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Crystals of cyclopentanone, C
5H
8O, and cyclobutanone, C
4H
6O, have been grown
in situ on a diffractometer. The two compounds are isostructural and contain two crystallographically independent molecules. Molecules sitting across twofold axes form antiparallel dipole–dipole dimers, while other molecules in general positions are linked together into ribbons by pairs of C—H
O interactions.
Supporting information
CCDC references: 819304; 819305
The liquids samples were sealed in 0.3 mm borosilicate glass capillaries which
were mounted on a diffractometer using a special attachment (Yufit & Howard,
2005). The crystals of both compounds were grown in situ on a
diffractometer by flash-freezing of the overcooled liquid at 220 K, followed
by partial melting of the resulting polycrystalline material and slow growing
of the crystals at 200.5 K. The cylindric crystals formed were then cooled
down to 200 K and data were collected at this temperature.
As it was mentioned in the Comment, in order to maintain consistency in
the description of the structures of CP and CB, the CB structure has been
refined in a nonstandard setting of the C2/c space group with an
acute β angle. The data have been collected in a standard setting and then
the cell parameters in the input file were changed manually. Also the signs of
the L indexes in the hkl file have been changed to the opposite
ones with the help of a locally written service program.
For both compounds, data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).
(CP) cyclopentan-1-one
top
Crystal data top
C5H8O | F(000) = 552 |
Mr = 84.11 | Dx = 1.152 Mg m−3 |
Monoclinic, C2/c | Melting point: 218 K |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 16.7421 (16) Å | Cell parameters from 1202 reflections |
b = 9.7941 (8) Å | θ = 29.6–2.4° |
c = 8.8898 (7) Å | µ = 0.08 mm−1 |
β = 93.69 (2)° | T = 200 K |
V = 1454.7 (2) Å3 | Cylinder, colourless |
Z = 12 | 0.5 × 0.3 × 0.3 mm |
Data collection top
Bruker SMART CCD 6000 area-detector diffractometer | 1336 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.035 |
Graphite monochromator | θmax = 29.5°, θmin = 2.4° |
Detector resolution: 8.0 pixels mm-1 | h = −15→23 |
ω scans | k = −13→13 |
6027 measured reflections | l = −9→7 |
1660 independent reflections | |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.035 | All H-atom parameters refined |
wR(F2) = 0.099 | w = 1/[σ2(Fo2) + (0.050P)2 + 0.3P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
1660 reflections | Δρmax = 0.17 e Å−3 |
132 parameters | Δρmin = −0.14 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0115 (18) |
Crystal data top
C5H8O | V = 1454.7 (2) Å3 |
Mr = 84.11 | Z = 12 |
Monoclinic, C2/c | Mo Kα radiation |
a = 16.7421 (16) Å | µ = 0.08 mm−1 |
b = 9.7941 (8) Å | T = 200 K |
c = 8.8898 (7) Å | 0.5 × 0.3 × 0.3 mm |
