A quadrupole-quadrupole stacking synthon in (2,3,5,6-tetra­fluorobenzene­thiol­ato-[kappa]S)(tri­phenylphosphine-[kappa]P)­gold(I)

The title compound, [Au(C₆HF₄S)(C₁₈H₁₅P)], with both aromatic and fluorinated aromatic rings in its molecular system, shows dimerization through a quadrupole-quadrupole stacking synthon. The dimer further aggregates through intermolecular [pi]-[pi] stacking and C-H...[pi] interactions, giving a supramolecular three-dimensional network.

S1. Comment

Many approaches to the construction and control of supramolecular systems based on Au^I complexes have been reported (Hao et al., 1999; Hunks et al., 2000; Tzeng et al., 1999). Non-covalent interactions, such as Au—Au contacts, hydrogen bonding and the π-π stacking synthon, play important roles in the molecular design of these systems and the architecture of their extended structures. The quadrupole-quadrupole stacking synthon is induced by cooperation between electron-deficient fluorinated aromatic and electron-rich aromatic rings, and contributes significantly to the assembly of molecules (Coates et al., 1997; Williams, 1993). The gold(I) phosphine thiolate complex, [Au(PPh₃)(SC₆F₅)], which has three phenyl and one perfluorinated phenyl rings, is the first example of an Au^I complex tightly aggregated through electrostatic quadrupole interactions and π-π stacking in crystals (Watase et al., 2003). Such an aggregate is disassembled in solution, but a dimeric form still exists even in solution. These results suggest that the quadrupole interaction in such a molecular system is more effective than other intermolecular interactions, leading to a new class of supramolecular aggregation. In order to investigate whether the quadrupole interaction is a general phenomenon in this type of Au^I complex, we have synthesized the title novel gold(I) phosphine complex, (I), [Au(PPh₃)(SC₆H-2,3,5,6-F₄)], with the tetrafluorobenzenethiolate ligand, SC₆H-2,3,5,6-F₄. In this communication, we report the observation in (I) of a dimeric association through distorted dual quadrupole synthons, owing to the H atom at the para-position of the thiolate ligand, and the compound's supramolecular three-dimensional network. \sch

The Au centre of (I) has linear two-coordinate geometry to the phosphine and thiolate ligands (Fig. 1 and Table 1). The P1—Au1—S1 axis deviates slightly from linearity [174.46 (8)°]. The Au—S and Au—P bond distances [2.306 (2) and 2.257 (2) Å, respectively] are normal for this type of gold(I) phosphine thiolate complex [literature values for P—Au—S are in the range 171.01–176.53°, for Au—S 2.285–2.303 Å and for Au—P 2.253–2.269 Å; Ahmed et al., 1999; de Vos et al., 1999; Forward et al., 1995; Kuz'mina et al., 1993; Nakamoto et al., 1993; Watase et al., 2003). The S1—C1 bond distance [1.758 (9) Å] and Au1—S1—C1 angle [108.0 (3)°] correspond to those of analogous compounds [S—C distances in the range 1.739–1.801 Å and Au—S—C angles in the range 96.35–110.82°] and show single-bond character for the thiolate.

The Au1—S1—C1—C2 torsion angle of 22.7 (9)° in (I) is relatively small for this type of gold(I) compound, bringing the tetrafluorinated phenyl ring nearly parallel to the P—Au—S axis, similar to the pentafluorobenzenethiolate analogue, [Au(PPh₃)(SC₆F₅)], [(II); Watase et al., 2003]. This orientation brings an ortho-substituted F atom close to the Au centre and the resulting Au1···F1 distance [2.899 (6) Å] is much shorter than the sum of the van der Waals radii (3.13 Å) of Au and F (1.66 and 1.47 Å, respectively; Bondi, 1964), indicating an intramolecular close contact. In addition, one of the phenyl rings (containing atom C7) of the phosphine ligand is almost parallel to the fluorinated phenyl ring (containing atom C1), but these rings are not coplanar. This characteristic conformation induces another intramolecular close contact, with an F1···H2 distance of 2.58 Å, shorter than the sum of the van der Waals radii (2.67 Å) of the H (1.20 Å) and F atoms; the C2—F1···H2 angle is 154.8°.

