Poly[μ-aqua-aqua-μ₄-naphthalene-1,8-di­carboxyl­ato-barium]: a layer structure

The title compound, [Ba(C₁₂H₆O₄)(H₂O)₂]_n, is represented by a layer-like structure built of BaO₈ polyhedra. The asymmetric unit contains a Ba²⁺ ion, half a coordinating water mol­ecule and half a μ₄-bridging naphthalene-1,8-dicarboxyl­ate (1,8-nap) ligand, the whole structure being generated by twofold rotational symmetry. The carboxyl­ate groups of the 1,8-nap ligands act as bridges linking four Ba²⁺ ions, while each Ba²⁺ ion is eight-coordinated by O atoms from four 1,8-nap ligands and two coordinating water mol­ecules. In the crystal, there are O—H⋯O hydrogen bonds involving the water mol­ecules and carboxyl­ate O atoms in the BaO₈ polyhedra. Each BaO₈ polyhedron is connected via corner-sharing water O atoms or edge-sharing ligand O atoms, forming a sheet parallel to the bc plane. These sheets stack along the a-axis direction and are connected via van der Waals forces only. The naphthalene groups protrude above and below the layers of the BaO₈ polyhedra and there are voids of ca 208 ų bounded by these groups. No residual electron density was found in this region. The crystal studied was twinned by pseudo-merohedry, with a refined twin component ratio of 0.5261 (1):0.4739 (1).

Related literature

For other compounds based on 1,8-nap ligands, see: Wen et al. (2007, 2008); Zhang et al. (2008); Fu et al. (2011).

Experimental

Crystal data

• [Ba(C₁₂H₆O₄)(H₂O)₂]

• M_r = 369.52

• Orthorhombic, I b c a

• a = 8.9643 (11) Å

• b = 30.539 (6) Å

• c = 8.9625 (12) Å

• V = 2453.6 (7) ų

• Z = 8

• Mo Kα radiation

• μ = 3.25 mm⁻¹

• T = 296 K

• 0.20 × 0.05 × 0.05 mm

Data collection

• Bruker APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.563, T_max = 0.855

• 7968 measured reflections

• 1511 independent reflections

• 1344 reflections with I > 2σ(I)

• R_int = 0.035

Refinement

• R[F² > 2σ(F²)] = 0.019

• wR(F²) = 0.043

• S = 1.05

• 1511 reflections

• 85 parameters

• H-atom parameters constrained

• Δρ_max = 0.54 e Å⁻³

• Δρ_min = −0.57 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2^i	0.86	2.07	2.777 (2)	140
Symmetry code: (i) -x+1, -y, -z.

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

Supporting information

S1. Comment

In recent years, supramolecular assembles based on polyoxometalates (POMs) have been intensively investigated in many field such as catalysis, electrical conductivity, and biological chemistry. The ligand naphthalene-1,8-dicarboxylic (1,8-nap) has been used extensively to construct a number of metal organic complexes (Wen et al., 2007,2008; Zhang et al., 2008), including the related barium compound Ba(C₁₂H₆O₄) [Fu et al., 2011]. To prepare a new barium complex incorporating 1,8-nap ligand, we have synthesized the title compound and report herein on its crystal structure.

The title compound is a non-interpenetrating two-dimensional layer-like structure consisting of BaO₈ clusters, which are similar to the reported compound Ba(C₁₂H₆O₄) [Fu et al., 2011]. As shown in Fig. 1 the asymmetric unit of the title complex contains one crystallographically independent Ba atom, one coordination water molecule and a half 1,8-nap ligand. Each barium atom is eight-coordinated by O atoms in a square antiprismatic geometry, in which six oxygen atoms come from four 1,8-nap ligands (two of them adopt a chelate connection) and two oxygen atoms come from two coordinated water molecules. The Ba–O bond distances range from 2.723 (2) to 2.8806 (14) Å, in which the Ba1–O3 water bond gives the longest bond distance.

The 1,8-nap ligands are not planar, with the carboxylate groups and the naphthalene ring dihedral angles being 49.0 (3)° and 52.4 (3)°, respectively. The carboxylate groups of the 1,8-nap ligand act as µ₂-bridges to link four Ba atoms. Furthermore, each BaO₈ polyhedra is connected via corner-sharing H₂O oxygen atoms or edge-sharing ligand oxygen atoms to form a two-dimensional sheet parallel to the bc plane. All Ba atoms in the two-dimensional layer are coplanar, with adjacent Ba···Ba distance of 4.4821 (6), 4.9292 (6) and 5.0972 (6) Å.

