Conformational analysis: crystallographic, molecular mechanics and quantum chemical studies of C—H...O hydrogen bonding in the flexible bis(nosylate) derivative of catechol

The single-crystal X-ray diffraction analysis of 2-{[(4-nitrophenoxy)sulfonyl]oxy}phenyl 4-nitrophenyl sulfate (4) reveals that an interesting intermolecular or extended structure (a one-dimensional hydrogen-bonded polymer) is formed because of pairs of intermolecular (aryl)C—H...O(nitro) hydrogen bonds between the C₂ symmetry monomer units. The axis of the hydrogen-bonded polymer runs co-linear with the [101] face diagonal of the monoclinic unit cell. Molecular mechanics calculations using a modified version of the MM+ force field and a random conformational search algorithm have been used to locate the important low-energy in vacuo conformations of (4). The MM-calculated conformation of (4) that most closely matches the X-ray structure lies some 26.5 kJ mol⁻¹ higher in energy than the global minimum-energy conformation, consistent with the notion that the crystallographically observed molecular architecture of (4) is a local energy minimum in the absence of its crystal lattice environment. Since the X-ray conformation of (4) was correctly calculated only when all of the neighbouring molecules in the crystal lattice were included in the simulation, hydrogen bonding and other non-bonded interactions in the crystal lattice clearly dictate the experimentally observed conformation of (4). Quantum chemical calculations (AM1 method) confirm the critical role played by the intermolecular (aryl)C—H...O(nitro) hydrogen bonds in controlling the crystallographically observed conformation of (4) and show that self-recognition in this system by hydrogen bonding is favoured on electrostatic grounds. Collectively, the molecular simulations suggest that because the lowest-energy molecular conformation of (4) does not permit the formation of an extended hydrogen-bonded `supramolecular' structure, it is not the preferred conformation in the crystalline solid state.

Computing details

Data collection: CrysAlis CCD 170 (Oxford Diffraction,2002); cell refinement: CrysAlis CCD 170 (Oxford Diffraction,2002); data reduction: CrysAlis RED 170 (Oxford Diffraction,2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: WinGX (Farrugia, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

2-{[(4-nitrophenoxy)sulfonyl]oxy}phenyl 4-nitrophenyl sulfate

Crystal data

C18H12N2O10S2	F(000) = 984
Mr = 480.42	Dx = 1.680 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 105 reflections
a = 11.667 (11) Å	θ = 4–32°
b = 10.803 (11) Å	µ = 0.35 mm^−1
c = 15.868 (16) Å	T = 100 K
β = 108.20 (9)°	Plate, colorless
V = 1900 (3) Å^3	0.50 × 0.40 × 0.10 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur 2 CCD diffractometer	3744 independent reflections
Radiation source: fine-focus sealed tube	3259 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ω–2θ scans	θmax = 34.1°, θmin = 4.6°
Absorption correction: multi-scan [c.f. r.h. blessing, acta cryst. (1995), a51, 33-38]	h = −18→18
Tmin = 0.846, Tmax = 0.966	k = −16→16
38881 measured reflections	l = −24→24

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.046	Hydrogen site location: difference Fourier map
wR(F^2) = 0.116	All H-atom parameters refined
S = 1.15	w = 1/[σ^2(Fo^2) + (0.049P)^2 + 2.7297P] where P = (Fo^2 + 2Fc^2)/3
3744 reflections	(Δ/σ)max < 0.001
169 parameters	Δρmax = 0.52 e Å^−3
0 restraints	Δρmin = −0.45 e Å^−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.

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.

All H atoms were cleanly located by difference Fourier synthesis and refined isotropically without restraints.

