2,2'-Methyl­enebis(3-hydroxy-2-cyclo­hexen-1-one)

In the title compound, C₁₃H₁₆O₄, the cyclo­hexene rings adopt a sofa conformation. Adjacent mol­ecules are connected by C-H...O intermolecular interactions. Each mol­ecule is characterized by O-H...O intramolecular hydrogen bonds. The anti arrangement of the enolic OH group and the carbonyl O atom in the solid state is similar to the anti arrangement of the NH and carbonyl groups in indigo.

S1. Comment

The bond lengths and angles of the two cyclohexene rings in the title compound, (I), conform to expectations (Peter et al., 1992; Lalancette et al., 1997; Govindasamy & Subramanian, 1997).

Rings 1 (C1–C6) and 2 (C1'–C6') have a sofa conformation. The asymmetry parameters [ΔC_s(C1) = 0.026 (1) and ΔC_s(C1') = 0.017 (1); Nardelli, 1995] satisfy the condition for the sofa conformation. The values of the total puckering amplitudes [Q_T = 0.476 (2) and 0.477 (3) Å for rings 1 and 2, respectively; Cremer & Pople, 1975] indicate that the two rings have the same conformation. Atoms O2 and O4 deviate from the ring 2 by 0.134 (2) and 0.062 (2) Å, respectively. Atoms O1 and O3 deviate from the ring 1 by 0.097 (2) and 0.066 (2) Å, respectively. Atom C7 deviates from rings 1 and 2 by −0.460 (2) and −0.394 (2) Å, respectively. The deviations of atoms C4 and C4' are −0.295 (2) and −0.364 (3) Å with respect to rings 1 and 2.

The two cyclohexene rings are attracted towards each other by O—H···O intramolecular hydrogen bonds. Atoms O2 and O3 act as donors whereas O4 and O1 act as acceptors. The O···O distance agrees well with earlier reported values (Li et al., 1999; Steiner, 1997; Paixao et al., 1999; Komen et al., 1999; Parvez et al., 1999). The average O···O distance observed in the present structure is 2.615 Å. The sequences of the bond distances along the systems: O1—C2—C1—C6—O3 and O4—C6'—C1'—C2'—O2 are indicative of some π conjugation, enhancing the polarization of charge that produces the two O—H···O hydrogen bonds. These are rather strong as indicated by the short values (1.78 and 1.84 Å) of the H···O distances. The angle C1—C7—C1' is 117.0 (2)°. The conformation of the two halves of the molecule is determined by the two O—H···O hydrogen bonds.

The packing is stabilized by intermolecular C—H···O interactions. The atoms C5 and C5' act as donors to form intermolecular interactions with the symmetry-related atoms O1 and O2.

S2. Experimental

The title compound was prepared by the addition of a 40% aqueous solution of formalin (6 ml) to a solution of cyclohexane-1,3-dione (15 g, 0.13 mol) in water (200 ml) and warming until the solution became cloudy. The 2–2'methylenebis(cyclohexane-1,3-dione) started to separate out. The reaction mixture was allowed to stand overnight and the ketone was collected by filtration and dried. Yield 8.0 g (50.6%), m.p. 403–405 K (Setter, 1995).

S3. Refinement

The H atoms are fixed geometrically and allowed to refine riding on the corresponding non-H atoms.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: SDP (Frenz, 1978); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1995).

2,2'-Methylenebis(3-hydroxy-2-cyclohexen-1-one)

Crystal data

C13H16O4	Dx = 1.309 Mg m^−3
Mr = 236.26	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, Pbca	Cell parameters from 15 reflections
a = 9.9313 (18) Å	θ = 2–28°
b = 10.3818 (14) Å	µ = 0.80 mm^−1
c = 23.253 (2) Å	T = 293 K
V = 2397.5 (6) Å^3	Rectangle, yellow
Z = 8	0.20 × 0.15 × 0.10 mm
F(000) = 1008