By considering the Ba atoms as the nodes, this two-dimensional layered structure can be topologically represented as a 6-connected (3,6) net.

In the crystal, there are O-H···O hydrogen bonds involving the water molecules and the carboxylate O atoms in the BaO₈ clusters (Fig. 2 and Table 1). There are no π-π stacking interactions, only van der Waals forces are present between the layers that stack along the a direction. The naphthalene groups protrude above and below the layers of the BaO₈ clusters and there are voids of ca. 208 ų bounded by these groups. No residual electron density was found in this region.

Related literature

For other compounds based on 1,8-nap ligands, see: Wen et al. (2007, 2008); Zhang et al. (2008); Fu et al. (2011).

S2. Experimental

A mixture of naphthalene-1,8-dicarboxylic (0.2 g), BaCO₃ (0.05 g) and H₂O (15 ml) was heated at 443 K for 3 d in a sealed 25 ml Teflon-lined stainless steel vessel under autogenous pressure. After cooling to room temperature at a rate of 20°C h^-1, colourless prismatic crystals suitable for single-crystal X-ray diffraction analysis were obtained in low yield.

S3. Refinement

The crystal is a pseudo-merohedral twin, with twin law (00-1, 0-10, -100) giving an ca. 1:1 ratio of twin moieties [refined BASF value = 0.5261 (1)]. The C-bound H atoms were positioned geometrically and refined with a riding model: C—H = 0.93 Å with U_iso(H) = 1.2U_eq(C). The water H atoms were located in difference Fourier maps and refined initially with distance restraints: O–H = 0.86 Å, then as riding atoms with U_iso(H) = 1.2U_eq(O).

Computing details

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

Figures

	Fig. 1. The molecular structure of the title compound showing the coordination environment of the Ba atom. Displacement ellipsoids are drawn at the 50% probability level
	Fig. 2. A view along the a axis of the crystal packing of the title compound. The O-H···O hydrogen bonds are shown as red dashed lines (see Table 1 for details).

Poly[µ-aqua-aqua-µ₄-naphthalene-1,8-dicarboxylato-barium]

Crystal data

[Ba(C12H6O4)(H2O)2]	F(000) = 1408
Mr = 369.52	Dx = 2.001 Mg m^−3
Orthorhombic, Ibca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2b 2c	Cell parameters from 2836 reflections
a = 8.9643 (11) Å	θ = 2.7–27.1°
b = 30.539 (6) Å	µ = 3.25 mm^−1
c = 8.9625 (12) Å	T = 296 K
V = 2453.6 (7) Å^3	Prism, colourless
Z = 8	0.20 × 0.05 × 0.05 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	1511 independent reflections
Radiation source: fine-focus sealed tube	1344 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
Detector resolution: 83.33 pixels mm^-1	θmax = 28.4°, θmin = 1.3°
ω scans	h = −11→5
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −40→38
Tmin = 0.563, Tmax = 0.855	l = −11→10
7968 measured reflections

