Herring-bone π–π interactions in trans-2,6-diphenyl-2,3,5,6-tetrahydrothiapyran-4-one

The structure of the title compound, C₁₇H₁₆OS, is primarily stabilized by T-shaped and parallel-displaced aromatic clusters. The distances between the centroids of the aromatic pairs are in the range 4.34–5.30 Å. In the crystal packing, the mol­ecules dimerize by means of π–π interactions of both face-to-face and edge-to-face types, and the aromatic rings associate in a cyclic edge-to-face tetrameric arrangement of the herring-bone type. These herring-bone interactions appear to insulate hydrogen-bond interactions in the crystal structure.

S1. Comment

Several experimental and theoretical investigations of aromatic interactions have emphasized their role in many important chemical and biological phenomena, such as shaping molecular conformations, determining intermolecular interactions (Meyer et al., 2003) and supramolecular assembly (Desiraju & Steiner, 1999). Two types of clusters, namely parallel-displaced (face-to-face) and T-shaped (edge-to-face), have been shown to be energetically favourable and observed in a large number of crystal and molecular structures (McGaughey et al., 1998). The association of these aromatic clusters into different types of arrangements, similar to what is commonly observed for hydrogen bonds, and the prediction of preferred intermolecular, i.e. aromatic versus hydrogen-bonding, interactions, for the design of supramolecular assemblies, are currently important topics of investigation in crystal engineering. The present discussion is concerned with intermolecular π–π interactions and their arrangements in crystal packing. Against this background, we present here the crystal structure and packing of the title compound, (I). \sch

The crystal structure of (I) is characterized by several edge-to-face and face-to-face π–π interactions. The geometrical parameters (Table 1) suggest that all of them have close to the ideal T-shaped or parallel-displaced geometry. Within the molecule, the aromatic rings are asymmetrically disposed (Fig. 1) on either side of the chair conformation of the thiapyran ring, i.e. one is in the equatorial position (ring A) and the other is in the axial position (ring B). Each of them is involved in three π–π interactions. The molecules form dimers in the unit cell, and they are cooperatively connected by edge-to-face interactions between ring A and ring B and by face-to-face interactions between rings B.

The characteristic feature of the crystal packing in (I) is the tetrameric association of the aromatic rings, as shown in Fig. 2a. The edge-to-face cyclic arrangement of the aromatic rings is similar to the herringbone interactions observed for benzene and other aromatic clusters (Vangala et al., 2002; Allen et al., 1997). Previously, we have examined the structure of the cis isomer of (I), (II), for its molecular symmetry, where both aromatic rings are in equatorial positions (Narsimhamurthy et al., 2000). Interestingly, similar edge-to-face aromatic clusters in a herringbone fashion are also observed in the structure of (II), although the interplanar angles between the aromatic rings (68°) are slightly distorted from the ideal T-shaped geometry (Fig. 2 b). There are no hydrogen bonds in either of these structures. The aromatic interactions appear to insulate hydrogen-bonding (Desiraju & Steiner, 1999), possibly due to the overwhelming presence of π donors and acceptors. This insulation of hydrogen-bonding by herringbone interactions, observed in the present examples of symmetric as well as in asymmetric stereoisomers, serves as a good model in the design of supramolecular assemblies and in crystal engineering.

S2. Experimental

Crystals of (I) (Sigma Chemicals, USA) were obtained by direct evaporation of an ethanol solution.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: INSIGHTII (Accelrys, 1998); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of the molecule of (I), showing the atom-numbering scheme and with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. Herringbone π–π interactions. The values indicate centre to centre distances (Å) between interacting aromatic pairs. (a) The association of molecules into dimers (diads) and cyclic edge-to face tetrameric arrangements of aromatic clusters. (b) The similar edge-to-face tetrameric arrangement for the symmetrical stereoisomer (II), reported by Narsimhamurthy et al. (2000).

