rac-trans-Cyclo­heptane-1,2-diol

In the title compound, C₇H₁₄O₂, a pair of vicinal trans-connected hydr­oxy groups is attached to a cyclo­heptane ring. The non-crystallographic mol­ecular symmetry is close to C₂. The O—C—C—O torsion angle of approximately 66° resembles those in trans-configured cyclo­hexane derivatives (including the pyran­oses) and is smaller than those in trans-configured cyclo­pentane derivatives (including the furan­oses). Chains of O—H...O hydrogen bonds form a cooperatively bonded hydrogen-bond system. All other inter­molecular contacts are of the van der Waals type. In terms of functional-group torsion, the title compound is thus a potential bidentate ligand with the ability to form a C₂-symmetrical chelate ring with a metal atom.

Key indicators

• Single-crystal X-ray study
• T = 200 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.042
• wR factor = 0.113
• Data-to-parameter ratio = 16.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 =          3

Author Response: checked, values are correct.

Alert level G
PLAT793_ALERT_1_G Check the Absolute Configuration of C1     = ...          R
PLAT793_ALERT_1_G Check the Absolute Configuration of C2     = ...          R

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The vicinal diol derived from cycloheptane was prepared as a chelating molecule bearing a conformationally flexible seven-membered hydrocarbon ring. The cycloheptane ring adopts a chair-like conformation. Accordingly, the molecular symmetry is close to C₂ symmetry (Fig. 1).

In the crystal structure, hydrophobic contacts close to planes with z = 1/4 and 3/4 divide the structure in sheets (Fig. 2). Fig. 3 shows an individual sheet (the one with 1/4 < z < 3/4) in a projection along [001]. The characteristic hydrogen bonds are highlighted. In the hydrogen-bond scheme, each hydroxy function acts both as a single hydrogen-bond donor and acceptor. The individual hydrogen bonds are embedded in cooperative chains of alternating polarity along [010] (green and yellow bonds in Fig. 3).

Related literature

For the synthesis of the title compound, see: Becker et al. (2001). [Should some background references be included to back up the comparison statements in the Abstract?]

S2. Experimental

The title compound was prepared by standard procedures upon acidic aqueous dihydroxylation of cycloheptene with hydrogen peroxide and formic acid (Becker et al., 2001).

S3. Refinement

All H atoms were located in difference maps and refined with individual isotropic temperature parameters. The C-bonded H atoms were refined as riding on their parent atoms. The O-bonded H atoms were refined with free positional parameters.

Computing details

Data collection: COLLECT (Nonius, 2004); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK (Otwinowski & Minor, 1997) 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: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. The molecular structure of (I), with atom labels and anisotropic displacement ellipsoids (drawn at the 50% probability level) for non-H atoms.
	Fig. 2. The packing of the molecules of (I) in the crystal, viewed along [010].
	Fig. 3. The packing of the molecules with 1/4 < z < 3/4, viewed along [001]. Chains of cooperative hydrogen bonds along [010] of alternating polarity are drawn using yellow and green bars.

rac-trans-Cycloheptane-1,2-diol

Crystal data

C7H14O2	F(000) = 576
Mr = 130.18	Dx = 1.176 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 1964 reflections
a = 10.1290 (3) Å	θ = 3.1–27.5°
b = 7.2290 (2) Å	µ = 0.08 mm^−1
c = 20.0750 (7) Å	T = 200 K
V = 1469.94 (8) Å^3	Block, colourless
Z = 8	0.24 × 0.15 × 0.06 mm

Data collection

Nonius KappaCCD area-detector diffractometer	1118 reflections with I > 2σ(I)
Radiation source: rotating anode	Rint = 0.028
MONTEL, graded multilayered X-ray optics monochromator	θmax = 27.5°, θmin = 3.6°
φ and ω scans	h = −13→13
3095 measured reflections	k = −9→9
1682 independent reflections	l = −26→25

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0558P)^2 + 0.1228P] where P = (Fo^2 + 2Fc^2)/3
1685 reflections	(Δ/σ)max < 0.001
102 parameters	Δρmax = 0.13 e Å^−3
0 restraints	Δρmin = −0.18 e Å^−3

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. The refU data value refers to the C-bonded H atoms. The value All H-atom parameters refined applies to the two O-bonded H atoms.

Five reflections were regarded as damaged and were excluded from the refinement.

