Conformational preferences and supramolecular aggregation in 2-nitro­phenyl­thiol­ates: 2-nitro­phenyl-[beta]-D-thio­galacto­pyran­oside

In the title compound, C₁₂H₁₅NO₇S, the molecular conformation shows a concerted disrotatory twist of the nitro group and the galactose fragment out of the plane of the aryl ring. The mol­ecules are linked by O-H...O hydrogen bonds [O...O range 2.725 (2)-3.024 (2) Å and O-H...O range 155-175°] to form a three-dimensional framework.

S1. Comment

We have recently discussed the interplay between molecular conformation and intermolecular forces, particularly soft hydrogen bonds of the C—H···O type, in a range of 2-nitrophenylthiolates, 2-O₂NC₆H₄SX (Low, Storey et al., 2000; Low, Glidewell & Wardell, 2000; Glidewell et al., 2000). Two distinct conformational types can be observed in this series of compounds: in one conformation, corresponding to the global energy minimum, both the nitro group and α-atom of substituent X are effectively coplanar with the nitrated aryl ring; the second conformer, in which the nitro group and the substituent X exhibit a significant and concerted twist out of the aryl ring plane, represents a local energy minimum and seems to occur only in the presence of intermolecular hydrogen bonds. As a further test of this idea, we report here a structural investigation of 2-nitrophenyl-β-D-thiogalactopyranoside, (I), selected for study because of the potential of the galactose fragment for the formation of multiple intermolecular O—H···O hydrogen bonds.

The nitro group in (I) (Fig. 1) is twisted out of the plane of the adjacent aryl ring and this is accompanied by the usual (Low, Storey et al., 2000; Low, Glidewell & Wardell, 2000; Glidewell et al., 2000) disrotatory twist of the S substituent out of this plane, as illustrated by the torsion angles C11—C12—N1—O11 and C12—C11—S1—C21 (Table 1). The extensive hydrogen bonding described below involves the nitro O11 atom as one of the hydrogen-bond acceptors. The β-D-galactopyranoside fragment adopts the usual chair conformation (Longchambon et al., 1975; Sheldrick, 1976), with all substituents other than O4 in equatorial sites.

The bond lengths in the nitroaryl ring portion (Table 1) do not show the marked quinonoid bond fixation observed in 2-O₂NC₆H₄SCH═CHPh (Low, Storey et al., 2000). The C—O bond lengths in the galactose fragment show the usual difference between C21—O5 and C25—O5; the exocyclic C—O bonds span the range 1.4151 (17)–1.4358 (17) Å, whereas in β-D-galactopyranose itself, the exocyclic C—O bond distances are all of similar lengths, apart from the hemiacetal bond at C1 (Sheldrick, 1976).

The molecules of (I) are linked by four different hydrogen bonds: O3 is both a hydrogen-bond donor and a double acceptor, O6 is both a donor and acceptor, O4 is a donor only and the nitro O11 atom is a single acceptor (Table 2). Each molecule acts as a hydrogen-bond donor to three others and as a hydrogen-bond acceptor from three further molecules, and the overall supramolecular structure takes the form of a three-dimensional framework, which is best analysed in terms of the interaction of the individual motifs parallel to [100], [010] and [001]. Atoms O4 and O6 in the molecule at (x, y, z) both act as donor to O3 in the molecule at (−1/2 + x, 3/2 − y, 1 − z), while O4 and O6 at (−1/2 + x, 3/2 − y, 1 − z), in turn, are donors to O3 at (−1 + x, y, z), and propagation of these interactions produces a spiral chain generated by the 2₁ screw axis along (x, 3/4, 1/2). The O4 and O6 donors individually generate C(5) and C(7) (Bernstein et al., 1995) spirals along [100]; embedded in the spiral chains are R¹₂(8) rings. At the same time, O2 in the molecule at (x, y, z) acts as donor to O6 at (1 + x, y, z), so producing by translation a C(8) chain parallel to [100]. The combination of this chain with the C(5) spiral generates a chain of fused R³₃(16) rings parallel to [100] (Fig. 2)

