Unexpected beauty and diversity in the structures of three homologous 4,5-di­alk­oxy-1-ethynyl-2-nitro­benzenes: the subtle interplay between intermolecular C—H...O hydrogen bonds and alkyl chain length

The synthesis, ¹H and ¹³C NMR spectra, and X-ray structures are described for three di­alk­oxy ethynyl­nitro­benzenes that differ only in the length of the alk­oxy chain, namely 1-ethynyl-2-nitro-4,5-dipropoxybenzene, C₁₄H₁₇NO₄, 1,2-di­but­oxy-4-ethynyl-5-nitro­benzene, C₁₆H₂₁NO₄, and 1-ethynyl-2-nitro-4,5-dipentoxy­benzene, C₁₈H₂₅NO₄. Despite the subtle changes in molecular structure, the crystal structures of the three compounds display great diversity. Thus, 1-ethynyl-2-nitro-4,5-dipropoxybenzene crystallizes in the trigonal crystal system in the space group , with Z = 18, 1,2-di­but­oxy-4-ethynyl-5-nitro­benzene crystallizes in the monoclinic crystal system in the space group P2₁/c, with Z = 4, and 1-ethynyl-2-nitro-4,5-dipentoxybenzene crystallizes in the tri­clinic crystal system in the space group , with Z = 2. The crystal structure of 1-ethynyl-2-nitro-4,5-dipropoxybenzene is dominated by planar hexamers formed by a bifurcated alkoxy sp-C—H...O,O′ interaction, while the structure of the di­but­oxy analogue is dominated by planar ribbons of molecules linked by a similar bifurcated alkoxy sp-C—H...O,O′ interaction. In contrast, the dipent­oxy analogue forms ribbons of molecules alternately connected by a self-complementary sp-C—H...O₂N interaction and a self-complementary sp²-C—H...O₂N interaction. Disordered solvent was included in the crystals of 1-ethynyl-2-nitro-4,5-dipropoxybenzene and its contribution was removed during refinement.

Computing details

For all structures, data collection: Bruker SMART; cell refinement: Bruker SMART; data reduction: Bruker SAINT; program(s) used to solve structure: SHELXT 2014/5 (Sheldrick, 2015); program(s) used to refine structure: SHELXL2017/1 (Sheldrick, 2015a); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: X-SEED (Barbour, 2001).

(1)

Crystal data

C14H17NO4	Dx = 1.234 Mg m^−3
Mr = 263.29	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3:H	Cell parameters from 5437 reflections
a = 26.6774 (16) Å	θ = 2.6–27.1°
c = 10.3451 (6) Å	µ = 0.09 mm^−1
V = 6376.1 (8) Å^3	T = 100 K
Z = 18	Cut rectangular prism, colourless
F(000) = 2520	0.07 × 0.07 × 0.04 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	3172 independent reflections
Radiation source: fine-focus sealed tube	2420 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
Detector resolution: 8.3660 pixels mm^-1	θmax = 27.2°, θmin = 1.5°
φ and ω scans	h = −34→34
Absorption correction: multi-scan (SADABS Version 2014; Bruker AXS)	k = −34→34
Tmin = 0.697, Tmax = 0.746	l = −13→13
28334 measured reflections

Refinement

Refinement on F^2	2 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.047	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.138	w = 1/[σ^2(Fo^2) + (0.0842P)^2 + 1.9773P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
3172 reflections	Δρmax = 0.43 e Å^−3
180 parameters	Δρmin = −0.20 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. # SQUEEZE RESULTS # Note: Data are Listed for all Voids in the P1 Unit Cell # i.e. Centre of Gravity, Solvent Accessible Volume, # Recovered number of Electrons in the Void and # Details about the Squeezed Material loop_ _platon_squeeze_void_nr _platon_squeeze_void_average_x _platon_squeeze_void_average_y _platon_squeeze_void_average_z _platon_squeeze_void_volume _platon_squeeze_void_count_electrons _platon_squeeze_void_content 1 0.000 0.000 0.000 125 38 ' ' 2 0.333 0.667 0.667 115 38 ' ' 3 0.667 0.333 0.333 115 38 ' '

_platon_squeeze_details 'Reasonable that the squeezed solvent corresponds to dichloromethane (42 e)'

