Download citation
Download citation
link to html
The title compound, C14H20O2, adopts a conformation in which the δ-valerolactone and cyclo­hexane rings are almost coplanar with one another. The γ-methyl substituent occupies an axial position with respect to the cyclo­hexane ring. The δ-valerolactone moiety adopts an envelope arrangement, while the cyclo­hexane ring exists in a chair conformation.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107011821/av3076sup1.cif
Contains datablocks global, V

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107011821/av3076Vsup2.hkl
Contains datablock V

CCDC reference: 649083

Comment top

The α-methylene-δ-valerolactone moiety is found in a wide range of natural products. Several of them, like vernolepin (Kupchan et al., 1968), teucriumlactone (Nangia et al., 1997) and artemisitene (Liao et al., 2001), have proven antibacterial and antitumour activities. Morever, the δ-valerolactones are also useful substrates for the preparation of versatile biodegradable polyesters with good mechanical properties (Lou et al., 2002), which may find biomedical and pharmaceutical applications (Albertsson & Varma, 2003). Enantiomerically pure α-methylene-δ-valerolactones are interesting chiral building blocks whose use in organic chemistry has been restricted by the limited availability of their synthesis (Suzuki et al., 1991; Krishna et al., 2004) The first synthesis by an asymmetric Michael reaction, leading to the enantio-enriched species, has been described recently by us (Krawczyk & Śliwiński, 2003; Krawczyk, Śliwiński et al., 2004; Krawczyk et al., 2006).

The present study is a continuation of our structural investigations of optically active bicyclic α-methylene-δ-valerolactones. Four crystal structures have been published previously, namely (4aS,8aS)-4a-methyl-3-methyleneperhydrochromen-2-one, (I) (Krawczyk, Śliwiński & Wolf, 2004), ethyl trans-(4aS,8aS)-3-methylene-2-oxohexahydrochromene-4a-carboxylate, (II) (Krawczyk, Śliwiński et al., 2004), trans-(4aR,8aR)-4a-methoxy-3-methyleneperhydrochromen-2-one, (III) (Wojciechowski et al., 2005), and (5R,6R)-methyl-9-methylene-2,7-dioxa-spiro[4.5]decane-1,8-dione, (IV) (Krawczyk et al., 2006). The title compound, (V), is fifth in the series. In compounds (I), (II), (III) and (V), the δ-valerolactone ring is condensed with the cyclohexane moiety along the individual Cδ—Cγ single bond. The molecule of (IV) adopts an unusual spiro arrangement, with the γ-lactone and δ-lactone rings sharing the pivotal C atom and strongly twisted with respect to one another.

A view of (V) with the atom-numbering scheme is shown in Fig. 1. The δ-valerolactone ring adopts a conformation close to a 5E envelope (Boeyens, 1978), with atoms O1, C1, C2, C3 and C5 almost coplanar (the average r.m.s. deviation from the mean plane is 0.04 Å) and atom C6 situated at the flap. The Cremer & Pople (1975) puckering parameters for the ring atom sequence O1/C2/C3/C5/C6/C1 are Q = 0.529 (1) Å, θ = 52.5 (2)° and ϕ = 251.8 (2)°. The conformation of unsaturated δ-valerolactones has been investigated by Brandänge et al. (2003). Their ab initio HF/6–31G* calculations on isolated molecules showed the high conformational mobility of the ring and indicated that the energy of the envelope conformer is almost 8.5 kJ mol-1 above the theoretically most stable half-chair arrangement.

The γ-methyl substituent occupies an axial position with respect to both the δ-valerolactone and the cyclohexane rings. The molecular conformation can be defined as extended with both rings almost coplanar to one another. A similar arrangement has been observed in compounds (II) and (III). In (I), both rings are roughly perpendicular to one another, leading to the folded conformation of the molecule. A superposition of (V) on the four structures, (I)–(IV), as presented in Fig. 2, clearly shows the high degree of similarity of the δ-valerolactone rings in all five compounds investigated to date.