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 69.8°, θmin = 3.8°
Graphite monochromator	h = 0→12
ω scans	k = 0→12
2264 measured reflections	l = 0→28
2264 independent reflections	3 standard reflections every 60 min
1829 reflections with I > 2σ(I)	intensity decay: 1%

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)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.176	Calculated w = 1/[σ^2(Fo^2) + (0.1P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.31	(Δ/σ)max = 0.003
2264 reflections	Δρmax = 0.20 e Å^−3
157 parameters	Δρmin = −0.14 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0075 (10)

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	0.01461 (15)	0.37135 (13)	0.07381 (7)	0.0597 (5)
O2	0.10450 (18)	0.29611 (15)	0.17239 (7)	0.0684 (5)
H2	0.0622	0.3172	0.1436	0.103*
O3	−0.21031 (16)	−0.01946 (14)	0.04335 (7)	0.0616 (5)
H3	−0.1828	−0.0355	0.0758	0.092*
C1	−0.11522 (17)	0.18421 (17)	0.06350 (8)	0.0422 (5)
O4	−0.11738 (17)	−0.09725 (15)	0.14432 (7)	0.0661 (5)
C1'	−0.02610 (18)	0.10732 (18)	0.16172 (8)	0.0473 (5)
C6'	−0.03227 (19)	−0.0280 (2)	0.16961 (8)	0.0510 (5)
C6	−0.16119 (17)	0.09093 (18)	0.02628 (8)	0.0459 (5)
C2	−0.04387 (19)	0.29085 (17)	0.04107 (9)	0.0466 (5)
C7	−0.13556 (18)	0.17381 (19)	0.12765 (8)	0.0472 (5)
H7A	−0.1463	0.2602	0.1429	0.057*
H7B	−0.2194	0.1283	0.1344	0.057*
C2'	0.0813 (2)	0.1751 (2)	0.18380 (9)	0.0536 (5)
C3	−0.0297 (3)	0.3098 (2)	−0.02241 (9)	0.0591 (6)
H3A	0.0551	0.2733	−0.0351	0.071*
H3B	−0.0284	0.4013	−0.0309	0.071*
C4	−0.1442 (2)	0.2468 (2)	−0.05494 (9)	0.0586 (6)
H4A	−0.1274	0.2525	−0.0960	0.070*
H4B	−0.2277	0.2917	−0.0467	0.070*
C5	−0.1575 (2)	0.1072 (2)	−0.03767 (9)	0.0551 (5)
H5A	−0.2394	0.0720	−0.0541	0.066*
H5B	−0.0820	0.0590	−0.0531	0.066*
C4'	0.1281 (3)	−0.0052 (3)	0.25192 (11)	0.0794 (8)
H4'1	0.2001	−0.0486	0.2724	0.095*
H4'2	0.0591	0.0182	0.2795	0.095*
C5'	0.0699 (3)	−0.0941 (2)	0.20758 (10)	0.0691 (7)
H5'1	0.1421	−0.1278	0.1838	0.083*
H5'2	0.0273	−0.1664	0.2268	0.083*
C3'	0.1823 (3)	0.1149 (3)	0.22326 (12)	0.0769 (8)
H3'1	0.2078	0.1768	0.2526	0.092*
H3'2	0.2625	0.0930	0.2015	0.092*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0665 (9)	0.0484 (8)	0.0643 (9)	−0.0103 (7)	−0.0127 (7)	0.0033 (6)
O2	0.0798 (11)	0.0648 (10)	0.0606 (10)	−0.0112 (8)	−0.0190 (8)	−0.0001 (7)
O3	0.0608 (9)	0.0555 (9)	0.0685 (9)	−0.0158 (7)	−0.0083 (7)	0.0019 (7)
C1	0.0351 (8)	0.0455 (10)	0.0461 (10)	0.0049 (7)	−0.0007 (7)	−0.0013 (7)
O4	0.0646 (9)	0.0662 (10)	0.0676 (10)	−0.0134 (7)	−0.0009 (8)	0.0105 (7)
C1'	0.0460 (10)	0.0572 (11)	0.0388 (9)	0.0024 (8)	0.0045 (8)	0.0002 (8)
C6'	0.0492 (11)	0.0605 (12)	0.0435 (10)	−0.0025 (9)	0.0076 (8)	0.0061 (8)
C6	0.0367 (9)	0.0469 (10)	0.0540 (11)	0.0013 (8)	−0.0025 (8)	0.0001 (8)
C2	0.0427 (9)	0.0411 (10)	0.0559 (11)	0.0039 (7)	−0.0064 (8)	0.0008 (8)
C7	0.0393 (9)	0.0531 (11)	0.0492 (10)	0.0041 (8)	0.0063 (8)	−0.0016 (8)
C2'	0.0568 (12)	0.0601 (12)	0.0439 (9)	−0.0008 (9)	−0.0018 (8)	−0.0006 (9)
C3	0.0675 (14)	0.0544 (12)	0.0555 (12)	−0.0041 (10)	0.0003 (10)	0.0081 (9)
C4	0.0687 (13)	0.0604 (13)	0.0466 (10)	0.0069 (11)	−0.0093 (10)	0.0025 (9)
C5	0.0567 (12)	0.0562 (12)	0.0524 (11)	0.0060 (9)	−0.0078 (9)	−0.0063 (9)
C4'	0.0877 (18)	0.0935 (19)	0.0571 (13)	−0.0018 (14)	−0.0199 (13)	0.0212 (13)
C5'	0.0796 (16)	0.0706 (15)	0.0572 (13)	0.0047 (12)	−0.0043 (12)	0.0153 (11)
C3'	0.0733 (16)	0.0923 (18)	0.0650 (14)	−0.0108 (14)	−0.0251 (13)	0.0136 (13)

