catena-Poly­[bis­[(2,2-bi­pyridine-[kappa]²N,N')­copper(II)]-[mu]₄-1,2,4,5-benzene­tetra­carboxyl­ato-[kappa]⁴O¹:O²:O³:O⁴]

In the title complex, [Cu₂(C₁₀H₂O₈)(C₁₀H₈N₂)₂]_n, the Cu^II cation has a four-coordinated environment, completed by two carboxyl O atoms belonging to two 1,2,4,5-benzene­tetra­carboxyl­ate anions (TCB^4-) and two N atoms from one 2,2'-bi­pyridine (2,2'-bipy) ligand, forming a distorted square-planar geometry. The [Cu(2,2'-bipy)]²⁺ moieties are bridged by TCB^4- anions, which lie about inversion centres, forming an infinite one-dimensional coordination polymer with a double-chain structure along the a axis. A two-dimensional network structure is formed via a face-to-face [pi]-[pi] interaction between the 2,2'-bipy rings belonging to two adjacent double chains, at a distance of approximately 3.56 Å.

S1. Comment

In recent years, the design and construction of metal-organic coordination polymers have been extensively studied, due to the crystallographic diversity of these compounds and their potential applications in catalysis, nonlinear optics and gas adsorption (Chen et al., 2003; Eddaoudi et al., 2001; Shi et al., 2003; Stein et al., 1993). In this field, 1,2,4,5-benzenetetracarboxylic acid (H₄TCB) is a good bridging ligand and numerous complexes with TCB⁴⁻ anions have been prepared. The TCB⁴⁻ anions usually coordinate to metal ions in a µ₂-bridging mode (Hu et al., 2003) and occasionally in a µ₄-bridging mode (Shi et al., 2001), while in the title complex, [Cu(2,2'-bpy)(TCB)_0.5]_n, (I), each TCB⁴⁻ anion binds four Cu^II ions in tetramonodentate mode. Moreover, it should be pointed out that new complexes are constantly being obtained via different reaction conditions, such as the use of different solvents, synthesis conditions or H-acceptors. \sch

In (I), each Cu^II cation has a four-coordinated environment, completed by two carboxyl O atoms belonging to two TCB⁴⁻ anions and two N atoms from one 2,2'-bipy ligand (Fig. 1). The bond lengths around the Cu^II centres are 1.956 (2) for Cu1—O3, 1.972 (2) for Cu1—O2ⁱ, 1.978 (2) for Cu1—N2 and 1.987 (2) Å for Cu1—N1 [symmetry code: (i) −x, 1 − y, −z]. The N2—Cu1—N1, O3—Cu1—O2ⁱ, O3—Cu1—N1 and O2ⁱ—Cu1—N2 bond angles are in the range 81.80 (10)–98.33 (10)°, which is significantly different from the ideal value.

From these bond angles and lengths, we can best describe the coordination of the Cu^II cation as a distorted square-planar geometry. Moreover, the coordination mode of the TCB⁴⁻ anion is similar to that in [Cu₂(TCB)(phen)₂]_n·(H₂O)_n (Shi et al., 2001): the four carboxylate groups are all deprotonated and coordinate to four Cu^II cations in a monodentate fashion, forming an infinite one-dimensional ribbon-like double-chain structure with cavities of approximately 4.5 × 6.1 Å along the a axis (Fig. 1). The Cu1···Cu1ⁱ and Cu1ⁱ···Cu1ⁱⁱ separation distances are 7.931 and 7.279 Å, respectively [symmetry code: (ii) x − 1, y, z]. Furthermore, there are π–π interactions between the aromatic rings of 2,2'-bipy ligands belonging to two adjacent double chains, with a distance of approximately 3.56 Å, resulting in a two-dimensional network structure (Fig. 2).

S2. Experimental

A solution (10 ml) of dimethylformamide containing CuCl₂·2H₂O (0.5 mmol, 0.085 g) and H₄TCB (0.5 mmol, 0.127 g) was added slowly to a solution (10 ml) of dimethylformamide containing 2,2'-bipy (0.5 mmol, 0.078 g). The mixture was stirred for 30 min and left to stand at room temperature for about a month. Light-blue prism-shaped crystals of (I) were obtained.

S3. Refinement

The all H atoms were positioned geometrically and allowed to ride on their parent atoms at distances of 0.93 Å, with U_iso(H) = 1.2U_eq(parent atom).