2,6-Diphenylthiapyran-4-one

Crystal data

C17H16OS	Z = 2
Mr = 268.38	F(000) = 284
Triclinic, P1	Dx = 1.270 Mg m^−3
a = 5.909 (2) Å	Cu Kα radiation, λ = 1.54180 Å
b = 9.706 (3) Å	Cell parameters from 25 reflections
c = 13.184 (5) Å	θ = 9.9–60.6°
α = 102.02 (3)°	µ = 1.94 mm^−1
β = 94.39 (3)°	T = 293 K
γ = 106.39 (3)°	Plate, colourless
V = 702.1 (4) Å^3	0.2 × 0.1 × 0.1 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.104
Radiation source: fine-focus sealed tube	θmax = 75.8°, θmin = 3.5°
Graphite monochromator	h = −7→6
ω/2θ scans	k = −11→11
2775 measured reflections	l = −12→16
2630 independent reflections	2 standard reflections every 200 reflections
2617 reflections with I > 2σ(I)	intensity decay: 9.1%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.057	All H-atom parameters refined
wR(F^2) = 0.160	w = 1/[σ^2(Fo^2) + (0.0685P)^2 + 0.44P] where P = (Fo^2 + 2Fc^2)/3
S = 1.23	(Δ/σ)max = 0.003
2630 reflections	Δρmax = 0.29 e Å^−3
237 parameters	Δρmin = −0.27 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.026 (3)

Special details

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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

− 2.7905 (0.0068) x + 4.9627 (0.0084) y + 9.2930 (0.0120) z = 6.2826 (0.0060)

* 0.0169 (0.0016) C2 * −0.0127 (0.0021) C7 * −0.0090 (0.0022) C8 * 0.0023 (0.0022) C9 * 0.0099 (0.0025) C10 * 0.0034 (0.0023) C11 * −0.0108 (0.0024) C12 − 2.2342 (0.0048) C5

Rms deviation of fitted atoms = 0.0104

− 2.0265 (0.0079) x + 7.7949 (0.0063) y − 9.4235 (0.0096) z = 1.2443 (0.0038)

Angle to previous plane (with approximate e.s.d.) = 89.55 (0.08)

* −0.0132 (0.0016) C6 * 0.0101 (0.0021) C13 * 0.0050 (0.0025) C14 * −0.0005 (0.0025) C15 * −0.0064 (0.0027) C16 * −0.0060 (0.0023) C17 * 0.0111 (0.0023) C18 − 0.8313 (0.0053) C3

