Cyclo­decyl 4-nitro­phenyl­acetate

Cyclodecyl 4-nitrophenylacetate, C₁₈H₂₅NO₄, has its ten-membered ring in the expected diamond-lattice boat-chair-boat [2323] conformation, with the substituent 4-nitro­phenyl­acet­oxy group in the BCB IIIe position. The ester unit has the expected Z conformation, with an O=C-O-C torsion angle of -0.3 (3)°, and the connection to the benzene ring is nearly perpendicular to the ester, with an O=C-C-C torsion angle of 85.5 (2)°. An inter­molecular contact exists between the ester C atom and a nitro O atom, having a C...O distance of 2.909 (2) Å.

S1. Comment

The conformations of cyclodecane (2) and its derivatives have been of interest for a long time. The boat–chair–boat conformation (BCB, 2a) was found for the solid state by X-ray diffraction near 173 K (Shenhav & Schaeffer, 1981) and by ¹³C NMR at 145 K (Drotloff, 1987). This conformation has C_2h symmetry as shown below, with the three types of C atoms labeled I, II and III. The mirror plane bisects the type I C atoms, and the axis bisects the bonds connecting the type III C atoms. The axial H atoms on the six V atoms of type I or type III form two planes, above and below the ring, with substantial non-bonded interactions. These intraannular positions are drawn as closed circles, and the open circles represent extraannular positions, which are relatively strain free and will be occupied by groups larger than hydrogen.

A dynamic NMR study of 2 (Pawar et al., 1998) found the expected three ¹³C peaks for 2a in solution by 102 K. Additional absorption for the twist-boat–chair–chair conformation (TBCC, 2b), about 0.7 kcal/mol higher in free energy than 2a, was also found at higher temperatures by these authors. The possible presence of a small amount of the twist-boat–chair conformation (TBC, 2c) could not be verified or disproved by the low-temperature NMR spectra.

Calculations confirm a low energy for BCB and provide estimates of relative energies for other conformations (Hendrickson, 1967; Saunders, 1991; Kolossvary & Guida, 1993; Pawar et al., 1998). Ab initio calculations at the MP2/6–311+G^* level (Wiberg, 2003) predict that six conformations of 2 will have populations of 10% or greater at 298 K, with TBCC most populated (23%), followed by BCB (21%).

Interconversion of carbon sites in the BCB conformation is expected to occur by way of TBC. Cheng (1973) has described the itinerary for this process, which equilibrates C atoms 1 and 4 etc. of 2a. Kolossvary & Guida (1993) carried out a comprehensive study of conformational equilibration for 2 with Allinger's MM2 program and concluded that 2a equilibrates only with 2c within a 12 kcal mol⁻¹ window. Wiberg (2003) calculated a free-energy barrier of 5.4 kcal mol⁻¹ for the BCB to TBC conversion at room temperature, in good agreement with a later experimental determination of this barrier (5.54 kcal mol⁻¹ at 136 K; Pawar et al., 2006).

1,1-Difluorocyclodecane was found by ¹⁹F NMR to have the F atoms at the IIe and IIa positions (Noe & Roberts, 1972). trans-1,6-Disubstituted cyclodecanes have four possible BCB conformations which avoid intraannular positions, and examples of three of them have been found by X-ray diffraction, viz. monoclinic modification of trans-1,6-diaminocyclodecane dihydrochloride (IIa, IIa; Huber-Buser & Dunitz, 1966), trans-1,6-cyclodecanediol (IIa, IIa; Ermer et al., 1973), triclinic modification of trans-1,6-diaminocyclodecane dihydrochloride (IIe, IIe; Huber-Buser & Dunitz, 1960, 1961) and trans-1,6-dibromocyclodecane (IIIe, IIIe; Dunitz & Weber, 1964). Disubstitution at the type Ie positions would also avoid the intraannular positions but has not been observed. This conformation lacks the Rln2 contribution to entropy that would favor the enantiomeric pairs of the observed conformations. Similarly, substitution at the Ie position has not been found for monosubstituted cyclodecanes. X-ray studies of cyclodecanol (Valente et al., 1998) and cyclodecylamine hydrochloride sesquihydrate (Nowacki & Mladeck, 1961; Mladeck & Nowacki, 1964) found the substituents at the IIe and IIIe positions of the BCB conformation, respectively.

