Poly[[μ₁₀-4,4′-(ethane-1,2-diyldi­­oxy)dibenzoato]dipotassium]

The title salt, [K₂(C₁₆H₁₂O₆)]_n, was obtained by the reaction of 1,2-bis­[4-(ethyl-carbox­yl)-phenox­yl]ethane with KOH in water. The anion lies on a crystallographic inversion center, which is located at the mid-point of the central C—C bond. The K⁺ cation is coordinated by six O atoms, two from the chelating carboxyl­ate group of the anion and four from four neighboring and monodentately binding anions, giving rise to an irregular [KO₆] coordination polyhedron. The coordination mode of the cation leads to the formation of K/O layers parallel to (100). These layers are linked by the nearly coplanar anions (r.m.s. deviation of 0.064 Å of the carboxyl, aryl and O—CH₂ groups from the least-squares plane) into a three-dimentional network.

Related literature

For the preparation, structures, properties and applications of metal carboxyl­ate compounds, see: Ma et al. (2005); Su et al. (2010); Zhang & Chen (2008); Zhu et al. (2008). For the preparation of the precusor, see: Ma & Yang (2011). For standard bond lengths, see: Allen et al. (1987).

Experimental

Crystal data

• [K₂(C₁₆H₁₂O₆)]

• M_r = 189.23

• Monoclinic, P 2₁ /c

• a = 18.0696 (7) Å

• b = 3.9866 (1) Å

• c = 11.3189 (5) Å

• β = 107.188 (2)°

• V = 778.96 (5) ų

• Z = 4

• Mo Kα radiation

• μ = 0.64 mm⁻¹

• T = 298 K

• 0.15 × 0.11 × 0.10 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.919, T_max = 0.938

• 7387 measured reflections

• 2146 independent reflections

• 1999 reflections with I > 2σ(I)

• R_int = 0.018

Refinement

• R[F² > 2σ(F²)] = 0.023

• wR(F²) = 0.067

• S = 1.01

• 2146 reflections

• 109 parameters

• H-atom parameters constrained

• Δρ_max = 0.39 e Å⁻³

• Δρ_min = −0.22 e Å⁻³

Table 1
Selected bond lengths (Å)

K1—O2^i	2.6558 (8)
K1—O1^ii	2.6780 (8)
K1—O2	2.7069 (8)
K1—O1^iii	2.7167 (8)
K1—O2^iv	2.8027 (8)
K1—O1	3.0335 (8)
Symmetry codes: (i) ; (ii) -x, -y+2, -z; (iii) -x, -y+1, -z; (iv) .

Data collection: SMART (Bruker, 2001); 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: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Supporting information

S1. Comment

The coordination chemistry of carboxylic compounds is attracting current attention, based on interesting properties like gas adsorption and separation, catalysis, magnetism, luminescence and host-guest chemistry (Su et al., 2010; Zhu et al., 2008) of these compounds. It is well-known that carboxylic acids are excellent building blocks for the construction of coordination polymers, yielding extended frameworks by virtue of their bridging abilities (Ma et al., 2005; Zhang & Chen, 2008). Hence, the present paper aims to promote the search for new metal carboxylic complexes exhibiting special properties in many fields, in particular those bearing multicarboxylic-type ligands, a promising but still rather underdeveloped field of research. We report here the structure of a new polymeric dipotassium dicarboxylic compound (Fig. 1).

In the asymmetric unit one half of the anion is present. The anion lies on a crystallographic inversion center, which is located at the mid point of the C8—C8ⁱ bond (symmetry code (i) = -x-1, -y-1, -z). All bond lengths and angles of the anion are within normal ranges (Allen et al., 1987). The K⁺ ion is coordinated by six oxygen atoms, two from the ligand and four from neighboring ligands, in a distorted [KO₆] polyhedron (Fig 2), whereby one anion coordinates all in all to ten K⁺ cations. The benzene rings of the anion are parallel to each other with a plane-to-plane distance of 3.488 Å. The carboxyl, aryl and O—CH₂ moieties are coplanar with an r.m.s. deviation of 0.0638 Å.