Rms deviation of fitted atoms = 0.0085

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
S1	0.15492 (12)	0.59902 (8)	0.24393 (5)	0.0537 (3)
O1	0.7468 (4)	0.6448 (2)	0.47868 (15)	0.0623 (6)
C13	0.3633 (5)	0.4113 (3)	0.12900 (18)	0.0396 (5)
C7	0.4434 (5)	0.8850 (3)	0.33522 (19)	0.0455 (6)
C4	0.5609 (5)	0.6159 (3)	0.42162 (19)	0.0464 (6)
C6	0.4157 (4)	0.5384 (3)	0.22534 (18)	0.0387 (5)
C2	0.2789 (5)	0.7503 (3)	0.3610 (2)	0.0484 (6)
C5	0.5013 (6)	0.4938 (3)	0.3225 (2)	0.0469 (6)
C17	0.5099 (7)	0.2767 (4)	−0.0122 (2)	0.0608 (8)
C3	0.3816 (6)	0.6948 (3)	0.4488 (2)	0.0529 (7)
C8	0.6821 (6)	0.9438 (3)	0.3759 (2)	0.0535 (7)
C14	0.1401 (6)	0.3106 (3)	0.0942 (2)	0.0545 (7)
C16	0.2876 (7)	0.1782 (4)	−0.0458 (2)	0.0665 (9)
C18	0.5480 (5)	0.3936 (3)	0.0745 (2)	0.0507 (7)
C15	0.1026 (7)	0.1948 (4)	0.0070 (3)	0.0693 (9)
C9	0.8244 (7)	1.0708 (4)	0.3520 (3)	0.0676 (9)
C12	0.3505 (7)	0.9570 (4)	0.2691 (2)	0.0643 (8)
C10	0.7281 (9)	1.1395 (4)	0.2873 (3)	0.0775 (12)
C11	0.4926 (10)	1.0826 (4)	0.2462 (3)	0.0800 (12)
H6	0.543 (5)	0.628 (3)	0.214 (2)	0.040 (7)*
H2	0.134 (5)	0.770 (3)	0.377 (2)	0.047 (7)*
H51	0.376 (5)	0.415 (3)	0.332 (2)	0.046 (7)*
H52	0.634 (6)	0.460 (3)	0.313 (2)	0.053 (8)*
H8	0.760 (6)	0.903 (3)	0.422 (2)	0.052 (8)*
H18	0.705 (6)	0.466 (4)	0.094 (3)	0.059 (9)*
H31	0.253 (6)	0.624 (4)	0.466 (3)	0.061 (9)*
H14	0.014 (6)	0.321 (4)	0.126 (3)	0.056 (9)*
H12	0.187 (7)	0.910 (4)	0.245 (3)	0.078 (12)*
H32	0.451 (6)	0.778 (4)	0.511 (3)	0.059 (9)*
H17	0.641 (8)	0.270 (5)	−0.049 (3)	0.092 (13)*
H15	−0.054 (7)	0.131 (4)	−0.016 (3)	0.069 (10)*
H11	0.430 (8)	1.121 (5)	0.202 (3)	0.091 (13)*
H10	0.845 (8)	1.234 (5)	0.273 (3)	0.099 (13)*
H16	0.262 (7)	0.099 (4)	−0.108 (3)	0.082 (11)*
H9	0.990 (8)	1.110 (4)	0.382 (3)	0.085 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0455 (4)	0.0507 (4)	0.0541 (4)	0.0166 (3)	−0.0034 (3)	−0.0096 (3)
O1	0.0730 (14)	0.0604 (12)	0.0439 (11)	0.0143 (10)	−0.0068 (10)	0.0054 (9)
C13	0.0503 (14)	0.0359 (12)	0.0310 (11)	0.0131 (10)	0.0027 (10)	0.0061 (9)
C7	0.0579 (15)	0.0404 (13)	0.0368 (12)	0.0205 (11)	0.0100 (11)	−0.0022 (10)
C4	0.0643 (17)	0.0404 (13)	0.0314 (12)	0.0096 (12)	0.0081 (11)	0.0103 (10)
C6	0.0433 (13)	0.0385 (12)	0.0317 (11)	0.0115 (10)	0.0050 (9)	0.0044 (9)
C2	0.0500 (15)	0.0448 (14)	0.0428 (13)	0.0137 (12)	0.0102 (11)	−0.0063 (11)
C5	0.0616 (17)	0.0449 (14)	0.0350 (13)	0.0202 (13)	0.0040 (11)	0.0070 (11)
C17	0.078 (2)	0.0692 (19)	0.0426 (15)	0.0388 (17)	0.0141 (14)	0.0044 (13)
C3	0.0684 (18)	0.0477 (15)	0.0356 (13)	0.0102 (13)	0.0168 (12)	0.0023 (11)
C8	0.0606 (17)	0.0458 (15)	0.0518 (16)	0.0171 (13)	0.0100 (13)	0.0049 (12)
C14	0.0552 (16)	0.0438 (15)	0.0544 (16)	0.0092 (12)	0.0090 (13)	−0.0022 (12)
C16	0.094 (2)	0.0562 (18)	0.0431 (15)	0.0356 (18)	−0.0058 (15)	−0.0134 (13)
C18	0.0541 (16)	0.0562 (16)	0.0403 (13)	0.0207 (13)	0.0042 (11)	0.0038 (12)
C15	0.068 (2)	0.0491 (17)	0.071 (2)	0.0113 (15)	−0.0081 (17)	−0.0130 (15)
C9	0.076 (2)	0.0466 (16)	0.070 (2)	0.0094 (15)	0.0246 (18)	−0.0002 (15)
C12	0.086 (2)	0.0593 (19)	0.0509 (17)	0.0353 (18)	0.0057 (16)	0.0033 (14)
C10	0.124 (4)	0.0455 (17)	0.067 (2)	0.027 (2)	0.044 (2)	0.0101 (16)
C11	0.141 (4)	0.063 (2)	0.0536 (19)	0.053 (3)	0.023 (2)	0.0178 (16)

Geometric parameters (Å, º)

