Poly[aquaneodymium(III)-μ₅-2-oxido-5-sulfonatobenzoato]

The title compound, [Nd(C₇H₃O₆S)(H₂O)]_n or [Nd(SSA)(H₂O)]_n (H₃SSA is 5-sulfosalicylic acid), was synthesized by the hydrothermal reaction of Nd₂O₃ with H₃SSA in water. The compound forms a three-dimensional network in which the asymmetric unit contains one Nd^III atom, one SSA ligand and one coordinated water mol­ecule. The central Nd^III ion is eight-coordinate, bonded to seven O atoms from five different SSA ligands [Nd—O = 2.405 (4)–2.612 (4) Å] and one aqua O atom [Nd—OW = 2.441 (4) Å].

S1. Comment

Owing to the high coordination numbers of lanthanide ions and the inherent flexibility of their coordination geometries, much effort has been devoted to the study of novel lanthanide metal complexes. For instance, a two-dimensional brick-wall network complex, [Tb(oba)(Hoba)(H₂O)₂]·H₂O (oba is ?; Liu et al., 2002), and a series of three-dimensional hybrid coordination polymers, [Ln₂(H₂O)₄{(1,2-BDC)₂(1,4-BDC)}] (1,2- and 1,4-BDC are?; Thirumurugan & Natarajan, 2004), have recently been reported. The H₃SSA ligand has a strong coordination ability, as it possesses three different chelating groups (–SO₃H, –OH, and –COOH). It has been used extensively to construct metal-organic coordination polymers, such as a ladder-structure complex, [Ba₂(SSA)₄(H₂O)₁₀] (Ma et al., 2003), and the two-dimensional complex [Eu(SSA)₂(H₂O)₅]_n (Starynowicz, 2000). However, much effort has been devoted to the investigation of transition metal-SSA coordination polymers, rather than the analoguous compounds with lanthanide metals. Recently, we have become interested in the study of lanthanide metal complexes of multidentate ligands to assemble novel topological architectures. Here, we report the hydrothermal synthesis and crystal structure of the title novel three-dimensional neodymium complex, [Nd(SSA)(H₂O)]_n, (I). \sch

The unit cell of (I) is composed of one Nd^III cation, one sulfosalicylate anion and one water molecule. Each eight-coordinate Nd^III ion is bonded to one water molecule, two sulfonate O atoms, three carboxylate O atoms and two hydroxyl O atoms from five different SSA ligands in a dodecahedral geometry. The Nd—O bond lengths are in the range 2.405 (4)–2.612 (4) Å and Nd—OW1 2.441 (4) Å, and the O—Nd—O bond angles are in the range 50.86 (13)–167.00 (15)°. As shown in Fig. 1, one carboxylate group, one hydroxyl group and the Nd^III ion form a six-membered ring. The closest Nd···Nd distance is 3.983 (5) Å, comparable with reported Nd—Nd distances (Zhang et al., 2003; Wan et al., 2003; Legendziewicz et al., 1999), indicating a lack of direct metal-metal interaction. Each pair of adjacent Nd1 and Nd1ⁱ atoms is bridged by a pair of hydroxyl groups in a µ₂-bridging coordination mode. Each pair of adjacent Nd1ⁱ and Nd1^v atoms is bridged by a pair of carboxylate groups in a chelating-bridging tridentate coordination mode. Pairs of adjacent Nd1 and Nd1ⁱ, and Nd1ⁱ and Nd1^v atoms are linked alternately into covalent chains running along the a axis, in which the Nd1···Nd1ⁱ and Nd1ⁱ···Nd1^v separations are 3.983 (5) and 4.132 (5) Å, respectively. These one-dimensional covalent chains are further interconnected, by a pair of sulfonate groups in the bidentate bridging coordination mode, into two-dimensional covalent networks parallel to the ab plane. These two-dimensional layers are further integrated by SSA ligands into a three-dimensional framework, forming clear-cut hexagonal tunnels running along the a axis with approximate dimensions 6 × 10 Å, as shown in Fig. 2.

It is worth noting that the 5-sulfosalicylic acid ligand is completely deprotonated in (I), behaving as a µ₅-bridge and linking five individual but symmetry-equivalent Nd atoms. In the three-dimensional framework, all the chelating units of SSA participate efficiently in the bonding to Nd atoms; the carboxylate group adopts a tridentate chelating-bridging mode connecting two Nd atoms, the hydroxyl group acts as a µ₂-bridge and the sulfonate group adopts a bidentate bridging mode bridging two Nd atoms.

