Poly[(μ₆-2-methyl-3,5-dinitro­benzoato)potassium]

In the structure of the title coordination polymer, [K(C₈H₅N₂O₆)]_n, each ligand bridges six K⁺ cations. The carboxyl­ate group coordinates both bidentately to one K⁺ ion and monodentately to two K⁺ ions, while one nitro group coordinates bidentately to a fourth K⁺ ion. The last two K⁺ ions are coordinated by the remaining nitro group, one in a bidentate fashion, the other monodentately through one O atom. This bridging mode results in a three-dimensional network. The coordination geometry of the K⁺ ion is represented by an irregular KO₉ polyhedron. Very weak C—H...O inter­actions are observed in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.049
• wR factor = 0.148
• Data-to-parameter ratio = 18.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C7     ...       1.53 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          2
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H81    ..  O4      ..       2.84 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H82    ..  O2      ..       2.78 Ang.
PLAT774_ALERT_1_C Suspect X-Y Bond in CIF:   K1     --  K1      ..       3.86 Ang.
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         10

Alert level G
PLAT072_ALERT_2_G SHELXL First Parameter in WGHT Unusually Large..       0.11
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K
PLAT764_ALERT_4_G Overcomplete CIF Bond List Detected (Rep/Expd) .       1.57 Ratio

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   7 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   5 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Methyl-benzoic acids have been studied as precursors in the synthesis of biologically active tin(IV) complexes (Shahzadi et al., 2007). The structure of compound (1) is a three-dimensional polymeric network in which K⁺ ions are bridged by carboxylate and nitro-group O atoms of the ligand (Fig. 1). The ligand's carboxylate group coordinates bidentately to K1. Its oxygen atoms also coordinate to K1⁽ⁱ⁾ and K1⁽ⁱⁱ⁾ [symmetry codes: (i) x,-y-3/2,z-1/2; (ii) x,-y+3/2,z+1/2]. The planes formed by atoms K1/O1/K1⁽ⁱ⁾/O2⁽ⁱ⁾ and K1/O2/K1⁽ⁱⁱ⁾/O1⁽ⁱⁱ⁾, each with s.u.s of 0.1326 (2) Å, make angles of 8.7 (1)° with the C7/O1/O2 plane forming a zig-zag molecular ribbon. A three-dimensional network (Fig. 2) composed of the ribbons inter-connected by nitro-groups represents the stucture of the title compound. The N1/O3/O4 nitro-group coordinates bidentately to K1^(vii); N2/O5/O6 is chelated to the K1^(vi), however, the O6 atom is also linked to K1^(iv). The carboxylic group C7/O1/O2 makes an angle of 38.0 (1)° to the methylbenzene ring, while the nitro-groups N1/O3/O4 and N2/O5/O6 are oriented at angles of 6.7 (1)° and 35.5 (1)°, respectively. K1 is nine-coordinate with a complicated geometry, while the coordination environment of a Na(I) ion in the complex with the same ligand consists of seven O atoms (Danish et al., 2010). Very weak interactions of the C—H···O type are also operating.

Related literature

Tin complexes with organic ligandshave attracted considerable interest due to their biological activity, see, for example: Shahzadi et al. (2007). For the structure of a sodium(I) complex with the 2-methyl-3,5-dinitro-benzoate ligand, see: Danish et al. (2010).

S2. Experimental

50 ml of aqueous solution containing 0.008 mol of 2-methyl-3,5-dinitro benzoic acid was added dropwise to 50 ml of an aqueous solution of potassium hydroxide (0.008 mol) with constant stirring at room temperature. The mixture was refluxed for 3 hours, then brought to room temperature and concentrated under reduced pressure. A brown solid was purified by repeated crystallization from ethanol-ethyl acetate (1:1) mixture to obtain brown single crystals.

S3. Refinement

H atoms attached to methyl and benzene-ring C atoms were positioned geometrically (C–H = 0.95–0.98 Å) and refined as riding with U_iso(H) = 1.2–1.5U_eq(C).

Computing details

Data collection: KM-4 Software (Kuma, 1996); cell refinement: KM-4 Software (Kuma, 1996); data reduction: DATAPROC (Kuma, 2001); 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. A structural unit of (1) with atom labelling scheme and 50% probability displacement ellipsoids. Symmetry codes: (i) x,-y-3/2,z-1/2; (ii) x,-y+3/2,z+1/2; (iii) -x,y-1/2,-z+3/2; (iv) -x+1,-y+2,-z+1; (v) -x+1,y-1/2,-z+1/2; (vi) -x+1,y+1/2;-z+1/2; (vii) -x,y+1/2,-z+3/2.
	Fig. 2. Packing diagram of the structure.

