Poly[(μ₅-3,5-di­nitro­benzoato)rubidium]

The asymmetric unit of the title compound, [Rb(C₇H₃N₂O₆)]_n, comprises an Rb cation and a 3,5-dinitro­benzoate anion. The Rb cation is eight-coordinated by O atoms from five 3,5-dinitro­benzoate anions. On the other hand, each 3,5-dinitro­benzoate anion links five Rb cations with the carboxyl­ate groups as μ₃-bridging. The metal atom is firstly linked by the carboxyl­ate groups into a chain along the c-axis direction, which is further linked by bonds between the Rb and nitro O atoms, giving a three-dimensional framework.

Related literature

For 3,5-dinitro­benzoate complexes, see: Askarinejad et al. (2007); Madej et al. (2007). For Rb—O bond lengths, see: Cametti et al. (2005).

Experimental

Crystal data

• [Rb(C₇H₃N₂O₆)]

• M_r = 296.58

• Monoclinic, I 2/a

• a = 7.2789 (15) Å

• b = 18.072 (4) Å

• c = 7.3652 (14) Å

• β = 91.70 (3)°

• V = 968.4 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 5.13 mm⁻¹

• T = 293 K

• 0.64 × 0.40 × 0.14 mm

Data collection

• Bruker SMART CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.396, T_max = 1.000

• 4663 measured reflections

• 896 independent reflections

• 760 reflections with I > 2σ(I)

• R_int = 0.053

Refinement

• R[F² > 2σ(F²)] = 0.033

• wR(F²) = 0.078

• S = 1.06

• 896 reflections

• 75 parameters

• H-atom parameters constrained

• Δρ_max = 0.29 e Å⁻³

• Δρ_min = −0.55 e Å⁻³

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); 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.

Supporting information

S1. Comment

In the coordination chemistry of 3,5-dinitrobenzoic acid, it has been found that the 3,5-dinitrobenzoate moiety functions as a multidentate ligand (Askarinejad et al., 2007; Madej et al., 2007) with versatile binding and coordination modes. In this paper, we report the crystal structure of the title compound, a new Rb complex obtained by the reaction of 3,5-dinitrobenzoic acid and RbOH in water.

The asymmetric unit of the title compound comprises a Rb cation and a 3,5-dinitrobenzoate anion. Rb cation lies on and the dinitrobenzoate is centred upon crystallographic twofold axes. The Rb cation is coordinated to eight O atoms from five 3,5-dinitrobenzoate anions (Fig. 1) with the Rb—O distances ranging from 2.761 (2) Å to 3.124 (4) Å, which are well within the range reported in the literature (Cametti et al., 2005). The Rb centre is firstly linked by the carboxylic groups to give a one-dimensional chain along the c-axis direction, which is further linked by the phenyl groups to give a three-dimensional framework of the title compound (Fig. 2).

Related literature

For 3,5-dinitrobenzoate complexes, see: Askarinejad et al. (2007); Madej et al. (2007). For Rb—O bond lengths, see: Cametti et al. (2005).

S2. Experimental

3,5-dinitrobenzoic acid and RbOH were commercially available and used without further purification. To asolution of 10 mmol 3,5-dinitrobenzoic acid in 30 ml bidistilled water, a solution of 10 mmol RbOH in 20 ml bidistilled water was added dropwise at room temperature. After vigorous stirring for 1 h, the resulting solution was then evaporated to a volume of about 15 ml in vacuum and filtered hot. The filtrate was then set aside for crystallization at room temperature. Three weeks later, colorless prism crystals of the titlecompound suitable for X-ray determination were isolated.

S3. Refinement

Carbon-bound H atoms were placed at calculated positions and were treated as riding on the parent C atoms with C – H = 0.93 Å, and with U_iso(H) = 1.2 U_eq(C).

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); 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 (Sheldrick, 2008).

Figures

	Fig. 1. The structure of (I), showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids. Symmetry codes: (i) 1.5 - x, y, 1 - z; (ii) x, 1.5 - y, -1/2 + z; (iii) 0.5 - x, 1.5 - y, 1.5 - z; (iv) 0.5 - x, y, 1 - z; (v) -1/2 + x, 1 - y, z; (vi) 1 - x, 1 - y, 1 - z.
	Fig. 2. The three-dimensional framework of (I).

Poly[(µ₅-3,5-dinitrobenzoato)rubidium]

Crystal data

[Rb(C7H3N2O6)]	F(000) = 576
Mr = 296.58	Dx = 2.034 Mg m^−3
Monoclinic, I2/a	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2ya	Cell parameters from 1610 reflections
a = 7.2789 (15) Å	θ = 3.0–25.4°
b = 18.072 (4) Å	µ = 5.13 mm^−1
c = 7.3652 (14) Å	T = 293 K
β = 91.70 (3)°	Prism, colorless
V = 968.4 (3) Å^3	0.64 × 0.40 × 0.14 mm
Z = 4

Data collection

Bruker SMART CCD diffractometer	896 independent reflections
Radiation source: fine-focus sealed tube	760 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.053
ϕ and ω scans	θmax = 25.3°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
Tmin = 0.396, Tmax = 1.000	k = −21→20
4663 measured reflections	l = −8→7