Atom O3 at (x, y, z) is itself a hydrogen-bond donor to O11 at (2 − x, 1/2 + y, 3/2 − z), while O3 at (2 − x, 1/2 + y, 3/2 − z) is a donor to O11 at (x, 1 + y, z); this hydrogen bond thus produces a C(10) spiral parallel to [010] generated by the 2₁ screw axis along (1, y, 3/4) (Fig. 3). The combination of the two types of spiral along [100] and [010], respectively, generates a third type of spiral, a C²₂(15) chain parallel to [001], in which alternate molecules act as donor donors and double acceptors of hydrogen bonds (Fig. 4). The [100] and [010] spirals can each be constructed using a single type of hydrogen bond; concurrent use of these two types generates the [001] spiral. By means of these three motifs parallel to [100], [010] and [001], the molecule at (x, y, z) is linked to those at (±1 + x, y, z), (x, ±1 + y, z) and (x, y, ±1 + z), so that a single framework is sufficient to define the entire crystal structure.

S2. Experimental

A sample of compound (I) was obtained from Aldrich. Crystals suitable for single-crystal X-ray diffraction analysis were grown from a solution in ethanol.

S3. Refinement

Compound (I) crystallized in the orthorhombic system; space group P2₁2₁2₁ was assigned uniquely from the systematic absences. H atoms were treated as riding atoms, with C—H = 0.93–0.98 Å and O—H = 0.82 Å. Examination of the structure with PLATON (Spek, 2000) showed that there were no solvent-accessible voids in the crystal lattice.

Computing details

Data collection: XPREP (Bruker, 1997); cell refinement: XPREP; data reduction: XPREP; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976) and PLATON (Spek, 2000); software used to prepare material for publication: SHELXL97 and WORDPERFECT macro PRPKAPPA (Ferguson, 1999).

Figures

	Fig. 1. The asymmetric unit of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. Part of the crystal structure of (I) showing a chain of fused R^33(16) rings parallel to [100]. For the sake of clarity, only the H atoms involved in the motif shown are drawn. The atoms marked with a star (*) or hash (#) are at the symmetry positions (−1/2 + x, 3/2 − y, 1 − z) and (1 + x, y, z), respectively.
	Fig. 3. Part of the crystal structure of (I) showing a C(10) spiral parallel to [010]. For the sake of clarity only the H atoms involved in the motif shown are drawn. The atom marked with a star (*) is at the symmetry position (2 − x, 1/2 + y, 3/2 − z).
	Fig. 4. Part of the crystal structure of (I) showing a C^22(15) spiral parallel to [001]. For the sake of clarity, only the H atoms involved in the motif shown are drawn. The atoms marked with a star (*) or hash (#) are at the symmetry positions (−1/2 + x, 3/2 − y, 1 − z) and (2 − x, 1/2 + y, 3/2 − z), respectively.

2-Nitrophenyl-β-D-thiogalactopyranoside

Crystal data

C12H15NO7S	Dx = 1.559 Mg m^−3
Mr = 317.31	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 3097 reflections
a = 8.2214 (4) Å	θ = 2.3–27.4°
b = 11.4293 (5) Å	µ = 0.27 mm^−1
c = 14.3861 (6) Å	T = 298 K
V = 1351.79 (10) Å^3	Block, yellow
Z = 4	0.37 × 0.30 × 0.30 mm
F(000) = 664

Data collection

KappaCCD diffractometer	3097 independent reflections
Radiation source: fine-focus sealed X-ray tube	2874 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
ϕ and ω scans with κ offsets	θmax = 27.4°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 1997)	h = −10→7
Tmin = 0.905, Tmax = 0.922	k = −14→14
10075 measured reflections	l = −18→18

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)] = 0.027	H-atom parameters constrained
wR(F^2) = 0.074	w = 1/[σ^2(Fo^2) + (0.051P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
3097 reflections	Δρmax = 0.23 e Å^−3
188 parameters	Δρmin = −0.21 e Å^−3
0 restraints	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.03 (6)

