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In the crystal structure, the title compound (exaltone), C15H28O, exhibits no disorder, and the 15-membered ring exists in the quinquangular [13353] C1 symmetry conformation. The crystal exhibits nonmerohedral twinning by twofold rotation about [100], but adjustment of the temperature to 90 K causes the [101] distance to equal the c axial length, allowing the twinning to be treated as pseudo-merohedral. The literature description of the structure as disordered ortho­rhom­bic with halved a-axis length is corrected.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107066139/gz3125sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107066139/gz3125Isup2.hkl
Contains datablock I

CCDC reference: 681554

Comment top

The conformations of cyclic ketones have been studied in solution by dynamic NMR spectroscopy (e.g. Anet et al., 1973, 1974) and in the solid state by X-ray crystallography (e.g. Groth, 1974, 1975, 1976, 1979). Completely ordered crystals were found for cyclodecanone at 113 K (Groth, 1976) and cycloundecanone at 108 K (Groth, 1974); the conformation in each case was based on a stable conformation of the parent hydrocarbon {[2323] (Pawar et al., 1998) or [335] (Pawar et al., 2006)}.

The ring skeletons for cyclododecanone (Groth, 1979) and cyclotetradecanone (Groth, 1975) matched those of cyclododecane ([3333]; Dunitz & Shearer, 1960) and cyclotetradecane ([3434]; Anet et al., 1972), but the crystals were disordered with respect to placement of the carbonyl groups. Groth (1979) concluded from preliminary studies of cyclotridecanone and cycloheptadecanone that the crystals were disordered, and the structures were not determined. Crystals of cyclopentadecanone [the title compound, (I)] and cyclohexadecanone were reported to be orthorhombic, and cell dimensions were given [incorrectly for compound (I); see below] by Groth (1976). The author concluded that the crystals were disordered, and attempts to solve both structures were unsuccessful.

Attempts to study the conformations of (I) in solution by low-temperature 1H and 13C NMR spectroscopy were inconclusive, and conformational assignments were not made (Cheng, 1973). Cyclopentadecanone phenylsemicarbazone has been reported to have a [3435] conformation in the solid state by X-ray diffraction (van den Hoek et al., 1979), and a [12345] conformation was found for the 2,4-dintrophenylhydrazone of (I) by the same method (Pawar et al., 2007). Strain energies have been calculated using MOLBUILD [Reference for software?] for several conformations of cyclopentadecane, and the [33333] conformation was predicted to be the most stable of those considered (Anet & Rawdah, 1978).

The molecular structure of (I) is shown in Fig. 1. The cyclopentadecane ring exists in the quinquangular [13353] conformation with corner positions at C atoms 3, 4, 7, 10 and 15, as described by the torsion angles in Table 1. The atoms of the C15 ring are coplanar to a mean deviation of 0.382 Å, with a maximum deviation of 0.603 (2) Å for atom C8. The O atom lies 1.646 (2) Å out of this plane, and the ketone plane (O1/C1/C2/C15) forms a dihedral angle of 66.12 (2)° with it.

While the unit cell has monoclinic symmetry, the lattice has a nearly C-centered orthorhombic metric, with the transformation (-1 0 0, 1 0 2, 0 1 0) yielding a cell with dimensions a = 15.663, b = 31.719 and c = 5.553 Å, and α = β = 90 and γ = 90.04°. Groth (1976) reported an orthorhombic cell at 113 K having dimensions 7.814 (4), 15.990 (8) and 5.589 (3) Å, noting that its cell volume (half ours) would yield Z = 2 and require disorder of the molecule. We note that the Groth cell has two of its dimensions near half those of the C-centered cell from our data. Examination of the packing in Fig. 2 suggests how the incorrect description of the unit-cell dimensions came about for this soft weakly-scattering compound. The centroid of the 15-membered ring is very near (3/4, 1/2, 1/2), and thus its equivalent by inversion through the center of the cell is related to it by an approximate translation of a/2, corresponding to the 7.81 Å ce l l dimension of the Groth cell. The vector from the origin to (1/2, 0, 1/2) is nearly orthogonal to our a axis, and corresponds to Groth's 15.99 Å ce l l dimension, half the 31.7 Å axis of the C-centered metric. The molecules related by the a/2 approximate translation would not overlap exactly, so would necessarily be disordered in the smaller cell, as pointed out by Groth (1976).

