2,5-Dihy-droxy-terephthalic acid dihydrate.

The title compound, C(8)H(6)O(6)·2H(2)O, was obtained by accident within a project on the synthesis of metal-organic coordination polymers by the reaction of LiOH with 2,5-dihy-droxy-terephthalic acid under solvothermal conditions. The asymmetric unit consists of half a 2,5-dihy-droxy-terephthalic acid mol-ecule located on a centre of inversion and one solvent water mol-ecule that occupies a general position. The 2,5-dihy-droxy-terephthalic acid mol-ecules are connected to the water mol-ecules via O-H⋯O hydrogen bonding to form a layer in the ab plane.

Related literature

For genernal background to supramolecular assembly and crystal engineering, see: Kitagawa et al. (2004 ▶).

Experimental

Crystal data

C8H6O6·2H2O

M = 234.16

Monoclinic,

a = 5.1883 (10) Å

b = 17.545 (4) Å

c = 5.4990 (12) Å

β = 103.03 (1)°

V = 487.68 (17) Å3

Z = 2

Mo Kα radiation

μ = 0.15 mm−1

T = 295 K

0.25 × 0.20 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.945, T max = 0.963

4475 measured reflections

1208 independent reflections

589 reflections with I > 2σ(I)

R int = 0.080

Refinement

R[F 2 > 2σ(F 2)] = 0.061

wR(F 2) = 0.193

S = 1.02

1208 reflections

73 parameters

H-atom parameters constrained

Δρmax = 0.36 e Å−3

Δρmin = −0.32 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810025766/nc2191sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810025766/nc2191Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C8H6O6·2H2O	F(000) = 244
Mr = 234.16	Dx = 1.595 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 5.1883 (10) Å	Cell parameters from 760 reflections
b = 17.545 (4) Å	θ = 2.3–22.5°
c = 5.4990 (12) Å	µ = 0.15 mm−1
β = 103.03 (1)°	T = 295 K
V = 487.68 (17) Å3	Tablular, light-yellow
Z = 2	0.25 × 0.20 × 0.20 mm

Bruker APEXII CCD diffractometer	1208 independent reflections
Radiation source: fine-focus sealed tube	589 reflections with I > 2σ(I)
graphite	Rint = 0.080
Detector resolution: 8.3333 pixels mm-1	θmax = 28.4°, θmin = 2.3°
φ and ω scans	h = −5→6
Absorption correction: multi-scan (SADABS; Bruker, 2009)	k = −23→23
Tmin = 0.945, Tmax = 0.963	l = −7→4
4475 measured reflections

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.193	H-atom parameters constrained
S = 1.02	w = 1/[σ2(Fo2) + (0.0851P)2] where P = (Fo2 + 2Fc2)/3
1208 reflections	(Δ/σ)max = 0.009
73 parameters	Δρmax = 0.36 e Å−3
0 restraints	Δρmin = −0.32 e Å−3

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.

	x	y	z	Uiso*/Ueq
O1	0.0253 (5)	0.35101 (13)	0.8449 (4)	0.0561 (7)
H1A	−0.0615	0.3231	0.9153	0.084*
O2	0.4188 (5)	0.59034 (13)	0.6391 (4)	0.0488 (7)
H2B	0.4915	0.6261	0.5857	0.073*
O3	0.2796 (5)	0.68281 (14)	0.8554 (4)	0.0536 (7)
O1W	0.6537 (4)	0.69917 (13)	1.4663 (4)	0.0524 (7)
H1WA	0.5399	0.7288	1.3796	0.079*
H1WB	0.7486	0.6811	1.3724	0.079*
C1	0.0087 (6)	0.42428 (18)	0.9234 (5)	0.0371 (8)
C2	0.1432 (6)	0.48027 (18)	0.8263 (5)	0.0394 (9)
H2A	0.2394	0.4671	0.7089	0.047*
C3	0.2843 (6)	0.61572 (19)	0.7961 (5)	0.0378 (8)
C4	0.1382 (6)	0.55608 (17)	0.9001 (5)	0.0337 (8)

	U11	U22	U33	U12	U13	U23
O1	0.0761 (17)	0.0361 (15)	0.0720 (15)	−0.0063 (12)	0.0504 (14)	−0.0070 (12)
O2	0.0610 (15)	0.0415 (15)	0.0545 (14)	−0.0033 (11)	0.0352 (12)	0.0004 (11)
O3	0.0678 (17)	0.0402 (15)	0.0639 (16)	−0.0083 (12)	0.0380 (13)	−0.0066 (12)
O1W	0.0646 (16)	0.0461 (16)	0.0575 (14)	0.0068 (12)	0.0371 (13)	0.0091 (12)
C1	0.0391 (18)	0.037 (2)	0.0386 (16)	0.0007 (14)	0.0155 (14)	−0.0015 (14)
C2	0.0412 (19)	0.043 (2)	0.0399 (17)	0.0012 (15)	0.0208 (15)	−0.0001 (15)
C3	0.0377 (18)	0.041 (2)	0.0366 (17)	−0.0011 (15)	0.0131 (14)	0.0051 (15)
C4	0.0338 (17)	0.0363 (19)	0.0324 (15)	0.0026 (13)	0.0105 (13)	0.0015 (13)

O1—C1	1.365 (4)	C1—C2	1.380 (4)
O1—H1A	0.8200	C1—C4i	1.405 (4)
O2—C3	1.305 (3)	C2—C4	1.393 (4)
O2—H2B	0.8200	C2—H2A	0.9300
O3—C3	1.223 (4)	C3—C4	1.480 (4)
O1W—H1WA	0.8485	C4—C1i	1.406 (4)
O1W—H1WB	0.8511
C1—O1—H1A	109.5	C4—C2—H2A	119.2
C3—O2—H2B	109.5	O3—C3—O2	123.4 (3)
H1WA—O1W—H1WB	108.2	O3—C3—C4	122.3 (3)
O1—C1—C2	118.3 (3)	O2—C3—C4	114.3 (3)
O1—C1—C4i	122.1 (3)	C2—C4—C1i	119.0 (3)
C2—C1—C4i	119.5 (3)	C2—C4—C3	121.2 (3)
C1—C2—C4	121.5 (3)	C1i—C4—C3	119.9 (3)
C1—C2—H2A	119.2

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O3i	0.82	1.88	2.597 (3)	146
O2—H2B···O1Wii	0.82	1.74	2.561 (3)	177
O1W—H1WB···O1iii	0.85	1.94	2.786 (3)	175.0
O1W—H1WA···O3iv	0.85	2.04	2.809 (3)	150.4

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O3i	0.82	1.88	2.597 (3)	146
O2—H2B⋯O1Wii	0.82	1.74	2.561 (3)	177
O1W—H1WB⋯O1iii	0.85	1.94	2.786 (3)	175.0
O1W—H1WA⋯O3iv	0.85	2.04	2.809 (3)	150.4

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .