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The title keto acid, (+)-23,24-dinor-3-oxo­chol-4-en-22-oic acid, C22H32O3, forms carboxyl-to-ketone hydrogen-bonding catemers [O...O = 2.699 (4) Å and O—H...O = 173°], linking mol­ecules screw-related in b. The four mol­ecules in the cell form two parallel counter-directional chains, screw-related in a. Intermolecular C—H...O=C close contacts to different neighboring mol­ecules were found for the ketone and the acid.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101018601/fr1353sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101018601/fr1353Isup2.hkl
Contains datablock I

CCDC reference: 180158

Comment top

Our interest in the crystal structures of keto carboxylic acids concerns the molecular characteristics that control their five known hydrogen-bonding patterns. The acid dimers that characterize functionally unelaborated acids also predominate generally in keto acids. However, in non-racemates with significant conformational restrictions, the prevalence of acid-to-ketone catemers rises dramatically (Brunskill et al., 1999). Consequently, we have sought subject materials with terpenoid origins, and now report the crystal structure and hydrogen-bonding behavior of (I), the seventh in our series of steroidal keto acids.

Fig. 1 shows the asymmetric unit of (I) with its steroid numbering. Among the few conformational options present, the substituents at C20, which has the S configuration, are staggered with respect to those at C17, so that the C16—C17—C20—C21 torsion angle is 176.8 (3)°. The carboxyl plane coincides approximately with the C20—H20 bond, but the carboxyl group is turned with its carbonyl toward the bottom (α) face of the molecule [torsion angle C17—C20—C22—O2 = 73.8 (6)°]. In both of the steroids we have previously examined having this 23,24-dinor-22-oic acid side chain, the hydrogen-bonding patterns are very different from that in (I), and in both, the carboxyl carbonyl is oriented β (Lalancette et al., 1998; Thompson et al., 1999).

Complete or partial averaging of carboxyl C—O bond lengths and C—C—O angles by disorder is frequent in hydrogen-bonding dimers (Leiserowitz, 1976). However, catemers, hydrates and other hydrogen-bonding structures whose geometry precludes the usual carboxyl-disordering processes are highly ordered, as is found here. Our own survey of 56 keto acid structures which are not acid dimers gives average values of 1.20 (1) and 1.32 (2) Å, and 124.5 (14) and 112.7 (17)° for these lengths and angles, respectively, in accord with typical values of 1.21/1.31 Å and 123/112°, respectively, cited for highly ordered dimeric carboxyls (Borthwick, 1980). In (I), these lengths and angles are 1.185 (5)/1.311 (5) Å and 124.3 (4)/113.1 (4)°, respectively. No disorder was detected in the three methyl groups (C18, C19 and C21), which all adopt staggered arrangements.

Fig. 2 shows the packing of the cell and illustrates the two parallel hydrogen-bonding catemers created by the acid-to-ketone hydrogen bonding among molecules screw-related in b [O···O = 2.699 (4) Å and O—H···O = 173°]. The two chains are screw-related in a, and lie with their long axes parallel, but with opposite end-to-end orientation. In spite of a relatively slight change in molecular shape, this is dramatically different from the case of the 5-α-dihydro analog, whose hydrogen bonding is of the acid-to-acid type (Lalancette et al., 1998).

Within each molecule of (I), the dihedral angle between the carboxyl (C20/C22/O2/O3) and ketone planes (C2/C3/C4/O1) is 79.3 (2)°. However, for each hydrogen bond, the intermolecular dihedral angle between these two planes is 64.4 (3)°. We characterize the geometry of hydrogen bonding to carbonyls using a combination of the H···OC angle and the H···OC—C torsion angle. These describe the approach of the H atom to the O atom in terms of its deviation from, respectively, CO axiality (ideal = 120°) and planarity with the carbonyl (ideal = 0°). In (I), these angles are 128 and -3°, respectively.

Intermolecular C—H···OC close contacts to different neighboring molecules were found, involving O1 (2.69 Å to H21A) and O2 (2.64 Å to H6B). These distances lie within the 2.7 Å range we often employ for non-bonded C—H···O packing interactions (Steiner, 1997). Using compiled data for a large number of such contacts, Steiner & Desiraju (1998) find significant statistical directionality even as far out as 3.0 Å, and conclude that these are legitimately viewed as `weak hydrogen bonds', with a greater contribution to packing forces than simple van der Waals attractions.