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

	x	y	z	Uiso*/Ueq
O1	−0.13320 (10)	0.85835 (13)	0.03853 (5)	0.0407 (3)
H81	−0.2133 (17)	0.819 (2)	0.0249 (8)	0.063 (5)*
O2	0.12953 (8)	0.78401 (14)	0.00365 (5)	0.0396 (3)
H82	0.1148 (16)	0.898 (3)	−0.0124 (10)	0.070 (6)*
C1	−0.06343 (12)	0.70624 (17)	0.06767 (6)	0.0296 (3)
H1	−0.0705	0.5979	0.0369	0.032 (3)*
C2	0.08021 (12)	0.76549 (18)	0.07061 (6)	0.0306 (3)
H2	0.0849	0.8892	0.0928	0.026 (3)*
C3	0.17267 (13)	0.63419 (18)	0.10705 (7)	0.0369 (4)
H31	0.2649	0.6714	0.0978	0.040 (4)*
H32	0.1601	0.5078	0.0891	0.040 (4)*
C4	0.15183 (14)	0.6295 (2)	0.18236 (8)	0.0431 (4)
H41	0.2372	0.5996	0.2038	0.051 (4)*
H42	0.1261	0.7549	0.1972	0.055 (5)*
C5	0.04863 (14)	0.4926 (2)	0.20740 (7)	0.0450 (4)
H51	0.0199	0.5317	0.2524	0.060 (5)*
H52	0.0907	0.3696	0.2118	0.053 (4)*
C6	−0.07353 (14)	0.4732 (2)	0.16324 (7)	0.0420 (4)
H61	−0.1446	0.4148	0.1898	0.057 (5)*
H62	−0.0521	0.3883	0.1261	0.049 (4)*
C7	−0.12639 (12)	0.65375 (19)	0.13391 (7)	0.0354 (3)
H71	−0.2229	0.6420	0.1276	0.048 (4)*
H72	−0.1110	0.7549	0.1662	0.044 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0333 (5)	0.0345 (6)	0.0544 (7)	−0.0006 (4)	−0.0094 (5)	0.0118 (4)
O2	0.0396 (6)	0.0378 (6)	0.0414 (6)	0.0049 (4)	0.0113 (4)	0.0086 (5)
C1	0.0299 (7)	0.0270 (7)	0.0320 (7)	0.0012 (5)	−0.0037 (5)	0.0006 (5)
C2	0.0301 (7)	0.0287 (7)	0.0331 (7)	0.0001 (5)	0.0031 (5)	−0.0001 (5)
C3	0.0290 (7)	0.0381 (8)	0.0436 (9)	0.0024 (6)	0.0005 (6)	0.0029 (6)
C4	0.0393 (8)	0.0484 (9)	0.0416 (9)	0.0003 (6)	−0.0098 (6)	0.0034 (7)
C5	0.0476 (8)	0.0488 (9)	0.0387 (9)	0.0023 (7)	−0.0023 (7)	0.0090 (7)
C6	0.0445 (8)	0.0429 (8)	0.0385 (8)	−0.0073 (6)	0.0001 (6)	0.0094 (6)
C7	0.0278 (7)	0.0429 (8)	0.0356 (8)	−0.0016 (6)	0.0008 (6)	−0.0004 (6)

Geometric parameters (Å, º)

O1—C1	1.4320 (15)	C4—C5	1.524 (2)
O1—H81	0.903 (18)	C4—H41	0.9900
O2—C2	1.4403 (15)	C4—H42	0.9900
O2—H82	0.90 (2)	C5—C6	1.529 (2)
C1—C2	1.5179 (18)	C5—H51	0.9900
C1—C7	1.5228 (18)	C5—H52	0.9900
C1—H1	1.0000	C6—C7	1.5288 (19)
C2—C3	1.5209 (18)	C6—H61	0.9900
C2—H2	1.0000	C6—H62	0.9900
C3—C4	1.527 (2)	C7—H71	0.9900
C3—H31	0.9900	C7—H72	0.9900
C3—H32	0.9900
C1—O1—H81	108.9 (10)	C3—C4—H41	108.3
C2—O2—H82	111.2 (12)	C5—C4—H42	108.3
O1—C1—C2	105.79 (10)	C3—C4—H42	108.3
O1—C1—C7	109.96 (10)	H41—C4—H42	107.4
C2—C1—C7	115.96 (11)	C4—C5—C6	115.05 (12)
O1—C1—H1	108.3	C4—C5—H51	108.5
C2—C1—H1	108.3	C6—C5—H51	108.5
C7—C1—H1	108.3	C4—C5—H52	108.5
O2—C2—C1	108.81 (10)	C6—C5—H52	108.5
O2—C2—C3	107.05 (10)	H51—C5—H52	107.5
C1—C2—C3	115.65 (11)	C5—C6—C7	115.36 (12)
O2—C2—H2	108.4	C5—C6—H61	108.4
C1—C2—H2	108.4	C7—C6—H61	108.4
C3—C2—H2	108.4	C5—C6—H62	108.4
C2—C3—C4	113.89 (11)	C7—C6—H62	108.4
C2—C3—H31	108.8	H61—C6—H62	107.5
C4—C3—H31	108.8	C1—C7—C6	113.73 (11)
C2—C3—H32	108.8	C1—C7—H71	108.8
C4—C3—H32	108.8	C6—C7—H71	108.8
H31—C3—H32	107.7	C1—C7—H72	108.8
C5—C4—C3	115.84 (12)	C6—C7—H72	108.8
C5—C4—H41	108.3	H71—C7—H72	107.7
O1—C1—C2—O2	−66.09 (12)	C2—C3—C4—C5	87.55 (15)
C7—C1—C2—O2	171.75 (10)	C3—C4—C5—C6	−37.73 (18)
O1—C1—C2—C3	173.44 (10)	C4—C5—C6—C7	−40.52 (19)
C7—C1—C2—C3	51.27 (16)	O1—C1—C7—C6	170.39 (11)
O2—C2—C3—C4	168.11 (10)	C2—C1—C7—C6	−69.68 (15)
C1—C2—C3—C4	−70.47 (15)	C5—C6—C7—C1	88.08 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H81···O2^i	0.90 (2)	1.85 (2)	2.7481 (13)	174.7 (15)
O2—H82···O1^ii	0.90 (2)	1.84 (2)	2.7208 (14)	164.0 (15)

Symmetry codes: (i) x−1/2, −y+3/2, −z; (ii) −x, −y+2, −z.