A three-dimensional network is spanned owing to the coordination mode of the potassium cations. The K⁺ cations and the O atoms of the carboxylate anions form a layer parallel to (100). These layers are finally connected by the substituted ethane moieties into a three-dimensional structure (Fig. 2).

Related literature

For the preparation, structures, properties and applications of metal carboxylate compounds, see: Ma et al. (2005); Su et al. (2010); Zhang & Chen (2008); Zhu et al. (2008). For the preparation of the precusor, see: Ma & Yang (2011). For standard bond lengths, see: Allen et al. (1987).

S2. Experimental

The precusor of the title compound was prepared by a reported procedure (Ma & Yang, 2011). The title compound was synthesized by the reaction of the precusor, diethyl 4,4'-(ethane-1,2-diyldioxy)-dibenzoate and potassium hydroxide in the conditions as follows: The precusor (1.0 g, 2.8 mM) and KOH (0.31 g, 5.6 mM) were put in water (150 cm³) in a 250 cm³ flask and the system was stirred for 24 h at 373 K for all solids dissolved and cooled down to room temperature. After filtration, a colorless solution was obtained. Evaporation of the solution gave a white solid (0.82 g, 77 %), which was washed with ethanol two times (10 ml each). Slow evaporation of a solution of the title compound in water led to the formation of colorless crystals, which were suitable for X-ray characterization.

S3. Refinement

Hydrogen atoms bonded to the C atoms of the anion were positioned geometrically and refined using a riding model with C—H = 0.93 - 0.97 Å and with Uiso(H) = 1.2 times Ueq(C). These hydrogen atoms were assigned isotropic thermal parameters and allowed to ride on their respective parent atoms.

Computing details

Data collection: SMART (Bruker, 2001); 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: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. Coordination environment around the K ions in the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius. [symmetry code: (A) -x-1, -y-1, -z; (B) -x, -y-1/2, -z+1/2; (C) -x, y+1/2, -z+1/2; (D) x-1, -y-3/2, z-1/2; (E) x-1, -y-1/2, z-1/2]
	Fig. 2. A view of the crystal packing along the b axis. Longer bonds between the K^+ ions and O atoms are shown with dotted lines.

Poly[[µ₁₀-4,4'-(ethane-1,2-diyldioxy)dibenzoato]dipotassium]

Crystal data

[K2(C16H12O6)]	F(000) = 388
Mr = 189.23	Dx = 1.614 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7387 reflections
a = 18.0696 (7) Å	θ = 3.5–29.6°
b = 3.9866 (1) Å	µ = 0.64 mm^−1
c = 11.3189 (5) Å	T = 298 K
β = 107.188 (2)°	Prism, colorless
V = 778.96 (5) Å^3	0.15 × 0.11 × 0.10 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	2146 independent reflections
Radiation source: fine-focus sealed tube	1999 reflections with I > 2σ(I)
Graphite Monochromator monochromator	Rint = 0.018
phi and ω scans	θmax = 29.6°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −25→25
Tmin = 0.919, Tmax = 0.938	k = −5→4
7387 measured reflections	l = −15→15