We noted splitting of spots in the diffraction pattern at nearer ambient temperatures, hinting that crystals of (I) are twinned. The twinning is a twofold rotation about [100], bringing the [101] and [001] vectors into near coincidence. At T = 150 K, these two distances differ by 0.6%, but we found that lowering the temperature to 90 K caused anisotropic shrinkage of the cell, making the [101] distance equal to the c axis and causing the split spots to coalesce (Fronczek & Fox, 2007). Thus, we measured diffraction data at 90 K, and were able to treat the twin as essentially perfectly pseudo-merohedral. Introducing one TWIN and one BASF command into the refinement in SHELXL97 (Sheldrick, 1997) lowered the R value from 0.296 to 0.059.

Related literature top

For related literature, see: Anet & Rawdah (1978); Anet et al. (1972, 1973, 1974); Cheng (1973); Dunitz & Shearer (1960); Fronczek & Fox (2007); Giral (1935); Groth (1974, 1975, 1976, 1979); Hoek et al. (1979); Pawar et al. (1998, 2006, 2007); Sheldrick (1997).

Experimental top

A commercial sample (Aldrich Chemical Company) of cyclopentadecanone was recrystallized from ethanol [m.p. 336.5 K; literature m.p. 338.5 K (Giral, 1935)]. Purity was determined by a room-temperature 13C NMR spectrum.

Refinement top

H atoms were placed in calculated positions, guided by difference maps, with C—H bond distances of 0.99 Å and with Uiso = 1.2Ueq(C), and thereafter treated as riding. The structure was refined as a pseudo-merohedral twin with twin law (1 0 0, 0 - 1 0, -1 0 - 1). The twinning was perfect, with the BASF parameter refined to 0.500 (2).

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: APEX2 (Bruker, 2006); data reduction: APEX2 (Bruker, 2006); 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: XSHELL (Bruker, 2004).

