Niobium monoxide, is the chemical compound with the formula NbO. It is a grey solid with metallic conductivity. It has an unusual cubic crystal structure, related to the rock salt structure, where both niobium and oxygen atoms are four coordinate square planar. The niobium atoms are arranged in octahedra and there is a structural similarity to the octahedral niobium clusters in lower halides of niobium. In NbO the Nb-Nb bond length is 298 pm which compares to 285 pm in the metal. One study of the bonding concludes that there are strong and nearly covalent bonds between the metal atoms.
It is a superconductor at 1.38 K. It is used in capacitors where a layer of Nb2O5 is formed around NbO grains as the dielectric.
NbO can be prepared by reduction of Nb2O5 by H2