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)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.067	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0361P)^2 + 0.4108P] where P = (Fo^2 + 2Fc^2)/3
2146 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.39 e Å^−3
0 restraints	Δρmin = −0.22 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 > 2sigma(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	−0.062276 (12)	0.69576 (6)	−0.14996 (2)	0.01343 (8)
O1	0.10069 (4)	0.8108 (2)	0.01861 (7)	0.01551 (16)
O2	0.08101 (4)	0.6705 (2)	−0.17911 (7)	0.01591 (16)
O3	0.41949 (4)	1.2442 (2)	−0.07832 (8)	0.02053 (18)
C1	0.12233 (6)	0.7855 (2)	−0.07712 (9)	0.01162 (18)
C2	0.20252 (5)	0.9047 (3)	−0.07224 (9)	0.01196 (18)
C3	0.23052 (6)	0.8522 (3)	−0.17345 (10)	0.01459 (19)
H3A	0.1997	0.7410	−0.2428	0.018*
C4	0.30339 (6)	0.9630 (3)	−0.17205 (10)	0.0162 (2)
H4A	0.3215	0.9234	−0.2396	0.019*
C5	0.34944 (6)	1.1339 (3)	−0.06932 (10)	0.0154 (2)
C6	0.32378 (6)	1.1810 (3)	0.03393 (10)	0.0170 (2)
H6A	0.3552	1.2870	0.1040	0.020*
C7	0.25020 (6)	1.0670 (3)	0.03085 (9)	0.0151 (2)
H7A	0.2327	1.1005	0.0994	0.018*
C8	0.46737 (6)	1.4328 (3)	0.02248 (11)	0.0192 (2)
H8A	0.4875	1.2908	0.0944	0.023*
H8B	0.4383	1.6153	0.0442	0.023*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.01384 (11)	0.01391 (12)	0.01382 (12)	−0.00019 (7)	0.00604 (8)	0.00031 (7)
O1	0.0156 (3)	0.0186 (4)	0.0148 (4)	−0.0019 (3)	0.0082 (3)	−0.0009 (3)
O2	0.0128 (3)	0.0207 (4)	0.0144 (3)	−0.0028 (3)	0.0041 (3)	−0.0033 (3)
O3	0.0129 (4)	0.0248 (4)	0.0266 (4)	−0.0065 (3)	0.0100 (3)	−0.0045 (3)
C1	0.0107 (4)	0.0106 (4)	0.0142 (4)	0.0004 (3)	0.0047 (3)	0.0010 (3)
C2	0.0101 (4)	0.0129 (4)	0.0132 (4)	−0.0003 (3)	0.0040 (3)	0.0014 (4)
C3	0.0126 (4)	0.0183 (5)	0.0132 (4)	−0.0010 (4)	0.0042 (4)	−0.0014 (4)
C4	0.0146 (4)	0.0207 (5)	0.0159 (5)	−0.0008 (4)	0.0083 (4)	0.0001 (4)
C5	0.0103 (4)	0.0155 (5)	0.0216 (5)	−0.0008 (3)	0.0066 (4)	0.0016 (4)
C6	0.0131 (4)	0.0203 (5)	0.0174 (5)	−0.0037 (4)	0.0042 (4)	−0.0041 (4)
C7	0.0135 (4)	0.0184 (5)	0.0148 (5)	−0.0020 (4)	0.0062 (4)	−0.0019 (4)
C8	0.0123 (4)	0.0186 (5)	0.0276 (6)	−0.0032 (4)	0.0073 (4)	−0.0011 (4)

Geometric parameters (Å, º)