Figures top
[Figure 1] Fig. 1. The molecule of (I). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. A unit-cell diagram for (I), viewed down the symmetry direction. The bold lines correspond to the cell reported by Groth (1976), and the dotted line, [101], has a length equal to that of the c axis in this twinned structure.
Cyclopentadecanone top
Crystal data top
C15H28OF(000) = 504
Mr = 224.37Dx = 1.080 Mg m3
Monoclinic, P21/cMelting point: 336.5 K
Hall symbol: -P 2ybcCu Kα radiation, λ = 1.54178 Å
a = 15.6634 (16) ÅCell parameters from 1310 reflections
b = 5.5531 (5) Åθ = 3.1–67.1°
c = 17.6928 (18) ŵ = 0.48 mm1
β = 116.315 (8)°T = 90 K
V = 1379.4 (3) Å3Lath, colourless
Z = 40.34 × 0.12 × 0.07 mm
Data collection top
Bruker Kappa APEXII CCD area-detector
diffractometer
2359 independent reflections
Radiation source: fine-focus sealed tube2007 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.052
ϕ and ω scansθmax = 67.6°, θmin = 2.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2002)
h = 1717
Tmin = 0.853, Tmax = 0.967k = 62
5210 measured reflectionsl = 2019
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.059Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.164H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.1051P)2 + 0.0175P]
where P = (Fo2 + 2Fc2)/3
2359 reflections(Δ/σ)max < 0.001
146 parametersΔρmax = 0.30 e Å3
0 restraintsΔρmin = 0.23 e Å3
Crystal data top
C15H28OV = 1379.4 (3) Å3
Mr = 224.37Z = 4
Monoclinic, P21/cCu Kα radiation
a = 15.6634 (16) ŵ = 0.48 mm1
b = 5.5531 (5) ÅT = 90 K
c = 17.6928 (18) Å0.34 × 0.12 × 0.07 mm
β = 116.315 (8)°
Data collection top
Bruker Kappa APEXII CCD area-detector
diffractometer
2359 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2002)
2007 reflections with I > 2σ(I)
Tmin = 0.853, Tmax = 0.967Rint = 0.052
5210 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0590 restraints
wR(F2) = 0.164H-atom parameters constrained
S = 1.08Δρmax = 0.30 e Å3
2359 reflectionsΔρmin = 0.23 e Å3
146 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
xyzUiso*/Ueq
O10.60985 (18)0.1031 (4)0.49740 (16)0.0375 (6)
C10.5870 (2)0.1048 (5)0.4775 (2)0.0251 (7)
C20.6166 (2)0.3050 (5)0.54111 (19)0.0273 (7)
H2A0.55870.37290.54210.033*
H2B0.64590.43410.52190.033*
C30.6859 (2)0.2361 (5)0.63058 (19)0.0282 (7)
H3A0.72140.09000.62920.034*
H3B0.64990.19760.66300.034*
C40.7561 (2)0.4378 (5)0.67466 (19)0.0277 (7)
H4A0.78840.40370.73590.033*
H4B0.72040.59040.66660.033*
C50.8314 (2)0.4708 (5)0.64291 (19)0.0260 (7)
H5A0.87580.33240.66180.031*
H5B0.79980.47040.58050.031*
C60.8883 (2)0.7024 (5)0.67346 (19)0.0271 (7)
H6A0.84490.84060.64860.033*
H6B0.91280.71230.73540.033*
C70.9716 (2)0.7260 (5)0.65205 (19)0.0292 (7)
H7A1.02060.60640.68580.035*
H7B1.00000.88780.66990.035*
C80.9488 (2)0.6918 (5)0.55938 (19)0.0280 (7)
H8A1.00860.70680.55360.034*
H8B0.92440.52630.54220.034*
C90.8768 (2)0.8681 (5)0.49947 (19)0.0248 (6)
H9A0.90171.03370.51550.030*
H9B0.81720.85540.50560.030*
C100.8540 (2)0.8260 (5)0.40634 (19)0.0261 (7)
H10A0.81770.96600.37290.031*
H10B0.91450.81780.40160.031*
C110.7964 (2)0.5957 (5)0.36799 (19)0.0269 (7)
H11A0.79630.56450.31290.032*
H11B0.82820.45790.40550.032*
C120.6946 (2)0.6108 (5)0.3555 (2)0.0277 (7)
H12A0.65570.69140.30100.033*
H12B0.69270.71260.40070.033*
C130.6499 (2)0.3687 (5)0.35609 (19)0.0271 (7)
H13A0.69200.28060.40800.033*
H13B0.64540.27290.30730.033*
C140.5508 (2)0.3906 (6)0.35226 (19)0.0260 (7)
H14A0.50370.41700.29300.031*
H14B0.54950.53360.38520.031*
C150.5212 (2)0.1684 (5)0.3865 (2)0.0286 (7)
H15A0.45650.19600.38150.034*
