Crystal structure of an ordered [WOF5]− salt: (1,10-phen-H)[WOF5] (1,10-phen = 1,10-phenanthroline)

The crystal of structure of (1,10-phen-H)[WOF5], a rare example of a [WOF5]− salt in which the oxygen and fluorine atoms are ordered, is reported.


Structural commentary
The individual bond valences of the [WOF 5 ] À anion in (1,10-phen-H)[WOF 5 ] (Table 1) reveal that the W O bond ( = 1.81) is approximately double the strength of the W-F eq bonds ( = 0.87-0.90), indicating complete O/F ordering; in a disordered anion, the W O bond valence is artificially decreased due to averaging with the W-F single bonds. The F1 atom possesses a valence sum significantly less than unity (V = 0.81) because of the trans influence of the oxido ligand and N1-H1Á Á ÁF1 hydrogen-bonding interaction substantially polarizing that bond.

Synthesis and crystallization
In the dry box, a 1/4"-o.d. FEP reactor, equipped with a 316stainless-steel valve and pre-passivated with F 2 (100%, Linde Gas), was charged with WF 6 (1,10-phen) (ca 0.01 g), prepared as described previously (Turnbull et al., 2019a). Acetonitrile (ca 0.1 mL), dried as previously described (Winfield, 1984), was distilled into the reactor through a glass vacuum line equipped with grease-free PTFE stopcocks (J. Young). The reactor was heated to 353 K in a hot-water bath and allowed to cool to ambient temperature over 16 h. The reactor was then cooled rapidly to 233 K and the solvent was removed under dynamic vacuum at that temperature, resulting in the formation of colourless needles of (1,10-phen-H) [WOF 5 ], together with an off-white microcrystalline material that was not further characterized, but is presumed to contain WF 6 (1,10phen) and (1,10-phen-H) [WOF 5 ].
The reactor was cut open and the crystals transferred onto an aluminium trough cooled to 193 K under a constant stream of liquid-N 2 -cooled, dry N 2 . The selected crystal was affixed to a Nylon cryo-loop submerged in perfluorinated polyether oil (Fomblin Z-25) and quickly transferred to the goniometer to minimize exposure to air.

Refinement details
Crystallographic data collection and refinement parameters are summarized in Table 3. All the hydrogen atoms were located in difference Fourier maps and were refined using a riding model, with the exception of H1, the position of which was refined freely (Table 2).  Table 2 Hydrogen-bond geometry (Å , ).

Refinement
Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = 0.016 wR(F 2 ) = 0.038 S = 1.06 2908 reflections 194 parameters 0 restraints Primary atom site location: dual Hydrogen site location: mixed H atoms treated by a mixture of independent and constrained refinement w = 1/[σ 2 (F o 2 ) + (0.0179P) 2 + 0.7231P] where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 0.97 e Å −3 Δρ min = −0.83 e Å −3 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.