Poly[aqua­(μ₃-benzene-1,2-dicarboxyl­ato)(μ₂-hydroxo)indium(III)]

In the title compound, [In(C₈H₄O₄)(OH)(H₂O)]_n, the coordination of the In^III ion is composed of six O atoms from three dianionic benzene-1,2-dicarboxylate ligands, two hydroxyl groups and one coordinated water mol­ecule in a distorted octa­hedral geometry. The In³⁺ ions are linked by the hydroxyl groups to form zigzag In–OH–In chains, which are further bridged by the benzene-1,2-dicarboxylic acid ligands to generate a two-dimensional layered structure featuring three types of rings (six-, 14- and 20-membered). Hydrogen bonds between the water mol­ecule and a carboxyl­ate O atom, and between the hydroxyl group and a carboxyl­ate O atom, are observed within the layers. In the crystal packing, there are π–­π stacking inter­actions between the benzene rings of adjacent layers, with a centroid-to-centroid distance of 3.668 (3) Å and a dihedral angle of 4.8 (2)°.

S1. Comment

The construction of coordination polymers is one of the most active areas of materials research in recent years. The intense interest in these materials is driven by their potential applications as functional materials (catalysis, magnetism, electric conductivity, gas storage and non-linear optics), as well as their intriguing structural topologies (Janiak, 2003; Kitagawa et al., 2004; O'Keeffe et al., 2000). Among linker molecules, rigid aromatic carboxylic acids, such as 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid and 1,4-benzenedicarboxylic acid, have been extensively studied because of their versatile coordinating modes (Yaghi et al., 1997; Dai et al., 2002; Karanović et al., 2002). 1,2-Benzenedicarboxylic acid (H₂BDC) is an important dicarboxylate ligand as it has multiple coordinating modes, which together with the varied coordination geometry of metal ions has led to the generation of products containing one-dimensional chains, two-dimensional layers and three-dimensional frameworks (Ma et al., 2004; Thirumurugan & Natarajan, 2004).

Much effort has so far been devoted to the study of transition metal-based coordination polymers. However, relatively little attention has been paid to the coordination polymers of main group metal ions, despite their important applications in ion exchange or electroluminescent devices (Lin et al., 2005; Liu & Xu, 2006). It has been postulated that the incorporation of main group metal ions might create diverse structures different from those containing transition metal ions. In the search for a further class of materials, we have introduced a trivalent metal, namely indium(III), in order to investigate the influence of the change of the metal centre on the coordination architecture during the course of the assembly of the metal centres with H₂BDC. The In^III ion is liable to hydrolyze, which limits its use in the construction of coordination polymers. However, by adding an appropriate basic reagent to deprotonate H₂BDC and carefully controlling the reaction conditions, we have found that In^III ions can be used to construct new frameworks. The hydrothermal reaction of InCl₃ with H₂BDC in the presence of 2-picoline yields the title complex, (I), and we present its structure here. To the best of our knowledge, no In–BDC species have been reported previously.

The asymmetric unit of (I) consists of one In^III ion, one BDC^2- dianion, one hydroxyl group and one coordinated water molecule. As depicted in Fig. 1, the In^III atom is six-coordinated by four O atoms from three BDC^2- ligands and one coordinated water molecule in a distorted square-planar geometry, and two O atoms from two hydroxyl groups in the apical positions. The In–O octahedron is slightly compressed, with axial In—O bond lengths of 2.071 (3) and 2.093 (3) Å, and equatorial In—O bond lengths of 2.133 (3)–2.244 (4) Å, and with O—In—O bond angles varying from 80.4 (1) to 173.5 (2)° (Table 1). The bond dimensions involving In are normal, and are comparable with the values in related indium(III) complexes (Sun et al., 2002).

The axial O-atom corners are shared by neighbouring octahedra to form a zigzag ···OH—In—OH—In··· chain propagating along the c axis, with an In—OH—In angle of 126.4 (1)°, as illustrated in Fig. 2. The In—OH—In angle in (I) is considerably larger than corresponding angles of 118.6 (2)–120.6 (2)° in the three-dimensional framework of {[In(OH)(p-BDC)]₄[p-H₂BDC]₃}_n (p-H₂BDC is 1,4-benzenedicarboxylic acid), where p-H₂BDC guest molecules are observed within the framework (Anokhina et al., 2005). The In—In separation is 3.72 Å, similar to the values of 3.63 Å in the compound {[In(OH)(p-BDC)]₄[p-H₂BDC]₃}_n and 3.77 Å in the compound {[In₂(OH)₃(p-BDC)_1.5]}_n (Gomez-Lor et al., 2002). Those values are longer, as expected, but comparable with those of purely inorganic structures, such as the corundum-like In₂O₃ structure or indium metal (d = 3.34 Å in both cases) (Prewitt et al., 1969). Neighbouring In^III ions in the zigzag chain are also bridged by a bidentate carboxylate group to form a six-membered ring, A (Fig. 2). The chain is repeated by translation about every 7.3 Å along the c direction, comparable with the length of the c axis.