H15B0.51760.02860.35050.034*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0567 (16)0.0171 (10)0.0427 (14)0.0019 (10)0.0257 (13)0.0027 (10)
C10.0309 (17)0.0144 (14)0.0364 (18)0.0027 (11)0.0207 (14)0.0017 (12)
C20.0283 (17)0.0153 (14)0.0309 (17)0.0004 (12)0.0064 (14)0.0001 (11)
C30.0346 (18)0.0190 (14)0.0289 (17)0.0012 (12)0.0121 (14)0.0044 (12)
C40.0356 (18)0.0210 (14)0.0205 (15)0.0006 (12)0.0069 (14)0.0012 (11)
C50.0329 (17)0.0199 (14)0.0197 (14)0.0007 (12)0.0067 (14)0.0025 (11)
C60.0346 (18)0.0196 (14)0.0228 (15)0.0008 (13)0.0087 (14)0.0004 (11)
C70.0287 (16)0.0247 (15)0.0286 (17)0.0002 (13)0.0076 (14)0.0013 (12)
C80.0328 (17)0.0202 (14)0.0306 (17)0.0014 (12)0.0137 (14)0.0018 (11)
C90.0278 (16)0.0168 (12)0.0279 (16)0.0000 (11)0.0104 (14)0.0021 (11)
C100.0258 (16)0.0223 (14)0.0283 (17)0.0043 (12)0.0102 (14)0.0018 (11)
C110.0320 (17)0.0225 (14)0.0245 (16)0.0068 (12)0.0110 (14)0.0044 (12)
C120.0279 (16)0.0205 (13)0.0283 (16)0.0017 (12)0.0065 (13)0.0021 (13)
C130.0337 (18)0.0204 (14)0.0270 (16)0.0021 (12)0.0131 (14)0.0002 (12)
C140.0299 (17)0.0203 (13)0.0229 (15)0.0003 (12)0.0074 (13)0.0010 (11)
C150.0346 (17)0.0200 (13)0.0298 (18)0.0067 (12)0.0130 (14)0.0044 (12)
Geometric parameters (Å, º) top
O1—C11.214 (3)C8—H8A0.9900
C1—C21.502 (4)C8—H8B0.9900
C1—C151.519 (4)C9—C101.541 (4)
C2—C31.519 (4)C9—H9A0.9900
C2—H2A0.9900C9—H9B0.9900
C2—H2B0.9900C10—C111.538 (4)
C3—C41.520 (4)C10—H10A0.9900
C3—H3A0.9900C10—H10B0.9900
C3—H3B0.9900C11—C121.512 (4)
C4—C51.526 (5)C11—H11A0.9900
C4—H4A0.9900C11—H11B0.9900
C4—H4B0.9900C12—C131.518 (4)
C5—C61.521 (4)C12—H12A0.9900
C5—H5A0.9900C12—H12B0.9900
C5—H5B0.9900C13—C141.528 (4)
C6—C71.517 (4)C13—H13A0.9900
C6—H6A0.9900C13—H13B0.9900
C6—H6B0.9900C14—C151.534 (4)
C7—C81.527 (4)C14—H14A0.9900
C7—H7A0.9900C14—H14B0.9900
C7—H7B0.9900C15—H15A0.9900
C8—C91.514 (4)C15—H15B0.9900
O1—C1—C2122.2 (3)H8A—C8—H8B107.6
O1—C1—C15120.2 (3)C8—C9—C10113.5 (2)
C2—C1—C15117.5 (2)C8—C9—H9A108.9
C1—C2—C3115.8 (2)C10—C9—H9A108.9
C1—C2—H2A108.3C8—C9—H9B108.9
C3—C2—H2A108.3C10—C9—H9B108.9
C1—C2—H2B108.3H9A—C9—H9B107.7
C3—C2—H2B108.3C11—C10—C9114.3 (2)
H2A—C2—H2B107.4C11—C10—H10A108.7
C2—C3—C4111.7 (2)C9—C10—H10A108.7
C2—C3—H3A109.3C11—C10—H10B108.7
C4—C3—H3A109.3C9—C10—H10B108.7
C2—C3—H3B109.3H10A—C10—H10B107.6
C4—C3—H3B109.3C12—C11—C10113.1 (3)
H3A—C3—H3B107.9C12—C11—H11A109.0
C3—C4—C5113.6 (3)C10—C11—H11A109.0
C3—C4—H4A108.8C12—C11—H11B109.0
C5—C4—H4A108.8C10—C11—H11B109.0
C3—C4—H4B108.8H11A—C11—H11B107.8
C5—C4—H4B108.8C11—C12—C13114.2 (2)
H4A—C4—H4B107.7C11—C12—H12A108.7
C6—C5—C4113.4 (2)C13—C12—H12A108.7
C6—C5—H5A108.9C11—C12—H12B108.7
C4—C5—H5A108.9C13—C12—H12B108.7
C6—C5—H5B108.9H12A—C12—H12B107.6
C4—C5—H5B108.9C12—C13—C14113.0 (2)
H5A—C5—H5B107.7C12—C13—H13A109.0
C7—C6—C5114.7 (3)C14—C13—H13A109.0
C7—C6—H6A108.6C12—C13—H13B109.0
C5—C6—H6A108.6C14—C13—H13B109.0
C7—C6—H6B108.6H13A—C13—H13B107.8
C5—C6—H6B108.6C13—C14—C15113.4 (2)
H6A—C6—H6B107.6C13—C14—H14A108.9
C6—C7—C8116.1 (3)C15—C14—H14A108.9
C6—C7—H7A108.3C13—C14—H14B108.9
C8—C7—H7A108.3C15—C14—H14B108.9
C6—C7—H7B108.3H14A—C14—H14B107.7
C8—C7—H7B108.3C1—C15—C14115.1 (2)
H7A—C7—H7B107.4C1—C15—H15A108.5
C9—C8—C7114.7 (3)C14—C15—H15A108.5
C9—C8—H8A108.6C1—C15—H15B108.5
C7—C8—H8A108.6C14—C15—H15B108.5
C9—C8—H8B108.6H15A—C15—H15B107.5
C7—C8—H8B108.6
O1—C1—C2—C36.5 (4)C8—C9—C10—C1170.2 (3)
C15—C1—C2—C3177.3 (3)C9—C10—C11—C1270.3 (3)
C1—C2—C3—C4144.6 (3)C10—C11—C12—C13154.0 (3)
C2—C3—C4—C572.9 (3)C11—C12—C13—C14174.2 (3)
C3—C4—C5—C6168.1 (2)C12—C13—C14—C15157.6 (3)
C4—C5—C6—C7172.8 (3)O1—C1—C15—C14136.1 (3)
C5—C6—C7—C852.9 (4)C2—C1—C15—C1447.6 (4)
C6—C7—C8—C959.9 (4)C13—C14—C15—C158.6 (3)
C7—C8—C9—C10178.9 (2)