S2. Experimental

A mixture of Nd₂O₃ (0.084 g, 0.25 mmol), 5-sulfosalicylic acid (0.110 g, 0.5 mmol) and NaOH (0.008 g, 0.2 mmol) in H₂O (Volume?) was sealed in a 25 ml Teflon-lined stainless steel vessel and heated to 433 K for 72 h. After the reaction, the vessel was cooled slowly to room temperature and rhombus purple crystals of (I) were produced.

S3. Refinement

The structure was solved by direct methods and successive Fourier difference syntheses. The organic H atoms were positioned geometrically (C—H bond fixed at 0.93 Å), and allowed to ride on their parent C atoms before the final cycle of refinement. The aqua H atoms were located from difference maps, the O—H distance fixed at 0.82 Å and refined using isotropic displacement parameters.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1994); data reduction: XPREP in SHELXTL (Siemens, 1994); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. Part of the crystal structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) −x, −y, −z; (ii) −x, −y, −1 − z; (iii) x, 1 + y, 1 + z; (iv) x − 1, y, z; (v) 1 + x, y, z; (vi) x, y − 1, z − 1.]
	Fig. 2. The packing structure of (I), viewed along [100]. H atoms have been omitted for clarity.

Poly[aquaneodymium(III)-µ₅-2-hydroxy-5-sulfonatobenzoato]

Crystal data

[Nd(C7H3O6S)(H2O)]	Z = 2
Mr = 377.41	F(000) = 358
Triclinic, P1	Dx = 2.737 Mg m^−3
a = 6.0553 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.2433 (3) Å	Cell parameters from 2164 reflections
c = 9.9694 (1) Å	θ = 2.2–25.0°
α = 111.733 (2)°	µ = 5.92 mm^−1
β = 94.984 (2)°	T = 293 K
γ = 93.813 (2)°	Rhombus, purple
V = 457.88 (2) Å^3	0.30 × 0.16 × 0.12 mm

Data collection

Siemens SMART CCD area-detector diffractometer	1621 independent reflections
Radiation source: fine-focus sealed tube	1538 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
ϕ and ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −7→7
Tmin = 0.334, Tmax = 0.492	k = −8→9
2425 measured reflections	l = −11→9