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)] = 0.019	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.043	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0197P)^2 + 0.1976P] where P = (Fo^2 + 2Fc^2)/3
1511 reflections	(Δ/σ)max = 0.001
85 parameters	Δρmax = 0.54 e Å^−3
0 restraints	Δρmin = −0.57 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. 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
Ba1	0.61452 (2)	0.0000	0.2500	0.02892 (7)
O1	0.4190 (2)	0.05878 (6)	0.5240 (3)	0.0360 (5)
C1	0.3754 (3)	0.07360 (9)	0.4035 (4)	0.0236 (6)
O2	0.3671 (2)	0.05119 (7)	0.2858 (2)	0.0341 (5)
C2	0.3410 (3)	0.12190 (9)	0.3935 (3)	0.0253 (6)
O3	0.7500	−0.04396 (9)	0.0000	0.0418 (8)
H3	0.7197	−0.0594	−0.0742	0.050*
C3	0.2500	0.14342 (12)	0.5000	0.0239 (8)
C4	0.2500	0.19041 (12)	0.5000	0.0324 (10)
C5	0.3323 (4)	0.21277 (11)	0.3902 (5)	0.0486 (10)
H5	0.3325	0.2432	0.3899	0.058*
C6	0.4105 (4)	0.19121 (11)	0.2860 (4)	0.0527 (10)
H6	0.4610	0.2067	0.2123	0.063*
C7	0.4163 (4)	0.14507 (10)	0.2877 (3)	0.0386 (8)
H7	0.4720	0.1303	0.2160	0.046*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.01894 (11)	0.03182 (12)	0.03599 (14)	0.000	0.000	0.00999 (13)
O1	0.0321 (12)	0.0315 (11)	0.0445 (13)	0.0027 (9)	−0.0065 (10)	0.0124 (10)
C1	0.0140 (12)	0.0213 (14)	0.0356 (16)	−0.0012 (10)	0.0042 (11)	−0.0009 (12)
O2	0.0330 (11)	0.0314 (11)	0.0380 (14)	−0.0029 (8)	0.0096 (8)	−0.0132 (9)
C2	0.0279 (15)	0.0225 (15)	0.0255 (15)	−0.0033 (12)	−0.0016 (11)	−0.0004 (12)
O3	0.0412 (19)	0.0472 (18)	0.037 (2)	0.000	−0.0162 (15)	0.000
C3	0.025 (2)	0.0220 (19)	0.025 (2)	0.000	−0.0046 (16)	0.000
C4	0.034 (2)	0.022 (2)	0.041 (3)	0.000	−0.0010 (19)	0.000
C5	0.061 (2)	0.0203 (17)	0.065 (3)	−0.0016 (16)	0.0042 (19)	0.0087 (16)
C6	0.067 (2)	0.0326 (18)	0.058 (3)	−0.0034 (16)	0.0213 (19)	0.0164 (15)
C7	0.0463 (18)	0.0366 (17)	0.033 (2)	−0.0007 (14)	0.0128 (13)	0.0060 (13)

Geometric parameters (Å, º)