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

	x	y	z	Uiso*/Ueq
O1	0.80137 (4)	0.82653 (4)	0.29721 (12)	0.0429 (3)
N1	0.75096 (5)	0.80819 (5)	0.32978 (11)	0.0256 (3)
C1	0.73231 (5)	0.70715 (5)	0.33025 (12)	0.0206 (3)
O2	0.73202 (4)	0.83983 (4)	0.36150 (11)	0.0375 (3)
C2	0.71127 (5)	0.74567 (5)	0.32948 (12)	0.0212 (3)
O3	0.55388 (4)	0.64527 (4)	0.32599 (9)	0.0261 (2)
C3	0.65221 (6)	0.72722 (5)	0.32879 (12)	0.0212 (3)
O4	0.59014 (4)	0.57189 (4)	0.32933 (9)	0.0244 (2)
C4	0.61230 (5)	0.66862 (5)	0.32747 (12)	0.0209 (3)
C5	0.63200 (5)	0.62827 (5)	0.32965 (12)	0.0209 (3)
C6	0.69061 (5)	0.64767 (5)	0.33122 (12)	0.0205 (3)
H6	0.703270	0.620132	0.333023	0.025*
C7	0.79185 (6)	0.72157 (5)	0.33451 (12)	0.0232 (3)
C8	0.83787 (6)	0.72495 (6)	0.33970 (14)	0.0286 (3)
C9	0.53135 (6)	0.68428 (6)	0.31049 (13)	0.0252 (3)
H9A	0.543558	0.704456	0.226250	0.030*
H9B	0.546036	0.713660	0.380149	0.030*
C10	0.46645 (6)	0.64833 (6)	0.31691 (16)	0.0336 (3)
H10A	0.454772	0.629926	0.403095	0.040*
H10B	0.452595	0.617229	0.251226	0.040*
C11	0.43856 (7)	0.68527 (7)	0.2930 (2)	0.0480 (5)
H11A	0.453678	0.717186	0.355410	0.072*
H11B	0.396514	0.661425	0.303249	0.072*
H11C	0.447534	0.700984	0.205091	0.072*
C12	0.60887 (6)	0.52969 (5)	0.33039 (13)	0.0239 (3)
H12A	0.630358	0.533250	0.411084	0.029*
H12B	0.634935	0.536310	0.256252	0.029*
C13	0.55624 (6)	0.47007 (6)	0.32152 (15)	0.0290 (3)
H13A	0.534786	0.466784	0.240927	0.035*
H13B	0.530215	0.463725	0.395589	0.035*
C14	0.57451 (7)	0.42451 (6)	0.32240 (17)	0.0374 (4)
H14A	0.598579	0.429645	0.246451	0.056*
H14B	0.540037	0.385883	0.320216	0.056*
H14C	0.596699	0.428606	0.401088	0.056*
H3	0.6402 (8)	0.7547 (7)	0.3249 (16)	0.045*
H8	0.8740 (5)	0.7274 (8)	0.3423 (16)	0.045*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0265 (6)	0.0225 (5)	0.0748 (8)	0.0085 (4)	0.0085 (5)	0.0029 (5)
N1	0.0259 (6)	0.0183 (6)	0.0312 (6)	0.0101 (5)	−0.0031 (5)	−0.0002 (4)
C1	0.0218 (6)	0.0205 (6)	0.0188 (6)	0.0101 (5)	−0.0019 (5)	−0.0009 (5)
O2	0.0337 (6)	0.0217 (5)	0.0597 (7)	0.0158 (4)	−0.0025 (5)	−0.0055 (5)
C2	0.0239 (6)	0.0166 (6)	0.0209 (6)	0.0085 (5)	−0.0011 (5)	0.0002 (5)
O3	0.0192 (5)	0.0203 (5)	0.0393 (6)	0.0102 (4)	−0.0003 (4)	0.0022 (4)
C3	0.0245 (6)	0.0200 (6)	0.0215 (6)	0.0128 (5)	−0.0019 (5)	0.0000 (5)
O4	0.0202 (5)	0.0162 (4)	0.0347 (5)	0.0075 (4)	−0.0003 (4)	0.0005 (4)
C4	0.0190 (6)	0.0221 (6)	0.0214 (6)	0.0101 (5)	−0.0005 (5)	0.0004 (5)
C5	0.0223 (6)	0.0186 (6)	0.0199 (6)	0.0087 (5)	−0.0014 (5)	−0.0006 (5)
C6	0.0230 (6)	0.0177 (6)	0.0220 (6)	0.0110 (5)	−0.0011 (5)	−0.0013 (5)
C7	0.0261 (7)	0.0166 (6)	0.0250 (6)	0.0092 (5)	−0.0019 (5)	−0.0018 (5)
C8	0.0229 (7)	0.0235 (7)	0.0380 (8)	0.0105 (6)	−0.0026 (6)	−0.0020 (6)
C9	0.0244 (7)	0.0240 (6)	0.0309 (7)	0.0149 (6)	−0.0005 (5)	0.0022 (5)
C10	0.0225 (7)	0.0295 (7)	0.0496 (9)	0.0136 (6)	0.0007 (6)	0.0032 (6)
C11	0.0307 (8)	0.0336 (8)	0.0846 (13)	0.0199 (7)	−0.0147 (8)	−0.0088 (8)
C12	0.0256 (7)	0.0188 (6)	0.0289 (7)	0.0123 (5)	0.0001 (5)	−0.0003 (5)
C13	0.0264 (7)	0.0204 (7)	0.0366 (7)	0.0089 (6)	−0.0018 (6)	−0.0015 (6)
C14	0.0381 (8)	0.0195 (7)	0.0520 (10)	0.0124 (6)	0.0014 (7)	0.0003 (6)

