Nitrogen Oxides

All nitrogen oxides are thermodynamically unstable with respect to decomposition to N2 and O2, but they are kinetically stable, ie. the rate of decomposition is very slow.

All the oxides contain Npπ-Opπ bonding.

Nitrous Oxide/Dinitrogen oxide (N2O):

The oxidation state of N is +1, and this compound is a colourless gas and chemically inert.

isoelectronic with CO2 and N3. The N-N bond order is ~2.5

Nitric Oxide/Nitrogen Monoxide (NO):

The oxidation state of N is +2, and this is a colourless, paramagnetic gas (ie. it is a radical, or contains an unpaired electron). It plays an important role in the formation of ozone in the atmosphere.

π-acid: acts as a 1-electron (σ-) or 3-electron (σ- + π-) donor in forming transition metal complexes, eg. Cr(NO)4 is a tetrahedral 18-electron complex.

Dinitrogen Trioxide (N2O3):

The oxidation state of N is +3. This is a blue solid or liquid, which dissociates to NO and NO2 in the gas phase, and reacts with water to give nitrous acid (HNO2).

Nitrogen Dioxide (NO2):

The oxidation state of N is +4. This exists in equilibrium between NO2 and N2O4. NO2 is a brown, paramagnetic gas (ie. it contains an unpaired electron), and N2O4 is a colourless, diamagnetic solid (ie. it contains only paired electrons).

Dinitrogen Pentoxide (N2O5):

The oxidation state of N is +5. This is the acid anhydride of nitric acid, and has a symmetric, planar structure.