The BDC^2- ligand adopts a tridentate bridging coordination mode through its bidentate and monodentate carboxylate groups. The equatorial carboxylate O atoms are shared with the BDC^2- anions that cross-link the octahedral chains into a two-dimensional layered structure (Fig. 3). Two other types of rings are observed in the two-dimensional layer. Ring B is a 14-membered ring, which consists of two BDC^2- anions and two In^III atoms, and ring C is a 20-membered ring containing two BDC^2- anions, five In^III atoms and two hydroxyl O atoms, as shown in Fig. 4. In the two-dimensional layered structure, all phenyl rings are located on both sides of the plane formed by the In—OH—In chains. It is interesting that the phenyl rings on one side are parallel and are twisted with respect to the phenyl rings on the other side, with a dihedral angle of 86.1 (1)°.

Hydrogen bonds between the coordinated water molecule and a carboxylate O atom, and between the hydroxyl group and a carboxylate O atom, are observed within the two-dimensional layer, with O—O distances in the range 2.838 (5)–3.149 (5) Å (Table 2). There are π–π stacking interactions between the phenyl rings of adjacent layers, with a centroid-to-centroid distance of 3.668 (3) Å and a dihedral angle of 4.8 (2)°, and these are responsible for the three-dimensional supramolecular framework structure (Fig. 5).

S2. Experimental

The title compound was synthesized by the hydrothermal method under autogenous pressure. A mixture of InCl₃ (221 mg, 1 mmol), 1,2-benzenedicarboxylic acid (166 mg, 1 mmol), and distilled water (15 ml) was stirred under ambient conditions. 2-Picoline (0.35 ml) was then added slowly to the suspension. The final mixture was sealed in a 25 ml Teflon-lined steel autoclave and heated at 433 K for 4 d, and then cooled to room temperature. Colourless plate-like crystals of (I) were obtained, and these were recovered by filtration, washed with distilled water and dried in air (yield 59%). Analysis, calculated for C₈H₇O₆In: C 30.58, H 2.25%; found: C 30.55, H 2.21%.

S3. Refinement

Aromatic H atoms were placed in calculated positions and treated using a riding-model approximation, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C). H atoms bonded to O atoms were visible in a difference map and were refined with a DFIX (SHELXTL; Sheldrick, 1997) restraint of O—H = 0.90(s.u.?) Å and with U_iso(H) = 1.5U_eq(O).

Computing details

Data collection: CrystalClear (Rigaku Corporation & Molecular Structure Corporation, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A drawing of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level. H atoms have been omitted for clarity. [Symmetry codes: (i) -x, -y + 1/2, z - 1/2; (ii)-x - 1/2, -y + 1/2, z; (iii) -x, -y + 1/2, z + 1/2.]
	Fig. 2. A view of the zigzag ···OH—In—OH—In··· chain and the six-membered ring A.
	Fig. 3. A perspective view of the two-dimensional layered structure of (I).
	Fig. 4. A perspective view of the six-, 14- and 20-membered rings A, B and C (atoms forming the rings are represented as balls).
	Fig. 5. A view of the packing of (I), viewed down the c axis.

Poly[aqua(µ₃-benzene-1,2-dicarboxylato)(µ₂-hydroxo)indium(III)]

Crystal data

[In(C8H4O4)(OH)(H2O)]	F(000) = 2432
Mr = 313.96	Dx = 2.270 Mg m^−3
OrthorhombicFdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 2708 reflections
a = 11.915 (1) Å	θ = 3.3–27.5°
b = 42.205 (5) Å	µ = 2.58 mm^−1
c = 7.3069 (9) Å	T = 295 K
V = 3674.4 (7) Å^3	Plate, colourless
Z = 16	0.25 × 0.18 × 0.01 mm

Data collection

Rigaku Mercury70 diffractometer	1888 independent reflections
Radiation source: fine-focus sealed tube	1822 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
ω scans	θmax = 27.5°, θmin = 3.3°
Absorption correction: multi-scan (CrystalClear; Rigaku Corporation & Molecular Structure Corporation, 2000)	h = −14→15
Tmin = 0.589, Tmax = 0.976	k = −54→49
6877 measured reflections	l = −9→7

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)] = 0.026	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.058	w = 1/[σ^2(Fo^2) + (0.0306P)^2 + 12.2335P] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
1888 reflections	Δρmax = 1.11 e Å^−3
145 parameters	Δρmin = −0.94 e Å^−3
4 restraints	Absolute structure: Flack (1983), with 755 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.02 (4)