Bond lengths in (V) are close to those observed in the related compounds (I)–(IV). In particular, two exocyclic double bonds, C2O2 [1.203 (2) Å] and C3C4 [1.318 (2) Å], are shorter than similar bonds observed in the O C—CC moiety [1.222 and 1.340 Å, respectively; Allen et al., 2004]. These bonds are separated by a relatively long C2—C3 bond [1.495 (2) Å; standard value 1.465 Å] and are quite coplanar, as indicated by a close to zero value of the O2—C2—C3—C4 torsion angle [-0.7 (3)°].

The syn conformation of the O2C2—C3C4 fragment in all investigated δ-valerolactones (I)–(V) prompts electronic interactions involving the bonding σ and π orbitals and the antibonding σ* and π* orbitals. The most important values (Table 2, Fig. 3) were computed by the Weinhold natural bond orbitals deletion procedure (Glendening et al., 1992) for wavefunctions calculated with GAUSSIAN03 (Frisch et al., 2004) at the HF/6–311++G(d,p) level of theory for the X-ray determined coordinates. In particular, the exocyclic C3C4 bond participates in electron-density transfer towards the carbonyl group in the ππ* fashion (Giuffreda et al., 2004), while the reverse back-donation is much weaker [60.2 and 13.3 kJ mol-1, respectively, for (V)]. In comparison with the above effect, the energies of mutual anti σσ* hyperconjugation (Weinhold, 2001) involving the endocyclic C2—O1 and vinyl C3C4 bonds are smaller [9.8 and 4.6 kJ mol-1, respectively, for (V)]. The resulting surplus of electron density accumulated on the carbonyl atom O2 is back-donated towards atoms C2 and C3 through the nπ(O2)–σ*(C2—C3) stereoelectronic effect (Graczyk & Mikołajczyk, 1994).

Examination of the crystal packing of (V) indicates that the intermolecular distances are larger than the sums of the respective van der Waals radii (Bondi, 1964).

Related literature top

For related literature, see: Albertsson, -Ch & Varma (2003); Allen et al. (2004); Boeyens (1978); Bondi (1964); Brandänge et al. (2003); Cremer & Pople (1975); Flack (1983); Frisch (2004); Giuffreda et al. (2004); Glendening et al. (1992); Graczyk & Mikołajczyk (1994); Krawczyk & Śliwiński (2003); Krawczyk et al. (2006); Krawczyk, Śliwiński & Wolf (2004); Krawczyk, Śliwiński, Wolf & Bodalski (2004); Krishna et al. (2004); Kupchan et al. (1968); Liao et al. (2001); Lou et al. (2002); Nangia et al. (1997); Suzuki et al. (1991); Weinhold (2001); Wojciechowski et al. (2005).

Experimental top

The synthesis of the enantiomerically pure α-methylene-δ-valerolactone, (V), was based on a highly stereoselective Michael reaction of the chiral enamine derived from (R)-1-phenylethylamine and (R)-dihydrocarvone with dicyclohexylammonium 2-(diethoxyphosphoryl)acrylate. Subsequent reduction of the carbonyl group in the adduct with KBH4 was followed by lactonization of the resulting 2-(diethoxyphosphoryl)-5-hydroxyalkanoic acid. The final step in the synthesis pathway was the Horner–Wadsworth–Emmons olefination of the obtained α-phosphono-δ-valerolactone with formaldehyde. The enantiomeric purity of (V) was confirmed as higher than 0.99 by gas chromatographic analysis on a chiral column. Details of the procedure have been described elsewhere (Krawczyk & Śliwiński, 2003; Krawczyk, Śliwiński et al., 2004; Krawczyk et al., 2006). Colourless crystals of (V) (m.p. 397 K) were grown within 4 d by slow evaporation of a solution in a 1:1 mixture of methanol and ethyl acetate.

