Two salts of the 6,6-difluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide anion with different cations

The crystal structures are reported of the 6,6-difluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide (or 9,9-difluoro-10-oxa-9-boraphenanthren-9-id)anion with two different cations, namely, potassium 6,6-difluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide featuring a polymeric structure, and bis(tetraphenylphosphonium) bis(6,6-difluoro-6H-dibenzo[c,e][1,2]oxaborinin-6-ide) acetonitrile trisolvate, which is composed of discrete cations, anions and acetonitrile solvent molecules linked by C—H⋯O, C—H⋯N and C—H⋯F hydrogen bonds.


Chemical context
Oxaboraphenanthrenes are interesting building blocks for organic optoelectronic materials. Recently, we have prepared various 9-substituted oxaboraphenanthrene derivatives and investigated their stability and luminescence behavior (Budanow et al., 2016). The starting material for our approach was 9-chloro-10,9-oxaboraphenanthrene (Budanow et al., 2014), which is, however, an air-sensitive compound. Therefore we were now interested in air-stable precursors for oxaboraphenanthrene preparation.

Figure 4
A perspective view of the second of the two anions in the asymmetric unit of (III). Displacement ellipsoids are drawn at the 50% probability level.

Figure 3
A perspective view of the first of the two anions in the asymmetric unit of (III). Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A perspective view of the asymmetric unit of (II). Displacement ellipsoids are drawn at the 50% probability level.

Database survey
There are no structures in the Cambridge Structural Database (version 5.41 of November 2019 plus three updates; Groom et al., 2016) Sato et al., 2020). Since in RUHZUS, the ligands at B are involved in a ring closure, this structure is excluded from the comparison with (II) and (III).

Figure 5
Packing diagram of (II) with a view onto the bc plane. H atoms are omitted for clarity.

Figure 6
Packing diagram of (II) viewed along the b-axis direction. H atoms are omitted for clarity.

Figure 7
Packing diagram of (III) viewed along the a-axis direction. H atoms and the minor occupied sites of the disordered acetonitrile molecule are omitted for clarity.

Synthesis and crystallization
Synthesis of 9,9-difluorido-10,9-oxaboraphenanthrene potassium (II): To a solution of 9-hydroxooxaboraphenanthrene (I) (1.556 g, 7.94 mmol) in methanol (70 ml) a solution of KHF 2 (2.669 g, 34.17 mmol) in methanol (30 ml) and water (30 ml) was added at room temperature and the resulting reacting mixture was stirred for 12 h. After removal of all volatiles in vacuo, the residue was extracted into acetonitrile (30 ml). The colorless suspension was filtered. All volatiles were removed in vacuo. The product was obtained as a colorless powder in a yield of 66% (1.34 g, 5.23 mmol). Slow evaporation of a saturated acetonitrile solution of (II) over Granopent led to colorless plates, which were suitable for an investigation by X-ray crystallography.
Synthesis of 9,9-difluorido-10,9-oxaboraphenanthrene tetraphenylphosphonium (III): To a solution of (II) (0.511 g, 2.0 mmol) in acetonitrile (25 ml) Ph 4 PBr (0.88 g, 2.10 mmol) was added at room temperature and the resulting reacting mixture was stirred for 12 h. The colorless suspension was filtered. After removal of all volatiles, the product was obtained as a colorless powder in a yield of 92% (0.221 g, 0.36 mmol). Slow evaporation of a saturated acetonitrile solution of (III) over Granopent led to colorless blocks, which were suitable for an investigation by X-ray crystallography.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The H atoms for both structures were refined using a riding model with C-H = 0.95 Å and with U iso (H) = 1.2U eq (C) or with C methyl -H = 0.98 Å and with U iso (H) = 1.5U eq (C). The methyl groups were allowed to rotate but not to tip. In (III), the C N group of one acetonitrile molecule is disordered over two sets of sites with a site occupation factor of 0.545 (5) for the major disorder component.

sup-2
Acta Cryst. (2020). E76, 1837-1840 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.