Geometric parameters (Å, º)

O1—N1	1.2262 (14)	C9—C10	1.5037 (18)
N1—O2	1.2255 (14)	C9—H9A	0.9900
N1—C2	1.4619 (16)	C9—H9B	0.9900
C1—C2	1.3955 (17)	C10—C11	1.523 (2)
C1—C6	1.4108 (16)	C10—H10A	0.9900
C1—C7	1.4361 (18)	C10—H10B	0.9900
C2—C3	1.3963 (18)	C11—H11A	0.9800
O3—C4	1.3587 (14)	C11—H11B	0.9800
O3—C9	1.4476 (15)	C11—H11C	0.9800
C3—C4	1.3831 (17)	C12—C13	1.5087 (17)
C3—H3	0.936 (14)	C12—H12A	0.9900
O4—C5	1.3527 (15)	C12—H12B	0.9900
O4—C12	1.4422 (14)	C13—C14	1.5191 (19)
C4—C5	1.4148 (17)	C13—H13A	0.9900
C5—C6	1.3796 (17)	C13—H13B	0.9900
C6—H6	0.9500	C14—H14A	0.9800
C7—C8	1.1862 (19)	C14—H14B	0.9800
C8—H8	0.935 (9)	C14—H14C	0.9800
O2—N1—O1	123.12 (11)	C9—C10—C11	111.07 (12)
O2—N1—C2	118.26 (11)	C9—C10—H10A	109.4
O1—N1—C2	118.62 (10)	C11—C10—H10A	109.4
C2—C1—C6	116.55 (11)	C9—C10—H10B	109.4
C2—C1—C7	126.96 (11)	C11—C10—H10B	109.4
C6—C1—C7	116.46 (10)	H10A—C10—H10B	108.0
C1—C2—C3	122.61 (11)	C10—C11—H11A	109.5
C1—C2—N1	120.76 (11)	C10—C11—H11B	109.5
C3—C2—N1	116.62 (11)	H11A—C11—H11B	109.5
C4—O3—C9	117.71 (9)	C10—C11—H11C	109.5
C4—C3—C2	119.58 (11)	H11A—C11—H11C	109.5
C4—C3—H3	120.8 (11)	H11B—C11—H11C	109.5
C2—C3—H3	119.5 (11)	O4—C12—C13	108.62 (10)
C5—O4—C12	116.89 (10)	O4—C12—H12A	110.0
O3—C4—C3	125.21 (11)	C13—C12—H12A	110.0
O3—C4—C5	115.38 (10)	O4—C12—H12B	110.0
C3—C4—C5	119.40 (11)	C13—C12—H12B	110.0
O4—C5—C6	124.60 (11)	H12A—C12—H12B	108.3
O4—C5—C4	115.58 (10)	C12—C13—C14	109.95 (12)
C6—C5—C4	119.82 (11)	C12—C13—H13A	109.7
C5—C6—C1	122.02 (11)	C14—C13—H13A	109.7
C5—C6—H6	119.0	C12—C13—H13B	109.7
C1—C6—H6	119.0	C14—C13—H13B	109.7
C8—C7—C1	170.34 (13)	H13A—C13—H13B	108.2
C7—C8—H8	179.0 (11)	C13—C14—H14A	109.5
O3—C9—C10	107.23 (10)	C13—C14—H14B	109.5
O3—C9—H9A	110.3	H14A—C14—H14B	109.5
C10—C9—H9A	110.3	C13—C14—H14C	109.5
O3—C9—H9B	110.3	H14A—C14—H14C	109.5
C10—C9—H9B	110.3	H14B—C14—H14C	109.5
H9A—C9—H9B	108.5
C3—C2—N1—O2	17.89 (17)	C1—C2—N1—O1	18.77 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···O3^i	0.94 (1)	2.48 (1)	3.4001 (16)	167 (2)
C8—H8···O4^i	0.94 (1)	2.62 (2)	3.3267 (16)	133 (1)
C3—H3···O2^ii	0.94 (1)	2.61 (1)	3.5459 (16)	177 (2)

Symmetry codes: (i) y+1/3, −x+y+2/3, −z+2/3; (ii) −x+4/3, −y+5/3, −z+2/3.

1,2-dibutoxy-4-ethynyl-5-nitrobenzene (2)

Crystal data

C16H21NO4	F(000) = 624
Mr = 291.34	Dx = 1.273 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.5209 (5) Å	Cell parameters from 3448 reflections
b = 18.0914 (10) Å	θ = 2.3–26.4°
c = 9.9579 (5) Å	µ = 0.09 mm^−1
β = 97.967 (1)°	T = 100 K
V = 1520.24 (14) Å^3	Irregular block, colourless
Z = 4	0.60 × 0.34 × 0.02 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	3370 independent reflections
Radiation source: fine-focus sealed tube	2449 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
Detector resolution: 8.3660 pixels mm^-1	θmax = 27.2°, θmin = 2.3°
φ and ω scans	h = −10→10
Absorption correction: multi-scan (SADABS Version 2014; Bruker AXS)	k = −23→23
Tmin = 0.682, Tmax = 0.746	l = −12→12
19579 measured reflections

