Ethyl 4-nitro­phenyl­acetate

Li, J.; Liu, J.; Peng, H.-Q.

doi:10.1107/S1600536807066184

Ethyl 4-nitrophenylacetate

In the asymmetric unit of the title compound, C₁₀H₁₁NO₄, there are two crystallographically independent molecules, which are connected via a C—H

O hydrogen bond. The crystal structure is stabilized by this hydrogen bond together with an N—O

π contact [O

Cg 3.297 (5) Å; Cg is the centroid of one of the benzene rings].

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807066184/is2259sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807066184/is2259Isup2.hkl Contains datablock I

CCDC reference: 677587

checkCIF report

Key indicators

Single-crystal X-ray study
T = 292 K
Mean (C-C) = 0.006 Å
R factor = 0.050
wR factor = 0.122
Data-to-parameter ratio = 8.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N1
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          6
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C10 H11 N O4

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.00
           From the CIF: _reflns_number_total               2318
           Count of symmetry unique reflns         2323
           Completeness (_total/calc)             99.78%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

Comment top

Ethyl 4-nitrophenylacetate, (I), has been widely used as an intermediator of the anti-rheumatoid drugs (Kevan et al., 1991; Sagamihara, 1988). The similar compound, cyclodecyl 4-nitrophenylacetate, has been reported by Brown et al. (2006). Here we present the molecular structure of (I), as shown in Fig. 1. In the asymmetric unit of (I), there is a dimer via a C—H···O interaction (Table 1). The angles involving the acetate groups in the dimer are 126.7 (4), 124.0 (4), 126.1 (4) and 123.1 (4)°, and the average distances of C=O and C—O are 1.202 (5) and 2.792 (5) Å, respectively. The C—N bond lengths on the benzene ring range from 1.202 (5) to 1.219 (4) Å. The benzene ring planes of the two independent molecules are nearly directional parallel with the dihedral angle of 19.2 (2)°, but no significant π-π interaction. The molecular packing diagram of (I) is stabilized by N1—O2···π contact [O2···Cgⁱ 3.297 (5) Å, N1—O2···Cgⁱ 156.3 (3)°; Cg is the centroid of the benzene C11—C16 ring; symmetry code: (i) 1/2 + x, 1 - y, z] together with hydrogen bond, as shown in Fig. 2.

Related literature top

For related literature, see: Brown et al. (2006); Kevan et al. (1991); Sagamihara (1988).

Experimental top

Ethyl 4-nitrophenylacetate was obtained from the Jiachen Chemical Company Inc, ShangHai. The crystals were grown by vapour diffusion of 95% ethanol.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL (Bruker, 2001).

Figures top

	Fig. 1. The asymmetric unit of the title compound with the atom numbering, showing displacement ellipsoids at the 50% probability level. The hydrogen bond is shown as a dashed line.
	Fig. 2. The molecular packing diagram of the title compound, with hydrogen bonds shown as dashed lines.

Ethyl 4-nitrophenylacetate top

Crystal data top

C₁₀H₁₁NO₄	F(000) = 880
M_r = 209.20	D_x = 1.342 Mg m⁻³
Orthorhombic, Pca2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2ac	Cell parameters from 1377 reflections
a = 15.9132 (13) Å	θ = 2.7–20.9°
b = 5.2298 (4) Å	µ = 0.11 mm⁻¹
c = 24.878 (2) Å	T = 292 K
V = 2070.4 (3) Å³	Plate, colorless
Z = 8	0.40 × 0.04 × 0.02 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2318 independent reflections
Radiation source: fine-focus sealed tube	1422 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.065
ϕ and ω scans	θ_max = 27.0°, θ_min = 1.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	h = −15→20
T_min = 0.959, T_max = 0.998	k = −6→6
13522 measured reflections	l = −31→31

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.122	H-atom parameters constrained
S = 1.01	w = 1/[σ²(F_o²) + (0.0579P)²] where P = (F_o² + 2F_c²)/3
2318 reflections	(Δ/σ)_max = 0.004
273 parameters	Δρ_max = 0.13 e Å⁻³
1 restraint	Δρ_min = −0.15 e Å⁻³