Experimental details

Crystal data
Chemical formulaC15H28O
Mr224.37
Crystal system, space groupMonoclinic, P21/c
Temperature (K)90
a, b, c (Å)15.6634 (16), 5.5531 (5), 17.6928 (18)
β (°) 116.315 (8)
V3)1379.4 (3)
Z4
Radiation typeCu Kα
µ (mm1)0.48
Crystal size (mm)0.34 × 0.12 × 0.07
Data collection
DiffractometerBruker Kappa APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2002)
Tmin, Tmax0.853, 0.967
No. of measured, independent and
observed [I > 2σ(I)] reflections
5210, 2359, 2007
Rint0.052
(sin θ/λ)max1)0.600
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.059, 0.164, 1.08
No. of reflections2359
No. of parameters146
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.30, 0.23

Computer programs: APEX2 (Bruker, 2006), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), XSHELL (Bruker, 2004).

Selected torsion angles (º) top
C15—C1—C2—C3177.3 (3)C8—C9—C10—C1170.2 (3)
C1—C2—C3—C4144.6 (3)C9—C10—C11—C1270.3 (3)
C2—C3—C4—C572.9 (3)C10—C11—C12—C13154.0 (3)
C3—C4—C5—C6168.1 (2)C11—C12—C13—C14174.2 (3)
C4—C5—C6—C7172.8 (3)C12—C13—C14—C15157.6 (3)
C5—C6—C7—C852.9 (4)C2—C1—C15—C1447.6 (4)
C6—C7—C8—C959.9 (4)C13—C14—C15—C158.6 (3)
C7—C8—C9—C10178.9 (2)
 

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