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
In1	−0.01299 (2)	0.242869 (6)	0.36134 (6)	0.01885 (9)
O1	−0.1127 (3)	0.28021 (9)	0.4814 (5)	0.0320 (8)
O2	−0.0747 (3)	0.29779 (9)	0.7603 (4)	0.0326 (8)
O3	−0.3573 (3)	0.28897 (8)	0.4431 (5)	0.0270 (8)
O4	−0.2902 (4)	0.30068 (10)	0.1636 (5)	0.0471 (11)
O5	0.0639 (2)	0.23700 (7)	0.6166 (5)	0.0232 (6)
H5A	0.122 (3)	0.2239 (10)	0.618 (10)	0.035*
O6	0.1346 (3)	0.27530 (10)	0.3254 (5)	0.0414 (10)
H6B	0.152 (6)	0.2837 (16)	0.216 (5)	0.062*
H6A	0.164 (6)	0.2810 (17)	0.432 (6)	0.062*
C1	−0.1654 (3)	0.33230 (10)	0.5537 (6)	0.0196 (9)
C2	−0.2455 (3)	0.33447 (11)	0.4147 (6)	0.0207 (9)
C3	−0.2822 (4)	0.36434 (11)	0.3620 (8)	0.0302 (9)
H3	−0.3360	0.3662	0.2704	0.036*
C4	−0.2405 (4)	0.39120 (12)	0.4425 (9)	0.0343 (12)
H4	−0.2653	0.4110	0.4040	0.041*
C5	−0.1613 (4)	0.38890 (11)	0.5818 (7)	0.0348 (11)
H5B	−0.1338	0.4071	0.6380	0.042*
C6	−0.1239 (4)	0.35947 (11)	0.6356 (7)	0.0284 (10)
H6C	−0.0703	0.3578	0.7276	0.034*
C7	−0.1141 (3)	0.30111 (10)	0.6030 (7)	0.0212 (8)
C8	−0.2991 (4)	0.30590 (11)	0.3295 (7)	0.0259 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
In1	0.02296 (13)	0.02252 (14)	0.01106 (13)	0.00047 (11)	0.00091 (16)	−0.00076 (17)
O1	0.038 (2)	0.0265 (19)	0.032 (2)	0.0138 (15)	−0.0075 (16)	−0.0132 (15)
O2	0.048 (2)	0.034 (2)	0.0162 (17)	0.0150 (17)	−0.0079 (16)	−0.0011 (14)
O3	0.0245 (17)	0.034 (2)	0.0225 (17)	−0.0091 (14)	−0.0019 (14)	0.0026 (14)
O4	0.064 (2)	0.058 (3)	0.019 (2)	−0.023 (2)	−0.0018 (17)	−0.0055 (16)
O5	0.0225 (14)	0.0346 (16)	0.0125 (14)	0.0079 (12)	−0.0032 (15)	−0.0018 (17)
O6	0.045 (2)	0.056 (3)	0.023 (2)	−0.0224 (19)	−0.0046 (17)	0.0037 (17)
C1	0.0168 (19)	0.025 (2)	0.017 (2)	−0.0011 (16)	0.0003 (15)	0.0007 (15)
C2	0.018 (2)	0.026 (2)	0.018 (2)	−0.0007 (17)	0.0022 (15)	0.0044 (18)
C3	0.030 (2)	0.035 (2)	0.026 (2)	0.0022 (19)	0.003 (3)	0.012 (3)
C4	0.036 (3)	0.021 (2)	0.046 (3)	0.006 (2)	0.010 (2)	0.009 (2)
C5	0.040 (3)	0.025 (2)	0.039 (3)	−0.0031 (19)	0.004 (2)	−0.002 (2)
C6	0.029 (2)	0.029 (2)	0.027 (3)	−0.0036 (17)	−0.002 (2)	−0.0101 (19)
C7	0.0146 (16)	0.026 (2)	0.023 (2)	0.0026 (14)	0.004 (2)	0.002 (2)
C8	0.022 (2)	0.032 (2)	0.024 (3)	−0.0010 (17)	−0.0052 (19)	0.0022 (18)

Geometric parameters (Å, º)