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

	x	y	z	Uiso*/Ueq
H2	0.154 (2)	0.819 (2)	0.0184 (15)	0.031 (5)*
H3	0.252 (2)	0.937 (2)	−0.0687 (16)	0.039 (6)*
H5	0.398 (2)	1.161 (2)	0.1430 (15)	0.034 (6)*
H6	0.313 (2)	1.038 (2)	0.2323 (15)	0.033 (6)*
H8	0.044 (2)	1.113 (2)	0.1134 (15)	0.032 (6)*
H9	0.0217 (19)	1.306 (2)	0.1819 (14)	0.027 (5)*
C1	0.22656 (11)	0.91878 (11)	0.13181 (8)	0.0153 (2)
C2	0.20539 (12)	0.88710 (12)	0.04331 (9)	0.0191 (2)
C3	0.26129 (13)	0.95543 (13)	−0.00709 (9)	0.0208 (2)
C4	0.33125 (11)	1.05558 (13)	0.03261 (9)	0.0191 (2)
C5	0.35078 (12)	1.09010 (13)	0.11985 (10)	0.0209 (2)
C6	0.29900 (12)	1.01842 (12)	0.17140 (9)	0.0187 (2)
C7	0.01307 (11)	1.00559 (11)	0.21010 (8)	0.0150 (2)
C8	0.02508 (12)	1.11599 (12)	0.16954 (9)	0.0195 (2)
C9	0.01233 (13)	1.22755 (13)	0.21008 (10)	0.0226 (3)
N1	0.39164 (11)	1.12738 (13)	−0.02011 (9)	0.0252 (2)
O1	0.42353 (11)	1.07070 (13)	−0.07604 (8)	0.0340 (3)
O2	0.40623 (13)	1.23840 (12)	−0.00470 (9)	0.0373 (3)
O3	0.21499 (9)	0.85264 (10)	0.28683 (6)	0.02118 (19)
O4	0.13349 (9)	0.70950 (9)	0.16017 (7)	0.02152 (19)
O5	0.02323 (8)	0.89236 (9)	0.16955 (6)	0.01697 (17)
S1	0.15557 (3)	0.83196 (3)	0.19503 (2)	0.01558 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0137 (5)	0.0166 (5)	0.0175 (5)	−0.0004 (4)	0.0076 (4)	−0.0010 (4)
C2	0.0197 (6)	0.0208 (5)	0.0174 (5)	−0.0034 (4)	0.0066 (4)	−0.0024 (4)
C3	0.0198 (6)	0.0266 (6)	0.0165 (5)	−0.0011 (5)	0.0064 (4)	0.0002 (4)
C4	0.0142 (5)	0.0221 (5)	0.0219 (5)	0.0006 (4)	0.0070 (4)	0.0050 (4)
C5	0.0180 (6)	0.0204 (5)	0.0252 (6)	−0.0043 (4)	0.0083 (5)	−0.0015 (4)
C6	0.0172 (5)	0.0205 (5)	0.0200 (5)	−0.0046 (4)	0.0080 (4)	−0.0051 (4)
C7	0.0112 (5)	0.0186 (5)	0.0158 (5)	−0.0006 (4)	0.0050 (4)	−0.0004 (4)
C8	0.0163 (5)	0.0224 (6)	0.0217 (6)	0.0007 (4)	0.0089 (4)	0.0035 (4)
C9	0.0189 (6)	0.0186 (5)	0.0326 (7)	0.0004 (4)	0.0115 (5)	0.0026 (5)
N1	0.0156 (5)	0.0351 (6)	0.0244 (6)	−0.0016 (4)	0.0054 (4)	0.0117 (5)
O1	0.0254 (5)	0.0512 (7)	0.0303 (6)	0.0108 (5)	0.0160 (5)	0.0182 (5)
O2	0.0379 (7)	0.0361 (6)	0.0343 (6)	−0.0160 (5)	0.0062 (5)	0.0109 (5)
O3	0.0169 (4)	0.0305 (5)	0.0161 (4)	0.0005 (4)	0.0050 (3)	0.0019 (3)
O4	0.0238 (5)	0.0161 (4)	0.0268 (5)	−0.0015 (3)	0.0110 (4)	−0.0003 (3)
O5	0.0132 (4)	0.0207 (4)	0.0182 (4)	−0.0010 (3)	0.0066 (3)	−0.0030 (3)
S1	0.01401 (14)	0.01714 (14)	0.01688 (14)	−0.00016 (9)	0.00667 (10)	0.00053 (9)

