A 1:1 flavone cocrystal with cyclic trimeric perfluoro-o-phenylenemercury

In the title compound, molecules are connected by Hg⋯O interactions. The 1:1 complexes pack in zigzag chains where they stack via two alternating stacking patterns, TPPM(cyclic trimeric perfluoro-o-phenylenemercury)–TPPM, and FLA(flavone)–FLA. The shortened F⋯F, CH⋯F and CH⋯π contacts consolidate the crystal structure.


Chemical context
Macrocyclic trimeric perfluoro-o-phenylenemercury [TPPM, (o-C 6 F 4 Hg) 3 ] Lewis acid containing three Hg atoms in a planar nine-membered cycle has been used successfully in recent decades as a multidentate Lewis acid host.Numerous studies registered an excellent oxo-and thiophilicity of this strong electron acceptor manifested in its reactions with various anions and neutral Lewis bases to give complexes wherein the Lewis bases were easily cooperatively coordinated by multiple TPPM binding sites (King et al., 2002a,b;Tikhonova et al., 2005;Castan ˜eda et al., 2015Castan ˜eda et al., , 2016;;Loveday et al., 2022).In particular, the oxophilicity of TPPM is welldocumented, and the reported examples revealed variable molar ratios and packing arrangements of the TPPM acceptor and O-containing Lewis bases in the crystals (King et al., 2002a,b;Tikhonova et al., 2005;Castan ˜eda et al., 2016).The O� � �Hg coordination bonds were the primary interactions in those crystals that involved two or three Hg atoms of TPPM and the O-donor molecules situated on one or both faces of the TPPM macrocycle.
Flavonoids are a family of polyphenolic compounds broadly produced in plants and found in the human diet.They are generally recognized as active pharmaceutical ingredients (API) with health-prolonging effects attributed to their antibacterial, antioxidant, antitumor, and anti-inflammatory properties (Cushnie & Lamb, 2005, 2011).Flavone (FLA), the simplest member of the class of flavones, can be tailored for significant modulation of its pharmacological activity and therefore serves as an effective scaffold in medicinal chemistry (Singh et al., 2014).While the crystal chemistry of the TPPM acceptor is rather rich, only single examples have been reported for the crystalline forms of FLA (Waller et al., 2003;van Tonder et al., 2009a,b;Jiang et al., 2014;Khandavilli et al., 2018;Li et al., 2019;He et al., 2015).To fill this gap, we decided to cocrystallize FLA with TPPM.From a crystal-engineering perspective, it might be predicted that FLA, containing a benzo-�-pyrone moiety bearing a phenyl substituent at position 2 and having a carbonyl group, would be predisposed for association with TPPM via oxophilic and stacking interactions.The crystal structure of the product of these interactions, the cocrystal (FLA)•(TPPM), is reported.

Structural commentary
The title compound, (FLA)•(TPPM) in a 1:1 molar ratio, crystallizes in the monoclinic space group P2 1 /n.The asymmetric unit comprises one FLA and one TPPM molecule (Fig. 1).The principal geometric parameters for both components are in good agreement with the literature values (Groom et al., 2016).The components are held together via two Hg-O contacts, Hg1� � �O1 = 2.829 (3) and Hg2� � �O1 = 2.947 (4) A ˚, that are considerably shorter than the sum of the van der Waals radii of mercury (2.1 A ˚) and oxygen (1.5 A ˚) atoms (Batsanov, 2001;Yakovenko et al., 2011).The Hg3� � �O1 distance is 3.097 (3) A ˚. Thus, an asymmetrical coordination of the FLA carbonyl oxygen atom, which is bonded to two Hg centers, is observed.The tilting angle between the virtually planar benzo-�-pyrone residue (the r.m.s.deviation of the 11 fitted atoms is 0.0243 A ˚) and the mean plane of TPPM is 49.97 (5) � .The FLA molecule has an angular shape indicated by the twisted angle between the benzo-�-pyrone moiety and the anchored phenyl ring of 23.3 (2) � , contrary to the practically planar geometry of FLA in its pure form (WADRAV; Waller et al., 2003) and in (� 6 -flavone)tricarbonylchromium(0) (FUGBEP; van Tonder et al., 2009b).

Figure 1
The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.

Figure 2
Supramolecular chain in the title compound generated through alternation of TPPM-TPPM and FLA-FLA stacking patterns.

Synthesis and crystallization
FLA (11.212 mg, 0.05 mmol) was dissolved in 5 mL of DCM and TPPM (52.290 mg, 0.05 mmol) was added to the solution.The mixture was sonicated for 10 min at ambient conditions (room temperature), and after that the solution was transferred to a 15 mL test tube and covered with a cotton cap.In 10 days transparent colorless crystals (mass of crystals collected 54.205 mg, 0.0427 mmol, 85.35%) were obtained.

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.

Figure 3
Figure 3View of the crystal packing.The central stacking chain is shown in red.

Table 2
Experimental details.Crystal data, data collection and structure refinement details are summarized in Table2.All non-hydrogen atoms were refined in anisotropic approximation.The H atoms were refined as riding in idealized positions, with U iso (H) = 1.2Ueq of the bearing C atom.