The low-temperature ¹³C spectrum of the substituted ring carbon of chlorocyclodecane (3) in solution showed three peaks at δ 67.67 (3a), 66.14 (3b) and 61.63 (3c), with populations of 31.2, 14.9 and 53.9% (Pawar et al., 1998). These peaks were assigned to IIe BCB, IIa BCB and a TBCC conformation, respectively, but the assignment for the major conformation (3c) was later changed to IIIe BCB (Pawar et al., 2006). The low-temperature ¹³C spectra for cyclodecyl acetate (4) in solution show three peaks for the substituted ring C atoms, with relative positions and intensities similar to 3, which suggested that the populated ring conformations are the same for 3 and 4 (Pawar et al., 1998). In the present work, an X-ray diffraction study of cyclodecyl 4-nitrophenylacetate, in which a 4-nitrophenyl group replaces a methyl hydrogen of 4, showed that the conformation in the solid state is IIIe BCB (below). This result suggests that IIIe BCB is the major conformation for 1 in solution, and by extension also for 3 and 4.

The O1—C1—O2—C9 torsion angle in 1 is experimentally indistinguishable from zero, showing that the ester has the expected Z conformation. The bond connecting the benzene ring to the CH₂ C atom is nearly perpendicular to the ester group [O1—C1—C2—C3 = 85.5 (2)°].

A notable intermolecular interaction exists (Fig. 3) involving the ester C and a nitrate O atom. It is quite similar to the perpendicular motif carbonyl–carbonyl interaction described by Allen et al. (1998). They found a median C···O distance of 3.35 Å in a population from the Cambridge Structural Database (Allen, 2002) having C···O < 3.6 Å. In 1, the C1···O4 (at x − 1, y − 1, z) distance is 2.909 (2) Å. For the perpendicular motif, Allen et al. (1998) find a mean C═O···C angle of 159.7 (7)° and a mean O···C═O angle of 97.2 (12)°. The analogous angles in (1) are 132.1 (2) and 97.2 (2)°, respectively. These interactions form chains in the [110] direction, as illustrated in Fig. 3.

S2. Experimental

Cyclodecyl 4-nitrophenylacetate (1) was synthesized by treatment of cyclodecanol with 4-nitrophenylacetyl chloride and dimethyl aniline. Diethyl ether was used as solvent. {Quantities of reagents, conditions?} The crude sample of 1 was recrystallized from hexane (m.p. 330 K), and the purity of the sample was established by ¹³C NMR spectroscopy. Crystals for the X-ray study were obtained from ethyl acetate by slow evaporation.

S3. Refinement

H atoms were placed in calculated positions, guided by difference maps, with C—H bond distances of 0.95–1.00 Å and U_iso(H) values of 1.2U_eq of the attached C atom, and thereafter treated as riding. The absolute structure could not be established from the X-ray data, and the positive direction of the polar axis is an arbitrary choice. Friedel pairs were averaged.

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The boat–chair–boat conformation of cyclodecane.
	Fig. 2. A displacement ellipsoid plot, at the 50% probability level.
	Fig. 3. The C···O intermolecular contacts. [Symmetry codes: (a) x + 1, y + 1, z; (b) x − 1, y − 1, z.]

Cyclodecyl 4-nitrophenylacetate

Crystal data

C18H25NO4	F(000) = 344
Mr = 319.39	Dx = 1.267 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1892 reflections
a = 7.5050 (15) Å	θ = 2.5–30.0°
b = 5.8492 (10) Å	µ = 0.09 mm^−1
c = 19.381 (4) Å	T = 115 K
β = 100.289 (10)°	Plate, colorless
V = 837.1 (3) Å^3	0.35 × 0.30 × 0.05 mm
Z = 2

Data collection

Nonius KappaCCD (with an Oxford Cryosystems Cryostream cooler) diffractometer	2008 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 29.9°, θmin = 2.7°
ω scans with κ offsets	h = −9→9
10156 measured reflections	k = −8→6
2326 independent reflections	l = −25→25

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)] = 0.038	H-atom parameters constrained
wR(F^2) = 0.087	w = 1/[σ^2(Fo^2) + (0.0343P)^2 + 0.2312P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
2326 reflections	Δρmax = 0.21 e Å^−3
209 parameters	Δρmin = −0.19 e Å^−3
1 restraint	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.043 (5)

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.