We categorize subtypes of catemers by describing the relationship of adjacent molecules in the chains as homochiral (screw, translation) and heterochiral (glide). Among hydrogen-bonding catemers overall, the observed prevalence within the former grouping, appropriate to (I), is screw > translation, however this is our first observation of a screw-related steroidal catemer. Among the six previous steroid keto acids whose X-ray structures we have reported, all three of the cases displaying catemeric hydrogen bonding were translational.

The KBr IR spectrum of (I) displays CO absorptions at 1723 (COOH) and 1649 cm-1 (ketone), consistent with known shifts produced when hydrogen bonding is removed from carboxyl CO and added to a ketone, plus an alkene absorption at 1614 cm-1. In CHCl3 solution, where dimers predominate, these peaks appear, normally, at 1707 and 1660 cm-1, with the CC peak at 1614 cm-1 and a large carboxyl-dilution shoulder at ca 1732 cm-1.

Experimental top

Compound (I), of known absolute stereochemistry and rotation, was purchased from Steraloids Inc., Newport, RI, USA, and recrystallized from 95% ethanol (m.p. 532 K).

Refinement top

All H atoms were found in electron-density difference maps but were placed in calculated positions and allowed to refine as riding models. C—H distances were 0.93–0.98 Å, and the O—H group was constrained to be 0.82 Å. A torsional parameter was refined for each methyl group.

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. A view of compound (I) with its steroid numbering. Displacement ellipsoids are set at the 20% probability level.
[Figure 2] Fig. 2. A packing diagram illustrating the screw-related parallel counter-directional pair of catemers passing through the cell in the b direction. All carbon-bound H atoms have been removed for clarity. Displacement ellipsoids are set at the 20% probability level.
(+)-4-Pregnen-3-one-20β-carboxylic acid top
Crystal data top
C22H32O3Dx = 1.188 Mg m3
Mr = 344.48Melting point: 532 K
Orthorhombic, P21212Mo Kα radiation, λ = 0.71073 Å
a = 9.684 (3) ÅCell parameters from 25 reflections
b = 27.325 (7) Åθ = 2.4–9.7°
c = 7.281 (4) ŵ = 0.08 mm1
V = 1926.7 (13) Å3T = 296 K
Z = 4Hexagonal rod, colourless
F(000) = 7520.31 × 0.15 × 0.10 mm
Data collection top
Siemens P4
diffractometer
1453 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.072
Graphite monochromatorθmax = 25.0°, θmin = 2.2°
2θ/θ scansh = 1111
Absorption correction: numerical
(Sheldrick, 1997)
k = 3232
Tmin = 0.98, Tmax = 0.99l = 88
7753 measured reflections3 standard reflections every 97 reflections
1990 independent reflections intensity decay: Variation < 3%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.050H-atom parameters constrained
wR(F2) = 0.114 w = 1/[σ2(Fo2) + (0.0512P)2 + 0.1332P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.04
1990 reflectionsΔρmax = 0.15 e Å3
227 parametersΔρmin = 0.13 e Å3
0 restraintsExtinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0048 (13)
Crystal data top
C22H32O3V = 1926.7 (13) Å3
Mr = 344.48Z = 4
Orthorhombic, P21212Mo Kα radiation
a = 9.684 (3) ŵ = 0.08 mm1
b = 27.325 (7) ÅT = 296 K
c = 7.281 (4) Å0.31 × 0.15 × 0.10 mm
Data collection top
Siemens P4
diffractometer
1453 reflections with I > 2σ(I)
Absorption correction: numerical
(Sheldrick, 1997)
Rint = 0.072
Tmin = 0.98, Tmax = 0.993 standard reflections every 97 reflections
7753 measured reflections intensity decay: Variation < 3%
1990 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0500 restraints
wR(F2) = 0.114H-atom parameters constrained
S = 1.06Δρmax = 0.15 e Å3
1990 reflectionsΔρmin = 0.13 e Å3
227 parameters
Special details top

