2-Norbornene-exo,endo-5,6-di­carboxyl­ic acid

The crystal structure of the title compound, C₉H₁₀O₄, contains infinite hydrogen-bonded chains of mol­ecules. The norborn­ene skeleton is slightly twisted.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.045
• wR factor = 0.106
• Data-to-parameter ratio = 13.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

The title compound, (I), alternatively called bicyclo[2.2.1]hept-2-ene-trans-5,6-dicarboxylic acid, was studied as part of a series of small-molecule models of organic polymers influencing the crystallization of inorganic salts, particularly CaCO₃ (Megson, 1997; Feast et al., 2002).

Compound (I) was prepared by the Diels–Alder addition of cyclopentadiene to fumaric acid (Diels & Alder, 1928; Alder & Stein, 1933). The asymmetric unit of (I) comprises one molecule. Both carboxyl groups form usual pairs of hydrogen bonds with their inversion equivalents (Fig. 1), linking the molecules into an infinite zigzag chain, the general direction of which is parallel to the crystallographic a axis. trans-Substitution results in a slight twisting of the norbornene skeleton, the C2═C3 and C5—C6 bonds forming an angle of 4.6 (2)°. On the other hand, the C5—C6 bond in (I) is slightly shorter than the corresponding bonds in cis-dicarboxylic acid derivatives, e.g. 1.566 (2)–1.574 (2) Å (Bolte et al., 2000, Batsanov & Hesselink, 2002a,b,c), due to lower steric repulsion between the carboxylic acid groups.

S2. Experimental

Fumaric acid (3.08 g, 27 mmol) and cyclopentadiene (2.3 ml, 2.3 g, 35 mmol) in 50 ml of dry THF were stirred at room temperature for 48 h. The solvent was removed using rotary evaporator and the residue recrystallized from doubly distilled water, yielding 4.41 g (93%) of (I) [m.p. 458–459 K, cf. 460–461 K (Alder & Stein, 1933)].

S3. Refinement

All H atoms were refined in isotropic approximation; C—H distances were in the range 0.97 (2)–0.99 (2) Å.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The molecular structure of (I), showing the intermolecular hydrogen bonding [symmetry codes: (i) −x, 1 − y, 1 − z; (ii) 1 − x, 1 − y, 1 − z]. Displacement ellipsoids are drawn at the 50% probability level.

bicyclo[2.2.1]hept-2-ene-trans-5,6-dicarboxylic acid

Crystal data

C9H10O4	Dx = 1.456 Mg m^−3
Mr = 182.17	Melting point: 185–185°C K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 12.698 (1) Å	Cell parameters from 471 reflections
b = 5.3906 (3) Å	θ = 10.2–20.0°
c = 12.153 (1) Å	µ = 0.12 mm^−1
β = 92.56 (1)°	T = 150 K
V = 831.04 (11) Å^3	Plate, colourless
Z = 4	0.40 × 0.22 × 0.16 mm
F(000) = 384

Data collection

SMART 1K CCD area-detector diffractometer	1773 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.039
Graphite monochromator	θmax = 29.0°, θmin = 1.6°
Detector resolution: 8 pixels mm^-1	h = −12→17
ω scans	k = −7→6
6167 measured reflections	l = −16→14
2187 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.045	All H-atom parameters refined
wR(F^2) = 0.106	w = 1/[σ^2(Fo^2) + (0.0291P)^2 + 0.6115P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.001
2187 reflections	Δρmax = 0.32 e Å^−3
159 parameters	Δρmin = −0.22 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: 0.024 (3)

Special details

Experimental. The data collection nominally covered more than a hemisphere of reciprocal space, by a combination of 4 sets of ω scans; each set at different ϕ and/or 2θ angles and each scan (10 s exposure) covering 0.3° in ω. Crystal to detector distance 4.52 cm. Crystal decay was monitored by repeating 50 initial frames at the end of data collection and comparing 42 duplicate reflections, which showed a 0.5% fall of intensity. "

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.

