5-{[4-(Dimethylamino)phenyl]ethynyl}pyrimidine–1,2,3,5-tetrafluoro-4,6-diiodobenzene (1/2)

In the title 1:2 co-crystal, C—I⋯N halogen bonds between one of the 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecules and the 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine molecule form [110] chains while the second 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecule resides in [100] channels.


Structure description
Halogen bonding is now a widely studied and accepted non-covalent interaction wherein a halogen atom, most commonly iodine, interacts with a Lewis base as halogen-bond acceptor (Cavallo et al., 2016). This interaction has predictable geometry and has accordingly been incorporated in strategies for the self-assembly of multicomponent molecular solids (Mir et al., 2019). Among the most studied ditopic halogen-bond donors are the three isomeric diiodotetrafluorobenzenes as the halogen-bond donor ability is increased by substitution of iodobenzenes with electronegative fluorine atoms (Roper et al., 2010). Herein we report a rare example of inclusion of a 1,2,3,5-tetrafluoro-4,6diiodobenzene molecule in a co-crystal in which one of the 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecules does not interact with the primary Lewis base.
In the extended structure, the APEP molecules are offsetstacked in a head-to-tail manner such that the halogen-bonded 13DIFB molecules are also alternately -stacked as shown in Fig. 4. With this arrangement, the second non-halogen-bonded 13DIFB molecule is located as a -stacked pair in channels that lie parallel to the a-axis direction (Fig. 4).
The pair of loosely -stacked 13DIFB molecules interact with the surrounding molecules as shown in the Hirshfeld surface plot in Fig. 5. This highlights a close IÁ Á Á contact to a Partial view of a chain of halogen-bonded APEP and 13DIFB molecules with pairs of 13DIFB molecules shown between APEP molecules.

Figure 3
Hirshfeld surface highlighting the halogen-bonding interactions to pyrimidine APEP.

Figure 5
Hirshfeld surface highlighting the close contacts to the solvate 13DIFB molecule.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at 50% and the halogen bond shown as a dashed line.

Figure 4
View of crystal packing of the title compound viewed along the a-axis direction.

Synthesis and crystallization
The pyrimidine APEP (8.3 mg) was dissolved in 2 ml of dichloromethane in a screw-cap vial. Three equivalents of 13DIFB were added and the solvent was allowed to slowly evaporate until crystals formed when the vial was sealed to prevent further loss of solvent.

data-1
IUCrData (  Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.