Orthonitrate

The orthonitrate ion is NO₄³⁻. It is only known in two compounds, Na₃NO₄ and K₃NO₄ which were prepared by fusion of the nitrate and oxide^[1], e.g.

NaNO₃ + Na₂O = Na₃NO₄

The orthonitrate ion is tetrahedral and the N-O bond length is 139 pm which compares with the sum of the covalent radii of 137 pm and with the bond lengths in nitrates (range 122-127 pm)and nitrites (range 113-123 pm) where there is double bonding^[1].

Other nitrogen oxoanions

Other nitrogen oxoanions include:

• nitrate, NO₃⁻
• nitrite, NO₂⁻
• peroxonitrite, (peroxynitrite), OONO⁻
• trioxodinitrate, (hyponitrate), [ON=NO₂]²⁻
• nitroxylate, [O₂N−NO₂]⁴⁻

References

1. ^ ^{a b} Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 0080379419.