Poly[(µ₆-2-methyl-3,5-dinitrobenzoato)potassium]

Crystal data

[K(C8H5N2O6)]	F(000) = 536
Mr = 264.24	Dx = 1.790 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 8.1632 (16) Å	θ = 6–15°
b = 16.998 (3) Å	µ = 0.56 mm^−1
c = 7.0684 (14) Å	T = 293 K
β = 90.49 (3)°	Block, brown
V = 980.7 (3) Å^3	0.43 × 0.32 × 0.22 mm
Z = 4

Data collection

Kuma KM-4 four-circle diffractometer	2200 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.033
Graphite monochromator	θmax = 30.1°, θmin = 2.4°
profile data from ω/2θ scans	h = −11→0
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008)	k = 0→23
Tmin = 0.889, Tmax = 0.920	l = −9→9
3035 measured reflections	3 standard reflections every 200 reflections
2855 independent reflections	intensity decay: 0.7%

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.148	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.1144P)^2 + 0.0549P] where P = (Fo^2 + 2Fc^2)/3
2855 reflections	(Δ/σ)max = 0.001
155 parameters	Δρmax = 0.72 e Å^−3
0 restraints	Δρmin = −0.72 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
K1	0.30646 (5)	0.70455 (2)	0.53719 (5)	0.03281 (15)
C1	0.24609 (16)	0.97819 (8)	0.52276 (19)	0.0220 (3)
C7	0.26751 (18)	0.88921 (9)	0.5373 (2)	0.0246 (3)
C2	0.30932 (17)	1.02265 (9)	0.3727 (2)	0.0233 (3)
C6	0.16004 (17)	1.01430 (9)	0.6686 (2)	0.0255 (3)
H6	0.1179	0.9844	0.7670	0.031*
C3	0.28318 (19)	1.10416 (9)	0.3816 (2)	0.0266 (3)
O1	0.25937 (19)	0.85008 (8)	0.38860 (17)	0.0395 (3)
O6	0.39480 (19)	1.22199 (8)	0.2829 (2)	0.0471 (4)
O2	0.28968 (18)	0.86252 (8)	0.69897 (17)	0.0373 (3)
N1	0.04619 (18)	1.13215 (9)	0.8188 (2)	0.0346 (3)
N2	0.34771 (18)	1.15683 (9)	0.2343 (2)	0.0334 (3)
C5	0.13803 (18)	1.09462 (9)	0.6657 (2)	0.0270 (3)
O5	0.3523 (2)	1.13326 (10)	0.0711 (2)	0.0526 (4)
C8	0.4096 (2)	0.98522 (10)	0.2191 (2)	0.0319 (3)
H81	0.3405	0.9739	0.1120	0.048*
H83	0.4573	0.9373	0.2656	0.048*
H82	0.4951	1.0207	0.1819	0.048*
C4	0.20004 (19)	1.14170 (10)	0.5248 (2)	0.0295 (3)
H4	0.1866	1.1960	0.5261	0.035*
O3	0.0391 (2)	1.20350 (9)	0.8230 (3)	0.0503 (4)
O4	−0.0210 (2)	1.08967 (10)	0.9335 (2)	0.0533 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.0473 (3)	0.0273 (2)	0.0239 (2)	−0.00228 (13)	0.00711 (15)	0.00005 (11)
C1	0.0202 (6)	0.0239 (6)	0.0219 (6)	0.0009 (5)	0.0005 (5)	−0.0003 (5)
C7	0.0229 (6)	0.0250 (7)	0.0259 (7)	0.0011 (5)	0.0041 (5)	0.0009 (5)
C2	0.0202 (6)	0.0269 (7)	0.0228 (6)	−0.0014 (5)	0.0016 (5)	−0.0004 (5)
C6	0.0217 (6)	0.0314 (8)	0.0234 (6)	0.0004 (5)	0.0042 (5)	0.0004 (5)
C3	0.0250 (7)	0.0270 (7)	0.0280 (7)	−0.0014 (5)	0.0026 (5)	0.0045 (5)
O1	0.0608 (9)	0.0291 (6)	0.0285 (6)	0.0017 (6)	0.0010 (5)	−0.0041 (5)
O6	0.0453 (8)	0.0310 (7)	0.0650 (10)	−0.0058 (5)	0.0100 (7)	0.0082 (6)
O2	0.0520 (8)	0.0329 (6)	0.0270 (6)	0.0053 (5)	0.0035 (5)	0.0063 (5)
N1	0.0266 (7)	0.0394 (8)	0.0381 (7)	0.0041 (5)	0.0069 (5)	−0.0106 (6)
N2	0.0282 (6)	0.0336 (7)	0.0385 (7)	−0.0012 (5)	0.0023 (6)	0.0121 (6)
C5	0.0212 (6)	0.0312 (7)	0.0288 (7)	0.0029 (5)	0.0038 (5)	−0.0050 (6)
O5	0.0650 (10)	0.0608 (10)	0.0321 (7)	−0.0112 (8)	0.0014 (7)	0.0126 (6)
C8	0.0306 (7)	0.0386 (9)	0.0268 (7)	−0.0033 (6)	0.0107 (6)	−0.0039 (6)
C4	0.0261 (7)	0.0262 (7)	0.0361 (8)	0.0022 (5)	0.0028 (6)	−0.0002 (6)
O3	0.0412 (8)	0.0410 (8)	0.0688 (10)	−0.0005 (5)	0.0146 (7)	−0.0228 (7)
O4	0.0585 (10)	0.0587 (9)	0.0432 (8)	0.0134 (7)	0.0271 (7)	0.0030 (7)