In1—O5^i	2.071 (3)	O6—H6B	0.90 (5)
In1—O5	2.093 (3)	O6—H6A	0.89 (5)
In1—O3^ii	2.133 (3)	C1—C6	1.385 (6)
In1—O2^i	2.140 (3)	C1—C2	1.397 (6)
In1—O1	2.159 (3)	C1—C7	1.496 (6)
In1—O6	2.244 (4)	C2—C3	1.389 (6)
O1—C7	1.252 (6)	C2—C8	1.500 (6)
O2—C7	1.250 (6)	C3—C4	1.370 (7)
O2—In1^iii	2.140 (3)	C3—H3	0.9300
O3—C8	1.297 (5)	C4—C5	1.392 (8)
O3—In1^ii	2.133 (3)	C4—H4	0.9300
O4—C8	1.237 (6)	C5—C6	1.377 (7)
O5—In1^iii	2.071 (3)	C5—H5B	0.9300
O5—H5A	0.89 (4)	C6—H6C	0.9300
O5^i—In1—O5	161.18 (2)	C6—C1—C2	120.3 (4)
O5^i—In1—O3^ii	106.74 (13)	C6—C1—C7	118.6 (4)
O5—In1—O3^ii	89.60 (13)	C2—C1—C7	120.8 (4)
O5^i—In1—O2^i	100.03 (12)	C3—C2—C1	118.5 (4)
O5—In1—O2^i	89.92 (12)	C3—C2—C8	118.7 (4)
O3^ii—In1—O2^i	86.85 (14)	C1—C2—C8	122.7 (4)
O5^i—In1—O1	83.70 (13)	C4—C3—C2	121.2 (5)
O5—In1—O1	88.01 (12)	C4—C3—H3	119.4
O3^ii—In1—O1	86.99 (15)	C2—C3—H3	119.4
O2^i—In1—O1	173.51 (15)	C3—C4—C5	120.2 (5)
O5^i—In1—O6	83.02 (13)	C3—C4—H4	119.9
O5—In1—O6	80.40 (13)	C5—C4—H4	119.9
O3^ii—In1—O6	169.97 (14)	C6—C5—C4	119.4 (5)
O2^i—In1—O6	93.79 (16)	C6—C5—H5B	120.3
O1—In1—O6	91.93 (16)	C4—C5—H5B	120.3
C7—O1—In1	144.1 (3)	C5—C6—C1	120.5 (5)
C7—O2—In1^iii	126.2 (3)	C5—C6—H6C	119.7
C8—O3—In1^ii	123.7 (3)	C1—C6—H6C	119.7
In1^iii—O5—In1	126.35 (13)	O2—C7—O1	124.7 (4)
In1^iii—O5—H5A	118 (5)	O2—C7—C1	118.3 (4)
In1—O5—H5A	115 (5)	O1—C7—C1	117.0 (4)
In1—O6—H6B	122 (5)	O4—C8—O3	125.1 (4)
In1—O6—H6A	112 (5)	O4—C8—C2	120.9 (4)
H6B—O6—H6A	126 (6)	O3—C8—C2	113.9 (4)
O5^i—In1—O1—C7	−134.5 (6)	C4—C5—C6—C1	−0.7 (8)
O5—In1—O1—C7	28.6 (6)	C2—C1—C6—C5	0.3 (7)
O3^ii—In1—O1—C7	118.3 (6)	C7—C1—C6—C5	173.9 (4)
O6—In1—O1—C7	−51.7 (6)	In1^iii—O2—C7—O1	3.6 (7)
O5^i—In1—O5—In1^iii	74.5 (4)	In1^iii—O2—C7—C1	−175.6 (3)
O3^ii—In1—O5—In1^iii	−76.2 (2)	In1—O1—C7—O2	−39.0 (9)
O2^i—In1—O5—In1^iii	−163.1 (2)	In1—O1—C7—C1	140.1 (4)
O1—In1—O5—In1^iii	10.8 (2)	C6—C1—C7—O2	30.6 (6)
O6—In1—O5—In1^iii	103.1 (2)	C2—C1—C7—O2	−155.9 (4)
C6—C1—C2—C3	−0.2 (7)	C6—C1—C7—O1	−148.6 (4)
C7—C1—C2—C3	−173.7 (4)	C2—C1—C7—O1	24.9 (6)
C6—C1—C2—C8	−175.9 (4)	In1^ii—O3—C8—O4	−18.7 (7)
C7—C1—C2—C8	10.7 (6)	In1^ii—O3—C8—C2	158.2 (3)
C1—C2—C3—C4	0.6 (7)	C3—C2—C8—O4	64.0 (7)
C8—C2—C3—C4	176.4 (5)	C1—C2—C8—O4	−120.4 (5)
C2—C3—C4—C5	−1.0 (8)	C3—C2—C8—O3	−113.1 (5)
C3—C4—C5—C6	1.1 (8)	C1—C2—C8—O3	62.6 (6)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5A···O4^iii	0.89 (4)	2.28 (2)	3.149 (5)	166 (5)
O6—H6A···O4^iv	0.89 (5)	1.96 (3)	2.838 (5)	169 (7)
O6—H6B···O3^v	0.90 (5)	2.01 (3)	2.854 (5)	156 (6)

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