Refinement top

All H atoms, except those of the methyl groups, were located in a difference Fourier map calculated after three cycles of anisotropic refinement. Their positional and isotropic displacement parameters were allowed to refine freely [C—H = 0.945 (18)–1.029 (17) Å]. The methyl H atoms were placed in calculated positions [C—H = 0.96 (2) Å] and refined as riding. Refinement of the Flack (1983) parameter is in agreement with the absolute configuration as assigned from the mechanism of the highly stereoselective Michael reaction (Krawczyk & Śliwiński, 2003). An attempt to refine the inverted structure led to a Flack parameter of 1.0 (2).

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 2003); program(s) used to solve structure: SHELXTL (Bruker, 2003); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The molecular structure of compound (V), showing the atom-numbering scheme. 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 superposition of structures (I)–(IV) on the title compound, (V); the latter is indicated as a dashed line. The least-squares fit is based on all common non-H atoms of the α-methylene-δ-valerolactone fragment. The largest r.m.s. deviation is 0.94 Å.
[Figure 3] Fig. 3. Natural bond orbitals in compound (V). (a) Involved in electron-density transfer from the exocyclic C3C4 to the C2O2 carbonyl group. (b) The back-donation from the O2 nπ lone pair towards the endocyclic C2—C3 bond.
(4aS,7R,8aR)-7-Isopropenyl-4a-methyl-3-methyleneperhydrochromen-2-one top
Crystal data top
C14H20O2Dx = 1.161 Mg m3
Mr = 220.30Cu Kα radiation, λ = 1.54178 Å
Orthorhombic, P212121Cell parameters from 5207 reflections
a = 6.4451 (1) Åθ = 6.3–71.0°
b = 13.9619 (2) ŵ = 0.60 mm1
c = 14.0081 (2) ÅT = 293 K
V = 1260.53 (3) Å3Prism, colourless
Z = 40.35 × 0.20 × 0.10 mm
F(000) = 480
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer
2404 independent reflections
Radiation source: fine-focus sealed tube2362 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.019
ω scansθmax = 71.0°, θmin = 4.5°
Absorption correction: multi-scan
(SHELXTL; Bruker, 2003)
h = 77
Tmin = 0.876, Tmax = 0.943k = 1617
14510 measured reflectionsl = 1716
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.034 w = 1/[σ2(Fo2) + (0.0627P)2 + 0.0879P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.097(Δ/σ)max = 0.006
S = 1.05Δρmax = 0.14 e Å3
2404 reflectionsΔρmin = 0.14 e Å3
211 parametersExtinction correction: SHELXTL (Bruker, 2003), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0043 (9)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), with 933 Friedel pairs
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.0 (2)
Crystal data top
C14H20O2V = 1260.53 (3) Å3
Mr = 220.30Z = 4
Orthorhombic, P212121Cu Kα radiation
a = 6.4451 (1) ŵ = 0.60 mm1
b = 13.9619 (2) ÅT = 293 K
c = 14.0081 (2) Å0.35 × 0.20 × 0.10 mm
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer
2404 independent reflections