Crystal data top

C₁₀H₁₁NO₄	V = 2070.4 (3) Å³
M_r = 209.20	Z = 8
Orthorhombic, Pca2₁	Mo Kα radiation
a = 15.9132 (13) Å	µ = 0.11 mm⁻¹
b = 5.2298 (4) Å	T = 292 K
c = 24.878 (2) Å	0.40 × 0.04 × 0.02 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2318 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	1422 reflections with I > 2σ(I)
T_min = 0.959, T_max = 0.998	R_int = 0.065
13522 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.050	1 restraint
wR(F²) = 0.122	H-atom parameters constrained
S = 1.01	Δρ_max = 0.13 e Å⁻³
2318 reflections	Δρ_min = −0.15 e Å⁻³
273 parameters

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	1.1982 (2)	1.1755 (8)	0.18201 (15)	0.0473 (10)
C2	1.1806 (3)	1.3761 (8)	0.14828 (17)	0.0556 (11)
H2	1.2230	1.4856	0.1368	0.067*
C3	1.0991 (3)	1.4122 (8)	0.13180 (17)	0.0559 (11)
H3	1.0864	1.5479	0.1091	0.067*
C4	1.0354 (3)	1.2492 (8)	0.14854 (17)	0.0521 (10)
C5	1.0559 (3)	1.0479 (8)	0.1821 (2)	0.0578 (12)
H5	1.0139	0.9359	0.1930	0.069*
C6	1.1363 (3)	1.0091 (8)	0.1995 (2)	0.0579 (13)
H6	1.1492	0.8744	0.2225	0.069*
C7	0.9459 (3)	1.2913 (9)	0.13058 (18)	0.0629 (13)
H7A	0.9096	1.2882	0.1619	0.076*
H7B	0.9415	1.4598	0.1145	0.076*
C8	0.9148 (3)	1.0963 (9)	0.09078 (17)	0.0527 (11)
C9	0.7949 (3)	0.9750 (9)	0.0399 (2)	0.0682 (15)
H9A	0.7939	0.8004	0.0531	0.082*
H9B	0.8261	0.9790	0.0064	0.082*
C10	0.7077 (3)	1.0715 (12)	0.0316 (2)	0.0842 (17)
H10A	0.6768	1.0582	0.0646	0.126*
H10B	0.6805	0.9713	0.0043	0.126*
H10C	0.7097	1.2471	0.0204	0.126*
C11	0.9635 (2)	0.3428 (7)	0.32274 (15)	0.0467 (10)
C12	0.9473 (3)	0.1331 (8)	0.35509 (17)	0.0541 (11)
H12	0.9903	0.0220	0.3649	0.065*
C13	0.8662 (3)	0.0924 (8)	0.37249 (18)	0.0556 (11)
H13	0.8547	−0.0456	0.3949	0.067*
C14	0.8017 (2)	0.2530 (8)	0.35717 (15)	0.0469 (10)
C15	0.8203 (3)	0.4571 (9)	0.3234 (2)	0.0570 (12)
H15	0.7772	0.5645	0.3122	0.068*
C16	0.9012 (2)	0.5043 (8)	0.30617 (19)	0.0501 (12)
H16	0.9131	0.6424	0.2839	0.060*
C17	0.7135 (2)	0.2026 (8)	0.37470 (17)	0.0561 (11)
H17A	0.7108	0.0337	0.3908	0.067*
H17B	0.6774	0.2020	0.3433	0.067*
C18	0.6801 (3)	0.3948 (8)	0.41442 (17)	0.0494 (10)
C19	0.5597 (3)	0.5179 (9)	0.4642 (2)	0.0631 (14)
H19A	0.5581	0.6910	0.4503	0.076*
H19B	0.5909	0.5186	0.4977	0.076*
C20	0.4726 (3)	0.4214 (11)	0.4734 (2)	0.0776 (15)
H20A	0.4414	0.4300	0.4404	0.116*
H20B	0.4455	0.5249	0.5002	0.116*
H20C	0.4749	0.2474	0.4856	0.116*
N1	1.2850 (2)	1.1303 (8)	0.19950 (16)	0.0625 (10)
N2	1.0504 (2)	0.3938 (8)	0.30557 (16)	0.0594 (10)
