[(Z)-N-(3-Fluorophenyl)-O-methylthiocarbamato-κS](triphenylphosphane-κP)gold(I): crystal structure, Hirshfeld surface analysis and computational study

A linear gold-atom geometry defined by phosphane-P and thiolate-S atoms is found in the title compound. The packing is stabilized by a combination of fluorobenzene-C—H⋯O(methoxy), phenyl-C—H⋯F, phenyl-C—H⋯S(thiolate) and phenyl-C—H⋯π(fluorobenzene, phenyl) interactions to generate a three-dimensional network.


Chemical context
In common with many other phosphanegold(I) thiolates (Yeo et al., 2018), molecules of the general formula R 3 PAu[SC(OR 0 ) NAr] have proven to exhibit anti-cancer potential (Ooi et al., 2017). Complimenting this activity is antibacterial potential against Gram-positive bacteria based on in vitro assays and time-kill profiles (Yeo et al., 2013) but not anti-amoebic effects, i.e. against Acanthamoeba castellanii (Siddiqui et al., 2017). In keeping with suggestions that the incorporation of fluorine atoms into molecules can enhance their pharmaceutical utility (Mü ller et al., 2007;Meanwell, 2018), it was thought of interest to synthesize fluoro analogues of R 3 PAu[SC(OR 0 ) NAr].
Herein, the compound with R = Ph, R 0 = Me and Ar = 3-fluorobenzene, (I), is described: synthesis, spectroscopic ISSN 2056-9890 characterization, crystal structure determination, analysis of the calculated Hirshfeld surfaces and interaction energies.
The overall molecular conformation of (I) is as usually found in molecules formulated as R 3 PAu[SC(OR 0 ) NAr]. However, a less common form is known whereby the N-bound aryl ring is orientated towards the gold atom rather than the alkoxy-oxygen atom (Kuan et al., 2008). So, rather than an intramolecular AuÁ Á ÁO contact, an intramolecular AuÁ Á Á contact is formed. The observation of both forms in Ph 3 PAu[SC(OEt) NPh], i.e. with AuÁ Á ÁO (Hall & Tiekink, 1993) or AuÁ Á Á (Yeo et al., 2016), suggests the energy difference between the conformations is relatively small. In related binuclear species, DFT calculations suggest that a AuÁ Á Á interaction is about 6 kcal mol À1 more stable than a AuÁ Á ÁO contact (Yeo et al., 2015).

Supramolecular features
Several directional intermolecular points of contact between molecules are noted in the extended structure of (I); see Table 1 for a listing of the geometric parameters characterizing these. Centrosymmetrically related molecules are connected via pairwise fluorobenzene-C-HÁ Á ÁO1 and phenyl-C-HÁ Á ÁF1 contacts Fig. 2(a). The dimeric aggregates are connected into a three-dimensional architecture by phenyl-C-HÁ Á ÁS1 interactions, with the phenyl-H atom involved in the latter interaction, i.e. H13, also participating in a C-HÁ Á Á(fluorobenzene) interaction and so may be considered bifurcated. The two remaining contacts are of the type phenyl-C-HÁ Á Á(fluorobenzene, phenyl) so the fluorobenzene ring accepts two contacts, one to either side of the ring. A view of the unit-cell contents is shown in Fig. 2

Hirshfeld surface analysis
In order to understand further the interactions operating in the molecular packing of (I), the Hirshfeld surfaces mapped over normalized contact distance d norm (McKinnon et al., 2004) and two-dimensional fingerprint plots (Spackman & McKinnon, 2002)  1285 Table 1 Hydrogen-bond geometry (Å , ).

Figure 2
Molecular packing in the crystal of (I): (a) the two-molecule aggregate sustained by fluorobenzene-C-HÁ Á ÁO and phenyl-C-HÁ Á ÁF contacts shown as blue and green dashed lines, respectively (non-participating H atoms are omitted) and (b) a view of the unit-cell contents down the a axis with phenyl-C-HÁ Á ÁS and phenyl-C-HÁ Á Á(fluorobenzene, phenyl) interactions shown as orange and purple dashed lines, respectively.

Figure 1
The molecular structures of (I) showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level.

Figure 4
Views of the Hirshfeld surface mapped for (I) over (a) d norm in the range of À0.222 to +1.382 arbitrary units and (b) the shape-index property. The C-HÁ Á ÁS and C-HÁ Á Á interaction are highlighted within red circles.