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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.078	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0418P)^2] where P = (Fo^2 + 2Fc^2)/3
896 reflections	(Δ/σ)max = 0.001
75 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.55 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
Rb1	0.2500	0.54657 (2)	0.5000	0.0557 (2)
C1	0.7500	0.8732 (3)	0.5000	0.0493 (11)
H1A	0.7500	0.9246	0.5000	0.059*
C2	0.6036 (4)	0.83316 (17)	0.5606 (4)	0.0451 (8)
C3	0.5991 (4)	0.75684 (17)	0.5597 (4)	0.0421 (7)
H3A	0.4961	0.7316	0.5986	0.050*
C4	0.7500	0.7185 (2)	0.5000	0.0387 (10)
C5	0.7500	0.6342 (2)	0.5000	0.0398 (10)
N1	0.4460 (5)	0.87295 (16)	0.6344 (4)	0.0595 (8)
O1	0.6019 (3)	0.60328 (12)	0.5293 (4)	0.0649 (7)
O2	0.3212 (4)	0.83742 (15)	0.6978 (4)	0.0696 (7)
O3	0.4500 (5)	0.94073 (15)	0.6317 (5)	0.0913 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Rb1	0.0317 (3)	0.0382 (3)	0.0985 (4)	0.000	0.0213 (2)	0.000
C1	0.066 (3)	0.040 (2)	0.043 (3)	0.000	0.004 (2)	0.000
C2	0.0482 (19)	0.0444 (17)	0.0429 (17)	0.0112 (15)	0.0053 (14)	0.0032 (14)
C3	0.0381 (17)	0.0441 (16)	0.0441 (17)	0.0020 (15)	0.0020 (13)	0.0032 (14)
C4	0.035 (2)	0.042 (2)	0.039 (2)	0.000	−0.0038 (18)	0.000
C5	0.028 (2)	0.035 (2)	0.056 (3)	0.000	−0.0009 (19)	0.000
N1	0.068 (2)	0.0532 (18)	0.0576 (18)	0.0181 (16)	0.0117 (15)	0.0056 (15)
O1	0.0359 (13)	0.0414 (12)	0.118 (2)	−0.0037 (11)	0.0118 (13)	0.0012 (13)
O2	0.0555 (16)	0.0686 (17)	0.0860 (18)	0.0089 (13)	0.0222 (14)	−0.0045 (14)
O3	0.113 (3)	0.0515 (15)	0.112 (2)	0.0326 (16)	0.049 (2)	0.0202 (16)

Geometric parameters (Å, º)

Rb1—O1	2.761 (2)	C1—C2	1.374 (4)
Rb1—O1^i	2.925 (2)	C1—C2^iii	1.374 (4)
Rb1—O2^ii	3.113 (3)	C1—H1A	0.9300
Rb1—O3^ii	3.125 (3)	C2—C3	1.380 (4)
O1—Rb1—O1^iv	136.43 (9)	C1—C2—C3	122.9 (3)
O1—Rb1—O1^i	132.92 (7)	C1—C2—N1	118.9 (3)
O1^iv—Rb1—O1^i	90.36 (6)	C3—C2—N1	118.2 (3)
O1^i—Rb1—O1^v	44.43 (9)	C2—C3—C4	118.9 (3)
O1—Rb1—O2^ii	82.42 (8)	C2—C3—H3A	120.5
O1^iv—Rb1—O2^ii	68.41 (8)	C4—C3—H3A	120.5
O1^i—Rb1—O2^ii	120.08 (7)	C3^iii—C4—C3	119.9 (4)
O1^v—Rb1—O2^ii	138.23 (8)	C3—C4—C5	120.07 (19)
O2^ii—Rb1—O2^vi	95.32 (11)	O1—C5—O1^iii	126.3 (4)
O1—Rb1—O3^ii	111.10 (10)	O1—C5—C4	116.83 (19)
O1^iv—Rb1—O3^ii	65.51 (9)	O1^iii—C5—C4	116.83 (19)
O1^i—Rb1—O3^ii	79.74 (8)	O2—N1—O3	123.5 (3)
O1^v—Rb1—O3^ii	108.31 (7)	O2—N1—C2	118.9 (3)
O2^ii—Rb1—O3^ii	40.35 (7)	O3—N1—C2	117.6 (3)
O2^vi—Rb1—O3^ii	131.54 (7)	C5—O1—Rb1	164.54 (19)
O2^ii—Rb1—O3^vi	131.54 (8)	C5—O1—Rb1^v	94.6 (2)
O3^ii—Rb1—O3^vi	171.57 (10)	Rb1—O1—Rb1^v	89.64 (6)
C2—C1—C2^iii	116.5 (4)	N1—O2—Rb1^ii	93.5 (2)
C2—C1—H1A	121.8	N1—O3—Rb1^ii	92.7 (2)
C3—C4—C5—O1	10.3 (2)	C3—C2—N1—O2	2.7 (5)
C3^iii—C4—C5—O1	−169.7 (2)	C1—C2—N1—O3	2.8 (4)
C1—C2—N1—O2	−175.8 (3)	C3—C2—N1—O3	−178.8 (3)

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