A remarkable structural feature of (I) is the dual intermolecular quadrupole interaction between the fluorinated phenyl ring of the thiolate ligand and the phenyl ring of the phosphine ligand of a neighbouring molecule, giving a pseudo-cyclic dimer structure (Fig. 2). The crystal structure of (I) has an identical space group and similar molecular packing to the previously reported pentafluorobenzenethiolate analogue, (II). In (II), two phenyl rings of the quadrupole synthon are nearly parallel, with a dihedral angle of 1.8 (3)° (Watase et al., 2003). In (I), the stacking configuration of the equivalent two rings [containing atoms C1 and C7ⁱ; symmetry code: (i) 1 − x, −y, 1 − z] is slightly distorted, with a dihedral angle of 4.3 (3)°, showing a wedge shape from the S atom toward the aromatic H atom at the para position of the tetrafluorobenzenethiolate ligand (Fig. 3). As a result of such a wedge-shaped configuration in (I), the distance between the stacked rings [C1-ring···C7ⁱ-ring 3.47 (1) Å, calculated by the average shift of the six C atoms of the C7ⁱ-ring from the best plane of the C1-ring] is 0.08 Å longer than that in (II). This wedge-shaped configuration is observed in (I) despite compounds (I) and (II) having similar crystal packing and despite the decrease in steric hindrance in (I) due to the smaller H atom at the para-position of the thiolate ligand. This fact suggests that the introduction of the H atom into the highly fluorinated phenyl ring may decrease the electronegativity of the ring and reduce the intermolecular quadrupole interaction, although another indirect effect of the substitution cannot be ruled out.

Although the quadrupole interaction is slightly lessened in (I), the unit cell is slightly smaller compared with (II), particularly the c axis direction, where the reduction is 1.0%. On the other hand, each phenyl and fluorinated phenyl ring forms other π–π stacking interactions, i.e. C₆H₅···C₆H₅ [C7-ring···C7ⁱⁱ-ring; symmetry code: (ii) 1 − x, 1 − y, 1 − z] and C₆HF₄···C₆HF₄ [C1-ring···C1ⁱⁱⁱ-ring; symmetry code: (iii) 2 − x, −y, 1 − z], on opposite sides of each ring. The distances of their stacking synthons are 3.46 (1) and 3.69 (2) Å, respectively (Fig. 4). These π–π stacking synthons are responsible for the construction of a two-dimensional supramolecular network, which is built up along the c axis. The layers are also linked to each other through a T-shaped C—H···π intermolecular interaction between phenyl rings of the phosphine ligand, where the distance of this synthon is 2.855 (8) Å [C13-ring···H15^iv; symmetry code: (iv) 1/2 − x, y + 1/2, 1/2 − z].

Through the ensemble of these intra- and intermolecular interactions, the title complex forms a tightly packed three-dimensional assembly of dimers in the crystal.

S2. Experimental

Tetrafluorobenzenethiol (0.2 g, 1 mmol) was reacted with [Au(PPh₃)Cl] (0.5 g, 1 mmol) in the presence of triethylamine (0.1 g, 1 mmol) in tetrahydrofuran for 3 h at room temperature. The white precipitate of Et₃NHCl was filtered off and the tetrahydrofuran was removed under reduced pressure, to give a white residue. Colourless crystals of (I) were obtained by recrystallization from dichloromethane-n-hexane (Ratio?).

S3. Refinement

All H atoms were placed in calculated positions (C—H = 0.95 Å) and treated as riding.

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: TEXSAN (Molecular Structure Corporation, 2000); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: TEXSAN; molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: TEXSAN.

Figures

	Fig. 1. A view of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Dotted lines show intramolecular close contacts.
	Fig. 2. The dimeric association of (I) through the quadrupole-quadrupole stacking synthon.
	Fig. 3. The wedge-shaped configuration of the quadrupole-quadrupole stacking synthon in (I).
	Fig. 4. The two-dimensional network through three types of synthon in (I), C6HF4—C6H5 (thick bars), C6HF4—C6HF4 (dotted lines) and C6H5—C6H5 (dashed lines). The C13- and C19-phenyl rings of the phosphine ligands have been omitted for clarity.

(I)

Crystal data

[Au(C6HF4S)(C18H15P)]	F(000) = 1224.00
Mr = 640.38	Dx = 1.944 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.7107 Å
Hall symbol: -P 2yn	Cell parameters from 28391 reflections
a = 8.2743 (3) Å	θ = 1.8–30.5°
b = 11.3537 (3) Å	µ = 6.96 mm^−1
c = 23.4382 (8) Å	T = 296 K
β = 96.579 (1)°	Prism, colourless
V = 2187.4 (1) Å^3	0.20 × 0.14 × 0.09 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID imaging-plate diffractometer	3410 reflections with F^2 > 3σ(F^2)
Detector resolution: 10.00 pixels mm^-1	Rint = 0.034
ω scans	θmax = 27.5°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −10→10
Tmin = 0.297, Tmax = 0.534	k = −14→13
23270 measured reflections	l = −28→30
5018 independent reflections