Geometric parameters (Å, º)

K1—O2^i	2.6511 (13)	C3—C4	1.380 (2)
K1—O1^ii	2.6826 (13)	C3—N2	1.473 (2)
K1—O1	2.7133 (14)	O1—K1^i	2.6826 (13)
K1—O2	2.9221 (14)	O6—N2	1.221 (2)
K1—O3^iii	2.9974 (18)	O6—K1^iv	3.0116 (18)
K1—O6^iv	3.0115 (18)	O6—K1^vi	3.3541 (19)
K1—O4^iii	3.0485 (18)	O2—K1^ii	2.6511 (13)
K1—O5^v	3.1388 (19)	N1—O3	1.214 (2)
K1—C7	3.1548 (17)	N1—O4	1.220 (2)
K1—N1^iii	3.2998 (16)	N1—C5	1.468 (2)
K1—O6^v	3.3541 (19)	N1—K1^vii	3.2997 (16)
K1—K1^i	3.8572 (7)	N2—O5	1.222 (2)
C1—C6	1.395 (2)	C5—C4	1.377 (2)
C1—C2	1.4042 (19)	O5—K1^vi	3.1388 (19)
C1—C7	1.526 (2)	C8—H81	0.9600
C7—O2	1.2414 (19)	C8—H83	0.9600
C7—O1	1.2450 (19)	C8—H82	0.9600
C2—C3	1.403 (2)	C4—H4	0.9300
C2—C8	1.506 (2)	O3—K1^vii	2.9973 (18)
C6—C5	1.377 (2)	O4—K1^vii	3.0485 (17)
C6—H6	0.9300
O2^i—K1—O1^ii	132.80 (4)	O3^iii—K1—K1^i	108.17 (4)
O2^i—K1—O1	92.12 (4)	O6^iv—K1—K1^i	102.38 (4)
O1^ii—K1—O1	130.77 (4)	O4^iii—K1—K1^i	108.96 (4)
O2^i—K1—O2	138.23 (4)	O5^v—K1—K1^i	85.65 (4)
O1^ii—K1—O2	87.03 (4)	C7—K1—K1^i	66.58 (3)
O1—K1—O2	46.12 (4)	N1^iii—K1—K1^i	116.03 (4)
O2^i—K1—O3^iii	104.67 (6)	O6^v—K1—K1^i	48.76 (3)
O1^ii—K1—O3^iii	63.25 (5)	C6—C1—C2	120.82 (14)
O1—K1—O3^iii	90.14 (4)	C6—C1—C7	116.39 (13)
O2—K1—O3^iii	80.16 (5)	C2—C1—C7	122.79 (12)
O2^i—K1—O6^iv	126.47 (5)	O2—C7—O1	126.02 (16)
O1^ii—K1—O6^iv	82.79 (5)	O2—C7—C1	116.09 (13)
O1—K1—O6^iv	84.09 (5)	O1—C7—C1	117.88 (14)
O2—K1—O6^iv	59.62 (4)	O2—C7—K1	67.84 (9)
O3^iii—K1—O6^iv	128.64 (5)	O1—C7—K1	58.19 (9)
O2^i—K1—O4^iii	75.65 (5)	C1—C7—K1	176.06 (10)
O1^ii—K1—O4^iii	66.40 (5)	C3—C2—C1	116.14 (13)
O1—K1—O4^iii	120.29 (5)	C3—C2—C8	122.20 (13)
O2—K1—O4^iii	121.57 (5)	C1—C2—C8	121.51 (14)
O3^iii—K1—O4^iii	41.55 (5)	C5—C6—C1	119.43 (14)
O6^iv—K1—O4^iii	148.60 (5)	C5—C6—H6	120.3
O2^i—K1—O5^v	69.70 (5)	C1—C6—H6	120.3
O1^ii—K1—O5^v	103.11 (5)	C4—C3—C2	124.41 (14)
