6,6′-Dioxo-2,2-bi(7-oxatri­cyclo­[3.2.1.1^3,8]­nonane)-4,4′-di­carboxyl­ic acid

The title mol­ecule, C₁₈H₁₈O₈, has C₂ molecular symmetry. In the crystal structure, each mol­ecule is connected to four neighbours via intermolecular O—H...O hydrogen bonds to form a two-dimensional network parallel to (100).

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.040
• wR factor = 0.089
• Data-to-parameter ratio = 6.3

checkCIF/PLATON results

No syntax errors found



Alert level C
STRVA01_ALERT_4_C           Flack parameter is too small
           From the CIF: _refine_ls_abs_structure_Flack  -10.000
           From the CIF: _refine_ls_abs_structure_Flack_su   10.000
PLAT032_ALERT_4_C Std. Uncertainty in Flack Parameter too High ...      10.00
PLAT033_ALERT_2_C Flack Parameter Value Deviates from Zero .......     -10.00
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       6.30
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O3     -   C6      ..       5.37 su
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.24
           From the CIF: _reflns_number_total                750
           Count of symmetry unique reflns          750
           Completeness (_total/calc)            100.00%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present           no

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

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

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Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2002); software used to prepare material for publication: SHELXTL.

6,6'-Dioxo-2,2-bi(7-oxatricyclo[3.2.1.1^3,8]nonane)-4,4'-dicarboxylic acid

Crystal data

C18H18O8	F(000) = 760
Mr = 362.32	Dx = 1.528 Mg m^−3
Orthorhombic, Aba2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: A2-2ac	Cell parameters from 1461 reflections
a = 9.8562 (12) Å	θ = 3.0–24.7°
b = 13.4978 (17) Å	µ = 0.12 mm^−1
c = 11.8371 (14) Å	T = 298 K
V = 1574.8 (3) Å^3	Block, colourless
Z = 4	0.29 × 0.25 × 0.10 mm

Data collection

Bruker APEX area-detector diffractometer	750 independent reflections
Radiation source: fine-focus sealed tube	736 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
φ and ω scans	θmax = 25.2°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2002)	h = −11→11
Tmin = 0.966, Tmax = 0.988	k = −13→16
3985 measured reflections	l = −14→12

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)] = 0.040	H-atom parameters constrained
wR(F^2) = 0.089	w = 1/[σ^2(Fo^2) + (0.029P)^2 + 1.6081P] where P = (Fo^2 + 2Fc^2)/3
S = 1.19	(Δ/σ)max < 0.001
750 reflections	Δρmax = 0.19 e Å^−3
119 parameters	Δρmin = −0.22 e Å^−3
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −10 (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	0.9561 (3)	0.8404 (2)	−0.1095 (3)	0.0546 (8)
H1	1.0216	0.8069	−0.1286	0.082*
O2	0.9646 (3)	0.7456 (2)	0.0432 (3)	0.0522 (8)
O3	0.8353 (3)	0.73798 (19)	0.2746 (2)	0.0494 (7)
O7	0.8902 (2)	0.89671 (19)	0.2866 (2)	0.0380 (6)
C1	0.8433 (4)	0.9898 (3)	0.2363 (3)	0.0347 (8)
H1A	0.8394	1.0433	0.2921	0.042*
C2	0.9273 (3)	1.0197 (2)	0.1314 (3)	0.0292 (7)
H2	0.9335	1.0922	0.1319	0.035*
C3	0.8317 (4)	0.9912 (2)	0.0326 (3)	0.0317 (8)
H3	0.8567	1.0195	−0.0407	0.038*
C4	0.8010 (3)	0.8784 (2)	0.0307 (3)	0.0315 (8)
H4	0.7290	0.8697	−0.0255	0.038*
C5	0.7321 (3)	0.8595 (3)	0.1479 (3)	0.0348 (8)
H5	0.6489	0.8203	0.1407	0.042*
C6	0.8228 (3)	0.8208 (3)	0.2393 (3)	0.0358 (8)
C8	0.7026 (3)	0.9663 (3)	0.1876 (3)	0.0389 (9)
H8	0.6263	0.9739	0.2399	0.047*
C9	0.6965 (4)	1.0292 (3)	0.0811 (4)	0.0408 (9)
H9A	0.6980	1.0997	0.0970	0.049*
H9B	0.6195	1.0130	0.0335	0.049*
C10	0.9157 (4)	0.8127 (3)	−0.0075 (3)	0.0324 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.070 (2)	0.0590 (18)	0.0353 (14)	0.0255 (16)	0.0073 (15)	0.0033 (15)
O2	0.0561 (18)	0.0447 (14)	0.0558 (17)	0.0186 (14)	0.0008 (16)	0.0143 (15)
O3	0.0627 (17)	0.0415 (16)	0.0441 (16)	0.0001 (13)	−0.0070 (15)	0.0159 (14)
O7	0.0370 (12)	0.0494 (15)	0.0275 (13)	−0.0081 (12)	−0.0051 (11)	0.0070 (12)
C1	0.0371 (18)	0.0355 (19)	0.0316 (17)	0.0004 (15)	0.0073 (17)	−0.0030 (15)
C2	0.0287 (16)	0.0287 (17)	0.0303 (16)	−0.0014 (14)	0.0024 (16)	−0.0011 (15)
C3	0.0324 (18)	0.0324 (17)	0.0305 (18)	0.0041 (14)	−0.0008 (16)	0.0051 (16)
C4	0.0309 (16)	0.0379 (18)	0.0256 (18)	0.0003 (14)	−0.0115 (15)	0.0038 (16)
C5	0.0272 (16)	0.0400 (19)	0.0372 (19)	−0.0082 (16)	−0.0018 (15)	0.0072 (17)
C6	0.0311 (17)	0.048 (2)	0.0287 (17)	−0.0039 (16)	0.0047 (15)	0.0038 (17)
C8	0.0270 (18)	0.050 (2)	0.040 (2)	0.0022 (16)	0.0095 (17)	0.0026 (18)
C9	0.0308 (18)	0.042 (2)	0.049 (2)	0.0040 (17)	0.0010 (17)	0.0062 (18)
C10	0.0346 (18)	0.0320 (18)	0.0306 (17)	−0.0039 (16)	−0.0107 (15)	−0.0045 (15)