O1	1.3401 (2)	1.2661 (7)	0.18162 (16)	0.0868 (11)
O2	1.2991 (2)	0.9635 (9)	0.23154 (18)	0.1051 (16)
O3	0.95456 (18)	0.9271 (7)	0.07121 (13)	0.0671 (10)
O4	0.83388 (17)	1.1435 (6)	0.07940 (12)	0.0630 (8)
O5	1.0631 (2)	0.5766 (7)	0.27657 (17)	0.0878 (12)
O6	1.1065 (2)	0.2546 (7)	0.32154 (15)	0.0766 (10)
O7	0.71909 (18)	0.5709 (6)	0.43392 (14)	0.0685 (9)
O8	0.59970 (17)	0.3485 (6)	0.42567 (12)	0.0607 (8)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.049 (2)	0.048 (2)	0.045 (2)	0.0003 (19)	0.0007 (19)	−0.0029 (18)
C2	0.064 (3)	0.048 (3)	0.055 (2)	−0.012 (2)	0.006 (2)	0.002 (2)
C3	0.069 (3)	0.043 (2)	0.055 (3)	0.001 (2)	−0.006 (2)	0.003 (2)
C4	0.061 (3)	0.041 (2)	0.054 (2)	0.003 (2)	0.003 (2)	−0.008 (2)
C5	0.054 (3)	0.049 (3)	0.070 (3)	−0.004 (2)	0.004 (2)	0.004 (2)
C6	0.055 (3)	0.051 (3)	0.068 (4)	−0.003 (2)	0.008 (2)	0.005 (2)
C7	0.053 (3)	0.054 (3)	0.082 (4)	0.008 (2)	−0.004 (2)	−0.011 (2)
C8	0.053 (3)	0.055 (3)	0.050 (2)	0.008 (2)	0.003 (2)	0.001 (2)
C9	0.069 (3)	0.072 (4)	0.064 (4)	−0.007 (3)	−0.014 (3)	−0.010 (2)
C10	0.065 (4)	0.104 (4)	0.083 (4)	0.001 (3)	−0.020 (3)	−0.006 (3)
C11	0.046 (2)	0.047 (2)	0.047 (2)	0.0012 (19)	−0.0004 (18)	−0.0049 (18)
C12	0.055 (3)	0.049 (3)	0.058 (2)	0.002 (2)	−0.002 (2)	0.005 (2)
C13	0.064 (3)	0.046 (3)	0.057 (3)	−0.001 (2)	0.010 (2)	0.007 (2)
C14	0.050 (3)	0.040 (2)	0.050 (2)	−0.004 (2)	0.0009 (19)	−0.0081 (19)
C15	0.047 (3)	0.058 (3)	0.066 (3)	0.004 (2)	−0.002 (2)	−0.002 (2)
C16	0.066 (3)	0.047 (3)	0.037 (2)	−0.002 (2)	0.003 (2)	0.0023 (17)
C17	0.057 (3)	0.048 (3)	0.063 (3)	−0.007 (2)	0.006 (2)	−0.007 (2)
C18	0.048 (3)	0.044 (3)	0.056 (3)	0.003 (2)	0.004 (2)	0.001 (2)
C19	0.057 (3)	0.077 (4)	0.056 (3)	0.002 (2)	0.007 (2)	−0.004 (2)
C20	0.066 (3)	0.096 (4)	0.071 (3)	−0.001 (3)	0.013 (3)	−0.001 (3)
N1	0.061 (3)	0.069 (3)	0.058 (2)	−0.008 (2)	−0.002 (2)	0.003 (2)
N2	0.052 (2)	0.065 (3)	0.061 (2)	0.001 (2)	0.0045 (19)	0.001 (2)
O1	0.059 (2)	0.094 (3)	0.107 (3)	−0.0180 (19)	−0.0037 (19)	0.018 (2)
O2	0.077 (3)	0.126 (3)	0.112 (4)	−0.001 (2)	−0.013 (2)	0.061 (3)
O3	0.059 (2)	0.067 (2)	0.076 (3)	0.0100 (17)	−0.0050 (16)	−0.023 (2)
O4	0.0493 (18)	0.066 (2)	0.074 (2)	0.0083 (15)	−0.0097 (15)	−0.0110 (16)
O5	0.072 (2)	0.087 (3)	0.104 (3)	−0.0159 (19)	0.015 (2)	0.041 (2)
O6	0.055 (2)	0.081 (3)	0.094 (2)	0.0124 (17)	0.0080 (18)	0.007 (2)
O7	0.066 (2)	0.062 (2)	0.078 (2)	−0.0127 (15)	0.0025 (16)	−0.0180 (19)
O8	0.0560 (18)	0.065 (2)	0.0611 (17)	−0.0103 (15)	0.0146 (15)	−0.0113 (16)