β = 93.69 (2)° | |
Data collection top
Bruker SMART CCD 6000 area-detector diffractometer | 1336 reflections with I > 2σ(I) |
6027 measured reflections | Rint = 0.035 |
1660 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
wR(F2) = 0.099 | All H-atom parameters refined |
S = 1.03 | Δρmax = 0.17 e Å−3 |
1660 reflections | Δρmin = −0.14 e Å−3 |
132 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 | Uiso*/Ueq | |
O1 | 0.17244 (6) | 0.63157 (9) | 0.50785 (12) | 0.0642 (3) | |
O2 | 0.0000 | 0.58323 (9) | 0.2500 | 0.0450 (3) | |
C1 | 0.16762 (6) | 0.70397 (11) | 0.39723 (15) | 0.0442 (3) | |
C2 | 0.20281 (7) | 0.67435 (12) | 0.24876 (16) | 0.0485 (3) | |
C3 | 0.19157 (7) | 0.80501 (11) | 0.15710 (17) | 0.0476 (3) | |
C4 | 0.11695 (7) | 0.86947 (11) | 0.21755 (14) | 0.0436 (3) | |
C5 | 0.12532 (7) | 0.84020 (12) | 0.38500 (14) | 0.0450 (3) | |
C11 | 0.0000 | 0.45920 (13) | 0.2500 | 0.0346 (3) | |
C12 | 0.04221 (7) | 0.36976 (10) | 0.36852 (14) | 0.0423 (3) | |
C13 | 0.03880 (7) | 0.22685 (10) | 0.29943 (14) | 0.0442 (3) | |
H21 | 0.1714 (8) | 0.5987 (15) | 0.2000 (18) | 0.071 (4)* | |
H22 | 0.2574 (9) | 0.6471 (14) | 0.2676 (17) | 0.063 (4)* | |
H31 | 0.2383 (8) | 0.8620 (13) | 0.1776 (16) | 0.054 (3)* | |
H32 | 0.1873 (8) | 0.7885 (14) | 0.0485 (19) | 0.065 (4)* | |
H41 | 0.0689 (8) | 0.8226 (13) | 0.1728 (16) | 0.051 (3)* | |
H42 | 0.1128 (7) | 0.9662 (14) | 0.1943 (15) | 0.053 (3)* | |
H51 | 0.1617 (8) | 0.9040 (14) | 0.4380 (17) | 0.064 (4)* | |
H52 | 0.0766 (9) | 0.8365 (15) | 0.4355 (18) | 0.073 (5)* | |
H121 | 0.0958 (8) | 0.4046 (14) | 0.3968 (16) | 0.061 (4)* | |
H122 | 0.0096 (8) | 0.3744 (13) | 0.4567 (17) | 0.058 (4)* | |
H131 | 0.0836 (8) | 0.2158 (13) | 0.2380 (15) | 0.052 (3)* | |
H132 | 0.0412 (8) | 0.1537 (14) | 0.3772 (16) | 0.056 (4)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0652 (6) | 0.0616 (5) | 0.0631 (8) | −0.0133 (4) | −0.0172 (5) | 0.0193 (4) |
O2 | 0.0551 (6) | 0.0298 (5) | 0.0497 (8) | 0.000 | 0.0006 (5) | 0.000 |
C1 | 0.0373 (5) | 0.0424 (5) | 0.0515 (9) | −0.0076 (4) | −0.0084 (5) | 0.0014 (5) |
C2 | 0.0397 (5) | 0.0410 (5) | 0.0645 (9) | 0.0051 (4) | 0.0008 (5) | −0.0087 (5) |
C3 | 0.0451 (6) | 0.0473 (6) | 0.0518 (9) | −0.0026 (4) | 0.0138 (5) | −0.0053 (5) |
C4 | 0.0470 (6) | 0.0397 (5) | 0.0446 (8) | 0.0055 (4) | 0.0068 (5) | 0.0013 (4) |
C5 | 0.0445 (5) | 0.0489 (6) | 0.0420 (8) | 0.0027 (4) | 0.0055 (5) | −0.0058 (5) |
C11 | 0.0380 (6) | 0.0311 (6) | 0.0353 (9) | 0.000 | 0.0067 (6) | 0.000 |
C12 | 0.0526 (6) | 0.0339 (5) | 0.0395 (8) | 0.0016 (4) | −0.0039 (5) | −0.0002 (4) |
C13 | 0.0597 (7) | 0.0325 (5) | 0.0406 (8) | 0.0077 (4) | 0.0049 (5) | 0.0018 (4) |
Geometric parameters (Å, º) top
O1—C1 | 1.2109 (15) | C4—H42 | 0.972 (13) |
O2—C11 | 1.2148 (15) | C5—H51 | 0.972 (15) |
C1—C2 | 1.5078 (18) | C5—H52 | 0.957 (15) |
C1—C5 | 1.5111 (15) | C11—C12i | 1.5103 (14) |