Figure 3
Views of the Hirshfeld surface for (I) mapped over d norm in the range À0.222 to +1.382 arbitrary units, highlighting C-HÁ Á ÁO/F interactions.

Figure 5
Views of the Hirshfeld surface mapped for (I) over (a) the shape-index property and (b) d norm in the range of À0.222 to +1.382 arbitrary units.
The overall two-dimensional fingerprint plot of (I) is shown in Fig. 8(a), and those delineated into HÁ Á ÁH, HÁ Á ÁC/CÁ Á ÁH, HÁ Á ÁF/FÁ Á ÁH, HÁ Á ÁS/SÁ Á ÁH and HÁ Á ÁO/OÁ Á ÁH contacts are shown in Fig. 8(b)-(f), respectively. The percentage contributions for the different interatomic contacts to the Hirshfeld surface are summarized in Table 3. The HÁ Á ÁH contacts are the most prominent of all contacts and contribute 44.9% to the entire surface. The delineated fingerprint plot in Fig. 8(b) features a beak-shaped peak tipped at d e + d i $2.3 Å . This tip corresponds to a methyl-H8CÁ Á ÁH33(phenyl) contact and has a distance 0.1 Å shorter than the sum of their van de Waals radii, Table 2. Consistent with the many C-HÁ Á Á interactions evident in the molecular packing, HÁ Á ÁC/CÁ Á ÁH contacts contribute 30.8% to the total surface contacts. The HÁ Á ÁC/ CÁ Á ÁH contacts shows a distinctive feature in the fingerprint plot of Fig Views of the Hirshfeld surface mapped for (I) over (a) d norm in the range of À0.222 to +1.382 arbitrary units and (b) the shape-index property, each highlighting the phenyl-C24-H24Á Á Á(C11-C16) interaction.

Figure 7
A view of the Hirshfeld surface mapped for (I) over the shape-index property highlighting weak C15-H15Á Á Á(C21-C26) and C32-H32Á Á Á(C11-C16) interactions.   and correspond to the phenyl-C36-H36Á Á ÁF1 contact in Table 1. While the C-HÁ Á ÁO1 and C-HÁ Á ÁS1 interactions are reflected through two sharp-symmetric wings at d e + d i $2.7 and $2.5 Å , respectively, Fig. 8(e) and (f), these types of contacts only contribute 6.9 and 3.2%, respectively, to the total interatomic contacts. The accumulated contribution of the remaining six different interatomic contacts is around 6.0% and these do not have a significant influence on the molecular packing.

Database survey
There are several literature precedents for (I), i.e. molecules of the general formula Ph 3 PAu[SC(OMe) NC 6 H 4 Y-3]. Selected geometric parameters for these are given in Table 5 Table 4 A summary of interaction energies (kcal mol À1 ) calculated for (I).

Figure 9
Overlay diagram for (I) (red image) and Ph 3 PAu[SC(OMe) NC 6 H 4 Y-3] for Y = H (green), H (chloroform solvate, aqua), Me (blue), Cl (triclinic form, pink) and Cl (monoclinic form, yellow). The molecules have been overlapped so the Au, S1 and C1 atoms are coincident. This being stated, the two overlay diagrams in Fig. 9 indicate differences in the relative dispositions of the terminal arene rings, as reflected in the differences in the dihedral angles between the planes through the CNOS and C 6 residues, which vary by up to nearly 15 . Finally, there is an isostructural relationship between (I) and the monoclinic form of the Y = Cl compound (Yeo et al., 2016).  The Ph 3 PAuCl precursor was prepared from the reduction of KAuCl 4 using sodium sulfite, followed by the addition of a stoichiometric amount of triphenylphosphane. The precipitate was used as isolated.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 6. The carbon-bound H atoms were placed in calculated positions (C-H = 0.95-0.98 Å ) and were included in the refinement in the riding-model approximation, with U iso (H) set to 1.2-1.5U eq (C). The maximum and minimum electron density peaks of 1.17 and 1.22 e Å À3 , respectively, are located 0.97 and 0.69 Å , respectively, from the Au atom.    (Farrugia, 2012) and

[(Z)-N-(3-Fluorophenyl)-O-methylthiocarbamato-κS](triphenylphosphane-κP)gold(I)
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 1.17 e Å −3 Δρ min = −1.22 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.