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

	x	y	z	Uiso*/Ueq
O1	0.14233 (19)	0.2770 (3)	0.28109 (7)	0.0242 (3)
O2	−0.02396 (17)	0.5877 (3)	0.29753 (7)	0.0189 (3)
O3	0.97463 (18)	0.9203 (3)	0.44547 (8)	0.0270 (4)
O4	0.8258 (2)	1.1657 (3)	0.37363 (10)	0.0378 (4)
N1	0.8345 (2)	0.9897 (3)	0.40891 (9)	0.0216 (4)
C1	0.0996 (2)	0.4253 (4)	0.31830 (10)	0.0175 (4)
C2	0.1853 (2)	0.4578 (4)	0.39462 (9)	0.0178 (4)
H2A	0.2159	0.3068	0.4167	0.021*
H2B	0.0980	0.5338	0.4198	0.021*
C3	0.3559 (2)	0.6022 (4)	0.40061 (9)	0.0159 (4)
C4	0.5205 (2)	0.5201 (4)	0.43639 (9)	0.0172 (4)
H4	0.5251	0.3751	0.4587	0.021*
C5	0.6780 (3)	0.6464 (4)	0.43999 (10)	0.0175 (4)
H5	0.7902	0.5905	0.4647	0.021*
C6	0.6674 (3)	0.8558 (4)	0.40665 (10)	0.0169 (4)
C7	0.5057 (2)	0.9450 (4)	0.37098 (10)	0.0178 (4)
H7	0.5022	1.0900	0.3487	0.021*
C8	0.3493 (3)	0.8171 (4)	0.36871 (10)	0.0178 (4)
H8	0.2366	0.8759	0.3453	0.021*
C9	−0.1133 (2)	0.5852 (4)	0.22357 (9)	0.0190 (4)
H9	−0.1214	0.4239	0.2062	0.023*
C10	−0.3037 (3)	0.6770 (4)	0.22249 (10)	0.0214 (4)
H10A	−0.3481	0.7457	0.1759	0.026*
H10B	−0.2973	0.8004	0.2578	0.026*
C11	−0.4416 (3)	0.4988 (4)	0.23727 (11)	0.0265 (5)
H11A	−0.4074	0.4504	0.2868	0.032*
H11B	−0.5613	0.5744	0.2323	0.032*
C12	−0.4634 (3)	0.2840 (5)	0.19159 (12)	0.0305 (5)
H12A	−0.5418	0.1761	0.2118	0.037*
H12B	−0.3428	0.2114	0.1957	0.037*
C13	−0.5416 (3)	0.3094 (5)	0.11330 (12)	0.0360 (6)
H13A	−0.6627	0.3808	0.1093	0.043*
H13B	−0.5603	0.1539	0.0932	0.043*
C14	−0.4340 (3)	0.4472 (5)	0.06687 (10)	0.0285 (5)
H14A	−0.5005	0.4422	0.0179	0.034*
H14B	−0.4296	0.6088	0.0822	0.034*
C15	−0.2396 (3)	0.3648 (4)	0.06767 (11)	0.0269 (5)
H15A	−0.1945	0.2927	0.1137	0.032*
H15B	−0.2426	0.2449	0.0314	0.032*
C16	−0.1040 (3)	0.5483 (5)	0.05495 (11)	0.0303 (5)
H16A	0.0156	0.4738	0.0581	0.036*
H16B	−0.1405	0.6032	0.0062	0.036*
C17	−0.0790 (3)	0.7576 (4)	0.10288 (11)	0.0290 (5)
H17A	−0.1988	0.8316	0.0999	0.035*