Special details

Geometry. Mean-plane data from the final SHELXL97 refinement run:-

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

	x	y	z	Uiso*/Ueq
S1	0.77449 (5)	0.61321 (4)	0.81936 (2)	0.03595 (10)
C11	0.71053 (17)	0.60652 (12)	0.93619 (9)	0.0288 (3)
C12	0.81725 (18)	0.57723 (12)	1.00849 (10)	0.0304 (3)
N1	0.99067 (17)	0.55948 (11)	0.99031 (9)	0.0369 (3)
O11	1.03245 (16)	0.52698 (13)	0.91302 (9)	0.0552 (4)
O12	1.08659 (16)	0.57771 (12)	1.05384 (9)	0.0542 (3)
C13	0.7683 (2)	0.56643 (15)	1.10035 (11)	0.0403 (4)
C14	0.6093 (2)	0.58725 (16)	1.12318 (11)	0.0458 (4)
C15	0.5008 (2)	0.62165 (16)	1.05453 (12)	0.0423 (4)
C16	0.54973 (19)	0.62961 (14)	0.96273 (11)	0.0353 (3)
C21	0.62772 (17)	0.71145 (13)	0.76760 (9)	0.0306 (3)
C22	0.71078 (17)	0.76739 (12)	0.68327 (10)	0.0303 (3)
O2	0.84180 (15)	0.83866 (11)	0.71266 (8)	0.0452 (3)
C23	0.59022 (19)	0.84516 (13)	0.63260 (10)	0.0314 (3)
O3	0.66404 (13)	0.88920 (10)	0.54919 (7)	0.0399 (2)
C24	0.43542 (18)	0.78063 (13)	0.60848 (10)	0.0315 (3)
O4	0.47163 (14)	0.69812 (11)	0.53711 (7)	0.0401 (3)
C25	0.36809 (17)	0.72243 (14)	0.69650 (10)	0.0331 (3)
C26	0.2202 (2)	0.64512 (16)	0.68063 (12)	0.0433 (4)
O6	0.09260 (10)	0.71183 (8)	0.64071 (8)	0.0573 (4)
O5	0.48775 (10)	0.64780 (8)	0.73943 (7)	0.0337 (2)
H13	0.8428	0.5453	1.1460	0.048*
H14	0.5742	0.5784	1.1842	0.055*
H15	0.3940	0.6396	1.0704	0.051*
H16	0.4742	0.6508	0.9176	0.042*
H21	0.5969	0.7721	0.8124	0.037*
H22	0.7507	0.7063	0.6413	0.036*
H2	0.9281	0.8063	0.7002	0.054*
H23	0.5628	0.9115	0.6728	0.038*
H3	0.7480	0.9241	0.5624	0.060*
H24	0.3553	0.8368	0.5850	0.038*
H4	0.3887	0.6623	0.5231	0.060*
H25	0.3384	0.7839	0.7408	0.040*
H26A	0.2487	0.5811	0.6395	0.052*
H26B	0.1845	0.6122	0.7393	0.052*
H6	0.0852	0.6964	0.5852	0.086*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.03172 (18)	0.0494 (2)	0.02675 (16)	0.01206 (17)	−0.00061 (14)	0.00108 (15)
C11	0.0280 (7)	0.0307 (6)	0.0277 (6)	−0.0007 (6)	−0.0014 (5)	−0.0009 (5)
C12	0.0280 (8)	0.0301 (6)	0.0330 (7)	0.0032 (5)	−0.0020 (6)	−0.0007 (5)
N1	0.0330 (7)	0.0378 (6)	0.0397 (7)	0.0087 (6)	−0.0038 (6)	0.0028 (6)
O11	0.0453 (7)	0.0764 (9)	0.0440 (7)	0.0283 (7)	0.0025 (6)	0.0005 (6)
O12	0.0364 (6)	0.0650 (8)	0.0611 (8)	0.0055 (6)	−0.0171 (6)	−0.0064 (6)
C13	0.0447 (9)	0.0456 (8)	0.0306 (7)	0.0022 (8)	−0.0064 (7)	0.0011 (6)
C14	0.0499 (10)	0.0566 (10)	0.0309 (8)	0.0023 (9)	0.0087 (7)	0.0010 (7)
C15	0.0321 (8)	0.0490 (9)	0.0457 (9)	0.0004 (7)	0.0103 (7)	−0.0019 (7)
C16	0.0266 (7)	0.0417 (8)	0.0377 (7)	0.0012 (6)	−0.0013 (6)	0.0033 (6)
C21	0.0254 (7)	0.0390 (7)	0.0272 (6)	0.0034 (6)	−0.0031 (5)	0.0001 (6)
C22	0.0240 (6)	0.0370 (7)	0.0297 (6)	0.0002 (6)	−0.0016 (6)	−0.0014 (6)
O2	0.0293 (6)	0.0516 (6)	0.0547 (7)	−0.0093 (5)	−0.0084 (5)	0.0009 (5)
C23	0.0288 (7)	0.0342 (7)	0.0311 (7)	0.0031 (6)	0.0016 (6)	0.0001 (5)
O3	0.0369 (6)	0.0446 (6)	0.0384 (5)	−0.0051 (5)	0.0008 (5)	0.0094 (5)
C24	0.0272 (7)	0.0379 (7)	0.0293 (7)	0.0060 (6)	−0.0036 (6)	0.0002 (6)
O4	0.0379 (6)	0.0514 (6)	0.0311 (5)	−0.0070 (5)	0.0019 (5)	−0.0083 (5)
C25	0.0240 (7)	0.0457 (8)	0.0295 (7)	0.0046 (6)	−0.0006 (5)	−0.0007 (6)
C26	0.0252 (7)	0.0657 (10)	0.0389 (8)	−0.0046 (7)	−0.0003 (7)	0.0041 (8)
O6	0.0268 (6)	0.1052 (11)	0.0399 (6)	0.0087 (7)	−0.0053 (5)	0.0005 (7)
O5	0.0255 (5)	0.0426 (5)	0.0330 (5)	−0.0012 (4)	−0.0041 (4)	0.0055 (4)