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The coordination environment of the Cu^II cation in (I), with the atom-numbering scheme, showing the double-chain structure with cavities of approximately 4.5 × 6.1 Å, viewed along the b axis [symmetry codes: (i) −x, 1 − y, −z; (ii) x − 1, y, z Query]. Displacement ellipsoids are drawn at the ??% probability level and H atoms have been omitted for clarity.
	Fig. 2. A view of the two-dimensional network structure in (I), formed by π–π interactions.

catena-Poly[bis[(2,2-bipyridine-κ²N,N')cobalt(II)]-µ-1,2,4,5- benzenetetracarboxylato-κ⁴O¹:O²:O³:O⁴]

Crystal data

[Cu2(C10H2O8)(C10H8N2)2]	F(000) = 696
Mr = 689.56	Dx = 1.796 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 532 reflections
a = 7.2794 (7) Å	θ = 2.4–22.0°
b = 12.5009 (12) Å	µ = 1.73 mm^−1
c = 14.4436 (14) Å	T = 273 K
β = 104.021 (2)°	Prism, blue
V = 1275.2 (2) Å^3	0.32 × 0.29 × 0.24 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	2263 independent reflections
Radiation source: fine-focus sealed tube	2179 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
ϕ and ω scans	θmax = 25.1°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −8→8
Tmin = 0.582, Tmax = 0.663	k = −14→14
9055 measured reflections	l = −17→17

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.036	H-atom parameters constrained
wR(F^2) = 0.087	w = 1/[σ^2(Fo^2) + (0.0367P)^2 + 1.7086P] where P = (Fo^2 + 2Fc^2)/3
S = 1.16	(Δ/σ)max < 0.001
2263 reflections	Δρmax = 0.48 e Å^−3
200 parameters	Δρmin = −0.29 e Å^−3
0 restraints	Extinction correction: SHELXTL (Bruker, 2000), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00