Geometric parameters (Å, º) top

C1—C2	1.372 (6)	C11—N2	1.471 (5)
C1—C6	1.385 (5)	C12—C13	1.378 (5)
C1—N1	1.468 (5)	C12—H12	0.9300
C2—C3	1.373 (5)	C13—C14	1.380 (5)
C2—H2	0.9300	C13—H13	0.9300
C3—C4	1.388 (6)	C14—C15	1.390 (6)
C3—H3	0.9300	C14—C17	1.494 (5)
C4—C5	1.382 (6)	C15—C16	1.380 (6)
C4—C7	1.510 (5)	C15—H15	0.9300
C5—C6	1.366 (6)	C16—H16	0.9300
C5—H5	0.9300	C17—C18	1.506 (6)
C6—H6	0.9300	C17—H17A	0.9700
C7—C8	1.505 (6)	C17—H17B	0.9700
C7—H7A	0.9700	C18—O7	1.212 (5)
C7—H7B	0.9700	C18—O8	1.332 (5)
C8—O3	1.192 (5)	C19—O8	1.452 (6)
C8—O4	1.341 (5)	C19—C20	1.493 (6)
C9—O4	1.458 (5)	C19—H19A	0.9700
C9—C10	1.491 (5)	C19—H19B	0.9700
C9—H9A	0.9700	C20—H20A	0.9600
C9—H9B	0.9700	C20—H20B	0.9600
C10—H10A	0.9600	C20—H20C	0.9600
C10—H10B	0.9600	N1—O2	1.202 (5)
C10—H10C	0.9600	N1—O1	1.212 (4)
C11—C16	1.365 (5)	N2—O5	1.215 (5)
C11—C12	1.385 (6)	N2—O6	1.219 (4)

C2—C1—C6	121.8 (4)	C11—C12—H12	120.7
C2—C1—N1	119.8 (4)	C12—C13—C14	121.0 (4)
C6—C1—N1	118.4 (4)	C12—C13—H13	119.5
C3—C2—C1	118.7 (4)	C14—C13—H13	119.5
C3—C2—H2	120.6	C13—C14—C15	118.4 (4)
C1—C2—H2	120.6	C13—C14—C17	120.7 (4)
C2—C3—C4	121.0 (4)	C15—C14—C17	120.8 (4)
C2—C3—H3	119.5	C16—C15—C14	121.6 (4)
C4—C3—H3	119.5	C16—C15—H15	119.2
C5—C4—C3	118.4 (4)	C14—C15—H15	119.2
C5—C4—C7	120.8 (4)	C11—C16—C15	118.2 (4)
C3—C4—C7	120.7 (4)	C11—C16—H16	120.9
C6—C5—C4	121.7 (4)	C15—C16—H16	120.9
C6—C5—H5	119.1	C14—C17—C18	113.9 (3)
C4—C5—H5	119.1	C14—C17—H17A	108.8
C5—C6—C1	118.2 (4)	C18—C17—H17A	108.8
C5—C6—H6	120.9	C14—C17—H17B	108.8
C1—C6—H6	120.9	C18—C17—H17B	108.8
C8—C7—C4	114.0 (3)	H17A—C17—H17B	107.7
C8—C7—H7A	108.8	O7—C18—O8	123.1 (4)
C4—C7—H7A	108.8	O7—C18—C17	126.1 (4)
C8—C7—H7B	108.8	O8—C18—C17	110.8 (4)
C4—C7—H7B	108.8	O8—C19—C20	107.6 (4)
H7A—C7—H7B	107.7	O8—C19—H19A	110.2
O3—C8—O4	124.0 (4)	C20—C19—H19A	110.2
O3—C8—C7	126.7 (4)	O8—C19—H19B	110.2
O4—C8—C7	109.3 (4)	C20—C19—H19B	110.2
O4—C9—C10	106.5 (4)	H19A—C19—H19B	108.5
O4—C9—H9A	110.4	C19—C20—H20A	109.5
C10—C9—H9A	110.4	C19—C20—H20B	109.5
O4—C9—H9B	110.4	H20A—C20—H20B	109.5
C10—C9—H9B	110.4	C19—C20—H20C	109.5
H9A—C9—H9B	108.6	H20A—C20—H20C	109.5
C9—C10—H10A	109.5	H20B—C20—H20C	109.5
C9—C10—H10B	109.5	O2—N1—O1	122.3 (4)
H10A—C10—H10B	109.5	O2—N1—C1	119.2 (4)
C9—C10—H10C	109.5	O1—N1—C1	118.5 (4)
H10A—C10—H10C	109.5	O5—N2—O6	122.8 (4)
H10B—C10—H10C	109.5	O5—N2—C11	118.1 (4)
C16—C11—C12	122.0 (4)	O6—N2—C11	119.1 (4)
C16—C11—N2	118.8 (4)	C8—O4—C9	116.1 (3)
C12—C11—N2	119.1 (4)	N2—O5—H6	155.7
C13—C12—C11	118.6 (4)	C18—O8—C19	116.7 (3)
C13—C12—H12	120.7