H17B	−0.0002	0.8669	0.0834	0.035*
C18	0.0009 (3)	0.7244 (4)	0.18113 (11)	0.0262 (5)
H18A	0.1202	0.6489	0.1847	0.031*
H18B	0.0221	0.8772	0.2030	0.031*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0240 (7)	0.0243 (8)	0.0234 (7)	0.0036 (7)	0.0023 (6)	−0.0029 (7)
O2	0.0177 (6)	0.0208 (7)	0.0164 (6)	0.0009 (6)	−0.0021 (5)	−0.0006 (6)
O3	0.0157 (7)	0.0330 (9)	0.0309 (8)	−0.0044 (7)	0.0000 (6)	−0.0064 (7)
O4	0.0261 (8)	0.0302 (10)	0.0562 (11)	−0.0092 (8)	0.0049 (8)	0.0149 (9)
N1	0.0147 (8)	0.0243 (10)	0.0262 (9)	−0.0031 (7)	0.0047 (7)	−0.0040 (8)
C1	0.0132 (8)	0.0183 (10)	0.0209 (9)	−0.0028 (8)	0.0031 (7)	0.0008 (8)
C2	0.0144 (8)	0.0212 (10)	0.0174 (9)	−0.0029 (8)	0.0019 (7)	0.0019 (8)
C3	0.0147 (8)	0.0190 (10)	0.0139 (8)	−0.0020 (8)	0.0027 (7)	−0.0026 (8)
C4	0.0182 (9)	0.0184 (10)	0.0144 (8)	−0.0001 (8)	0.0011 (7)	−0.0006 (8)
C5	0.0133 (8)	0.0227 (11)	0.0156 (9)	0.0006 (8)	−0.0002 (7)	−0.0024 (8)
C6	0.0140 (8)	0.0202 (10)	0.0168 (8)	−0.0055 (8)	0.0037 (7)	−0.0035 (8)
C7	0.0188 (9)	0.0177 (9)	0.0170 (8)	−0.0004 (9)	0.0034 (7)	0.0005 (8)
C8	0.0148 (8)	0.0203 (10)	0.0178 (9)	−0.0005 (8)	0.0012 (7)	−0.0010 (8)
C9	0.0184 (9)	0.0234 (10)	0.0139 (9)	−0.0002 (9)	−0.0009 (7)	−0.0014 (8)
C10	0.0216 (10)	0.0253 (11)	0.0162 (9)	0.0040 (9)	0.0003 (8)	−0.0043 (8)
C11	0.0178 (9)	0.0387 (14)	0.0229 (10)	0.0023 (10)	0.0030 (8)	−0.0013 (10)
C12	0.0270 (11)	0.0365 (14)	0.0280 (11)	−0.0070 (11)	0.0050 (9)	−0.0010 (11)
C13	0.0313 (12)	0.0449 (16)	0.0293 (12)	−0.0074 (12)	−0.0010 (9)	−0.0066 (12)
C14	0.0306 (11)	0.0346 (13)	0.0171 (9)	0.0041 (12)	−0.0042 (8)	−0.0033 (10)
C15	0.0313 (11)	0.0281 (12)	0.0198 (10)	0.0055 (10)	0.0011 (8)	−0.0031 (9)
C16	0.0338 (12)	0.0376 (14)	0.0203 (10)	0.0028 (12)	0.0070 (9)	−0.0004 (10)
C17	0.0350 (12)	0.0303 (13)	0.0216 (11)	−0.0048 (11)	0.0046 (9)	0.0039 (10)
C18	0.0247 (10)	0.0323 (13)	0.0210 (10)	−0.0050 (10)	0.0024 (8)	0.0014 (9)