Absorption correction: multi-scan
(SHELXTL; Bruker, 2003)
2362 reflections with I > 2σ(I)
Tmin = 0.876, Tmax = 0.943Rint = 0.019
14510 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.034H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.097Δρmax = 0.14 e Å3
S = 1.05Δρmin = 0.14 e Å3
2404 reflectionsAbsolute structure: Flack (1983), with 933 Friedel pairs
211 parametersAbsolute structure parameter: 0.0 (2)
0 restraints
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
O10.24221 (16)0.14905 (8)0.46270 (6)0.0616 (3)
O20.2594 (2)0.09988 (13)0.61025 (8)0.0934 (5)
C10.34711 (19)0.17901 (9)0.37539 (9)0.0463 (3)
C20.3514 (3)0.11511 (11)0.53709 (10)0.0607 (4)
C30.5783 (2)0.09699 (10)0.52438 (10)0.0558 (3)
C40.6806 (4)0.06331 (15)0.59859 (14)0.0776 (5)
C50.6777 (2)0.11617 (11)0.42942 (11)0.0575 (3)
C60.5202 (2)0.11055 (9)0.34789 (9)0.0488 (3)
C70.6136 (2)0.14868 (14)0.25465 (11)0.0612 (4)
C80.4542 (2)0.15914 (13)0.17503 (10)0.0623 (4)
C90.2776 (2)0.22594 (10)0.20560 (9)0.0512 (3)
C100.1818 (2)0.19015 (10)0.29952 (9)0.0494 (3)
C110.4454 (3)0.00745 (10)0.33590 (12)0.0658 (4)
C120.1109 (2)0.24099 (11)0.13121 (10)0.0570 (3)
C130.0006 (4)0.33299 (15)0.13465 (17)0.0894 (6)
C140.0569 (3)0.17350 (15)0.06828 (12)0.0717 (4)
H110.406 (2)0.2413 (10)0.3895 (9)0.045 (3)*
H410.609 (3)0.0522 (14)0.6575 (14)0.075 (5)*
H420.823 (5)0.047 (2)0.5893 (18)0.114 (8)*
H510.741 (3)0.1839 (12)0.4312 (11)0.058 (4)*
H520.791 (3)0.0723 (14)0.4181 (13)0.078 (5)*
H710.668 (3)0.2100 (13)0.2679 (12)0.060 (4)*
H720.732 (4)0.1077 (16)0.2325 (14)0.084 (6)*
H810.403 (3)0.0933 (14)0.1536 (13)0.076 (5)*
H820.524 (3)0.1857 (14)0.1191 (13)0.082 (6)*
H910.330 (3)0.2898 (12)0.2211 (11)0.057 (4)*
H1010.113 (3)0.1295 (12)0.2878 (11)0.056 (4)*
H1020.071 (3)0.2349 (11)0.3228 (10)0.052 (4)*
H1110.38560.01450.39470.086 (6)*
H1120.56070.03270.31920.126 (9)*
H1130.34290.00480.28620.089 (6)*
H1310.09250.38390.11780.133 (10)*
H1320.05270.34340.19800.113 (9)*
H1330.11420.33160.09040.111 (8)*
H1410.062 (3)0.1831 (13)0.0286 (13)0.071 (5)*
H1420.131 (4)0.1139 (19)0.0662 (17)0.106 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0517 (5)0.0867 (7)0.0466 (5)0.0080 (5)0.0059 (4)0.0064 (4)
O20.0829 (8)0.1415 (12)0.0557 (6)0.0078 (9)0.0081 (7)0.0230 (7)
C10.0435 (6)0.0502 (6)0.0451 (6)0.0004 (5)0.0019 (5)0.0008 (5)
C20.0642 (9)0.0703 (8)0.0475 (7)0.0006 (7)0.0001 (6)0.0034 (6)
C30.0609 (8)0.0489 (6)0.0575 (7)0.0017 (6)0.0104 (7)0.0013 (5)
C40.0820 (12)0.0824 (11)0.0684 (10)0.0101 (10)0.0138 (10)0.0108 (8)
C50.0461 (7)0.0645 (8)0.0620 (8)0.0015 (6)0.0060 (6)0.0011 (6)
C60.0417 (6)0.0522 (7)0.0525 (7)0.0004 (5)0.0011 (5)0.0017 (5)
C70.0405 (7)0.0840 (10)0.0591 (8)0.0042 (7)0.0087 (6)0.0032 (7)
C80.0499 (7)0.0870 (11)0.0501 (7)0.0032 (7)0.0088 (6)0.0063 (7)
C90.0474 (7)0.0548 (7)0.0514 (7)0.0040 (5)0.0013 (6)0.0057 (5)
C100.0409 (6)0.0574 (7)0.0498 (7)0.0029 (5)0.0028 (5)0.0002 (6)
C110.0769 (10)0.0513 (7)0.0691 (9)0.0033 (7)0.0119 (8)0.0068 (6)