Refinement

Refinement on F^2	2 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.041	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.103	w = 1/[σ^2(Fo^2) + (0.0447P)^2 + 0.5063P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
3370 reflections	Δρmax = 0.25 e Å^−3
198 parameters	Δρmin = −0.18 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq
O1	0.24462 (15)	0.41330 (6)	−0.09599 (12)	0.0331 (3)
N1	0.22644 (15)	0.34657 (7)	−0.09358 (12)	0.0194 (3)
C1	0.41750 (17)	0.33670 (8)	0.12054 (14)	0.0153 (3)
O2	0.13376 (14)	0.31327 (7)	−0.17849 (12)	0.0335 (3)
C2	0.31940 (17)	0.30296 (8)	0.01366 (14)	0.0153 (3)
O3	0.38628 (12)	0.10631 (5)	0.09739 (10)	0.0170 (2)
C3	0.30591 (17)	0.22633 (8)	0.00230 (14)	0.0156 (3)
H3	0.2381 (18)	0.2081 (9)	−0.0705 (14)	0.019*
H8	0.4862 (18)	0.5273 (7)	0.1967 (15)	0.019*
O4	0.57880 (12)	0.16462 (5)	0.28966 (10)	0.0169 (2)
C4	0.39137 (16)	0.18124 (8)	0.09726 (14)	0.0146 (3)
C5	0.49571 (16)	0.21339 (8)	0.20434 (14)	0.0145 (3)
C6	0.50568 (17)	0.28947 (8)	0.21533 (14)	0.0150 (3)
H6	0.573938	0.310557	0.288897	0.018*
C7	0.43705 (17)	0.41478 (8)	0.14269 (14)	0.0183 (3)
C8	0.46506 (19)	0.47713 (9)	0.17401 (16)	0.0227 (3)
C9	0.27503 (17)	0.07150 (8)	−0.00558 (14)	0.0168 (3)
H9A	0.307039	0.079990	−0.096176	0.020*
H9B	0.167922	0.092592	−0.005009	0.020*
C10	0.27354 (17)	−0.01003 (8)	0.02436 (14)	0.0167 (3)
H10A	0.236740	−0.017855	0.113319	0.020*
H10B	0.382713	−0.029677	0.030183	0.020*
C11	0.16582 (18)	−0.05231 (8)	−0.08441 (15)	0.0190 (3)
H11A	0.057299	−0.031722	−0.092033	0.023*
H11B	0.204412	−0.045622	−0.172931	0.023*
C12	0.16069 (19)	−0.13435 (8)	−0.05226 (16)	0.0231 (4)
H12A	0.266801	−0.155571	−0.050285	0.035*
H12B	0.086938	−0.159234	−0.122124	0.035*
H12C	0.125019	−0.141126	0.036353	0.035*
C13	0.69850 (17)	0.19390 (8)	0.39333 (14)	0.0161 (3)
H13A	0.648403	0.224452	0.458108	0.019*
H13B	0.773813	0.225262	0.351626	0.019*
C14	0.78460 (17)	0.12937 (8)	0.46602 (14)	0.0175 (3)
H14A	0.844815	0.102735	0.402880	0.021*
H14B	0.706485	0.094605	0.495658	0.021*
C15	0.89834 (18)	0.15516 (9)	0.58933 (15)	0.0200 (3)
H15A	0.974564	0.190909	0.559722	0.024*
H15B	0.837535	0.180877	0.653162	0.024*
C16	0.9892 (2)	0.09090 (10)	0.66219 (17)	0.0288 (4)
H16A	0.914086	0.055400	0.691711	0.043*
H16B	1.059132	0.109511	0.741391	0.043*
H16C	1.052701	0.066468	0.600332	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0427 (8)	0.0206 (7)	0.0324 (7)	0.0030 (5)	−0.0069 (6)	0.0077 (5)
N1	0.0194 (7)	0.0200 (7)	0.0184 (7)	0.0039 (5)	0.0015 (5)	0.0017 (5)
C1	0.0153 (7)	0.0148 (7)	0.0164 (7)	−0.0001 (6)	0.0039 (6)	0.0014 (6)
O2	0.0371 (7)	0.0301 (7)	0.0271 (6)	0.0032 (5)	−0.0167 (5)	−0.0001 (5)
C2	0.0147 (7)	0.0178 (8)	0.0136 (7)	0.0037 (6)	0.0021 (6)	0.0032 (6)
O3	0.0199 (5)	0.0123 (5)	0.0169 (5)	−0.0012 (4)	−0.0043 (4)	−0.0008 (4)
C3	0.0132 (7)	0.0193 (8)	0.0137 (7)	−0.0004 (6)	0.0002 (6)	−0.0016 (6)
O4	0.0198 (5)	0.0130 (5)	0.0155 (5)	−0.0010 (4)	−0.0060 (4)	0.0011 (4)
C4	0.0137 (7)	0.0159 (7)	0.0145 (7)	0.0001 (6)	0.0022 (5)	−0.0002 (6)
C5	0.0139 (7)	0.0163 (7)	0.0128 (7)	0.0015 (6)	0.0006 (5)	0.0021 (6)
C6	0.0138 (7)	0.0181 (8)	0.0130 (7)	−0.0011 (6)	0.0008 (5)	−0.0010 (6)
C7	0.0179 (8)	0.0208 (8)	0.0156 (7)	0.0029 (6)	0.0006 (6)	0.0035 (6)
C8	0.0261 (9)	0.0172 (8)	0.0235 (8)	0.0015 (7)	−0.0016 (6)	0.0026 (7)
C9	0.0152 (7)	0.0184 (8)	0.0152 (7)	−0.0011 (6)	−0.0032 (6)	−0.0015 (6)
C10	0.0152 (7)	0.0165 (8)	0.0172 (7)	−0.0002 (6)	−0.0018 (6)	−0.0001 (6)
C11	0.0207 (8)	0.0163 (8)	0.0186 (7)	0.0000 (6)	−0.0022 (6)	−0.0018 (6)
C12	0.0237 (8)	0.0184 (8)	0.0257 (8)	−0.0008 (6)	−0.0026 (7)	−0.0012 (7)
C13	0.0167 (7)	0.0161 (7)	0.0143 (7)	−0.0031 (6)	−0.0025 (6)	−0.0010 (6)
C14	0.0190 (8)	0.0166 (8)	0.0156 (7)	0.0005 (6)	−0.0022 (6)	0.0006 (6)
C15	0.0183 (7)	0.0249 (9)	0.0154 (7)	0.0026 (6)	−0.0029 (6)	−0.0007 (6)
C16	0.0256 (9)	0.0363 (10)	0.0220 (8)	0.0039 (7)	−0.0056 (7)	0.0075 (7)