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

	x	y	z	Uiso*/Ueq
O1	0.08686 (10)	0.7105 (2)	0.43274 (11)	0.0334 (3)
H01	0.032 (2)	0.704 (5)	0.481 (2)	0.071 (8)*
O2	0.05741 (10)	0.3044 (2)	0.41813 (11)	0.0318 (3)
O3	0.45985 (9)	0.2297 (2)	0.41626 (10)	0.0273 (3)
H03	0.5147 (19)	0.301 (4)	0.4585 (19)	0.049 (7)*
O4	0.38292 (9)	0.5890 (2)	0.45826 (10)	0.0283 (3)
C1	0.29903 (12)	0.1375 (3)	0.24774 (12)	0.0196 (3)
H1	0.3371 (14)	−0.021 (3)	0.2579 (14)	0.021 (4)*
C2	0.34528 (13)	0.3228 (3)	0.16899 (12)	0.0240 (3)
H2	0.4209 (16)	0.331 (4)	0.1535 (16)	0.029 (5)*
C3	0.26965 (14)	0.4828 (3)	0.13903 (12)	0.0256 (4)
H3	0.2763 (15)	0.629 (4)	0.0938 (17)	0.033 (5)*
C4	0.17152 (13)	0.4121 (3)	0.19849 (12)	0.0216 (3)
H4	0.1028 (15)	0.477 (3)	0.1713 (15)	0.023 (5)*
C5	0.20037 (11)	0.4853 (3)	0.32208 (12)	0.0172 (3)
H5	0.2327 (14)	0.648 (4)	0.3265 (14)	0.021 (4)*
C6	0.28176 (11)	0.2821 (3)	0.35717 (11)	0.0169 (3)
H6	0.2518 (14)	0.170 (4)	0.4107 (15)	0.024 (5)*
C7	0.18371 (13)	0.1273 (3)	0.20292 (13)	0.0227 (3)
H71	0.1353 (15)	0.045 (3)	0.2529 (15)	0.023 (5)*
H72	0.1763 (16)	0.050 (4)	0.1295 (17)	0.031 (5)*
C8	0.10782 (11)	0.4889 (3)	0.39496 (12)	0.0183 (3)
C9	0.37962 (11)	0.3847 (3)	0.41454 (12)	0.0191 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0368 (7)	0.0199 (6)	0.0452 (8)	0.0004 (5)	0.0207 (6)	−0.0036 (5)
O2	0.0309 (6)	0.0224 (6)	0.0437 (7)	−0.0059 (5)	0.0182 (5)	−0.0065 (5)
O3	0.0187 (5)	0.0309 (6)	0.0315 (6)	0.0052 (5)	−0.0065 (5)	−0.0124 (5)
O4	0.0240 (6)	0.0252 (6)	0.0350 (6)	0.0032 (5)	−0.0080 (5)	−0.0106 (5)
C1	0.0215 (7)	0.0182 (7)	0.0190 (7)	−0.0009 (6)	0.0003 (5)	−0.0033 (5)
C2	0.0284 (8)	0.0259 (8)	0.0180 (7)	−0.0045 (7)	0.0056 (6)	−0.0053 (6)
C3	0.0375 (9)	0.0243 (8)	0.0153 (7)	−0.0039 (7)	0.0047 (6)	−0.0001 (6)
C4	0.0237 (7)	0.0231 (7)	0.0175 (7)	0.0005 (6)	−0.0035 (6)	0.0012 (6)
C5	0.0173 (7)	0.0167 (7)	0.0175 (6)	−0.0008 (5)	0.0000 (5)	0.0007 (5)
C6	0.0170 (6)	0.0182 (6)	0.0156 (6)	−0.0007 (5)	0.0006 (5)	0.0008 (5)
C7	0.0249 (8)	0.0210 (7)	0.0216 (7)	−0.0023 (6)	−0.0046 (6)	−0.0024 (6)
C8	0.0170 (6)	0.0192 (7)	0.0186 (7)	0.0013 (5)	−0.0020 (5)	0.0001 (5)
C9	0.0174 (7)	0.0241 (7)	0.0159 (6)	0.0004 (6)	0.0012 (5)	−0.0015 (6)

Geometric parameters (Å, º)

O1—C8	1.3111 (19)	C3—C4	1.517 (2)
O1—H01	0.94 (3)	C3—H3	0.97 (2)
O2—C8	1.2227 (19)	C4—C7	1.544 (2)
O3—C9	1.3173 (18)	C4—C5	1.580 (2)
O3—H03	0.93 (2)	C4—H4	0.985 (19)
O4—C9	1.2227 (19)	C5—C8	1.503 (2)
C1—C2	1.520 (2)	C5—C6	1.553 (2)
C1—C7	1.540 (2)	C5—H5	0.969 (19)
C1—C6	1.565 (2)	C6—C9	1.503 (2)
C1—H1	0.984 (18)	C6—H6	0.978 (19)
C2—C3	1.330 (2)	C7—H71	0.988 (19)
C2—H2	0.99 (2)	C7—H72	0.99 (2)
C8—O1—H01	110.7 (18)	C6—C5—C4	102.02 (11)
C9—O3—H03	107.9 (15)	C8—C5—H5	107.2 (11)
C2—C1—C7	100.88 (12)	C6—C5—H5	110.4 (10)
C2—C1—C6	106.29 (12)	C4—C5—H5	111.0 (10)
C7—C1—C6	98.70 (12)	C9—C6—C5	113.20 (12)
C2—C1—H1	116.5 (10)	C9—C6—C1	115.68 (12)
C7—C1—H1	117.8 (10)	C5—C6—C1	103.58 (11)
C6—C1—H1	114.3 (10)	C9—C6—H6	104.9 (11)
C3—C2—C1	107.72 (14)	C5—C6—H6	110.2 (11)
C3—C2—H2	127.9 (12)	C1—C6—H6	109.3 (11)
C1—C2—H2	123.9 (12)	C1—C7—C4	93.96 (12)
C2—C3—C4	107.76 (14)	C1—C7—H71	114.0 (11)
C2—C3—H3	127.1 (12)	C4—C7—H71	113.8 (11)
C4—C3—H3	124.8 (12)	C1—C7—H72	112.7 (12)
C3—C4—C7	100.57 (13)	C4—C7—H72	112.7 (12)
C3—C4—C5	103.27 (12)	H71—C7—H72	109.2 (16)
C7—C4—C5	101.33 (12)	O2—C8—O1	122.95 (14)
C3—C4—H4	119.0 (11)	O2—C8—C5	123.80 (14)
C7—C4—H4	117.0 (11)	O1—C8—C5	113.24 (13)
C5—C4—H4	113.2 (11)	O4—C9—O3	123.58 (14)
C8—C5—C6	112.08 (12)	O4—C9—C6	123.02 (13)
C8—C5—C4	114.16 (12)	O3—C9—C6	113.36 (13)
O2—C8—C5—C6	−49.76 (19)	C5—C6—C9—O4	20.6 (2)
C8—C5—C6—C9	−105.37 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H01···O2^i	0.94 (3)	1.70 (3)	2.6350 (17)	173 (3)
O3—H03···O4^ii	0.93 (2)	1.72 (2)	2.6446 (16)	176 (2)

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