Azide group (methyl azide) template

Methyl azide CH₃N₃: the terminal N⁻ lone pair forms N≡N⁺ as the N=N π bond moves onto the nitrogen bonded to carbon; the same picture as the azide ion N₃⁻.

What the template shows

• R–N=N⁺=N⁻ ↔ R–N⁻–N⁺≡N: the charge moves between the two outer nitrogens
• Resonance contributors
• Methyl azide
• Linear N₃ unit, central N⁺ in both forms
• Both forms have full octets and the central nitrogen is N⁺ in each; the N₃ unit is linear (sp central N).
• The azide ion N₃⁻ has three forms: ⁻N=N⁺=N⁻ (major, symmetric) and the two equivalent forms ²⁻N–N⁺≡N and N≡N⁺–N²⁻; it is linear with two equal N–N bonds, like CO₂, which has the same number of valence electrons.
• The R–N⁻–N⁺≡N form shows the N≡N unit that leaves as N₂ (Curtius rearrangement, Staudinger reaction) and the 1,3-dipole of azide–alkyne click chemistry.
• Contributors are not in equilibrium: the real species is one hybrid of them · every part of this figure is editable

Drawn with 8 atoms, 3 arrows, 2 shapes – every one editable in MolDraw.

Sources

• Housecroft & Sharpe, Inorganic Chemistry, 5th ed., Pearson 2018 Textbook
• Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 7 Textbook