Geometric parameters (Å, º)

O1—N1	1.2178 (16)	C10—C11	1.5248 (19)
N1—O2	1.2314 (16)	C10—H10A	0.9900
N1—C2	1.4683 (18)	C10—H10B	0.9900
C1—C2	1.399 (2)	C11—C12	1.520 (2)
C1—C6	1.4103 (19)	C11—H11A	0.9900
C1—C7	1.436 (2)	C11—H11B	0.9900
C2—C3	1.394 (2)	C12—H12A	0.9800
O3—C4	1.3564 (17)	C12—H12B	0.9800
O3—C9	1.4412 (16)	C12—H12C	0.9800
C3—C4	1.378 (2)	C13—C14	1.509 (2)
C3—H3	0.923 (13)	C13—H13A	0.9900
O4—C5	1.3546 (16)	C13—H13B	0.9900
O4—C13	1.4473 (16)	C14—C15	1.5281 (19)
C4—C5	1.4152 (19)	C14—H14A	0.9900
C5—C6	1.382 (2)	C14—H14B	0.9900
C6—H6	0.9500	C15—C16	1.524 (2)
C7—C8	1.186 (2)	C15—H15A	0.9900
C8—H8	0.947 (13)	C15—H15B	0.9900
C9—C10	1.505 (2)	C16—H16A	0.9800
C9—H9A	0.9900	C16—H16B	0.9800
C9—H9B	0.9900	C16—H16C	0.9800
O1—N1—O2	122.87 (13)	C12—C11—C10	111.85 (12)
O1—N1—C2	119.33 (12)	C12—C11—H11A	109.2
O2—N1—C2	117.80 (12)	C10—C11—H11A	109.2
C2—C1—C6	116.84 (13)	C12—C11—H11B	109.2
C2—C1—C7	126.19 (13)	C10—C11—H11B	109.2
C6—C1—C7	116.97 (13)	H11A—C11—H11B	107.9
C3—C2—C1	121.96 (13)	C11—C12—H12A	109.5
C3—C2—N1	116.44 (13)	C11—C12—H12B	109.5
C1—C2—N1	121.60 (13)	H12A—C12—H12B	109.5
C4—O3—C9	117.00 (11)	C11—C12—H12C	109.5
C4—C3—C2	120.21 (13)	H12A—C12—H12C	109.5
C4—C3—H3	122.8 (10)	H12B—C12—H12C	109.5
C2—C3—H3	117.0 (10)	O4—C13—C14	107.86 (11)
C5—O4—C13	117.67 (11)	O4—C13—H13A	110.1
O3—C4—C3	125.34 (13)	C14—C13—H13A	110.1
O3—C4—C5	115.27 (12)	O4—C13—H13B	110.1
C3—C4—C5	119.39 (13)	C14—C13—H13B	110.1
O4—C5—C6	125.30 (13)	H13A—C13—H13B	108.4
O4—C5—C4	115.09 (12)	C13—C14—C15	111.17 (12)
C6—C5—C4	119.61 (13)	C13—C14—H14A	109.4
C5—C6—C1	121.94 (13)	C15—C14—H14A	109.4
C5—C6—H6	119.0	C13—C14—H14B	109.4
C1—C6—H6	119.0	C15—C14—H14B	109.4
C8—C7—C1	172.37 (16)	H14A—C14—H14B	108.0
C7—C8—H8	178.5 (10)	C16—C15—C14	111.92 (13)
O3—C9—C10	108.06 (11)	C16—C15—H15A	109.2
O3—C9—H9A	110.1	C14—C15—H15A	109.2
C10—C9—H9A	110.1	C16—C15—H15B	109.2
O3—C9—H9B	110.1	C14—C15—H15B	109.2
C10—C9—H9B	110.1	H15A—C15—H15B	107.9
H9A—C9—H9B	108.4	C15—C16—H16A	109.5
C9—C10—C11	111.82 (12)	C15—C16—H16B	109.5
C9—C10—H10A	109.3	H16A—C16—H16B	109.5
C11—C10—H10A	109.3	C15—C16—H16C	109.5
C9—C10—H10B	109.3	H16A—C16—H16C	109.5
C11—C10—H10B	109.3	H16B—C16—H16C	109.5
H10A—C10—H10B	107.9
C1—C2—N1—O1	6.1 (2)	C3—C2—N1—O2	6.1 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···O3^i	0.95 (1)	2.61 (1)	3.3835 (19)	139 (1)
C8—H8···O4^i	0.95 (1)	2.55 (1)	3.4371 (19)	156 (1)