Experimental. crystal mounted on glass fiber using epoxy resin

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.1113 (3)0.45528 (9)0.8176 (4)0.0703 (9)
O20.2437 (3)0.89431 (12)0.5441 (6)0.1049 (14)
O30.4631 (3)0.90123 (10)0.4765 (5)0.0790 (10)
C10.2259 (4)0.57278 (12)0.9705 (5)0.0479 (10)
C20.2075 (5)0.51783 (13)1.0002 (5)0.0558 (11)
C30.1814 (4)0.49261 (12)0.8234 (6)0.0517 (10)
C40.2499 (4)0.51243 (13)0.6639 (5)0.0515 (10)
C50.3257 (4)0.55335 (12)0.6638 (5)0.0427 (9)
C60.4048 (5)0.56829 (13)0.4963 (5)0.0544 (11)
C70.3782 (4)0.62151 (13)0.4436 (5)0.0512 (10)
C80.4060 (4)0.65541 (11)0.6051 (4)0.0357 (8)
C90.3171 (4)0.64046 (11)0.7702 (4)0.0354 (8)
C100.3375 (4)0.58592 (11)0.8304 (5)0.0374 (8)
C110.3295 (4)0.67672 (11)0.9282 (4)0.0411 (9)
C120.3068 (4)0.72992 (11)0.8724 (4)0.0383 (9)
C130.4006 (3)0.74492 (12)0.7139 (4)0.0330 (8)
C140.3737 (3)0.70812 (12)0.5584 (4)0.0352 (8)
C150.4401 (4)0.73125 (13)0.3902 (5)0.0456 (10)
C160.4247 (4)0.78633 (13)0.4208 (5)0.0456 (10)
C170.3632 (4)0.79328 (12)0.6146 (5)0.0382 (8)
C180.5514 (4)0.74581 (13)0.7735 (5)0.0461 (9)
C190.4832 (4)0.57791 (13)0.9136 (6)0.0528 (10)
C200.4040 (4)0.84230 (12)0.6991 (5)0.0521 (10)
C210.3384 (6)0.85185 (16)0.8871 (6)0.0892 (17)
C220.3597 (5)0.88193 (14)0.5670 (7)0.0598 (11)
H3A0.43350.91710.38940.118*
H1A0.24890.58791.08710.057*
H1B0.13870.58650.92980.057*
H2A0.29000.50451.05670.067*
H2B0.13050.51221.08280.067*
H4A0.24060.49560.55360.062*
H6A0.37890.54730.39460.065*
H6B0.50270.56380.51880.065*
H7A0.43750.63050.34160.061*
H7B0.28300.62520.40420.061*
H8A0.50360.65290.63930.043*
H9A0.22120.64280.72810.042*
H11A0.42080.67370.98200.049*
H11B0.26260.66811.02200.049*
H12A0.21120.73440.83640.046*
H12B0.32460.75090.97710.046*
H14A0.27400.70920.53590.042*
H15A0.39300.72120.27890.055*
H15B0.53670.72220.38120.055*
H16A0.36390.80030.32900.055*
H16B0.51390.80230.41220.055*
H17A0.26250.79370.60060.046*
H18A0.57360.71570.83490.069*
H18B0.56630.77280.85570.069*
H18C0.60940.74950.66740.069*
H19A0.49320.54430.94940.079*
H19B0.49440.59851.01920.079*
H19C0.55210.58590.82370.079*
H20A0.50470.84340.71200.063*
H21A0.36810.88310.93220.134*
H21B0.36620.82670.97140.134*
H21C0.23960.85170.87540.134*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.088 (2)0.0385 (15)0.084 (2)0.0176 (15)0.014 (2)0.0114 (16)