O1—K1—O5^v	112.37 (5)	C4—C3—N2	114.73 (15)
O2—K1—O5^v	119.66 (5)	C2—C3—N2	120.86 (14)
O3^iii—K1—O5^v	156.64 (5)	C7—O1—K1^i	163.63 (12)
O6^iv—K1—O5^v	62.99 (5)	C7—O1—K1	98.86 (10)
O4^iii—K1—O5^v	116.73 (5)	K1^i—O1—K1	91.26 (4)
O2^i—K1—C7	115.06 (4)	N2—O6—K1^iv	138.32 (12)
O1^ii—K1—C7	109.20 (4)	N2—O6—K1^vi	87.65 (10)
O1—K1—C7	22.95 (4)	K1^iv—O6—K1^vi	74.37 (4)
O2—K1—C7	23.17 (4)	C7—O2—K1^ii	173.37 (12)
O3^iii—K1—C7	84.88 (4)	C7—O2—K1	89.00 (10)
O6^iv—K1—C7	70.65 (4)	K1^ii—O2—K1	87.45 (4)
O4^iii—K1—C7	124.07 (5)	O3—N1—O4	123.59 (16)
O5^v—K1—C7	118.28 (5)	O3—N1—C5	118.47 (16)
O2^i—K1—N1^iii	94.55 (5)	O4—N1—C5	117.93 (16)
O1^ii—K1—N1^iii	56.83 (5)	O3—N1—K1^vii	65.06 (9)
O1—K1—N1^iii	109.77 (5)	O4—N1—K1^vii	67.48 (10)
O2—K1—N1^iii	100.25 (4)	C5—N1—K1^vii	147.35 (11)
O3^iii—K1—N1^iii	21.56 (4)	O6—N2—O5	123.42 (15)
O6^iv—K1—N1^iii	136.87 (4)	O6—N2—C3	117.79 (15)
O4^iii—K1—N1^iii	21.69 (4)	O5—N2—C3	118.79 (15)
O5^v—K1—N1^iii	135.22 (5)	C6—C5—C4	122.57 (14)
C7—K1—N1^iii	106.43 (4)	C6—C5—N1	119.15 (14)
O2^i—K1—O6^v	57.45 (4)	C4—C5—N1	118.28 (15)
O1^ii—K1—O6^v	140.00 (5)	N2—O5—K1^vi	97.94 (12)
O1—K1—O6^v	76.10 (4)	C2—C8—H81	109.5
O2—K1—O6^v	102.69 (4)	C2—C8—H83	109.5
O3^iii—K1—O6^v	156.18 (5)	H81—C8—H83	109.5
O6^iv—K1—O6^v	69.96 (4)	C2—C8—H82	109.5
O4^iii—K1—O6^v	131.53 (4)	H81—C8—H82	109.5
O5^v—K1—O6^v	38.52 (4)	H83—C8—H82	109.5
C7—K1—O6^v	89.20 (4)	C5—C4—C3	116.61 (15)
N1^iii—K1—O6^v	151.93 (4)	C5—C4—H4	121.7
O2^i—K1—K1^i	49.19 (3)	C3—C4—H4	121.7
O1^ii—K1—K1^i	171.19 (3)	N1—O3—K1^vii	93.38 (10)
O1—K1—K1^i	44.05 (3)	N1—O4—K1^vii	90.82 (11)
O2—K1—K1^i	89.48 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O4^viii	0.93	2.59	3.518 (2)	174
C8—H81···O4^ix	0.96	2.84	3.576 (3)	134
C8—H82···O2^iv	0.96	2.78	3.610 (2)	146

Symmetry codes: (iv) −x+1, −y+2, −z+1; (viii) −x, −y+2, −z+2; (ix) −x, −y+2, −z+1.