C120.0515 (7)0.0689 (8)0.0506 (7)0.0031 (6)0.0016 (6)0.0114 (6)
C130.0918 (13)0.0818 (12)0.0947 (14)0.0205 (11)0.0313 (12)0.0038 (10)
C140.0698 (10)0.0842 (11)0.0611 (8)0.0032 (8)0.0127 (8)0.0001 (8)
Geometric parameters (Å, º) top
O1—C21.3439 (17)C5—H511.029 (17)
O1—C11.4588 (14)C5—H520.96 (2)
O2—C21.203 (2)C7—H710.945 (18)
C3—C41.318 (2)C7—H721.00 (2)
C3—C51.501 (2)C8—H811.02 (2)
C2—C31.495 (2)C8—H820.979 (19)
C9—C121.5115 (19)C9—H910.977 (17)
C12—C141.337 (2)C10—H1010.969 (16)
C12—C131.473 (2)C10—H1021.004 (16)
C1—C101.5130 (18)C11—H1110.9600
C1—C61.5185 (18)C11—H1120.9600
C5—C61.5303 (18)C11—H1130.9600
C6—C111.5272 (19)C13—H1310.9600
C6—C71.5337 (19)C13—H1320.9600
C7—C81.524 (2)C13—H1330.9600
C8—C91.532 (2)C14—H1410.955 (19)
C9—C101.5370 (17)C14—H1420.96 (3)
C1—H110.970 (15)
C2—O1—C1120.56 (10)C7—C8—H81110.2 (11)
O2—C2—O1117.68 (14)C9—C8—H81113.0 (12)
O2—C2—C3123.64 (14)C7—C8—H82108.1 (12)
O1—C2—C3118.68 (13)C9—C8—H82109.7 (12)
C4—C3—C2117.12 (16)H81—C8—H82104.7 (15)
C4—C3—C5123.34 (16)C12—C9—C8114.82 (11)
C2—C3—C5119.54 (13)C12—C9—C10110.47 (10)
O1—C1—C10106.97 (10)C8—C9—C10109.86 (11)
O1—C1—C6111.87 (10)C12—C9—H91105.8 (10)
C10—C1—C6113.82 (10)C8—C9—H91111.2 (10)
O1—C1—H11105.6 (8)C10—C9—H91104.2 (9)
C10—C1—H11109.2 (8)C1—C10—C9110.58 (10)
C6—C1—H11109.1 (8)C1—C10—H101110.6 (9)
C3—C4—H41119.8 (13)C9—C10—H101108.8 (9)
C3—C4—H42117.3 (16)C1—C10—H102109.7 (8)
H41—C4—H42123 (2)C9—C10—H102111.2 (8)
C3—C5—C6111.66 (12)H101—C10—H102105.9 (13)
C3—C5—H51108.1 (9)C6—C11—H111109.5
C6—C5—H51109.0 (9)C6—C11—H112109.5
C3—C5—H52110.8 (11)H111—C11—H112109.5
C6—C5—H52110.2 (12)C6—C11—H113109.5
H51—C5—H52106.9 (15)H111—C11—H113109.5
C1—C6—C11112.93 (12)H112—C11—H113109.5
C1—C6—C5105.42 (11)C14—C12—C13120.63 (16)
C11—C6—C5109.86 (12)C14—C12—C9122.82 (15)
C1—C6—C7106.62 (12)C13—C12—C9116.46 (14)
C11—C6—C7110.94 (12)C12—C13—H131109.5
C5—C6—C7110.92 (11)C12—C13—H132109.5
C8—C7—C6113.06 (11)H131—C13—H132109.5
C8—C7—H71108.0 (11)C12—C13—H133109.5
C6—C7—H71107.1 (10)H131—C13—H133109.5
C8—C7—H72109.9 (12)H132—C13—H133109.5
C6—C7—H72111.4 (12)C12—C14—H141119.5 (11)
H71—C7—H72107.1 (17)C12—C14—H142120.0 (15)
C7—C8—C9110.77 (12)H141—C14—H142120.3 (19)
O2—C2—C3—C40.7 (3)O1—C1—C6—C7178.78 (11)
O1—C2—C3—C4179.70 (15)C10—C1—C6—C757.37 (14)
C1—C6—C5—C354.19 (14)C3—C5—C6—C1167.77 (16)
C6—C5—C3—C224.85 (18)C3—C5—C6—C7169.22 (13)
C5—C3—C2—O10.5 (2)C1—C6—C7—C856.85 (17)
C3—C2—O1—C17.7 (2)C11—C6—C7—C866.48 (18)
C2—O1—C1—C641.39 (16)C5—C6—C7—C8171.13 (13)
C8—C9—C12—C1431.9 (2)C6—C7—C8—C957.89 (18)
C10—C9—C12—C1493.00 (17)C7—C8—C9—C12180.00 (12)
C2—O1—C1—C10166.67 (12)C7—C8—C9—C1054.78 (16)
C1—O1—C2—O2173.23 (15)O1—C1—C10—C9177.58 (10)
O2—C2—C3—C5178.54 (16)C6—C1—C10—C958.33 (14)
C4—C3—C5—C6154.29 (16)C12—C9—C10—C1177.61 (11)
O1—C1—C6—C1156.69 (14)C8—C9—C10—C154.70 (15)
C10—C1—C6—C1164.71 (15)C8—C9—C12—C13151.69 (16)
O1—C1—C6—C563.26 (13)C10—C9—C12—C1383.41 (18)
C10—C1—C6—C5175.33 (11)