K1—O2^i	2.6558 (8)	C1—C2	1.5104 (13)
K1—O1^ii	2.6780 (8)	C2—C7	1.3886 (14)
K1—O2	2.7069 (8)	C2—C3	1.3981 (14)
K1—O1^iii	2.7167 (8)	C3—C4	1.3845 (14)
K1—O2^iv	2.8027 (8)	C3—H3A	0.9300
K1—O1	3.0335 (8)	C4—C5	1.3918 (15)
O1—C1	1.2599 (12)	C4—H4A	0.9300
O1—K1^ii	2.6780 (8)	C5—C6	1.3914 (15)
O1—K1^iii	2.7167 (8)	C6—C7	1.3957 (14)
O2—C1	1.2613 (12)	C6—H6A	0.9300
O2—K1^iv	2.6558 (8)	C7—H7A	0.9300
O2—K1^i	2.8027 (8)	C8—C8^v	1.514 (2)
O3—C5	1.3719 (12)	C8—H8A	0.9700
O3—C8	1.4254 (14)	C8—H8B	0.9700
O2^i—K1—O1^ii	83.27 (2)	C2—C1—K1	163.16 (7)
O2^i—K1—O2	81.85 (2)	O1—C1—K1^i	130.55 (7)
O1^ii—K1—O2	120.61 (2)	O2—C1—K1^i	52.82 (5)
O2^i—K1—O1^iii	158.48 (3)	C2—C1—K1^i	85.79 (5)
O1^ii—K1—O1^iii	95.29 (2)	K1—C1—K1^i	77.91 (2)
O2—K1—O1^iii	116.57 (2)	C7—C2—C3	118.26 (9)
O2^i—K1—O2^iv	93.79 (2)	C7—C2—C1	121.84 (9)
O1^ii—K1—O2^iv	159.03 (2)	C3—C2—C1	119.90 (9)
O2—K1—O2^iv	79.21 (2)	C4—C3—C2	121.06 (10)
O1^iii—K1—O2^iv	79.87 (2)	C4—C3—K1^i	124.14 (7)
O2^i—K1—O1	103.98 (2)	C2—C3—K1^i	86.80 (6)
O1^ii—K1—O1	84.40 (2)	C4—C3—H3A	119.5
O2—K1—O1	45.30 (2)	C2—C3—H3A	119.5
O1^iii—K1—O1	97.22 (2)	K1^i—C3—H3A	59.1
O2^iv—K1—O1	116.36 (2)	C3—C4—C5	119.85 (9)
C1—O1—K1^ii	137.18 (7)	C3—C4—H4A	120.1
C1—O1—K1^iii	127.26 (6)	C5—C4—H4A	120.1
K1^ii—O1—K1^iii	95.29 (2)	O3—C5—C6	124.26 (10)
C1—O1—K1	86.40 (6)	O3—C5—C4	115.58 (9)
K1^ii—O1—K1	95.60 (2)	C6—C5—C4	120.15 (9)
K1^iii—O1—K1	82.78 (2)	C5—C6—C7	119.12 (10)
C1—O2—K1^iv	147.07 (7)	C5—C6—H6A	120.4
C1—O2—K1	101.75 (6)	C7—C6—H6A	120.4
K1^iv—O2—K1	101.23 (3)	C2—C7—C6	121.51 (9)
C1—O2—K1^i	106.17 (6)	C2—C7—H7A	119.2
K1^iv—O2—K1^i	93.79 (2)	C6—C7—H7A	119.2
K1—O2—K1^i	97.56 (3)	O3—C8—C8^v	105.46 (12)
C5—O3—C8	117.68 (9)	O3—C8—H8A	110.6
O1—C1—O2	124.48 (9)	C8^v—C8—H8A	110.6
O1—C1—C2	118.78 (9)	O3—C8—H8B	110.6
O2—C1—C2	116.73 (9)	C8^v—C8—H8B	110.6
O1—C1—K1	70.54 (5)	H8A—C8—H8B	108.8
O2—C1—K1	55.63 (5)
O2^i—K1—O1—C1	−55.46 (6)	K1—O2—C1—K1^i	−101.55 (4)
O1^ii—K1—O1—C1	−137.08 (7)	O2^i—K1—C1—O1	126.93 (6)
O2—K1—O1—C1	7.68 (5)	O1^ii—K1—C1—O1	43.72 (7)
O1^iii—K1—O1—C1	128.28 (6)	O2—K1—C1—O1	−165.70 (10)
O2^iv—K1—O1—C1	46.04 (6)	O1^iii—K1—C1—O1	−56.46 (7)
O2^i—K1—O1—K1^ii	81.62 (3)	O2^iv—K1—C1—O1	−139.16 (6)
O1^ii—K1—O1—K1^ii	0.0	C1^iv—K1—C1—O1	−158.75 (5)