Geometric parameters (Å, º)

C11—C12	1.4013 (19)	O2—H2	0.8200
C12—C13	1.387 (2)	C23—O3	1.4358 (17)
C13—C14	1.369 (3)	C23—C24	1.511 (2)
C14—C15	1.388 (2)	C23—H23	0.9800
C15—C16	1.384 (2)	O3—H3	0.8200
C16—C11	1.401 (2)	C24—O4	1.4255 (18)
C12—N1	1.464 (2)	C24—C25	1.534 (2)
N1—O11	1.2215 (18)	C24—H24	0.9800
N1—O12	1.2250 (18)	O4—H4	0.8200
C13—H13	0.9300	C25—O5	1.4412 (16)
C14—H14	0.9300	C25—C26	1.520 (2)
C15—H15	0.9300	C25—H25	0.9800
C16—H16	0.9300	C26—O6	1.4186 (19)
C21—O5	1.4205 (16)	C26—H26A	0.9700
C21—C22	1.5320 (19)	C26—H26B	0.9700
C21—H21	0.9800	O6—H6	0.8200
C22—O2	1.4151 (17)	S1—C11	1.7628 (14)
C22—C23	1.518 (2)	S1—C21	1.8086 (14)
C22—H22	0.9800
C11—S1—C21	102.73 (7)	C23—C22—H22	109.9
C16—C11—C12	115.70 (13)	C21—C22—H22	109.9
C16—C11—S1	122.21 (11)	C22—O2—H2	109.5
C12—C11—S1	122.09 (11)	O3—C23—C24	109.58 (12)
C13—C12—C11	123.15 (14)	O3—C23—C22	109.31 (12)
C13—C12—N1	116.14 (13)	C24—C23—C22	111.98 (12)
C11—C12—N1	120.69 (13)	O3—C23—H23	108.6
O11—N1—O12	123.35 (15)	C24—C23—H23	108.6
O11—N1—C12	118.60 (13)	C22—C23—H23	108.6
O12—N1—C12	118.04 (14)	C23—O3—H3	109.5
C14—C13—C12	119.36 (15)	O4—C24—C23	108.20 (12)
C14—C13—H13	120.3	O4—C24—C25	112.52 (12)
C12—C13—H13	120.3	C23—C24—C25	109.03 (12)
C13—C14—C15	119.49 (15)	O4—C24—H24	109.0
C13—C14—H14	120.3	C23—C24—H24	109.0
C15—C14—H14	120.3	C25—C24—H24	109.0
C16—C15—C14	120.74 (16)	C24—O4—H4	109.5
C16—C15—H15	119.6	O5—C25—C26	105.44 (13)
C14—C15—H15	119.6	O5—C25—C24	111.36 (11)
C15—C16—C11	121.46 (15)	C26—C25—C24	114.64 (12)
C15—C16—H16	119.3	O5—C25—H25	108.4
C11—C16—H16	119.3	C26—C25—H25	108.4
O5—C21—C22	110.42 (11)	C24—C25—H25	108.4
O5—C21—S1	109.88 (9)	O6—C26—C25	109.87 (13)