Geometric parameters (Å, º)

O1—C1	1.208 (3)	C10—H10B	0.9900
O2—C1	1.338 (2)	C11—C12	1.529 (3)
O2—C9	1.470 (2)	C11—H11A	0.9900
O3—N1	1.228 (2)	C11—H11B	0.9900
O4—N1	1.231 (2)	C12—C13	1.533 (3)
N1—C6	1.472 (3)	C12—H12A	0.9900
C1—C2	1.516 (3)	C12—H12B	0.9900
C2—C3	1.521 (3)	C13—C14	1.540 (3)
C2—H2A	0.9900	C13—H13A	0.9900
C2—H2B	0.9900	C13—H13B	0.9900
C3—C4	1.390 (3)	C14—C15	1.534 (3)
C3—C8	1.398 (3)	C14—H14A	0.9900
C4—C5	1.385 (3)	C14—H14B	0.9900
C4—H4	0.9500	C15—C16	1.529 (3)
C5—C6	1.380 (3)	C15—H15A	0.9900
C5—H5	0.9500	C15—H15B	0.9900
C6—C7	1.387 (3)	C16—C17	1.528 (3)
C7—C8	1.386 (3)	C16—H16A	0.9900
C7—H7	0.9500	C16—H16B	0.9900
C8—H8	0.9500	C17—C18	1.540 (3)
C9—C10	1.523 (3)	C17—H17A	0.9900
C9—C18	1.525 (3)	C17—H17B	0.9900
C9—H9	1.0000	C18—H18A	0.9900
C10—C11	1.532 (3)	C18—H18B	0.9900
C10—H10A	0.9900
C1—O2—C9	117.18 (16)	C12—C11—H11B	108.0
O3—N1—O4	123.50 (18)	C10—C11—H11B	108.0
O3—N1—C6	118.59 (18)	H11A—C11—H11B	107.2
O4—N1—C6	117.90 (17)	C11—C12—C13	118.4 (2)
O1—C1—O2	125.04 (18)	C11—C12—H12A	107.7
O1—C1—C2	124.13 (18)	C13—C12—H12A	107.7
O2—C1—C2	110.78 (17)	C11—C12—H12B	107.7
C1—C2—C3	110.42 (15)	C13—C12—H12B	107.7
C1—C2—H2A	109.6	H12A—C12—H12B	107.1
C3—C2—H2A	109.6	C12—C13—C14	118.74 (19)
C1—C2—H2B	109.6	C12—C13—H13A	107.6
C3—C2—H2B	109.6	C14—C13—H13A	107.6
H2A—C2—H2B	108.1	C12—C13—H13B	107.6
C4—C3—C8	119.31 (18)	C14—C13—H13B	107.6
C4—C3—C2	120.49 (19)	H13A—C13—H13B	107.1
C8—C3—C2	120.18 (18)	C15—C14—C13	115.3 (2)
C5—C4—C3	121.02 (19)	C15—C14—H14A	108.5
C5—C4—H4	119.5	C13—C14—H14A	108.5
C3—C4—H4	119.5	C15—C14—H14B	108.5
C6—C5—C4	118.22 (18)	C13—C14—H14B	108.5
C6—C5—H5	120.9	H14A—C14—H14B	107.5
C4—C5—H5	120.9	C16—C15—C14	115.9 (2)
C5—C6—C7	122.60 (18)	C16—C15—H15A	108.3
C5—C6—N1	118.74 (17)	C14—C15—H15A	108.3
C7—C6—N1	118.66 (18)	C16—C15—H15B	108.3
C8—C7—C6	118.3 (2)	C14—C15—H15B	108.3
C8—C7—H7	120.9	H15A—C15—H15B	107.4
C6—C7—H7	120.9	C17—C16—C15	118.54 (18)
C7—C8—C3	120.54 (19)	C17—C16—H16A	107.7
C7—C8—H8	119.7	C15—C16—H16A	107.7
C3—C8—H8	119.7	C17—C16—H16B	107.7
O2—C9—C10	105.86 (15)	C15—C16—H16B	107.7
O2—C9—C18	108.55 (15)	H16A—C16—H16B	107.1
C10—C9—C18	114.87 (18)	C16—C17—C18	118.8 (2)
O2—C9—H9	109.1	C16—C17—H17A	107.6
C10—C9—H9	109.1	C18—C17—H17A	107.6
C18—C9—H9	109.1	C16—C17—H17B	107.6
C9—C10—C11	114.91 (19)	C18—C17—H17B	107.6
C9—C10—H10A	108.5	H17A—C17—H17B	107.1
C11—C10—H10A	108.5	C9—C18—C17	116.17 (18)
C9—C10—H10B	108.5	C9—C18—H18A	108.2
C11—C10—H10B	108.5	C17—C18—H18A	108.2
H10A—C10—H10B	107.5	C9—C18—H18B	108.2
C12—C11—C10	117.19 (17)	C17—C18—H18B	108.2
C12—C11—H11A	108.0	H18A—C18—H18B	107.4
C10—C11—H11A	108.0
C9—O2—C1—O1	−0.3 (3)	C6—C7—C8—C3	−1.1 (3)
C9—O2—C1—C2	177.31 (15)	C4—C3—C8—C7	1.7 (3)
O1—C1—C2—C3	85.5 (2)	C2—C3—C8—C7	−176.82 (17)
O2—C1—C2—C3	−92.17 (19)	C1—O2—C9—C10	148.21 (17)
C1—C2—C3—C4	−123.94 (19)	C1—O2—C9—C18	−88.0 (2)
C1—C2—C3—C8	54.6 (2)	O2—C9—C10—C11	−84.4 (2)
C8—C3—C4—C5	−0.9 (3)	C18—C9—C10—C11	155.83 (18)
C2—C3—C4—C5	177.59 (17)	C9—C10—C11—C12	−54.3 (2)
C3—C4—C5—C6	−0.4 (3)	C10—C11—C12—C13	−66.1 (3)
C4—C5—C6—C7	1.1 (3)	C11—C12—C13—C14	64.4 (3)
C4—C5—C6—N1	−178.81 (17)	C12—C13—C14—C15	56.2 (3)
O3—N1—C6—C5	−6.3 (3)	C13—C14—C15—C16	−150.6 (2)
O4—N1—C6—C5	173.44 (18)	C14—C15—C16—C17	56.1 (3)
O3—N1—C6—C7	173.76 (18)	C15—C16—C17—C18	65.1 (3)
O4—N1—C6—C7	−6.4 (3)	O2—C9—C18—C17	−175.31 (18)
C5—C6—C7—C8	−0.3 (3)	C10—C9—C18—C17	−57.1 (3)
N1—C6—C7—C8	179.56 (17)	C16—C17—C18—C9	−65.0 (3)