Dihedral angles obtained from experimental and theoretical geometries. Full table in ESI, Section 2.

Crystal structure geometry			Computational geometry
Sample	φ 1/°	φ 2/°	Model	φ 1/°	φ 2/°
[H][N(Tf)(Ac)]	84	169	[N(Tf)(Ac)]−	58	169
[H][N(Tf)(Ac)]	84	169	[H][N(Tf)(Ac)]	78	171
[K][N(Tf)(Ac)]	180	180	[N(Tf)(Ac)]−	180	180
[H][N(TFA)(Ms)]	181	61	[N(TFA)(Ms)]−	179	50
[H][N(TFA)(Ms)]	181	61	[H][N(TFA)(Ms)]	171	61