C22—C21—S1	106.72 (9)	O6—C26—H26A	109.7
O5—C21—H21	109.9	C25—C26—H26A	109.7
C22—C21—H21	109.9	O6—C26—H26B	109.7
S1—C21—H21	109.9	C25—C26—H26B	109.7
O2—C22—C23	107.66 (12)	H26A—C26—H26B	108.2
O2—C22—C21	110.05 (11)	C26—O6—H6	109.5
C23—C22—C21	109.49 (12)	C21—O5—C25	111.85 (10)
O2—C22—H22	109.9
C21—S1—C11—C16	24.36 (14)	S1—C21—C22—C23	176.28 (9)
C21—S1—C11—C12	−155.93 (12)	S1—C21—O5—C25	−179.18 (9)
C16—C11—C12—C13	2.6 (2)	O5—C21—C22—C23	56.89 (15)
S1—C11—C12—C13	−177.11 (12)	O2—C22—C23—O3	65.42 (14)
C16—C11—C12—N1	−175.59 (13)	C21—C22—C23—O3	−174.95 (11)
S1—C11—C12—N1	4.69 (19)	O2—C22—C23—C24	−172.96 (12)
C13—C12—N1—O11	154.42 (15)	C21—C22—C23—C24	−53.32 (15)
C11—C12—N1—O11	−27.3 (2)	O3—C23—C24—O4	51.02 (15)
C13—C12—N1—O12	−25.3 (2)	C22—C23—C24—O4	−70.45 (15)
C11—C12—N1—O12	152.99 (14)	O3—C23—C24—C25	173.70 (12)
C11—C12—C13—C14	−1.3 (2)	C22—C23—C24—C25	52.23 (16)
N1—C12—C13—C14	176.96 (15)	O4—C24—C25—O5	64.90 (15)
C12—C13—C14—C15	−1.6 (3)	C23—C24—C25—O5	−55.14 (16)
C13—C14—C15—C16	3.1 (3)	C24—C25—O5—C21	61.34 (15)
C14—C15—C16—C11	−1.8 (3)	O4—C24—C25—C26	−54.69 (17)
C12—C11—C16—C15	−1.1 (2)	C23—C24—C25—C26	−174.73 (13)
S1—C11—C16—C15	178.66 (13)	O5—C25—C26—O6	178.30 (12)
C11—S1—C21—O5	−85.82 (10)	C24—C25—C26—O6	−58.86 (17)
C11—S1—C21—C22	154.44 (10)	C25—O5—C21—C22	−61.72 (14)
O5—C21—C22—O2	175.05 (11)	C26—C25—O5—C21	−173.75 (11)
S1—C21—C22—O2	−65.57 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O6^i	0.82	1.93	2.725 (2)	163
O3—H3···O11^ii	0.82	2.18	3.000 (2)	175
O4—H4···O3^iii	0.82	2.20	2.989 (2)	161
O6—H6···O3^iii	0.82	2.26	3.024 (2)	155

Symmetry codes: (i) x+1, y, z; (ii) −x+2, y+1/2, −z+3/2; (iii) x−1/2, −y+3/2, −z+1.