C2—C3 | 1.5223 (18) | C11—C12 | 1.5103 (14) |
C2—H21 | 0.991 (15) | C12—C13 | 1.5282 (14) |
C2—H22 | 0.957 (15) | C12—H121 | 0.978 (14) |
C3—C4 | 1.5279 (14) | C12—H122 | 0.985 (15) |
C3—H31 | 0.968 (14) | C13—C13i | 1.521 (2) |
C3—H32 | 0.977 (16) | C13—H131 | 0.961 (13) |
C4—C5 | 1.5136 (18) | C13—H132 | 0.995 (14) |
C4—H41 | 0.987 (13) | | |
| | | |
O1—C1—C2 | 126.07 (11) | C1—C5—C4 | 104.55 (9) |
O1—C1—C5 | 125.59 (12) | C1—C5—H51 | 104.8 (8) |
C2—C1—C5 | 108.34 (10) | C4—C5—H51 | 111.7 (9) |
C1—C2—C3 | 105.37 (9) | C1—C5—H52 | 110.1 (9) |
C1—C2—H21 | 107.5 (9) | C4—C5—H52 | 116.1 (9) |
C3—C2—H21 | 110.5 (9) | H51—C5—H52 | 108.9 (12) |
C1—C2—H22 | 108.8 (9) | O2—C11—C12i | 125.45 (6) |
C3—C2—H22 | 114.3 (8) | O2—C11—C12 | 125.45 (6) |
H21—C2—H22 | 110.0 (11) | C12i—C11—C12 | 109.10 (11) |
C2—C3—C4 | 103.58 (9) | C11—C12—C13 | 104.31 (10) |
C2—C3—H31 | 108.3 (8) | C11—C12—H121 | 111.0 (8) |
C4—C3—H31 | 111.4 (8) | C13—C12—H121 | 115.6 (8) |
C2—C3—H32 | 112.8 (8) | C11—C12—H122 | 105.7 (8) |
C4—C3—H32 | 114.0 (8) | C13—C12—H122 | 110.7 (8) |
H31—C3—H32 | 106.8 (12) | H121—C12—H122 | 109.1 (12) |
C5—C4—C3 | 103.98 (10) | C13i—C13—C12 | 103.92 (7) |
C5—C4—H41 | 109.2 (8) | C13i—C13—H131 | 109.9 (8) |
C3—C4—H41 | 109.2 (7) | C12—C13—H131 | 108.7 (8) |
C5—C4—H42 | 113.3 (8) | C13i—C13—H132 | 113.4 (8) |
C3—C4—H42 | 112.2 (7) | C12—C13—H132 | 112.5 (8) |
H41—C4—H42 | 108.8 (11) | H131—C13—H132 | 108.3 (10) |
| | | |
O1—C1—C2—C3 | −171.34 (11) | C2—C1—C5—C4 | 15.14 (12) |
C5—C1—C2—C3 | 8.45 (12) | C3—C4—C5—C1 | −32.72 (11) |
C1—C2—C3—C4 | −28.46 (13) | O2—C11—C12—C13 | −168.18 (5) |
C2—C3—C4—C5 | 38.05 (12) | C12i—C11—C12—C13 | 11.82 (5) |
O1—C1—C5—C4 | −165.06 (11) | C11—C12—C13—C13i | −30.96 (13) |
Symmetry code: (i) −x, y, −z+1/2. |
(CB) cyclobutan-1-one
top
Crystal data top
C4H6O | Dx = 1.151 Mg m−3 |
Mr = 70.09 | Melting point: 218 K |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 15.5022 (16) Å | Cell parameters from 1067 reflections |
b = 9.0662 (9) Å | θ = 2.6–30.5° |
c = 8.6531 (7) Å | µ = 0.08 mm−1 |
β = 85.83 (3)° | T = 200 K |
V = 1212.9 (2) Å3 | Cylinder, colourless |
Z = 12 | 0.5 × 0.35 × 0.35 mm |
F(000) = 456 | |
Data collection top
Bruker SMART CCD 6000 area-detector diffractometer | 1127 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.036 |
Graphite monochromator | θmax = 30.5°, θmin = 2.6° |
Detector resolution: 5.6 pixels mm-1 | h = −16→22 |
ω scans | k = −12→12 |
5379 measured reflections | l = −7→7 |
1440 independent reflections | |
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)] = 0.039 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.121 | All H-atom parameters refined |
S = 1.06 | w = 1/[σ2(Fo2) + (0.070P)2 + 0.150P], where P = (Fo2 + 2Fc2)/3 |
1440 reflections | (Δ/σ)max < 0.001 |
106 parameters | Δρmax = 0.23 e Å−3 |
0 restraints | Δρmin = −0.15 e Å−3 |
Crystal data top