Geometric parameters (Å, º)

C1—C2	1.391 (2)	C7—C8	1.383 (2)
C1—C6	1.391 (2)	C7—C7^i	1.392 (3)
C1—S1	1.7581 (17)	C7—O5	1.4042 (19)
C2—C3	1.391 (2)	C8—C9	1.396 (2)
C2—H2	0.95 (2)	C8—H8	0.98 (2)
C3—C4	1.383 (2)	C9—C9^i	1.384 (3)
C3—H3	0.97 (2)	C9—H9	0.98 (2)
C4—C5	1.382 (2)	N1—O2	1.225 (2)
C4—N1	1.472 (2)	N1—O1	1.228 (2)
C5—C6	1.394 (2)	O3—S1	1.4219 (19)
C5—H5	0.95 (2)	O4—S1	1.4259 (16)
C6—H6	0.95 (2)	O5—S1	1.6072 (17)
C2—C1—C6	122.52 (12)	C8—C7—O5	120.17 (13)
C2—C1—S1	118.56 (11)	C7^i—C7—O5	119.38 (7)
C6—C1—S1	118.89 (11)	C7—C8—C9	119.29 (14)
C1—C2—C3	118.86 (13)	C7—C8—H8	118.2 (13)
C1—C2—H2	119.8 (13)	C9—C8—H8	122.5 (13)
C3—C2—H2	121.3 (13)	C9^i—C9—C8	120.29 (9)
C4—C3—C2	117.98 (13)	C9^i—C9—H9	120.1 (12)
C4—C3—H3	118.8 (14)	C8—C9—H9	119.6 (12)
C2—C3—H3	123.2 (14)	O2—N1—O1	125.30 (14)
C5—C4—C3	123.82 (13)	O2—N1—C4	117.63 (14)
C5—C4—N1	117.95 (14)	O1—N1—C4	117.06 (15)
C3—C4—N1	118.20 (13)	C7—O5—S1	116.77 (9)
C4—C5—C6	118.15 (13)	O3—S1—O4	120.95 (7)
C4—C5—H5	119.9 (14)	O3—S1—O5	108.45 (10)
C6—C5—H5	122.0 (14)	O4—S1—O5	103.66 (8)
C1—C6—C5	118.58 (13)	O3—S1—C1	109.57 (9)
C1—C6—H6	121.2 (14)	O4—S1—C1	109.51 (8)
C5—C6—H6	120.3 (14)	O5—S1—C1	103.10 (8)
C8—C7—C7^i	120.41 (8)
C6—C1—C2—C3	1.8 (2)	C3—C4—N1—O2	148.12 (14)
S1—C1—C2—C3	180.00 (10)	C5—C4—N1—O1	146.11 (14)
C1—C2—C3—C4	−2.9 (2)	C3—C4—N1—O1	−32.00 (18)
C2—C3—C4—C5	1.4 (2)	C8—C7—O5—S1	90.88 (15)
C2—C3—C4—N1	179.36 (12)	C7^i—C7—O5—S1	−91.21 (17)
C3—C4—C5—C6	1.3 (2)	C7—O5—S1—O3	38.27 (10)
N1—C4—C5—C6	−176.65 (12)	C7—O5—S1—O4	167.99 (9)
C2—C1—C6—C5	0.9 (2)	C7—O5—S1—C1	−77.84 (12)
S1—C1—C6—C5	−177.26 (10)	C2—C1—S1—O3	162.48 (11)
C4—C5—C6—C1	−2.5 (2)	C6—C1—S1—O3	−19.24 (12)
C7^i—C7—C8—C9	0.9 (2)	C2—C1—S1—O4	27.66 (13)
O5—C7—C8—C9	178.75 (12)	C6—C1—S1—O4	−154.07 (11)
C7—C8—C9—C9^i	−0.1 (2)	C2—C1—S1—O5	−82.20 (14)
C5—C4—N1—O2	−33.77 (19)	C6—C1—S1—O5	96.07 (14)

Symmetry code: (i) −x, y, −z+1/2.