Comparison of carbamazepine multicomponent crystal forms according to intermolecular interactions, the angle between CBZ dimers and the (020) plane, and the enthalpy of vaporisation of the guest molecules.

Crystal form	Intermolecular energya (kJ mol−1)				Dimer ∢ (020) plane (°)	Vaporisation enthalpyb (kJ mol−1)
	CBZ + guest	CBZ dimer	CBZ stack	CBZ across (020)
CBZ·2H2Oc	−29.9	−37.5	−50.1	−20.2	67.4	149.4
	−13.2
2CBZ·BZQ	−22.6	−33.1	−46.4	−21.2	61.2	100.2
CBZ·FORMd	−18.9	−31.7	−44.3	−21.5	59.8	92.8
	−21.9
	−23.1	−34.3	−44.2
	−21.3
2CBZ·DIOXe	−27.5	−30.0	−48.2	−21.0	63.2	—

^aObtained from Mercury® (UNI Intermolecular Potentials) and previously reported elsewhere (see ref. 55).

^bCalculated vaporization enthalpies per formula unit for the decomposition of multicomponent materials into CBZ polymorph (I). The attachment energies of the 2CBZ·DIOX structure are not included (due to the disorder of the dioxane molecule).

^cCBZ is linked to molecules of water through O–H⋯O hydrogen bonds between the hydroxyl group of water and the carbonyl of CBZ, but also via weaker N–H⋯O hydrogen bonds between the amine of CBZ and the water oxygen.

^dThe reason why four types of CBZ : guest interactions as well as two types of CBZ stacking and two dimers exist in CBZ·FORM is because its asymmetric unit consists of two CBZ and two formamide molecules in a triclinic cell. The non-equivalent CBZ molecules form different dimers which, in turn, interact with non-equivalent formamide molecules.

^eNo calculations of vaporisation enthalpy were performed for 2CBZ·DIOX due to complications related to the disorder of the solvent molecule. The intermolecular energy were calculated from the doubled unit cell (see ref. 44).