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.079	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.051P)^2 + 2.194P] where P = (Fo^2 + 2Fc^2)/3
1595 reflections	(Δ/σ)max = 0.003
151 parameters	Δρmax = 1.17 e Å^−3
3 restraints	Δρmin = −1.30 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
Nd1	−0.23316 (4)	0.14573 (3)	−0.03182 (3)	0.01093 (14)
S1	0.0344 (2)	−0.40495 (18)	−0.77894 (14)	0.0149 (3)
O1W	−0.5582 (8)	0.3097 (7)	−0.0107 (5)	0.0306 (11)
H1WB	−0.665 (10)	0.299 (12)	−0.071 (8)	0.046*
H1WA	−0.591 (15)	0.391 (8)	0.060 (7)	0.046*
O1	0.4395 (7)	−0.0791 (6)	−0.1402 (4)	0.0189 (9)
O2	0.5286 (7)	0.0544 (6)	−0.2847 (5)	0.0227 (10)
O3	−0.0233 (6)	−0.0957 (5)	−0.1471 (4)	0.0128 (8)
O4	−0.1324 (7)	−0.5559 (6)	−0.8420 (4)	0.0219 (9)
O5	0.2618 (8)	−0.4474 (7)	−0.7925 (5)	0.0385 (13)
O6	−0.0144 (8)	−0.2715 (6)	−0.8413 (5)	0.0270 (10)
C1	0.1842 (10)	−0.1353 (7)	−0.3503 (6)	0.0165 (12)
C2	−0.0105 (9)	−0.1685 (7)	−0.2922 (6)	0.0118 (11)
C3	−0.1930 (10)	−0.2748 (8)	−0.3881 (6)	0.0165 (12)
H3A	−0.3227	−0.2973	−0.3515	0.020*
C4	−0.1820 (10)	−0.3465 (8)	−0.5362 (6)	0.0182 (12)
H4A	−0.3027	−0.4190	−0.5985	0.022*
C5	0.0098 (10)	−0.3099 (8)	−0.5922 (6)	0.0143 (11)
C6	0.1911 (10)	−0.2032 (8)	−0.5011 (6)	0.0169 (12)
H6A	0.3168	−0.1767	−0.5396	0.020*
C7	0.3936 (10)	−0.0455 (8)	−0.2555 (6)	0.0158 (12)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nd1	0.0102 (2)	0.0126 (2)	0.0081 (2)	0.00036 (12)	0.00113 (12)	0.00190 (14)
S1	0.0181 (7)	0.0163 (7)	0.0062 (6)	−0.0025 (5)	0.0026 (5)	−0.0001 (5)
O1W	0.028 (3)	0.031 (3)	0.023 (2)	0.020 (2)	−0.003 (2)	−0.001 (2)
O1	0.018 (2)	0.028 (2)	0.008 (2)	−0.0062 (18)	−0.0014 (16)	0.0063 (18)
O2	0.022 (2)	0.028 (2)	0.018 (2)	−0.0094 (18)	0.0006 (18)	0.0111 (19)
O3	0.016 (2)	0.015 (2)	0.0043 (17)	0.0024 (15)	0.0008 (15)	0.0012 (15)
O4	0.031 (2)	0.017 (2)	0.013 (2)	−0.0071 (18)	0.0008 (18)	0.0020 (17)
O5	0.023 (3)	0.051 (3)	0.025 (3)	0.009 (2)	0.012 (2)	−0.007 (2)
O6	0.035 (3)	0.028 (3)	0.017 (2)	−0.010 (2)	0.0010 (19)	0.010 (2)
C1	0.019 (3)	0.013 (3)	0.013 (3)	0.001 (2)	0.002 (2)	0.001 (2)
C2	0.019 (3)	0.012 (3)	0.003 (2)	0.005 (2)	0.002 (2)	0.001 (2)
C3	0.014 (3)	0.024 (3)	0.008 (3)	0.004 (2)	0.002 (2)	0.002 (2)
C4	0.018 (3)	0.024 (3)	0.009 (3)	−0.001 (2)	0.001 (2)	0.003 (2)
C5	0.019 (3)	0.017 (3)	0.007 (3)	0.002 (2)	0.000 (2)	0.005 (2)
C6	0.019 (3)	0.016 (3)	0.017 (3)	−0.001 (2)	0.004 (2)	0.007 (2)
C7	0.017 (3)	0.016 (3)	0.010 (3)	0.000 (2)	0.001 (2)	0.000 (2)

Geometric parameters (Å, º)