C6—C1—C2—C3	0.3 (6)	N2—C11—C16—C15	−178.7 (4)
N1—C1—C2—C3	179.0 (3)	C14—C15—C16—C11	0.6 (6)
C1—C2—C3—C4	−0.3 (6)	C13—C14—C17—C18	110.9 (4)
C2—C3—C4—C5	−0.4 (6)	C15—C14—C17—C18	−71.5 (5)
C2—C3—C4—C7	179.5 (4)	C14—C17—C18—O7	−3.5 (6)
C3—C4—C5—C6	1.1 (7)	C14—C17—C18—O8	176.0 (3)
C7—C4—C5—C6	−178.9 (4)	C2—C1—N1—O2	175.6 (5)
C4—C5—C6—C1	−1.0 (7)	C6—C1—N1—O2	−5.7 (6)
C2—C1—C6—C5	0.3 (7)	C2—C1—N1—O1	−3.2 (6)
N1—C1—C6—C5	−178.4 (4)	C6—C1—N1—O1	175.5 (4)
C5—C4—C7—C8	−71.4 (5)	C16—C11—N2—O5	−1.0 (6)
C3—C4—C7—C8	108.6 (4)	C12—C11—N2—O5	179.0 (4)
C4—C7—C8—O3	−3.9 (7)	C16—C11—N2—O6	177.9 (4)
C4—C7—C8—O4	177.1 (4)	C12—C11—N2—O6	−2.2 (6)
C16—C11—C12—C13	−2.3 (6)	O3—C8—O4—C9	−0.9 (6)
N2—C11—C12—C13	177.7 (4)	C7—C8—O4—C9	178.2 (4)
C11—C12—C13—C14	1.5 (6)	C10—C9—O4—C8	−176.9 (4)
C12—C13—C14—C15	0.3 (6)	O6—N2—O5—H6	0.9
C12—C13—C14—C17	177.9 (4)	C11—N2—O5—H6	179.7
C13—C14—C15—C16	−1.4 (6)	O7—C18—O8—C19	−1.4 (6)
C17—C14—C15—C16	−179.0 (4)	C17—C18—O8—C19	179.1 (4)
C12—C11—C16—C15	1.3 (6)	C20—C19—O8—C18	−176.3 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O5	0.93	2.47	3.186 (6)	134

Experimental details

Crystal data
Chemical formula	C₁₀H₁₁NO₄
M_r	209.20
Crystal system, space group	Orthorhombic, Pca2₁
Temperature (K)	292
a, b, c (Å)	15.9132 (13), 5.2298 (4), 24.878 (2)
V (Å³)	2070.4 (3)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.40 × 0.04 × 0.02

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2001)
T_min, T_max	0.959, 0.998
No. of measured, independent and observed [I > 2σ(I)] reflections	13522, 2318, 1422
R_int	0.065
(sin θ/λ)_max (Å⁻¹)	0.639

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.050, 0.122, 1.01
No. of reflections	2318
No. of parameters	273
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.13, −0.15

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2001).