O2—K1—O1—K1^ii	144.76 (4)	C3^iv—K1—C1—O1	−147.22 (6)
O1^iii—K1—O1—K1^ii	−94.64 (2)	K1^iii—K1—C1—O1	−39.24 (5)
O2^iv—K1—O1—K1^ii	−176.88 (2)	K1^vi—K1—C1—O1	−97.19 (6)
O2^i—K1—O1—K1^iii	176.26 (2)	K1^vii—K1—C1—O1	82.81 (6)
O1^ii—K1—O1—K1^iii	94.64 (2)	O2^i—K1—C1—O2	−67.37 (5)
O2—K1—O1—K1^iii	−120.60 (4)	O1^ii—K1—C1—O2	−150.59 (6)
O1^iii—K1—O1—K1^iii	0.0	O1^iii—K1—C1—O2	109.24 (6)
O2^iv—K1—O1—K1^iii	−82.24 (3)	O2^iv—K1—C1—O2	26.54 (6)
O2^i—K1—O2—C1	111.19 (5)	O1—K1—C1—O2	165.70 (10)
O1^ii—K1—O2—C1	34.03 (7)	C1^iv—K1—C1—O2	6.95 (7)
O1^iii—K1—O2—C1	−80.53 (7)	O2^i—K1—C1—C2	0.4 (2)
O2^iv—K1—O2—C1	−153.35 (6)	O1^ii—K1—C1—C2	−82.8 (2)
O1—K1—O2—C1	−7.82 (6)	O2—K1—C1—C2	67.7 (2)
O2^i—K1—O2—K1^iv	−92.56 (4)	O1^iii—K1—C1—C2	177.0 (2)
O1^ii—K1—O2—K1^iv	−169.72 (2)	O2^iv—K1—C1—C2	94.3 (2)
O1^iii—K1—O2—K1^iv	75.72 (3)	O1—K1—C1—C2	−126.6 (3)
O2^iv—K1—O2—K1^iv	2.91 (2)	O2^i—K1—C1—K1^i	−14.40 (2)
O1—K1—O2—K1^iv	148.43 (4)	O1^ii—K1—C1—K1^i	−97.62 (2)
O2^i—K1—O2—K1^i	2.85 (2)	O2—K1—C1—K1^i	52.97 (6)
O1^ii—K1—O2—K1^i	−74.31 (3)	O1^iii—K1—C1—K1^i	162.21 (2)
O1^iii—K1—O2—K1^i	171.14 (2)	O2^iv—K1—C1—K1^i	79.51 (2)
O2^iv—K1—O2—K1^i	98.32 (4)	O1—K1—C1—K1^i	−141.33 (6)
O1—K1—O2—K1^i	−116.16 (4)	O1—C1—C2—C7	−5.67 (15)
K1^ii—O1—C1—O2	−108.67 (11)	O2—C1—C2—C7	173.34 (10)
K1^iii—O1—C1—O2	63.78 (13)	O1—C1—C2—C3	174.29 (9)
K1—O1—C1—O2	−14.32 (10)	O2—C1—C2—C3	−6.70 (14)
K1^ii—O1—C1—C2	70.25 (13)	C7—C2—C3—C4	−0.94 (16)
K1^iii—O1—C1—C2	−117.29 (9)	C1—C2—C3—C4	179.10 (10)
K1—O1—C1—C2	164.60 (8)	C7—C2—C3—K1^i	−129.43 (9)
K1^ii—O1—C1—K1	−94.35 (8)	C1—C2—C3—K1^i	50.60 (9)
K1^iii—O1—C1—K1	78.10 (6)	C2—C3—C4—C5	−0.93 (17)
K1^ii—O1—C1—K1^i	−40.84 (13)	K1^i—C3—C4—C5	108.31 (10)
K1^iii—O1—C1—K1^i	131.62 (6)	C8—O3—C5—C6	−3.09 (16)
K1—O1—C1—K1^i	53.52 (7)	C8—O3—C5—C4	177.44 (10)
K1^iv—O2—C1—O1	−116.98 (12)	C3—C4—C5—O3	−177.77 (10)
K1—O2—C1—O1	16.41 (11)	C3—C4—C5—C6	2.74 (17)
K1^i—O2—C1—O1	117.97 (9)	O3—C5—C6—C7	177.93 (10)
K1^iv—O2—C1—C2	64.08 (15)	C4—C5—C6—C7	−2.63 (17)
K1—O2—C1—C2	−162.53 (7)	C3—C2—C7—C6	1.04 (16)
K1^i—O2—C1—C2	−60.98 (9)	C1—C2—C7—C6	−179.00 (10)
K1^iv—O2—C1—K1	−133.39 (13)	C5—C6—C7—C2	0.73 (17)
K1^i—O2—C1—K1	101.55 (4)	C5—O3—C8—C8^v	−170.63 (11)
K1^iv—O2—C1—K1^i	125.05 (13)

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