Nd1—O1^i	2.405 (4)	O1—Nd1^v	2.488 (4)
Nd1—O3	2.407 (4)	O2—C7	1.249 (7)
Nd1—O3^i	2.431 (4)	O2—Nd1^v	2.612 (4)
Nd1—O1W	2.441 (4)	O3—C2	1.357 (6)
Nd1—O6^ii	2.453 (4)	O3—Nd1^i	2.431 (4)
Nd1—O4^iii	2.481 (4)	O4—Nd1^vi	2.481 (4)
Nd1—O1^iv	2.488 (4)	O6—Nd1^ii	2.453 (4)
Nd1—O2^iv	2.612 (4)	C1—C6	1.402 (8)
Nd1—C7^iv	2.935 (6)	C1—C2	1.412 (8)
Nd1—Nd1^i	3.9835 (5)	C1—C7	1.483 (8)
S1—O5	1.448 (5)	C2—C3	1.403 (8)
S1—O4	1.452 (4)	C3—C4	1.383 (8)
S1—O6	1.484 (5)	C3—H3A	0.9300
S1—C5	1.757 (6)	C4—C5	1.393 (8)
O1W—H1WB	0.82 (7)	C4—H4A	0.9300
O1W—H1WA	0.82 (7)	C5—C6	1.382 (8)
O1—C7	1.291 (7)	C6—H6A	0.9300
O1—Nd1^i	2.405 (4)	C7—Nd1^v	2.935 (6)
O1^i—Nd1—O3	108.83 (14)	C7^iv—Nd1—Nd1^i	115.41 (11)
O1^i—Nd1—O3^i	70.46 (13)	O5—S1—O4	114.2 (3)
O3—Nd1—O3^i	69.15 (14)	O5—S1—O6	111.0 (3)
O1^i—Nd1—O1W	74.01 (17)	O4—S1—O6	109.9 (3)
O3—Nd1—O1W	154.36 (15)	O5—S1—C5	107.2 (3)
O3^i—Nd1—O1W	132.59 (15)	O4—S1—C5	107.3 (3)
O1^i—Nd1—O6^ii	167.00 (15)	O6—S1—C5	107.0 (3)
O3—Nd1—O6^ii	78.23 (15)	Nd1—O1W—H1WB	130 (7)
O3^i—Nd1—O6^ii	103.20 (15)	Nd1—O1W—H1WA	129 (7)
O1W—Nd1—O6^ii	104.56 (18)	H1WB—O1W—H1WA	101 (9)
O1^i—Nd1—O4^iii	87.13 (14)	C7—O1—Nd1^i	136.7 (4)
O3—Nd1—O4^iii	133.73 (14)	C7—O1—Nd1^v	96.8 (3)
O3^i—Nd1—O4^iii	76.71 (14)	Nd1^i—O1—Nd1^v	115.22 (15)
O1W—Nd1—O4^iii	71.10 (16)	C7—O2—Nd1^v	92.0 (3)
O6^ii—Nd1—O4^iii	80.28 (15)	C2—O3—Nd1	124.8 (3)
O1^i—Nd1—O1^iv	64.78 (15)	C2—O3—Nd1^i	122.8 (3)
O3—Nd1—O1^iv	83.85 (14)	Nd1—O3—Nd1^i	110.85 (14)
O3^i—Nd1—O1^iv	115.38 (13)	S1—O4—Nd1^vi	146.6 (3)
O1W—Nd1—O1^iv	74.32 (16)	S1—O6—Nd1^ii	127.1 (3)
O6^ii—Nd1—O1^iv	127.74 (14)	C6—C1—C2	120.3 (5)
O4^iii—Nd1—O1^iv	140.28 (15)	C6—C1—C7	117.7 (5)
O1^i—Nd1—O2^iv	111.66 (13)	C2—C1—C7	121.7 (5)
O3—Nd1—O2^iv	86.44 (14)	O3—C2—C3	120.6 (5)
O3^i—Nd1—O2^iv	154.09 (14)	O3—C2—C1	120.8 (5)
O1W—Nd1—O2^iv	69.45 (15)	C3—C2—C1	118.6 (5)
O6^ii—Nd1—O2^iv	79.14 (14)	C4—C3—C2	120.8 (5)
O4^iii—Nd1—O2^iv	128.60 (14)	C4—C3—H3A	119.6
O1^iv—Nd1—O2^iv	50.86 (13)	C2—C3—H3A	119.6
O1^i—Nd1—C7^iv	87.63 (14)	C3—C4—C5	120.0 (6)
O3—Nd1—C7^iv	87.01 (14)	C3—C4—H4A	120.0
O3^i—Nd1—C7^iv	139.00 (15)	C5—C4—H4A	120.0
O1W—Nd1—C7^iv	67.48 (16)	C6—C5—C4	120.8 (5)
O6^ii—Nd1—C7^iv	103.88 (15)	C6—C5—S1	117.7 (4)
O4^iii—Nd1—C7^iv	138.08 (16)	C4—C5—S1	121.4 (4)
O1^iv—Nd1—C7^iv	25.89 (15)	C5—C6—C1	119.5 (5)
O2^iv—Nd1—C7^iv	25.17 (15)	C5—C6—H6A	120.3
O1^i—Nd1—Nd1^i	89.48 (11)	C1—C6—H6A	120.3
O3—Nd1—Nd1^i	34.78 (9)	O2—C7—O1	119.4 (5)
O3^i—Nd1—Nd1^i	34.37 (9)	O2—C7—C1	123.4 (5)
O1W—Nd1—Nd1^i	163.27 (13)	O1—C7—C1	117.2 (5)
O6^ii—Nd1—Nd1^i	90.92 (12)	O2—C7—Nd1^v	62.8 (3)
O4^iii—Nd1—Nd1^i	106.10 (11)	O1—C7—Nd1^v	57.3 (3)
O1^iv—Nd1—Nd1^i	101.36 (11)	C1—C7—Nd1^v	171.4 (4)
O2^iv—Nd1—Nd1^i	120.76 (11)

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