Experimental details

Crystal data
Chemical formulaC14H20O2
Mr220.30
Crystal system, space groupOrthorhombic, P212121
Temperature (K)293
a, b, c (Å)6.4451 (1), 13.9619 (2), 14.0081 (2)
V3)1260.53 (3)
Z4
Radiation typeCu Kα
µ (mm1)0.60
Crystal size (mm)0.35 × 0.20 × 0.10
Data collection
DiffractometerBruker SMART APEX CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SHELXTL; Bruker, 2003)
Tmin, Tmax0.876, 0.943
No. of measured, independent and
observed [I > 2σ(I)] reflections
14510, 2404, 2362
Rint0.019
(sin θ/λ)max1)0.613
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.097, 1.05
No. of reflections2404
No. of parameters211
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.14, 0.14
Absolute structureFlack (1983), with 933 Friedel pairs
Absolute structure parameter0.0 (2)

Computer programs: SMART (Bruker, 2003), SMART, SAINT-Plus (Bruker, 2003), SHELXTL (Bruker, 2003), SHELXTL.

Selected geometric parameters (Å, º) top
O1—C21.3439 (17)C2—C31.495 (2)
O1—C11.4588 (14)C9—C121.5115 (19)
O2—C21.203 (2)C12—C141.337 (2)
C3—C41.318 (2)C12—C131.473 (2)
C3—C51.501 (2)
C2—O1—C1120.56 (10)C4—C3—C2117.12 (16)
O2—C2—O1117.68 (14)C4—C3—C5123.34 (16)
O2—C2—C3123.64 (14)C2—C3—C5119.54 (13)
O1—C2—C3118.68 (13)
O2—C2—C3—C40.7 (3)C3—C2—O1—C17.7 (2)
O1—C2—C3—C4179.70 (15)C2—O1—C1—C641.39 (16)
C1—C6—C5—C354.19 (14)C8—C9—C12—C1431.9 (2)
C6—C5—C3—C224.85 (18)C10—C9—C12—C1493.00 (17)
C5—C3—C2—O10.5 (2)
Energy of the selected electronic interactions calculated using natural bond orbital theory top
Type of interactionStabilization energy (kJ mol-1)
(I)(II)(III)(IV)(V)
σ(C3C4)–σ*(C2—O1)7.88.68.99.29.8
σ(C2—O1)–σ*(C3C4)5.34.74.85.04.6
π(C3C4)–π*(C2O2)57.857.256.862.060.2
π(C2O2)–π*(C3C4)13.313.113.114.013.3
nπ(O2)–σ*(C2—C3)66.366.966.164.867.3
Stabilization energies were calculated using GAUSSIAN03 (Frisch et al.. 2004) at the HF/6-311++G(d,p) level of theory for X-ray determined coordinates. The standard NBO deletion procedure (Glendening et al., 1992) was applied.
 

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds