catena-Poly[[bis­(1-ethyl-1H-imidazole)copper(II)]-μ-benzene-1,3-dicarboxyl­ato]

In the title compound, [Cu(C₈H₄O₄)(C₅H₈N₂)₂]_n, each Cu^II atom (site symmetry ) is four-coordinated by two carboxyl­ate O atoms from two different benzene-1,3-dicarboxyl­ate ligands and two N atoms from two 1-ethyl-1H-imidazole ligands in a trans-CuN₂O₂ square-planar arrangement. Each benzene-1,3-dicarboxyl­ate ligand, which possesses crystallographic twofold rotation symmetry, links two adjacent Cu^II atoms in a bis-monodentate mode, resulting in a chain with the 1-ethyl-1H-imidazole ligands attached on both sides.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.035
• wR factor = 0.112
• Data-to-parameter ratio = 17.4

checkCIF/PLATON results

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Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cu1         (2)       2.10

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

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

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S1. Comment

In the presence of secondary ligands, such as 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen), bidentate organic carboxylic acid ligands can construct polymeric structures (Qi et al., 2003). Two coordination positions of metal ions can be occupied by the N atoms from the secondary ligand. The rest of the coordination positions are available for the carboxylate ligands, leading to the formation of a chain structure. We have now selected 1,3-benzenedicarboxylic acid (1,3-H₂BDC) as a bridging ligand and 1-ethyl-1H-imidazole (L) as a secondary ligand, generating the title coordination polymer, [Cu(1,3-BDC)(L)₂], (I), (Table 1) which is reported here.

In compound (I), the Cu^II atom (site symmetry 1) is four-coordinated by two carboxylate O atoms from two different 1,3-BDC ligands, and two N atoms from two L ligands in a square-planar coordination environment (Fig. 1). The Cu—O and Cu—N distances are within their normal ranges (Table 1). A very long Cu1—O2 contact of 2.652 (2)Å would lead to a very distorted CuN₂O₄ octahedron. The complete 1,3-BDC dianion is generated by crystallographic 2-fold symmetry. As shown in Fig. 2, each 1,4-BDC acts as a bis-modentate ligand that binds two Cu^II atoms, generating a unique chain. Interestingly, the L ligands are attached on both sides of the chains.

Related literature

For related literature, see: see: Qi et al. (2003).

S2. Experimental

A mixture of CuCl₂^.2H₂O (0.5 mmol), 1,3-H₂BDC (0.5 mmol), L (0.5 mmol), and H₂O (500 mmol) was adjusted to pH = 5.8 by addition of aqueous NaOH solution, and heated at 458 K for 2 days. After the mixture was slowly cooled to room temperature, blue crystals of (I) were yielded (29% yield).

S3. Refinement

All H atoms on C atoms were positioned geometrically (C—H = 0.93–0.96 Å) and refined as riding, with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C).

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: PROCESS-AUTO (Rigaku, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1990); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. A fragment of the chain structure of (I). Displacement ellipsoids are drawn at the 30% probability level. (H atoms have been omitted). Symmetry codes: (i) 2 - x, y, 1.5 - z; (ii) 2 - x, -y, 1 - z;
	Fig. 2. View of the chain structure of (I).

catena-Poly[[bis(1-ethyl-1H-imidazole)copper(II)]-µ-benzene-1,3-dicarboxylato]

Crystal data

[Cu(C8H4O4)(C5H8N2)2]	F(000) = 868
Mr = 419.92	Dx = 1.468 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 7827 reflections
a = 15.817 (3) Å	θ = 3.0–27.5°
b = 7.2249 (14) Å	µ = 1.18 mm^−1
c = 17.509 (4) Å	T = 293 K
β = 108.29 (3)°	Block, blue
V = 1899.9 (7) Å^3	0.33 × 0.21 × 0.19 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID diffractometer	2178 independent reflections
Radiation source: rotating anode	1801 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
Detector resolution: 10.0 pixels mm^-1	θmax = 27.5°, θmin = 3.1°
ω scans	h = −18→20
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −9→9
Tmin = 0.671, Tmax = 0.798	l = −22→22
9040 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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.112	H-atom parameters constrained
S = 1.15	w = 1/[σ^2(Fo^2) + (0.0642P)^2 + 0.6587P] where P = (Fo^2 + 2Fc^2)/3
2178 reflections	(Δ/σ)max = 0.001
125 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.38 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
C1	1.14471 (14)	−0.2801 (3)	0.55401 (13)	0.0411 (5)
H1	1.1061	−0.3779	0.5332	0.049*
C2	1.2802 (2)	−0.4741 (4)	0.6142 (2)	0.0550 (7)
H2A	1.3402	−0.4590	0.6118	0.066*
H2B	1.2508	−0.5680	0.5753	0.066*
C3	1.26507 (16)	−0.1258 (4)	0.61419 (16)	0.0538 (6)
H3	1.3238	−0.0954	0.6420	0.065*
C4	1.19657 (18)	−0.0070 (4)	0.58733 (19)	0.0528 (7)
H4	1.2000	0.1208	0.5937	0.063*
C5	1.02334 (13)	0.2495 (3)	0.61465 (13)	0.0382 (5)
C6	1.01289 (13)	0.3540 (3)	0.68534 (13)	0.0364 (5)
C7	1.0000	0.2586 (4)	0.7500	0.0328 (6)
H7	1.0000	0.1299	0.7500	0.039*
C8	1.01330 (17)	0.5460 (4)	0.68607 (19)	0.0514 (7)
H8	1.0225	0.6109	0.6435	0.062*
C9	1.0000	0.6412 (5)	0.7500	0.0596 (10)
H9	1.0000	0.7699	0.7500	0.072*
C10	1.2842 (2)	−0.5379 (5)	0.6975 (2)	0.0709 (9)
H10A	1.3160	−0.6528	0.7095	0.106*
H10B	1.2248	−0.5549	0.6998	0.106*
H10C	1.3142	−0.4463	0.7363	0.106*
N1	1.12108 (11)	−0.1053 (3)	0.54914 (11)	0.0399 (4)
N2	1.23206 (12)	−0.2991 (3)	0.59294 (12)	0.0432 (5)
O1	0.99755 (10)	0.0808 (2)	0.60769 (9)	0.0419 (4)
O2	1.05357 (11)	0.3279 (3)	0.56545 (10)	0.0507 (4)
Cu1	1.0000	0.0000	0.5000	0.03463 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0336 (10)	0.0512 (14)	0.0385 (11)	−0.0042 (9)	0.0114 (9)	0.0039 (10)
C2	0.0433 (14)	0.0570 (17)	0.0656 (18)	0.0091 (11)	0.0181 (13)	0.0106 (12)
C3	0.0326 (11)	0.0609 (16)	0.0605 (15)	−0.0072 (11)	0.0041 (11)	−0.0050 (13)
C4	0.0374 (14)	0.0526 (16)	0.0620 (17)	−0.0073 (10)	0.0064 (13)	−0.0069 (12)
C5	0.0279 (9)	0.0486 (13)	0.0346 (10)	0.0005 (8)	0.0049 (9)	0.0071 (9)
C6	0.0232 (9)	0.0399 (12)	0.0430 (11)	−0.0007 (8)	0.0057 (8)	0.0031 (9)
C7	0.0241 (12)	0.0329 (15)	0.0368 (14)	0.000	0.0027 (11)	0.000
C8	0.0448 (13)	0.0417 (13)	0.0746 (19)	0.0004 (10)	0.0287 (13)	0.0125 (12)
C9	0.060 (2)	0.0329 (19)	0.097 (3)	0.000	0.040 (2)	0.000
C10	0.0600 (19)	0.078 (2)	0.067 (2)	0.0048 (15)	0.0088 (16)	0.0277 (16)
N1	0.0298 (8)	0.0495 (12)	0.0382 (9)	−0.0041 (8)	0.0075 (7)	0.0015 (8)
N2	0.0311 (9)	0.0544 (12)	0.0437 (10)	0.0017 (8)	0.0108 (8)	0.0065 (9)
O1	0.0425 (8)	0.0473 (10)	0.0361 (8)	−0.0061 (7)	0.0127 (7)	−0.0019 (7)
O2	0.0496 (9)	0.0599 (12)	0.0455 (9)	−0.0032 (8)	0.0189 (8)	0.0111 (8)
Cu1	0.0287 (2)	0.0414 (2)	0.0322 (2)	−0.00322 (13)	0.00727 (16)	0.00134 (14)

Geometric parameters (Å, º)

Cu1—N1	1.9881 (18)	C4—H4	0.9300
Cu1—O1	1.9858 (16)	C5—O2	1.245 (3)
Cu1—O1^i	1.9858 (16)	C5—O1	1.280 (3)
Cu1—N1^i	1.9881 (18)	C5—C6	1.502 (3)
C1—N1	1.313 (3)	C6—C8	1.387 (3)
C1—N2	1.342 (3)	C6—C7	1.394 (3)
C1—H1	0.9300	C7—C6^ii	1.394 (3)
C2—N2	1.462 (3)	C7—H7	0.9300
C2—C10	1.513 (4)	C8—C9	1.385 (4)
C2—H2A	0.9700	C8—H8	0.9300
C2—H2B	0.9700	C9—C8^ii	1.385 (4)
C3—C4	1.346 (4)	C9—H9	0.9300
C3—N2	1.362 (3)	C10—H10A	0.9600
C3—H3	0.9300	C10—H10B	0.9600
C4—N1	1.370 (3)	C10—H10C	0.9600
O1^i—Cu1—O1	180.0	C8—C6—C5	120.6 (2)
O1^i—Cu1—N1^i	90.26 (8)	C7—C6—C5	120.2 (2)
O1—Cu1—N1^i	89.74 (8)	C6^ii—C7—C6	120.8 (3)
O1^i—Cu1—N1	89.74 (8)	C6^ii—C7—H7	119.6
O1—Cu1—N1	90.26 (8)	C6—C7—H7	119.6
N1^i—Cu1—N1	180.0	C9—C8—C6	120.2 (3)
N1—C1—N2	111.0 (2)	C9—C8—H8	119.9
N1—C1—H1	124.5	C6—C8—H8	119.9
N2—C1—H1	124.5	C8—C9—C8^ii	120.5 (4)
N2—C2—C10	111.7 (3)	C8—C9—H9	119.8
N2—C2—H2A	109.3	C8^ii—C9—H9	119.8
C10—C2—H2A	109.3	C2—C10—H10A	109.5
N2—C2—H2B	109.3	C2—C10—H10B	109.5
C10—C2—H2B	109.3	H10A—C10—H10B	109.5
H2A—C2—H2B	107.9	C2—C10—H10C	109.5
C4—C3—N2	107.0 (2)	H10A—C10—H10C	109.5
C4—C3—H3	126.5	H10B—C10—H10C	109.5
N2—C3—H3	126.5	C1—N1—C4	106.3 (2)
C3—C4—N1	108.8 (2)	C1—N1—Cu1	127.75 (15)
C3—C4—H4	125.6	C4—N1—Cu1	125.94 (18)
N1—C4—H4	125.6	C1—N2—C3	106.9 (2)
O2—C5—O1	123.2 (2)	C1—N2—C2	126.0 (2)
O2—C5—C6	120.5 (2)	C3—N2—C2	126.9 (2)
O1—C5—C6	116.28 (18)	C5—O1—Cu1	105.65 (14)
C8—C6—C7	119.2 (2)

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