S1—C6	1.814 (3)	C17—H17	0.96 (4)
S1—C2	1.830 (3)	C3—H31	0.94 (4)
O1—C4	1.210 (3)	C3—H32	0.99 (3)
C13—C14	1.378 (4)	C8—C9	1.394 (4)
C13—C18	1.383 (4)	C8—H8	0.95 (3)
C13—C6	1.517 (3)	C14—C15	1.384 (4)
C7—C8	1.380 (4)	C14—H14	0.90 (3)
C7—C12	1.395 (4)	C16—C15	1.369 (5)
C7—C2	1.513 (4)	C16—H16	0.97 (4)
C4—C3	1.496 (4)	C18—H18	0.97 (3)
C4—C5	1.512 (4)	C15—H15	0.94 (4)
C6—C5	1.530 (3)	C9—C10	1.369 (6)
C6—H6	1.02 (3)	C9—H9	0.96 (4)
C2—C3	1.528 (4)	C12—C11	1.377 (6)
C2—H2	0.96 (3)	C12—H12	0.94 (4)
C5—H51	0.94 (3)	C10—C11	1.364 (7)
C5—H52	0.94 (3)	C10—H10	1.04 (5)
C17—C16	1.364 (5)	C11—H11	0.86 (4)
C17—C18	1.386 (4)
C6—S1—C2	99.25 (13)	C4—C3—H31	105 (2)
C14—C13—C18	118.2 (2)	C2—C3—H31	107 (2)
C14—C13—C6	122.9 (2)	C4—C3—H32	109.5 (19)
C18—C13—C6	118.8 (2)	C2—C3—H32	109.9 (19)
C8—C7—C12	117.6 (3)	H31—C3—H32	109 (3)
C8—C7—C2	123.4 (3)	C7—C8—C9	121.1 (3)
C12—C7—C2	119.0 (3)	C7—C8—H8	123.4 (19)
O1—C4—C3	121.4 (2)	C9—C8—H8	115.6 (19)
O1—C4—C5	120.0 (3)	C13—C14—C15	120.7 (3)
C3—C4—C5	118.5 (2)	C13—C14—H14	121 (2)
C13—C6—C5	110.6 (2)	C15—C14—H14	118 (2)
C13—C6—S1	110.64 (17)	C17—C16—C15	119.7 (3)
C5—C6—S1	110.82 (18)	C17—C16—H16	119 (2)
C13—C6—H6	109.8 (15)	C15—C16—H16	121 (2)
C5—C6—H6	109.8 (15)	C13—C18—C17	120.8 (3)
S1—C6—H6	105.1 (15)	C13—C18—H18	120.1 (19)
C7—C2—C3	115.8 (2)	C17—C18—H18	119.1 (19)
C7—C2—S1	111.69 (18)	C16—C15—C14	120.4 (3)
C3—C2—S1	110.58 (19)	C16—C15—H15	122 (2)
C7—C2—H2	109.1 (17)	C14—C15—H15	118 (2)
C3—C2—H2	109.8 (17)	C10—C9—C8	120.1 (4)
S1—C2—H2	98.4 (18)	C10—C9—H9	121 (2)
C4—C5—C6	113.7 (2)	C8—C9—H9	119 (2)
C4—C5—H51	107.5 (18)	C11—C12—C7	120.9 (4)
C6—C5—H51	107.2 (18)	C11—C12—H12	127 (2)
C4—C5—H52	109 (2)	C7—C12—H12	112 (2)
C6—C5—H52	111.7 (19)	C11—C10—C9	119.6 (4)
H51—C5—H52	108 (3)	C11—C10—H10	125 (3)
C16—C17—C18	120.2 (3)	C9—C10—H10	116 (3)
C16—C17—H17	121 (3)	C10—C11—C12	120.8 (4)
C18—C17—H17	118 (3)	C10—C11—H11	121 (3)
C4—C3—C2	115.9 (2)	C12—C11—H11	118 (3)
C14—C13—C6—C5	92.9 (3)	C7—C2—C3—C4	−74.2 (3)
C18—C13—C6—C5	−85.9 (3)	S1—C2—C3—C4	54.1 (3)
C14—C13—C6—S1	−30.3 (3)	C12—C7—C8—C9	0.3 (4)
C18—C13—C6—S1	150.9 (2)	C2—C7—C8—C9	−178.1 (3)
C2—S1—C6—C13	−178.90 (17)	C18—C13—C14—C15	0.1 (4)
C2—S1—C6—C5	58.0 (2)	C6—C13—C14—C15	−178.7 (3)
C8—C7—C2—C3	9.2 (3)	C18—C17—C16—C15	−0.5 (5)
C12—C7—C2—C3	−169.2 (2)	C14—C13—C18—C17	−0.6 (4)
C8—C7—C2—S1	−118.6 (2)	C6—C13—C18—C17	178.2 (2)
C12—C7—C2—S1	63.0 (3)	C16—C17—C18—C13	0.9 (5)
C6—S1—C2—C7	75.0 (2)	C17—C16—C15—C14	0.0 (5)
C6—S1—C2—C3	−55.6 (2)	C13—C14—C15—C16	0.3 (5)
O1—C4—C5—C6	−131.7 (3)	C7—C8—C9—C10	0.0 (5)
C3—C4—C5—C6	50.6 (3)	C8—C7—C12—C11	−0.4 (4)
C13—C6—C5—C4	179.1 (2)	C2—C7—C12—C11	178.0 (3)
S1—C6—C5—C4	−57.8 (3)	C8—C9—C10—C11	−0.1 (5)
O1—C4—C3—C2	133.1 (3)	C9—C10—C11—C12	0.0 (5)
C5—C4—C3—C2	−49.3 (3)	C7—C12—C11—C10	0.3 (5)