C4H6O | V = 1212.9 (2) Å3 |
Mr = 70.09 | Z = 12 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.5022 (16) Å | µ = 0.08 mm−1 |
b = 9.0662 (9) Å | T = 200 K |
c = 8.6531 (7) Å | 0.5 × 0.35 × 0.35 mm |
β = 85.83 (3)° | |
Data collection top
Bruker SMART CCD 6000 area-detector diffractometer | 1127 reflections with I > 2σ(I) |
5379 measured reflections | Rint = 0.036 |
1440 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.039 | 0 restraints |
wR(F2) = 0.121 | All H-atom parameters refined |
S = 1.06 | Δρmax = 0.23 e Å−3 |
1440 reflections | Δρmin = −0.15 e Å−3 |
106 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 | Uiso*/Ueq | |
O1 | 0.16529 (5) | 0.62858 (10) | 0.49939 (11) | 0.0558 (3) | |
O2 | 0.0000 | 0.59104 (11) | 0.2500 | 0.0470 (3) | |
C1 | 0.16682 (6) | 0.70470 (11) | 0.38539 (13) | 0.0408 (3) | |
C2 | 0.20760 (8) | 0.68827 (13) | 0.22340 (16) | 0.0489 (3) | |
C3 | 0.16675 (9) | 0.83723 (13) | 0.18330 (17) | 0.0536 (4) | |
C4 | 0.12918 (8) | 0.85412 (11) | 0.35121 (16) | 0.0479 (3) | |
C11 | 0.0000 | 0.45850 (15) | 0.2500 | 0.0351 (3) | |
C12 | 0.04292 (8) | 0.34379 (12) | 0.34572 (17) | 0.0456 (3) | |
C13 | 0.0000 | 0.22420 (18) | 0.2500 | 0.0561 (5) | |
H13 | 0.0421 (9) | 0.1647 (17) | 0.190 (2) | 0.071 (4)* | |
H21 | 0.1859 (9) | 0.6060 (16) | 0.1639 (18) | 0.064 (4)* | |
H22 | 0.2693 (10) | 0.6906 (17) | 0.2224 (19) | 0.069 (4)* | |
H31 | 0.1201 (10) | 0.8302 (17) | 0.113 (2) | 0.072 (5)* | |
H32 | 0.2084 (9) | 0.9098 (18) | 0.1445 (19) | 0.069 (4)* | |
H41 | 0.0674 (9) | 0.8597 (15) | 0.3670 (17) | 0.059 (4)* | |
H42 | 0.1562 (10) | 0.9319 (19) | 0.413 (2) | 0.074 (5)* | |
H121 | 0.0225 (9) | 0.3462 (15) | 0.4496 (19) | 0.057 (4)* | |
H122 | 0.1040 (9) | 0.3508 (16) | 0.3344 (17) | 0.063 (4)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0602 (5) | 0.0582 (5) | 0.0500 (7) | −0.0060 (4) | −0.0111 (4) | 0.0156 (4) |
O2 | 0.0567 (6) | 0.0391 (5) | 0.0466 (9) | 0.000 | −0.0129 (5) | 0.000 |
C1 | 0.0386 (5) | 0.0400 (5) | 0.0445 (8) | −0.0075 (3) | −0.0075 (4) | 0.0020 (4) |
C2 | 0.0486 (6) | 0.0453 (6) | 0.0518 (10) | −0.0079 (4) | 0.0038 (5) | −0.0043 (5) |
C3 | 0.0719 (8) | 0.0447 (6) | 0.0449 (10) | −0.0134 (5) | −0.0094 (6) | 0.0055 (5) |
C4 | 0.0588 (7) | 0.0373 (5) | 0.0477 (10) | −0.0017 (4) | −0.0055 (5) | −0.0011 (4) |
C11 | 0.0350 (6) | 0.0416 (6) | 0.0284 (10) | 0.000 | −0.0011 (5) | 0.000 |
C12 | 0.0490 (6) | 0.0473 (6) | 0.0404 (10) | 0.0081 (4) | −0.0030 (5) | 0.0047 (4) |
C13 | 0.0820 (12) | 0.0387 (8) | 0.0462 (13) | 0.000 | 0.0063 (9) | 0.000 |
Geometric parameters (Å, º) top
O1—C1 | 1.2028 (14) | C4—H41 | 0.959 (13) |
O2—C11 | 1.2016 (16) | C4—H42 | 0.998 (17) |
C1—C2 | 1.5026 (18) | C11—C12 | 1.5135 (14) |
C1—C4 | 1.5126 (15) | C11—C12i | 1.5135 (14) |
C2—C3 | 1.5419 (18) | C12—C13 | 1.5442 (17) |
C2—H21 | 0.980 (14) | C12—H121 | 0.931 (16) |
C2—H22 | 0.956 (16) | C12—H122 | 0.947 (14) |