Symmetry code: (i) −x+1, y+1/2, −z+1/2.

(3)

Crystal data

C18H25NO4	Z = 2
Mr = 319.39	F(000) = 344
Triclinic, P1	Dx = 1.181 Mg m^−3
a = 4.570 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.415 (8) Å	Cell parameters from 852 reflections
c = 20.968 (18) Å	θ = 2.3–25.6°
α = 94.003 (12)°	µ = 0.08 mm^−1
β = 90.758 (12)°	T = 100 K
γ = 93.435 (11)°	Square, colourless
V = 898.2 (14) Å^3	0.46 × 0.14 × 0.14 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	2914 independent reflections
Radiation source: fine-focus sealed tube	1604 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.055
Detector resolution: 8.3660 pixels mm^-1	θmax = 24.4°, θmin = 2.0°
φ and ω scans	h = −5→5
Absorption correction: multi-scan (SADABS Version 2014; Bruker AXS)	k = −10→10
Tmin = 0.382, Tmax = 0.746	l = −24→23
5380 measured reflections

Refinement

Refinement on F^2	2 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.085	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.262	w = 1/[σ^2(Fo^2) + (0.1254P)^2 + 0.8636P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
2914 reflections	Δρmax = 0.36 e Å^−3
216 parameters	Δρmin = −0.32 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq
O1	0.5970 (9)	0.2146 (5)	0.48201 (18)	0.0588 (11)
N1	0.4403 (9)	0.2986 (5)	0.5092 (2)	0.0370 (10)
C1	0.6541 (10)	0.2513 (5)	0.6159 (2)	0.0315 (12)
O2	0.2526 (9)	0.3609 (5)	0.48100 (18)	0.0590 (12)
C2	0.4709 (10)	0.3307 (5)	0.5786 (2)	0.0295 (11)
O3	0.1873 (6)	0.5814 (3)	0.70199 (15)	0.0326 (8)
C3	0.3139 (10)	0.4410 (5)	0.6053 (2)	0.0298 (11)
O4	0.5189 (7)	0.4440 (3)	0.77303 (15)	0.0345 (9)
C4	0.3319 (9)	0.4762 (5)	0.6707 (2)	0.0266 (11)
C5	0.5148 (9)	0.4001 (5)	0.7095 (2)	0.0290 (11)
C6	0.6704 (10)	0.2917 (5)	0.6818 (2)	0.0310 (11)
H6	0.793656	0.242129	0.708311	0.037*
C7	0.8201 (11)	0.1340 (5)	0.5926 (2)	0.0363 (12)
C8	0.9653 (13)	0.0361 (6)	0.5791 (3)	0.0473 (14)
C9	0.0258 (10)	0.6727 (5)	0.6633 (2)	0.0330 (12)
H9A	−0.122640	0.615029	0.636202	0.040*
H9B	0.160789	0.724363	0.635096	0.040*
C10	−0.1205 (10)	0.7763 (5)	0.7078 (2)	0.0345 (12)
H10A	−0.249033	0.721845	0.736309	0.041*
H10B	−0.247428	0.833281	0.682280	0.041*
C11	0.0872 (10)	0.8788 (5)	0.7493 (2)	0.0379 (13)
H11A	0.224340	0.822607	0.772683	0.045*
H11B	0.204592	0.939463	0.721230	0.045*
C12	−0.0696 (10)	0.9732 (5)	0.7969 (3)	0.0406 (13)
H12A	−0.184891	0.912351	0.825290	0.049*
H12B	−0.208957	1.028117	0.773504	0.049*
C13	0.1374 (13)	1.0785 (6)	0.8384 (3)	0.0603 (17)