Refinement

Refinement on F^2	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.037	w = 1/[σ^2(Fo^2) + {0.05[Max(Fo^2,0) + 2Fc^2]/3}^2]
wR(F^2) = 0.103	(Δ/σ)max = 0.0003
S = 1.58	Δρmax = 0.93 e Å^−3
3410 reflections	Δρmin = −0.98 e Å^−3
280 parameters

Special details

Refinement. Refinement using reflections with F² > 3.0 σ(F²). The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 3.0 σ(F²) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Au1	0.64650 (4)	0.07903 (2)	0.36232 (1)	0.04664 (9)
S1	0.7740 (4)	−0.1014 (2)	0.3735 (1)	0.0650 (7)
P1	0.5290 (2)	0.2561 (2)	0.34276 (8)	0.0403 (5)
F1	0.6665 (8)	0.0186 (5)	0.4831 (2)	0.082 (2)
F2	0.7776 (9)	−0.0286 (6)	0.5901 (3)	0.097 (2)
F3	1.1357 (8)	−0.3088 (6)	0.5302 (3)	0.095 (2)
F4	1.0328 (8)	−0.2613 (5)	0.4204 (3)	0.080 (2)
C1	0.845 (1)	−0.1191 (7)	0.4466 (4)	0.050 (2)
C2	0.787 (1)	−0.0624 (7)	0.4930 (4)	0.054 (2)
C3	0.846 (1)	−0.0870 (7)	0.5494 (4)	0.061 (3)
C4	0.962 (1)	−0.1685 (8)	0.5640 (4)	0.061 (3)
C5	1.021 (1)	−0.2256 (8)	0.5185 (4)	0.065 (3)
C6	0.966 (1)	−0.2005 (7)	0.4627 (4)	0.054 (3)
C7	0.4243 (9)	0.3187 (6)	0.3988 (3)	0.039 (2)
C8	0.471 (1)	0.2876 (7)	0.4557 (4)	0.051 (2)
C9	0.402 (1)	0.3437 (9)	0.4998 (4)	0.062 (3)
C10	0.281 (1)	0.4267 (8)	0.4865 (4)	0.066 (3)
C11	0.233 (1)	0.4579 (8)	0.4300 (4)	0.062 (3)
C12	0.303 (1)	0.4027 (7)	0.3865 (4)	0.055 (2)
C13	0.6771 (10)	0.3668 (7)	0.3269 (3)	0.044 (2)
C14	0.796 (1)	0.3353 (8)	0.2921 (4)	0.057 (3)
C15	0.910 (1)	0.4172 (9)	0.2795 (5)	0.069 (3)
C16	0.910 (1)	0.5286 (9)	0.3015 (5)	0.067 (3)
C17	0.793 (1)	0.5591 (8)	0.3357 (5)	0.065 (3)
C18	0.678 (1)	0.4791 (7)	0.3494 (4)	0.050 (2)
C19	0.3794 (10)	0.2496 (6)	0.2806 (3)	0.042 (2)
C20	0.254 (1)	0.1667 (8)	0.2808 (4)	0.056 (3)
C21	0.140 (1)	0.1540 (9)	0.2345 (4)	0.069 (3)
C22	0.142 (1)	0.2243 (9)	0.1877 (4)	0.070 (3)
C23	0.264 (1)	0.3062 (8)	0.1867 (4)	0.065 (3)
C24	0.382 (1)	0.3187 (7)	0.2324 (4)	0.052 (2)
H1	1.0011	−0.1855	0.6028	0.0737*
H2	0.5512	0.2281	0.4645	0.0614*
H3	0.4368	0.3250	0.5388	0.0749*
H4	0.2302	0.4627	0.5164	0.0794*
H5	0.1533	0.5171	0.4212	0.0739*
H6	0.2671	0.4221	0.3476	0.0654*
H7	0.7982	0.2576	0.2771	0.0689*
H8	0.9889	0.3958	0.2550	0.0832*
H9	0.9903	0.5841	0.2933	0.0798*
H10	0.7911	0.6371	0.3504	0.0786*
H11	0.5995	0.5013	0.3741	0.0605*