C3—C4 | 1.533 (2) | C13—C12i | 1.5443 (17) |
C3—H31 | 0.981 (16) | C13—H13 | 0.967 (15) |
C3—H32 | 0.965 (16) | | |
| | | |
O1—C1—C2 | 133.63 (11) | C3—C4—H41 | 116.6 (9) |
O1—C1—C4 | 133.58 (11) | C1—C4—H42 | 110.1 (9) |
C2—C1—C4 | 92.78 (9) | C3—C4—H42 | 115.9 (9) |
C1—C2—C3 | 88.35 (9) | H41—C4—H42 | 109.9 (12) |
C1—C2—H21 | 115.4 (9) | O2—C11—C12 | 133.41 (6) |
C3—C2—H21 | 112.7 (8) | O2—C11—C12i | 133.40 (6) |
C1—C2—H22 | 111.0 (10) | C12—C11—C12i | 93.19 (12) |
C3—C2—H22 | 113.9 (10) | C11—C12—C13 | 88.00 (9) |
H21—C2—H22 | 113.2 (12) | C11—C12—H121 | 112.3 (9) |
C4—C3—C2 | 90.46 (9) | C13—C12—H121 | 113.9 (9) |
C4—C3—H31 | 110.4 (10) | C11—C12—H122 | 111.9 (9) |
C2—C3—H31 | 114.6 (9) | C13—C12—H122 | 117.3 (9) |
C4—C3—H32 | 117.4 (10) | H121—C12—H122 | 111.4 (12) |
C2—C3—H32 | 113.5 (9) | C12—C13—C12i | 90.80 (12) |
H31—C3—H32 | 109.6 (14) | C12—C13—H13 | 112.2 (9) |
C1—C4—C3 | 88.31 (9) | C12i—C13—H13 | 113.9 (10) |
C1—C4—H41 | 114.5 (8) | | |
| | | |
O1—C1—C2—C3 | 178.28 (12) | C2—C3—C4—C1 | −2.25 (8) |
C4—C1—C2—C3 | −2.30 (9) | O2—C11—C12—C13 | 180.0 |
C1—C2—C3—C4 | 2.26 (8) | C12i—C11—C12—C13 | 0.0 |
O1—C1—C4—C3 | −178.27 (12) | C11—C12—C13—C12i | 0.0 |
C2—C1—C4—C3 | 2.31 (9) | | |
Symmetry code: (i) −x, y, −z+1/2. |
Experimental details
| (CP) | (CB) |
Crystal data |
Chemical formula | C5H8O | C4H6O |
Mr | 84.11 | 70.09 |
Crystal system, space group | Monoclinic, C2/c | Monoclinic, C2/c |
Temperature (K) | 200 | 200 |
a, b, c (Å) | 16.7421 (16), 9.7941 (8), 8.8898 (7) | 15.5022 (16), 9.0662 (9), 8.6531 (7) |
β (°) | 93.69 (2) | 85.83 (3) |
V (Å3) | 1454.7 (2) | 1212.9 (2) |
Z | 12 | 12 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.08 | 0.08 |
Crystal size (mm) | 0.5 × 0.3 × 0.3 | 0.5 × 0.35 × 0.35 |
|
Data collection |
Diffractometer | Bruker SMART CCD 6000 area-detector diffractometer | Bruker SMART CCD 6000 area-detector diffractometer |
Absorption correction | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6027, 1660, 1336 | 5379, 1440, 1127 |
Rint | 0.035 | 0.036 |
(sin θ/λ)max (Å−1) | 0.692 | 0.713 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.099, 1.03 | 0.039, 0.121, 1.06 |
No. of reflections | 1660 | 1440 |
No. of parameters | 132 | 106 |
H-atom treatment | All H-atom parameters refined | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.17, −0.14 | 0.23, −0.15 |
Table 1. Parameters of intermolecular contacts in CP and CB (Å, °) topCompound | D—H···A | D—H | H···A | D···A | D—H···A |
CP | C12—H122···O2i | 0.985 (15) | 2.655 (15) | 3.5384 (13) | 149.4 (11) |
CB | C12—H121···O2i | 0.931 (16) | 2.659 (16) | 3.5625 (13) | 163.7 (12) |
CP | O2···C1 | | | 3.1915 (15) | |
CB | O2···C1 | | | 3.2295 (13) | |
CP | O1···C1ii | | | 3.2425 (12) | |
CB | O1···C1ii | | | 3.0924 (11) | |
Symmetry codes: (i) -x+1/2, -y+3/2, -z+1;
(ii) -x, -y+1, -z+1 and x, -y+1, z-1/2.
