non-stoichiometric or doped systems. The Co–O bond lengths in CoO6 octahedra vary with oxidation state, spin state, and local structural distortions, frequently lying around 1.9 to 2.05 angstroms for common cobalt oxides. The ideal geometry is Oh, but real structures often exhibit distortions due to lattice strain, tilting of octahedra, or Jahn–Teller effects.

Electronic structure in CoO6 units depends on the cobalt oxidation state and spin state. Co2+ (d7) can be high-spin in octahedral fields, while Co3+ (d6) may be low-spin (t2g^6 eg^0) or high-spin (t2g^4 eg^2) depending on the ligand field and temperature. Such spin-state behavior influences magnetic, electronic, and catalytic properties.

Applications of materials containing CoO6 octahedra are broad, including catalysis (notably in oxygen evolution reactions), energy storage, and solid-state devices. These properties are tuned through composition, doping, and controlled synthesis methods such as solid-state reactions, sol–gel, or thin-film deposition, with structural characterization by X-ray and neutron diffraction and spectroscopic probes.