Geometric parameters (Å, º)

O1—C2	1.271 (2)	C2'—C3'	1.496 (3)
O2—C2'	1.304 (3)	C3—C4	1.515 (3)
O2—H2	0.8200	C3—H3A	0.9700
O3—C6	1.307 (2)	C3—H3B	0.9700
O3—H3	0.8200	C4—C5	1.510 (3)
C1—C6	1.377 (3)	C4—H4A	0.9700
C1—C2	1.414 (3)	C4—H4B	0.9700
C1—C7	1.509 (2)	C5—H5A	0.9700
O4—C6'	1.256 (2)	C5—H5B	0.9700
C1'—C2'	1.377 (3)	C4'—C5'	1.500 (4)
C1'—C6'	1.418 (3)	C4'—C3'	1.513 (4)
C1'—C7	1.512 (3)	C4'—H4'1	0.9700
C6'—C5'	1.510 (3)	C4'—H4'2	0.9700
C6—C5	1.497 (3)	C5'—H5'1	0.9700
C2—C3	1.496 (3)	C5'—H5'2	0.9700
C7—H7A	0.9700	C3'—H3'1	0.9700
C7—H7B	0.9700	C3'—H3'2	0.9700
C2'—O2—H2	109.5	H3A—C3—H3B	108.0
C6—O3—H3	109.5	C3—C4—C5	110.32 (17)
C6—C1—C2	119.02 (17)	C3—C4—H4A	109.6
C6—C1—C7	121.77 (17)	C5—C4—H4A	109.6
C2—C1—C7	119.19 (17)	C3—C4—H4B	109.6
C2'—C1'—C6'	119.44 (19)	C5—C4—H4B	109.6
C2'—C1'—C7	121.25 (18)	H4A—C4—H4B	108.1
C6'—C1'—C7	119.28 (18)	C6—C5—C4	111.99 (17)
O4—C6'—C1'	122.41 (19)	C6—C5—H5A	109.2
O4—C6'—C5'	117.72 (19)	C4—C5—H5A	109.2
C1'—C6'—C5'	119.82 (19)	C6—C5—H5B	109.2
O3—C6—C1	123.34 (18)	C4—C5—H5B	109.2
O3—C6—C5	114.17 (17)	H5A—C5—H5B	107.9
C1—C6—C5	122.48 (17)	C5'—C4'—C3'	110.0 (2)
O1—C2—C1	121.52 (18)	C5'—C4'—H4'1	109.7
O1—C2—C3	117.49 (18)	C3'—C4'—H4'1	109.7
C1—C2—C3	120.94 (17)	C5'—C4'—H4'2	109.7
C1'—C7—C1	117.02 (15)	C3'—C4'—H4'2	109.7
C1'—C7—H7A	108.0	H4'1—C4'—H4'2	108.2
C1—C7—H7A	108.0	C6'—C5'—C4'	112.4 (2)
C1'—C7—H7B	108.0	C6'—C5'—H5'1	109.1
C1—C7—H7B	108.0	C4'—C5'—H5'1	109.1