H13A	0.275222	1.025110	0.862082	0.090*
H13B	0.021880	1.135181	0.868596	0.090*
H13C	0.246599	1.141996	0.810842	0.090*
C14	0.7373 (11)	0.3898 (5)	0.8135 (2)	0.0354 (12)
H14A	0.936232	0.418935	0.799172	0.043*
H14B	0.716549	0.284282	0.811463	0.043*
C15	0.6920 (12)	0.4506 (5)	0.8810 (2)	0.0420 (13)
H15A	0.828665	0.407640	0.910064	0.050*
H15B	0.489858	0.422903	0.893716	0.050*
C16	0.7393 (14)	0.6118 (6)	0.8896 (3)	0.0523 (16)
H16A	0.606104	0.655330	0.859921	0.063*
H16B	0.943233	0.639925	0.878241	0.063*
C17	0.6833 (16)	0.6703 (6)	0.9585 (3)	0.0654 (18)
H17A	0.479985	0.640869	0.969787	0.078*
H17B	0.817275	0.626639	0.987940	0.078*
C18	0.726 (2)	0.8298 (8)	0.9686 (3)	0.111 (3)
H18A	0.928128	0.859964	0.958565	0.167*
H18B	0.687568	0.859377	1.013337	0.167*
H18C	0.590164	0.874182	0.940628	0.167*
H3	0.187 (15)	0.483 (8)	0.578 (3)	0.133*
H8	1.065 (17)	−0.045 (6)	0.564 (4)	0.133*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.069 (3)	0.063 (3)	0.044 (2)	0.018 (2)	0.000 (2)	−0.006 (2)
N1	0.035 (2)	0.031 (2)	0.043 (3)	−0.010 (2)	−0.003 (2)	0.003 (2)
C1	0.028 (3)	0.029 (3)	0.036 (3)	−0.012 (2)	0.003 (2)	0.002 (2)
O2	0.068 (3)	0.067 (3)	0.041 (2)	0.005 (2)	−0.013 (2)	0.002 (2)
C2	0.028 (3)	0.026 (3)	0.033 (3)	−0.013 (2)	−0.002 (2)	0.003 (2)
O3	0.0285 (18)	0.0289 (18)	0.040 (2)	−0.0013 (14)	−0.0064 (14)	0.0051 (15)
C3	0.024 (2)	0.026 (3)	0.038 (3)	−0.011 (2)	−0.004 (2)	0.006 (2)
O4	0.0329 (18)	0.037 (2)	0.0327 (19)	−0.0043 (15)	−0.0057 (14)	0.0033 (15)
C4	0.022 (2)	0.020 (2)	0.037 (3)	−0.0078 (19)	0.002 (2)	0.005 (2)
C5	0.023 (2)	0.027 (3)	0.036 (3)	−0.011 (2)	−0.002 (2)	0.005 (2)
C6	0.025 (3)	0.027 (3)	0.040 (3)	−0.007 (2)	−0.004 (2)	0.006 (2)
C7	0.037 (3)	0.029 (3)	0.041 (3)	−0.010 (2)	0.001 (2)	0.001 (2)
C8	0.061 (4)	0.039 (3)	0.041 (3)	−0.003 (3)	0.002 (3)	0.001 (3)
C9	0.023 (2)	0.032 (3)	0.044 (3)	0.003 (2)	−0.003 (2)	0.007 (2)
C10	0.025 (3)	0.029 (3)	0.050 (3)	−0.003 (2)	−0.002 (2)	0.012 (2)
C11	0.030 (3)	0.030 (3)	0.054 (3)	−0.002 (2)	0.000 (2)	0.007 (2)
C12	0.032 (3)	0.030 (3)	0.060 (3)	−0.001 (2)	−0.002 (2)	0.009 (2)
C13	0.053 (4)	0.045 (4)	0.080 (4)	0.001 (3)	−0.010 (3)	−0.010 (3)
C14	0.037 (3)	0.032 (3)	0.037 (3)	−0.005 (2)	−0.007 (2)	0.008 (2)
C15	0.048 (3)	0.042 (3)	0.035 (3)	−0.009 (2)	−0.005 (2)	0.007 (2)
C16	0.069 (4)	0.042 (3)	0.044 (3)	−0.014 (3)	−0.007 (3)	0.001 (3)
C17	0.096 (5)	0.052 (4)	0.047 (4)	0.002 (4)	−0.008 (3)	−0.005 (3)
C18	0.210 (11)	0.063 (5)	0.057 (5)	0.001 (6)	−0.002 (5)	−0.013 (4)

Geometric parameters (Å, º)

O1—N1	1.215 (5)	C11—C12	1.507 (7)
N1—O2	1.234 (5)	C11—H11A	0.9900
N1—C2	1.469 (6)	C11—H11B	0.9900
C1—C6	1.408 (6)	C12—C13	1.542 (7)
C1—C2	1.418 (7)	C12—H12A	0.9900
C1—C7	1.438 (7)	C12—H12B	0.9900
C2—C3	1.388 (7)	C13—H13A	0.9800
O3—C4	1.359 (5)	C13—H13B	0.9800
O3—C9	1.449 (5)	C13—H13C	0.9800
C3—C4	1.388 (7)	C14—C15	1.511 (7)
C3—H3	0.93 (2)	C14—H14A	0.9900
O4—C5	1.366 (5)	C14—H14B	0.9900
O4—C14	1.440 (6)	C15—C16	1.518 (7)
C4—C5	1.417 (6)	C15—H15A	0.9900
C5—C6	1.379 (6)	C15—H15B	0.9900
C6—H6	0.9500	C16—C17	1.540 (8)
C7—C8	1.188 (7)	C16—H16A	0.9900
C8—H8	0.95 (2)	C16—H16B	0.9900
C9—C10	1.496 (6)	C17—C18	1.503 (9)
C9—H9A	0.9900	C17—H17A	0.9900
C9—H9B	0.9900	C17—H17B	0.9900
C10—C11	1.529 (6)	C18—H18A	0.9800
C10—H10A	0.9900	C18—H18B	0.9800
C10—H10B	0.9900	C18—H18C	0.9800
O1—N1—O2	123.0 (4)	C11—C12—C13	113.8 (4)
O1—N1—C2	120.1 (4)	C11—C12—H12A	108.8
O2—N1—C2	116.9 (4)	C13—C12—H12A	108.8
C6—C1—C2	116.1 (4)	C11—C12—H12B	108.8
C6—C1—C7	117.8 (5)	C13—C12—H12B	108.8
C2—C1—C7	126.1 (4)	H12A—C12—H12B	107.7
C3—C2—C1	122.2 (4)	C12—C13—H13A	109.5
C3—C2—N1	117.1 (4)	C12—C13—H13B	109.5
C1—C2—N1	120.7 (4)	H13A—C13—H13B	109.5
C4—O3—C9	117.2 (4)	C12—C13—H13C	109.5
C2—C3—C4	120.0 (4)	H13A—C13—H13C	109.5
C2—C3—H3	117 (5)	H13B—C13—H13C	109.5
C4—C3—H3	123 (5)	O4—C14—C15	107.7 (4)
C5—O4—C14	117.8 (4)	O4—C14—H14A	110.2
O3—C4—C3	125.0 (4)	C15—C14—H14A	110.2
O3—C4—C5	115.5 (4)	O4—C14—H14B	110.2
C3—C4—C5	119.4 (4)	C15—C14—H14B	110.2
O4—C5—C6	125.7 (4)	H14A—C14—H14B	108.5
O4—C5—C4	114.8 (4)	C14—C15—C16	113.9 (4)
C6—C5—C4	119.5 (4)	C14—C15—H15A	108.8
C5—C6—C1	122.7 (5)	C16—C15—H15A	108.8
C5—C6—H6	118.7	C14—C15—H15B	108.8
C1—C6—H6	118.7	C16—C15—H15B	108.8
C8—C7—C1	173.9 (6)	H15A—C15—H15B	107.7
C7—C8—H8	173 (5)	C15—C16—C17	112.4 (5)
O3—C9—C10	107.5 (4)	C15—C16—H16A	109.1
O3—C9—H9A	110.2	C17—C16—H16A	109.1
C10—C9—H9A	110.2	C15—C16—H16B	109.1
O3—C9—H9B	110.2	C17—C16—H16B	109.1
C10—C9—H9B	110.2	H16A—C16—H16B	107.8
H9A—C9—H9B	108.5	C18—C17—C16	113.9 (6)
C9—C10—C11	115.2 (4)	C18—C17—H17A	108.8
C9—C10—H10A	108.5	C16—C17—H17A	108.8
C11—C10—H10A	108.5	C18—C17—H17B	108.8
C9—C10—H10B	108.5	C16—C17—H17B	108.8
C11—C10—H10B	108.5	H17A—C17—H17B	107.7
H10A—C10—H10B	107.5	C17—C18—H18A	109.5
C12—C11—C10	113.3 (4)	C17—C18—H18B	109.5
C12—C11—H11A	108.9	H18A—C18—H18B	109.5
C10—C11—H11A	108.9	C17—C18—H18C	109.5
C12—C11—H11B	108.9	H18A—C18—H18C	109.5
C10—C11—H11B	108.9	H18B—C18—H18C	109.5
H11A—C11—H11B	107.7
C1—C2—N1—O1	−8.4 (6)	C3—C2—N1—O2	−8.0 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O2^i	0.93 (2)	2.88 (3)	3.793 (7)	167 (7)
C9—H9A···O2^i	0.99	2.55	3.254 (7)	128
C8—H8···O1^ii	0.95 (2)	2.45 (3)	3.381 (8)	167 (8)

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