Ba1—O1^i	2.723 (2)	C2—C7	1.362 (4)
Ba1—O1^ii	2.723 (2)	C2—C3	1.417 (3)
Ba1—O2^iii	2.7324 (19)	O3—Ba1^viii	2.8806 (14)
Ba1—O2	2.7324 (19)	O3—H3	0.8587
Ba1—O2^iv	2.7703 (19)	C3—C2^ix	1.417 (3)
Ba1—O2^v	2.7703 (19)	C3—C4	1.435 (5)
Ba1—O3^vi	2.8806 (14)	C4—C5^ix	1.407 (4)
Ba1—O3	2.8806 (14)	C4—C5	1.407 (4)
O1—C1	1.234 (4)	C5—C6	1.341 (5)
O1—Ba1^ii	2.723 (2)	C5—H5	0.9300
C1—O2	1.259 (4)	C6—C7	1.410 (4)
C1—C2	1.509 (4)	C6—H6	0.9300
O2—Ba1^vii	2.7703 (19)	C7—H7	0.9300
O1^i—Ba1—O1^ii	167.34 (9)	O2^iv—Ba1—Ba1^vii	144.82 (4)
O1^i—Ba1—O2^iii	101.55 (6)	O2^v—Ba1—Ba1^vii	144.82 (4)
O1^ii—Ba1—O2^iii	67.71 (6)	O3^vi—Ba1—Ba1^vii	114.937 (13)
O1^i—Ba1—O2	67.71 (6)	O3—Ba1—Ba1^vii	114.937 (13)
O1^ii—Ba1—O2	101.55 (6)	C1^iii—Ba1—Ba1^vii	50.87 (4)
O2^iii—Ba1—O2	71.48 (8)	C1—Ba1—Ba1^vii	50.87 (4)
O1^i—Ba1—O2^iv	68.40 (6)	O1^i—Ba1—Ba1^iv	96.33 (4)
O1^ii—Ba1—O2^iv	123.25 (6)	O1^ii—Ba1—Ba1^iv	96.33 (4)
O2^iii—Ba1—O2^iv	166.59 (9)	O2^iii—Ba1—Ba1^iv	144.26 (4)
O2—Ba1—O2^iv	110.74 (7)	O2—Ba1—Ba1^iv	144.26 (4)
O1^i—Ba1—O2^v	123.25 (6)	O2^iv—Ba1—Ba1^iv	35.18 (4)
O1^ii—Ba1—O2^v	68.40 (6)	O2^v—Ba1—Ba1^iv	35.18 (4)
O2^iii—Ba1—O2^v	110.74 (7)	O3^vi—Ba1—Ba1^iv	65.063 (13)
O2—Ba1—O2^v	166.59 (9)	O3—Ba1—Ba1^iv	65.063 (13)
O2^iv—Ba1—O2^v	70.35 (8)	C1^iii—Ba1—Ba1^iv	129.13 (4)
O1^i—Ba1—O3^vi	108.54 (7)	C1—Ba1—Ba1^iv	129.13 (4)
O1^ii—Ba1—O3^vi	77.00 (7)	Ba1^vii—Ba1—Ba1^iv	180.0
O2^iii—Ba1—O3^vi	134.45 (5)	C1—O1—Ba1^ii	149.05 (19)
O2—Ba1—O3^vi	89.09 (5)	O1—C1—O2	123.5 (3)
O2^iv—Ba1—O3^vi	58.83 (5)	O1—C1—C2	118.3 (3)
O2^v—Ba1—O3^vi	80.11 (6)	O2—C1—C2	118.0 (3)
O1^i—Ba1—O3	77.00 (7)	O1—C1—Ba1	84.93 (16)
O1^ii—Ba1—O3	108.54 (7)	O2—C1—Ba1	48.58 (13)
O2^iii—Ba1—O3	89.09 (5)	C2—C1—Ba1	138.71 (18)
O2—Ba1—O3	134.45 (5)	C1—O2—Ba1	111.20 (16)
O2^iv—Ba1—O3	80.11 (6)	C1—O2—Ba1^vii	116.85 (16)
O2^v—Ba1—O3	58.83 (5)	Ba1—O2—Ba1^vii	109.08 (7)
O3^vi—Ba1—O3	130.13 (3)	C7—C2—C3	120.9 (3)
O1^i—Ba1—C1^iii	93.75 (7)	C7—C2—C1	116.6 (3)
O1^ii—Ba1—C1^iii	78.20 (7)	C3—C2—C1	122.1 (3)
O2^iii—Ba1—C1^iii	20.22 (6)	Ba1^viii—O3—Ba1	124.44 (10)
O2—Ba1—C1^iii	85.06 (6)	Ba1^viii—O3—H3	77.7
O2^iv—Ba1—C1^iii	147.38 (7)	Ba1—O3—H3	136.4
O2^v—Ba1—C1^iii	100.91 (6)	C2—C3—C2^ix	124.8 (3)
O3^vi—Ba1—C1^iii	152.80 (6)	C2—C3—C4	117.62 (17)
O3—Ba1—C1^iii	69.07 (6)	C2^ix—C3—C4	117.62 (17)
O1^i—Ba1—C1	78.20 (7)	C5^ix—C4—C5	121.9 (4)
O1^ii—Ba1—C1	93.75 (7)	C5^ix—C4—C3	119.0 (2)
O2^iii—Ba1—C1	85.06 (6)	C5—C4—C3	119.0 (2)
O2—Ba1—C1	20.22 (6)	C6—C5—C4	121.6 (3)
O2^iv—Ba1—C1	100.91 (6)	C6—C5—H5	119.2
O2^v—Ba1—C1	147.38 (7)	C4—C5—H5	119.2
O3^vi—Ba1—C1	69.07 (6)	C5—C6—C7	120.2 (3)
O3—Ba1—C1	152.80 (6)	C5—C6—H6	119.9
C1^iii—Ba1—C1	101.74 (9)	C7—C6—H6	119.9
O1^i—Ba1—Ba1^vii	83.67 (4)	C2—C7—C6	120.5 (3)
O1^ii—Ba1—Ba1^vii	83.67 (4)	C2—C7—H7	119.7
O2^iii—Ba1—Ba1^vii	35.74 (4)	C6—C7—H7	119.7
O2—Ba1—Ba1^vii	35.74 (4)

Symmetry codes: (i) −x+1, y, z−1/2; (ii) −x+1, −y, −z+1; (iii) x, −y, −z+1/2; (iv) x+1/2, y, −z+1/2; (v) x+1/2, −y, z; (vi) −x+3/2, −y, z+1/2; (vii) x−1/2, y, −z+1/2; (viii) −x+3/2, −y, z−1/2; (ix) −x+1/2, y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2^x	0.86	2.07	2.777 (2)	140

Symmetry code: (x) −x+1, −y, −z.