[Author: code (ii) does not match that given in the
Comment and Fig. 3 of (-x+1/2, -y+3/2, -z+1),
i.e. code (i)] |
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Over the last several years there has been a noticable increase of single-crystal X-ray studies of compounds which are liquid or gaseous under ambient conditions. These studies nowadays include not only straightforward structural determinations of pure compounds, sometimes of new potentially important classes such as room-temperature ionic liquids (Choudhury et al., 2005), but also expand into the emerging area of low-temperature polymorphism (Kirchner et al., 2009) and thus provide fascinating insights into the formation of molecular complexes (cocrystals) in liquid mixtures (Kirchner et al., 2010). Despite such interest, there are still a number of chemical classes left almost untouched. Interesting results were reported recently on polymorphism in such simple compounds as cyclohexanone (Shallard-Brown et al., 2005; Ibberson, 2006; Yufit & Howard, 2008) and cyclohexanol (Ibberson et al., 2008). Surprisingly, the Cambridge Structural Database (Version 5.3.1, November 2010; Allen, 2002) contains no information on the structures of other small cyclic ketones and alcohols. In order to close the gap, we have performed a single-crystal X-ray study of two compounds of this class, namely cyclopentanone (CP) and cyclobutanone (CB), and report here the results obtained.
The crystals of the two compounds turned out to be isostructural (but not isomorphous) and, in both cases, contain two crystallographically independent molecules, one in a general position and one in a special position on a twofold axis, which passes through both atoms of carbonyl group. The geometry of the independent molecules in each compound is identical (Fig. 1). The CP molecules adopt a half-chair conformation, while the CB molecules are planar. The bond lengths and angles in CP and CB are close to calculated values (Mukhopadhyay et al., 2009). Slight elongation of the carbonyl bond in CP [1.2109 (15) and 1.2148 (15) Å] in comparison with CB [1.2016 (16) and 1.2028 (14) Å] corresponds to theoretical calculations and reflects a higher polarity of that bond in CP.
As noted above, the crystals of CP and CB are isostructural; however, the difference in one methylene group between these two molecules slightly distorts the packing. As a result, similarity to the CP orientation and position of the CB molecules in the unit cell can be achieved only by refining the CB structure using a cell with an acute monoclinic angle and an opposite direction of the c axis (Fig 2). In order to maintain consistency of the description of intermolecular interactions in these structures and make the comparisons more simple, the structure of CB has been refined in such a nonstandard setting of the C2/c space group.
The packing of molecules in CP and CB is of note: molecules in general positions form dimers with an antiparallel arrangement of the carbonyl groups and with corresponding O1···C1(-x+1/2, -y+3/2, -z+1) distances of 3.1915 (15) and 3.2295 (13) Å in CP and CB, respectively (Fig. 3). Such an arrangement indicates the presence of strong dipole–dipole interactions between these molecules. The geometrical parameters of these and other intermolecular contacts are given in Table 1. In contrast, the molecules in special positions are linked together in ribbons, parallel to the c direction, by pairs of C—H···O interactions. There are short O···C(carbonyl) contacts [3.2425 (12) and 3.0924 (11)Å in CP and CB, respectively] between molecules in ribbons and in dimers, but in these contacts the carbonyl groups are nonparallel and form O1—C1—O2—C11 torsion angles of -46.90 (8) and -47.91 (8)° in CP and CB, respectively, and therefore can not be regarded as dipole–dipole interactions. The planes of the carbonyl groups are at 57.29 (7) (in CP) and 62.58 (8)° (in CB) to each other, so one of the lone pairs of electrons of the O atom is directed towards the carbonyl C atom of one of dimers.
Thus, these small cyclic ketones show several different types of intermolecular interactions within the same structure. The observed packing pattern is quite different from those found in several polymorphs of cyclohexanone, where the molecules are linked by various C—H···O interactions but not by dipole–dipole interactions (Shallard-Brown et al., 2005; Ibberson, 2006; Yufit & Howard, 2008). Interestingly, solvent cyclopentanone molecules in other crystals either do not interact with each other (Toda et al., 2000) or form C—H···O-linked dimers or chains (Bock et al., 1998; Liu et al., 2006), similar to those found in CP, but no dipole–dipole-linked dimers were observed. To the best of our knowledge, no cocrystals containing cyclobutanone molecules have been reported so far.