O20.064 (2)0.089 (2)0.162 (4)0.0206 (18)0.010 (3)0.065 (3)
O30.071 (2)0.0652 (19)0.101 (3)0.0041 (16)0.008 (2)0.0381 (19)
C10.065 (3)0.038 (2)0.041 (2)0.0078 (18)0.004 (2)0.0039 (17)
C20.069 (3)0.044 (2)0.054 (2)0.006 (2)0.004 (2)0.001 (2)
C30.058 (2)0.031 (2)0.066 (2)0.0019 (19)0.002 (2)0.005 (2)
C40.069 (3)0.039 (2)0.046 (2)0.007 (2)0.000 (2)0.0124 (18)
C50.050 (2)0.038 (2)0.039 (2)0.0047 (18)0.0006 (19)0.0045 (17)
C60.074 (3)0.042 (2)0.048 (2)0.001 (2)0.013 (2)0.0139 (19)
C70.074 (3)0.047 (2)0.032 (2)0.005 (2)0.012 (2)0.0037 (18)
C80.0389 (19)0.0381 (18)0.0302 (17)0.0016 (16)0.0023 (17)0.0036 (16)
C90.0379 (19)0.0347 (18)0.0336 (17)0.0021 (15)0.0048 (17)0.0001 (15)
C100.042 (2)0.0328 (18)0.0379 (18)0.0012 (16)0.0012 (18)0.0039 (16)
C110.053 (2)0.0388 (19)0.0312 (19)0.0030 (17)0.000 (2)0.0012 (16)
C120.050 (2)0.0351 (18)0.0299 (18)0.0010 (16)0.0017 (18)0.0016 (15)
C130.0323 (18)0.0323 (17)0.0345 (18)0.0010 (15)0.0026 (16)0.0006 (16)
C140.0330 (18)0.0420 (19)0.0307 (17)0.0001 (16)0.0000 (17)0.0006 (16)
C150.052 (2)0.049 (2)0.036 (2)0.0022 (17)0.007 (2)0.0057 (18)
C160.044 (2)0.047 (2)0.046 (2)0.0012 (17)0.001 (2)0.0096 (19)
C170.0326 (18)0.0416 (19)0.0405 (19)0.0002 (16)0.0036 (18)0.0057 (17)
C180.047 (2)0.046 (2)0.045 (2)0.0001 (18)0.0094 (19)0.0028 (18)
C190.064 (3)0.038 (2)0.057 (2)0.0086 (18)0.006 (2)0.000 (2)
C200.060 (3)0.040 (2)0.057 (2)0.0024 (19)0.002 (2)0.009 (2)
C210.150 (5)0.049 (3)0.069 (3)0.002 (3)0.019 (4)0.012 (2)
C220.061 (3)0.037 (2)0.082 (3)0.000 (2)0.004 (3)0.005 (2)
Geometric parameters (Å, º) top
O1—C31.226 (4)C1—H1B0.9700
O2—C221.185 (5)C2—H2A0.9700
O3—C221.310 (5)C2—H2B0.9700
C1—C21.528 (5)C4—H4A0.9300
C1—C101.529 (5)C6—H6A0.9700
C2—C31.482 (5)C6—H6B0.9700
C3—C41.443 (5)C7—H7A0.9700
C4—C51.338 (5)C7—H7B0.9700
C5—C61.497 (5)C8—H8A0.9800
C5—C101.509 (5)C9—H9A0.9800
C6—C71.526 (5)C11—H11A0.9700
C7—C81.521 (5)C11—H11B0.9700
C8—C141.513 (4)C12—H12A0.9700
C8—C91.534 (4)C12—H12B0.9700
C9—C111.523 (4)C14—H14A0.9800
C9—C101.566 (4)C15—H15A0.9700
C10—C191.550 (5)C15—H15B0.9700
C11—C121.525 (4)C16—H16A0.9700
C12—C131.525 (5)C16—H16B0.9700
C13—C181.524 (5)C17—H17A0.9800
C13—C141.537 (4)C18—H18A0.9600
C13—C171.549 (4)C18—H18B0.9600
C14—C151.521 (5)C18—H18C0.9600
C15—C161.529 (5)C19—H19A0.9600
C16—C171.543 (5)C19—H19B0.9600
C17—C201.526 (5)C19—H19C0.9600
C20—C221.511 (6)C20—H20A0.9800
