Niobium(II) oxide
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| Other names
niobium(II) oxide, columbium monoxide
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.031.631 |
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PubChem CID
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| Properties | |
| NbO | |
| Molar mass | 108.906 g/mol |
| Appearance | grey solid |
| Density | 7.3 gcm3 |
| Melting point | 1,940 °C (3,520 °F; 2,210 K) |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Niobium monoxide is the inorganic compound with the formula NbO. It is a grey solid with metallic conductivity.
It adopts an unusual structure, being cubic as is rock salt structure, but where both niobium and oxygen atoms are four coordinate square planar. The niobium centers 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 strong and nearly covalent bonds exist between the metal centers.
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 More typically, it is prepared by comproportionation:
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