H7A—C7—H7B	107.3	C6'—C5'—H5'2	109.1
O2—C2'—C1'	123.59 (19)	C4'—C5'—H5'2	109.1
O2—C2'—C3'	114.12 (19)	H5'1—C5'—H5'2	107.9
C1'—C2'—C3'	122.3 (2)	C2'—C3'—C4'	112.1 (2)
C2—C3—C4	111.43 (18)	C2'—C3'—H3'1	109.2
C2—C3—H3A	109.3	C4'—C3'—H3'1	109.2
C4—C3—H3A	109.3	C2'—C3'—H3'2	109.2
C2—C3—H3B	109.3	C4'—C3'—H3'2	109.2
C4—C3—H3B	109.3	H3'1—C3'—H3'2	107.9
C2'—C1'—C6'—O4	−170.41 (18)	C6'—C1'—C2'—O2	170.75 (18)
C7—C1'—C6'—O4	7.8 (3)	C7—C1'—C2'—O2	−7.4 (3)
C2'—C1'—C6'—C5'	6.9 (3)	C6'—C1'—C2'—C3'	−9.1 (3)
C7—C1'—C6'—C5'	−174.98 (18)	C7—C1'—C2'—C3'	172.8 (2)
C2—C1—C6—O3	169.67 (17)	O1—C2—C3—C4	−156.59 (18)
C7—C1—C6—O3	−8.6 (3)	C1—C2—C3—C4	25.9 (3)
C2—C1—C6—C5	−9.6 (3)	C2—C3—C4—C5	−53.1 (2)
C7—C1—C6—C5	172.14 (17)	O3—C6—C5—C4	161.36 (17)
C6—C1—C2—O1	−171.40 (17)	C1—C6—C5—C4	−19.3 (3)
C7—C1—C2—O1	6.9 (3)	C3—C4—C5—C6	50.0 (2)
C6—C1—C2—C3	6.0 (3)	O4—C6'—C5'—C4'	−157.6 (2)
C7—C1—C2—C3	−175.68 (17)	C1'—C6'—C5'—C4'	25.0 (3)
C2'—C1'—C7—C1	89.4 (2)	C3'—C4'—C5'—C6'	−53.0 (3)
C6'—C1'—C7—C1	−88.7 (2)	O2—C2'—C3'—C4'	159.6 (2)
C6—C1—C7—C1'	90.6 (2)	C1'—C2'—C3'—C4'	−20.6 (4)
C2—C1—C7—C1'	−87.7 (2)	C5'—C4'—C3'—C2'	50.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3B···O1^i	0.97	2.57	3.522 (3)	168
C5—H5A···O1^ii	0.97	2.56	3.371 (3)	141
C5′—H5′1···O2^iii	0.97	2.65	3.525 (3)	150
C5′—H5′2···O2^iv	0.97	2.71	3.477 (3)	136
O2—H2···O1	0.82	1.78	2.581 (2)	165
O3—H3···O4	0.82	1.84	2.649 (2)	171

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