C20—C211.531 (6)C21—H21A0.9600
O3—H3A0.8200C21—H21B0.9600
C1—H1A0.9700C21—H21C0.9600
C2—C1—C10114.1 (3)C7—C6—H6B109.2
C3—C2—C1110.7 (3)H6A—C6—H6B107.9
O1—C3—C4122.6 (4)C8—C7—H7A109.5
O1—C3—C2120.7 (4)C6—C7—H7A109.5
C4—C3—C2116.5 (3)C8—C7—H7B109.5
C5—C4—C3124.5 (3)C6—C7—H7B109.5
C4—C5—C6120.6 (3)H7A—C7—H7B108.1
C4—C5—C10122.3 (3)C14—C8—H8A108.9
C6—C5—C10117.1 (3)C7—C8—H8A108.9
C5—C6—C7112.3 (3)C9—C8—H8A108.9
C8—C7—C6110.8 (3)C11—C9—H9A105.6
C14—C8—C7111.7 (3)C8—C9—H9A105.6
C14—C8—C9108.3 (3)C10—C9—H9A105.6
C7—C8—C9110.1 (3)C9—C11—H11A108.7
C11—C9—C8112.0 (3)C12—C11—H11A108.7
C11—C9—C10113.5 (3)C9—C11—H11B108.7
C8—C9—C10113.7 (3)C12—C11—H11B108.7
C5—C10—C1110.1 (3)H11A—C11—H11B107.6
C5—C10—C19107.5 (3)C13—C12—H12A109.3
C1—C10—C19110.5 (3)C11—C12—H12A109.3
C5—C10—C9109.1 (3)C13—C12—H12B109.3
C1—C10—C9108.7 (3)C11—C12—H12B109.3
C19—C10—C9111.0 (3)H12A—C12—H12B107.9
C9—C11—C12114.1 (3)C8—C14—H14A105.7
C13—C12—C11111.8 (3)C15—C14—H14A105.7
C18—C13—C12111.1 (3)C13—C14—H14A105.7
C18—C13—C14112.5 (3)C14—C15—H15A110.9
C12—C13—C14106.3 (2)C16—C15—H15A110.9
C18—C13—C17110.1 (3)C14—C15—H15B110.8
C12—C13—C17116.3 (3)C16—C15—H15B110.9
C14—C13—C17100.1 (3)H15A—C15—H15B108.9
C8—C14—C15119.3 (3)C15—C16—H16A110.3
C8—C14—C13115.0 (3)C17—C16—H16A110.3
C15—C14—C13104.5 (3)C15—C16—H16B110.3
C14—C15—C16104.5 (3)C17—C16—H16B110.3
C15—C16—C17107.0 (3)H16A—C16—H16B108.6
C20—C17—C16112.1 (3)C20—C17—H17A106.9
C20—C17—C13120.0 (3)C16—C17—H17A106.9
C16—C17—C13103.4 (3)C13—C17—H17A106.9
C22—C20—C17107.4 (3)C13—C18—H18A109.5
C22—C20—C21109.2 (3)C13—C18—H18B109.5
C17—C20—C21113.7 (3)H18A—C18—H18B109.5
O2—C22—O3122.7 (4)C13—C18—H18C109.5
O2—C22—C20124.3 (4)H18A—C18—H18C109.5
O3—C22—C20113.0 (4)H18B—C18—H18C109.5
C22—O3—H3A109.5C10—C19—H19A109.5
C2—C1—H1A108.7C10—C19—H19B109.5
C10—C1—H1A108.7H19A—C19—H19B109.5
C2—C1—H1B108.7C10—C19—H19C109.5
C10—C1—H1B108.7H19A—C19—H19C109.5
H1A—C1—H1B107.6H19B—C19—H19C109.5
C3—C2—H2A109.5C22—C20—H20A108.8
C1—C2—H2A109.5C17—C20—H20A108.8
C3—C2—H2B109.5C21—C20—H20A108.8
C1—C2—H2B109.5C20—C21—H21A109.5
H2A—C2—H2B108.1C20—C21—H21B109.5
C5—C4—H4A117.7H21A—C21—H21B109.5
C3—C4—H4A117.7C20—C21—H21C109.5
C5—C6—H6A109.2H21A—C21—H21C109.5
C7—C6—H6A109.2H21B—C21—H21C109.5
C5—C6—H6B109.2
C10—C1—C2—C354.7 (5)C9—C11—C12—C1353.8 (4)
C1—C2—C3—O1150.0 (4)C11—C12—C13—C1867.4 (4)
C1—C2—C3—C433.9 (5)C11—C12—C13—C1455.3 (4)
O1—C3—C4—C5179.0 (4)C11—C12—C13—C17165.6 (3)
C2—C3—C4—C55.0 (6)C7—C8—C14—C1554.1 (4)
C3—C4—C5—C6173.6 (4)C9—C8—C14—C15175.5 (3)
C3—C4—C5—C105.4 (6)C7—C8—C14—C13179.4 (3)
C4—C5—C6—C7129.9 (4)C9—C8—C14—C1359.2 (3)
C10—C5—C6—C751.0 (5)C18—C13—C14—C860.8 (4)
C5—C6—C7—C854.1 (5)C12—C13—C14—C861.0 (4)
C6—C7—C8—C14177.3 (3)C17—C13—C14—C8177.6 (3)
C6—C7—C8—C956.9 (4)C18—C13—C14—C1571.9 (4)
C14—C8—C9—C1151.3 (4)C12—C13—C14—C15166.3 (3)
C7—C8—C9—C11173.7 (3)C17—C13—C14—C1544.9 (3)
C14—C8—C9—C10178.5 (3)C8—C14—C15—C16161.9 (3)
C7—C8—C9—C1056.1 (4)C13—C14—C15—C1631.7 (4)
C4—C5—C10—C114.5 (5)C14—C15—C16—C175.6 (4)
C6—C5—C10—C1166.4 (3)C15—C16—C17—C20152.7 (3)
C4—C5—C10—C19105.9 (4)C15—C16—C17—C1322.1 (4)
C6—C5—C10—C1973.2 (4)C18—C13—C17—C2047.6 (4)
C4—C5—C10—C9133.7 (4)C12—C13—C17—C2079.9 (4)
C6—C5—C10—C947.2 (4)C14—C13—C17—C20166.2 (3)
C2—C1—C10—C544.2 (4)C18—C13—C17—C1678.2 (3)
C2—C1—C10—C1974.4 (4)C12—C13—C17—C16154.4 (3)
C2—C1—C10—C9163.6 (3)C14—C13—C17—C1640.4 (3)
C11—C9—C10—C5179.0 (3)C16—C17—C20—C2255.8 (4)
C8—C9—C10—C549.6 (4)C13—C17—C20—C22177.4 (3)
C11—C9—C10—C160.9 (4)C16—C17—C20—C21176.8 (3)
C8—C9—C10—C1169.6 (3)C13—C17—C20—C2161.7 (5)
C11—C9—C10—C1960.8 (4)C17—C20—C22—O273.8 (6)
C8—C9—C10—C1968.7 (4)C21—C20—C22—O249.9 (6)
C8—C9—C11—C1250.9 (4)C17—C20—C22—O3105.3 (4)
C10—C9—C11—C12178.8 (3)C21—C20—C22—O3130.9 (4)

Experimental details

Crystal data
Chemical formulaC22H32O3
Mr344.48
Crystal system, space groupOrthorhombic, P21212
Temperature (K)296
a, b, c (Å)9.684 (3), 27.325 (7), 7.281 (4)
V3)1926.7 (13)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.31 × 0.15 × 0.10
Data collection
DiffractometerSiemens P4
diffractometer
Absorption correctionNumerical
(Sheldrick, 1997)
Tmin, Tmax0.98, 0.99
No. of measured, independent and
observed [I > 2σ(I)] reflections
7753, 1990, 1453
Rint0.072
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.050, 0.114, 1.06
No. of reflections1990
No. of parameters227
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.15, 0.13

Computer programs: XSCANS (Siemens, 1996), XSCANS, SHELXTL (Sheldrick, 1997), SHELXTL.

Selected geometric parameters (Å, º) top
O2—C221.185 (5)O3—C221.310 (5)
O2—C22—C20124.3 (4)O3—C22—C20113.0 (4)
C16—C17—C20—C21176.8 (3)C17—C20—C22—O273.8 (6)
 

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