H12	0.2488	0.1186	0.3137	0.0672*
H13	0.0585	0.0954	0.2348	0.0829*
H14	0.0605	0.2169	0.1560	0.0836*
H15	0.2667	0.3548	0.1539	0.0786*
H16	0.4651	0.3756	0.2309	0.0623*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Au1	0.0538 (2)	0.0362 (2)	0.0482 (2)	0.0062 (1)	−0.0011 (1)	0.0021 (1)
S1	0.092 (2)	0.046 (1)	0.053 (1)	0.023 (1)	−0.008 (1)	−0.0054 (9)
P1	0.044 (1)	0.0360 (9)	0.0407 (10)	0.0006 (8)	0.0035 (8)	0.0018 (7)
F1	0.104 (5)	0.077 (4)	0.069 (4)	0.042 (3)	0.028 (3)	0.012 (3)
F2	0.132 (6)	0.092 (4)	0.072 (4)	0.011 (4)	0.039 (4)	−0.002 (3)
F3	0.076 (4)	0.088 (4)	0.114 (5)	0.030 (3)	−0.014 (4)	0.019 (4)
F4	0.092 (4)	0.068 (3)	0.083 (4)	0.030 (3)	0.018 (3)	−0.003 (3)
C1	0.059 (6)	0.040 (4)	0.050 (5)	−0.001 (4)	0.009 (4)	0.000 (3)
C2	0.060 (6)	0.040 (4)	0.062 (5)	0.004 (4)	0.011 (4)	0.001 (4)
C3	0.073 (7)	0.049 (5)	0.061 (6)	−0.016 (4)	0.016 (5)	−0.001 (4)
C4	0.068 (6)	0.055 (5)	0.059 (6)	−0.013 (5)	−0.005 (5)	0.014 (4)
C5	0.054 (6)	0.065 (6)	0.074 (7)	−0.001 (5)	−0.003 (5)	0.014 (5)
C6	0.061 (6)	0.040 (4)	0.062 (6)	0.004 (4)	0.005 (4)	−0.002 (4)
C7	0.041 (4)	0.034 (3)	0.043 (4)	0.001 (3)	0.006 (3)	0.002 (3)
C8	0.051 (5)	0.049 (4)	0.054 (5)	−0.010 (4)	0.007 (4)	0.000 (4)
C9	0.073 (7)	0.075 (6)	0.038 (5)	−0.008 (5)	−0.001 (4)	−0.005 (4)
C10	0.072 (7)	0.067 (6)	0.063 (6)	−0.005 (5)	0.021 (5)	−0.017 (5)
C11	0.060 (6)	0.055 (5)	0.072 (6)	0.005 (4)	0.016 (5)	−0.013 (4)
C12	0.063 (6)	0.051 (4)	0.050 (5)	0.015 (4)	0.009 (4)	−0.001 (4)
C13	0.040 (4)	0.049 (4)	0.043 (4)	−0.003 (3)	0.001 (3)	0.002 (3)
C14	0.059 (6)	0.050 (5)	0.063 (6)	0.002 (4)	0.005 (4)	−0.004 (4)
C15	0.065 (6)	0.082 (7)	0.064 (6)	−0.006 (5)	0.021 (5)	0.008 (5)
C16	0.053 (6)	0.064 (5)	0.081 (7)	−0.013 (4)	−0.001 (5)	0.023 (5)
C17	0.062 (6)	0.050 (5)	0.083 (7)	−0.006 (4)	0.002 (5)	0.003 (4)
C18	0.050 (5)	0.052 (5)	0.050 (5)	0.001 (4)	0.009 (4)	−0.003 (4)
C19	0.047 (5)	0.039 (4)	0.039 (4)	0.001 (3)	0.006 (3)	−0.004 (3)
C20	0.062 (6)	0.061 (5)	0.044 (5)	−0.014 (4)	0.002 (4)	0.001 (4)
C21	0.077 (7)	0.064 (6)	0.063 (6)	−0.012 (5)	−0.006 (5)	0.002 (5)
C22	0.074 (7)	0.065 (6)	0.063 (6)	0.006 (5)	−0.019 (5)	−0.011 (5)
C23	0.086 (7)	0.064 (5)	0.044 (5)	0.009 (5)	−0.004 (5)	0.002 (4)
C24	0.063 (6)	0.047 (4)	0.046 (5)	0.001 (4)	0.010 (4)	0.008 (3)

Geometric parameters (Å, º)

Au1—S1	2.306 (2)	C10—H4	0.950
Au1—P1	2.257 (2)	C11—C12	1.38 (1)
Au1—F1	2.899 (6)	C11—H5	0.950
S1—C1	1.758 (9)	C12—H6	0.950
P1—C7	1.801 (8)	C13—C14	1.39 (1)
P1—C13	1.823 (8)	C13—C18	1.38 (1)
P1—C19	1.802 (8)	C14—C15	1.38 (1)
F1—C2	1.355 (10)	C14—H7	0.950
F1—H2	2.581	C15—C16	1.37 (1)
F2—C3	1.34 (1)	C15—H8	0.950
F3—C5	1.35 (1)	C16—C17	1.37 (1)
F4—C6	1.37 (1)	C16—H9	0.950
C1—C2	1.40 (1)	C17—C18	1.38 (1)
C1—C6	1.39 (1)	C17—H10	0.950
C2—C3	1.39 (1)	C18—H11	0.950
C3—C4	1.35 (1)	C19—C20	1.40 (1)
C4—C5	1.38 (1)	C19—C24	1.38 (1)
C4—H1	0.950	C20—C21	1.36 (1)
C5—C6	1.36 (1)	C20—H12	0.950
C7—C8	1.39 (1)	C21—C22	1.36 (1)
C7—C12	1.39 (1)	C21—H13	0.950
C8—C9	1.40 (1)	C22—C23	1.37 (1)
C8—H2	0.950	C22—H14	0.950
C9—C10	1.38 (1)	C23—C24	1.37 (1)
C9—H3	0.950	C23—H15	0.950
C10—C11	1.38 (1)	C24—H16	0.950
S1—Au1—P1	174.46 (8)	C10—C11—C12	119.8 (9)
S1—Au1—F1	72.8 (1)	C10—C11—H5	120.1
Au1—S1—C1	108.0 (3)	C12—C11—H5	120.1
Au1—P1—C7	115.8 (2)	C7—C12—C11	120.6 (8)
Au1—P1—C13	111.8 (3)	C7—C12—H6	119.7
Au1—P1—C19	111.6 (2)	C11—C12—H6	119.7
C7—P1—C13	105.5 (3)	P1—C13—C14	118.5 (6)
C7—P1—C19	105.2 (3)	P1—C13—C18	122.2 (6)
C13—P1—C19	106.2 (4)	C14—C13—C18	119.3 (7)
Au1—F1—C2	106.6 (5)	C13—C14—C15	119.8 (8)
Au1—F1—H2	68.8	C13—C14—H7	120.1
C2—F1—H2	154.8	C15—C14—H7	120.1
S1—C1—C2	127.0 (7)	C14—C15—C16	121.0 (9)
S1—C1—C6	119.4 (7)	C14—C15—H8	119.5
C2—C1—C6	113.6 (8)	C16—C15—H8	119.5
F1—C2—C1	119.4 (8)	C15—C16—C17	118.9 (9)
F1—C2—C3	118.2 (8)	C15—C16—H9	120.5
C1—C2—C3	122.4 (8)	C17—C16—H9	120.5
F2—C3—C2	116.6 (9)	C16—C17—C18	121.6 (9)
F2—C3—C4	120.5 (9)	C16—C17—H10	119.2
C2—C3—C4	122.8 (9)	C13—C18—C17	119.4 (8)
C3—C4—C5	115.5 (9)	C13—C18—H11	120.3
C3—C4—H1	122.3	C17—C18—H11	120.3
C5—C4—H1	122.3	P1—C19—C20	117.7 (6)
F3—C5—C4	118.4 (9)	P1—C19—C24	124.6 (6)
F3—C5—C6	119.2 (9)	C20—C19—C24	117.8 (8)
C4—C5—C6	122.4 (9)	C19—C20—C21	120.8 (8)
F4—C6—C1	118.6 (8)	C19—C20—H12	119.6
F4—C6—C5	118.1 (8)	C21—C20—H12	119.6
C1—C6—C5	123.3 (9)	C20—C21—C22	120.7 (9)
P1—C7—C8	119.6 (6)	C20—C21—H13	119.7
P1—C7—C12	121.0 (6)	C22—C21—H13	119.7
C8—C7—C12	119.4 (7)	C21—C22—C23	119.3 (9)
C7—C8—C9	120.0 (8)	C21—C22—H14	120.4
C7—C8—H2	120.0	C23—C22—H14	120.4
C9—C8—H2	120.0	C22—C23—C24	120.9 (8)
C8—C9—C10	119.6 (8)	C22—C23—H15	119.6
C8—C9—H3	120.2	C24—C23—H15	119.6
C10—C9—H3	120.2	C19—C24—C23	120.5 (8)
C9—C10—C11	120.6 (8)	C19—C24—H16	119.8
C9—C10—H4	119.7	C23—C24—H16	119.8
C11—C10—H4	119.7
Au1—S1—C1—C2	22.7 (9)	Au1—P1—C13—C14	42.4 (7)
Au1—S1—C1—C6	−160.3 (6)	Au1—P1—C13—C18	−136.0 (6)
Au1—P1—C7—C8	26.1 (7)	Au1—P1—C19—C20	55.3 (7)
Au1—P1—C7—C12	−157.3 (6)	Au1—P1—C19—C24	−123.3 (7)