Geometric parameters (Å, º)

O1—C10	1.325 (5)	C3—C4	1.553 (4)
O1—H1	0.8200	C3—H3	0.9800
O2—C10	1.188 (4)	C4—C10	1.506 (5)
O3—C6	1.199 (4)	C4—C5	1.565 (5)
O7—C6	1.344 (4)	C4—H4	0.9800
O7—C1	1.466 (4)	C5—C6	1.498 (5)
C1—C8	1.535 (5)	C5—C8	1.543 (5)
C1—C2	1.546 (5)	C5—H5	0.9800
C1—H1A	0.9800	C8—C9	1.521 (5)
C2—C2^i	1.529 (6)	C8—H8	0.9800
C2—C3	1.550 (5)	C9—H9A	0.9700
C2—H2	0.9800	C9—H9B	0.9700
C3—C9	1.539 (5)
C10—O1—H1	109.5	C5—C4—H4	105.6
C6—O7—C1	109.2 (3)	C6—C5—C8	102.6 (3)
O7—C1—C8	105.1 (3)	C6—C5—C4	116.0 (3)
O7—C1—C2	112.5 (3)	C8—C5—C4	101.5 (3)
C8—C1—C2	103.7 (3)	C6—C5—H5	111.9
O7—C1—H1A	111.7	C8—C5—H5	111.9
C8—C1—H1A	111.7	C4—C5—H5	111.9
C2—C1—H1A	111.7	O3—C6—O7	121.0 (3)
C2^i—C2—C1	114.3 (2)	O3—C6—C5	129.6 (4)
C2^i—C2—C3	118.9 (2)	O7—C6—C5	109.3 (3)
C1—C2—C3	102.4 (2)	C9—C8—C1	103.4 (3)
C2^i—C2—H2	106.8	C9—C8—C5	106.0 (3)
C1—C2—H2	106.8	C1—C8—C5	97.9 (3)
C3—C2—H2	106.8	C9—C8—H8	115.8
C9—C3—C2	99.3 (3)	C1—C8—H8	115.8
C9—C3—C4	99.4 (3)	C5—C8—H8	115.8
C2—C3—C4	111.9 (3)	C8—C9—C3	95.1 (3)
C9—C3—H3	114.7	C8—C9—H9A	112.7
C2—C3—H3	114.7	C3—C9—H9A	112.7
C4—C3—H3	114.7	C8—C9—H9B	112.7
C10—C4—C3	115.8 (3)	C3—C9—H9B	112.7
C10—C4—C5	119.7 (3)	H9A—C9—H9B	110.2
C3—C4—C5	103.4 (3)	O2—C10—O1	123.5 (4)
C10—C4—H4	105.6	O2—C10—C4	127.0 (4)
C3—C4—H4	105.6	O1—C10—C4	109.5 (3)

Symmetry code: (i) −x+2, −y+2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3^ii	0.82	1.92	2.689 (4)	157

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