Crystal structure of dichlorido[2-(diphenylphosphanyl)-3,4,5,6-tetrafluorobenzene-1-thiolato-κ2 P,S]gold(III)

The title compound, [Au(C18H10F4PS)Cl2], crystallizes as neutral molecules, with the AuIII atom coordinated by two Cl atoms and by the P and S atoms of the bidentate phosphanyl thiolate ligand, in a slightly distorted square-planar environment. The molecules are linked into centrosymmetric dimers via long axial Au—Cl bonds of 3.393 (4) Å. This axial Au—Cl distance is longer than is usually seen, although one other example has been given. Dimer formation may explain the unexpectedly low solubility of the compound in common polar solvents. There is also a separate intermolecular Au—F contact of 3.561 (6) Å, but this distance seems too long to be regarded as a bond. Two putative C—H⋯F hydrogen bonds appear to link the dimers into sheets parallel to (110). There is a short intermolecular F⋯F contact of 2.695 (10) Å between two dimers related by the twofold axis.


Related literature
For synthetic details, see: Eller (1971); Eller & Meek (1970). Hollis & Lippard (1983) describe a similarly long axial Au-Cl bond in a mixed-valence gold compound, although other axial Au-Cl bonds in the literature are in the 3.0-3.1 Å range, as in Elder & Watkins (1986

S1. Synthesis and crystallization
The preparation of the compound is described by Eller (1971), and synthesis of the then novel ligand is given in Eller & Meek (1970).

S2. Refinement
To reduce the number of parameters varied, the phenyl groups C16-C21 and C22-C27 were constrained as rigid hexagons, with C-C distances of 1.385 Å. Aromatic H atoms were placed geometrically, with their U eq values set 1.2 times the U iso of their bonded C atoms.

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

Figure 2
Packing of the title complex, viewed along a direction near to the a axis. The centrosymmetric dimers are shown, as well as the proximity of F3(1,y -1,z) to a sixth coordination site for the gold atom. Long Au-Cl bonds are gived as dashed lines.

Dichlorido[2-(diphenylphosphanyl)-3,4,5,6-tetrafluorobenzene-1-thiolato-κ 2 P,S]gold(III)
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.00 e Å −3 Δρ min = −0.87 e Å −3 Special details Experimental. Data reduction followed procedures in Corfield et al. (1973), with programs written by Corfield and by Graeme Gainsford. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. To reduce the number of parameters varied, the phenyl groups C16-C21 and C22-C27 were constrained as rigid hexagons, with C-C distances of 1.385 Å. U eq values for the aromatic H atoms were set 1.2 times the U iso of their bonded C atoms.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Au 0.03240 (2)