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
Cu1	0.12671 (5)	0.51437 (3)	0.28264 (2)	0.02411 (15)
O1	−0.4480 (3)	0.5500 (2)	−0.24253 (15)	0.0426 (6)
O2	−0.2239 (3)	0.43644 (19)	−0.17381 (14)	0.0330 (5)
O3	−0.0839 (3)	0.44152 (18)	0.19560 (14)	0.0324 (5)
O4	−0.1984 (3)	0.59946 (19)	0.22122 (15)	0.0382 (5)
N1	0.1225 (3)	0.4282 (2)	0.39770 (16)	0.0238 (5)
N2	0.2687 (3)	0.6143 (2)	0.38029 (16)	0.0242 (5)
C1	0.0426 (4)	0.3322 (3)	0.3988 (2)	0.0306 (7)
H1	−0.0242	0.3022	0.3416	0.037*
C2	0.0567 (4)	0.2764 (3)	0.4827 (2)	0.0339 (7)
H2	0.0002	0.2096	0.4819	0.041*
C3	0.1547 (4)	0.3203 (3)	0.5674 (2)	0.0325 (7)
H3	0.1661	0.2834	0.6244	0.039*
C4	0.2364 (4)	0.4200 (2)	0.5671 (2)	0.0270 (6)
H4	0.3016	0.4517	0.6238	0.032*
C5	0.2193 (4)	0.4722 (2)	0.4807 (2)	0.0223 (6)
C6	0.2981 (4)	0.5794 (2)	0.47109 (18)	0.0214 (6)
C7	0.3906 (4)	0.6431 (2)	0.5471 (2)	0.0281 (7)
H7	0.4128	0.6180	0.6094	0.034*
C8	0.4487 (4)	0.7443 (3)	0.5284 (2)	0.0344 (7)
H8	0.5097	0.7885	0.5782	0.041*
C9	0.4154 (5)	0.7792 (3)	0.4349 (2)	0.0363 (7)
H9	0.4526	0.8473	0.4211	0.044*
C10	0.3270 (4)	0.7120 (3)	0.3631 (2)	0.0328 (7)
H10	0.3069	0.7351	0.3003	0.039*
C11	−0.2089 (4)	0.5153 (2)	0.17650 (19)	0.0233 (6)
C12	−0.3650 (4)	0.5008 (2)	0.08769 (19)	0.0189 (6)
C13	−0.3111 (4)	0.4928 (2)	0.00192 (19)	0.0197 (6)
H13	−0.1830	0.4877	0.0033	0.024*
C14	−0.4422 (4)	0.4924 (2)	−0.08563 (19)	0.0186 (5)
C15	−0.3708 (4)	0.4925 (2)	−0.1755 (2)	0.0221 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0210 (2)	0.0394 (3)	0.0107 (2)	0.00225 (14)	0.00139 (14)	−0.00150 (13)
O1	0.0477 (14)	0.0616 (16)	0.0207 (11)	0.0184 (12)	0.0126 (10)	0.0148 (11)
O2	0.0282 (11)	0.0565 (14)	0.0166 (10)	0.0131 (10)	0.0098 (8)	0.0046 (9)
O3	0.0264 (11)	0.0454 (13)	0.0196 (10)	0.0097 (10)	−0.0060 (8)	−0.0056 (9)
O4	0.0401 (13)	0.0430 (13)	0.0261 (12)	0.0014 (11)	−0.0028 (9)	−0.0140 (10)
N1	0.0188 (11)	0.0359 (14)	0.0161 (11)	0.0012 (10)	0.0028 (9)	−0.0032 (10)
N2	0.0206 (12)	0.0339 (14)	0.0177 (12)	0.0014 (10)	0.0041 (9)	0.0012 (10)
C1	0.0275 (15)	0.0352 (17)	0.0288 (16)	−0.0013 (13)	0.0062 (13)	−0.0077 (13)
C2	0.0335 (17)	0.0290 (16)	0.0422 (19)	0.0026 (13)	0.0151 (14)	0.0015 (14)
C3	0.0330 (17)	0.0388 (18)	0.0274 (16)	0.0074 (14)	0.0104 (13)	0.0065 (13)
C4	0.0253 (15)	0.0374 (17)	0.0185 (14)	0.0058 (13)	0.0058 (11)	−0.0004 (12)
C5	0.0161 (13)	0.0329 (16)	0.0184 (14)	0.0049 (11)	0.0053 (11)	−0.0030 (11)
C6	0.0173 (13)	0.0320 (16)	0.0152 (13)	0.0054 (11)	0.0043 (10)	−0.0017 (11)
C7	0.0253 (15)	0.0368 (17)	0.0202 (14)	0.0023 (12)	0.0018 (12)	−0.0013 (12)
C8	0.0291 (16)	0.0392 (18)	0.0331 (17)	−0.0032 (13)	0.0042 (13)	−0.0111 (14)
C9	0.0371 (18)	0.0309 (17)	0.0421 (19)	−0.0032 (14)	0.0118 (15)	0.0004 (14)
C10	0.0340 (17)	0.0396 (18)	0.0256 (16)	0.0012 (14)	0.0087 (13)	0.0060 (13)
C11	0.0212 (14)	0.0376 (17)	0.0104 (13)	−0.0027 (12)	0.0024 (11)	−0.0008 (11)
C12	0.0180 (13)	0.0207 (14)	0.0159 (13)	−0.0002 (10)	−0.0002 (11)	0.0013 (10)
C13	0.0168 (13)	0.0261 (15)	0.0157 (14)	0.0006 (11)	0.0026 (11)	−0.0001 (10)
C14	0.0190 (13)	0.0224 (14)	0.0135 (13)	0.0006 (10)	0.0023 (10)	0.0000 (10)
C15	0.0206 (14)	0.0309 (15)	0.0144 (14)	−0.0027 (11)	0.0032 (11)	−0.0020 (11)

Geometric parameters (Å, º)

Cu1—O3	1.956 (2)	C4—C5	1.387 (4)
Cu1—O2^i	1.972 (2)	C4—H4	0.9300
Cu1—N2	1.978 (2)	C5—C6	1.478 (4)
Cu1—N1	1.987 (2)	C6—C7	1.391 (4)
O1—C15	1.227 (4)	C7—C8	1.381 (5)
O2—C15	1.274 (3)	C7—H7	0.9300
O2—Cu1^i	1.972 (2)	C8—C9	1.384 (5)
O3—C11	1.278 (4)	C8—H8	0.9300
O4—C11	1.228 (4)	C9—C10	1.368 (5)
N1—C1	1.336 (4)	C9—H9	0.9300
N1—C5	1.351 (4)	C10—H10	0.9300
N2—C10	1.335 (4)	C11—C12	1.504 (4)
N2—C6	1.349 (3)	C12—C13	1.391 (4)
C1—C2	1.382 (4)	C12—C14^ii	1.399 (4)
C1—H1	0.9300	C13—C14	1.387 (4)
C2—C3	1.373 (4)	C13—H13	0.9300
C2—H2	0.9300	C14—C12^ii	1.399 (4)
C3—C4	1.381 (4)	C14—C15	1.511 (4)
C3—H3	0.9300
O3—Cu1—O2^i	90.54 (9)	N2—C6—C5	114.3 (2)
O3—Cu1—N2	160.94 (9)	C7—C6—C5	124.8 (2)
O2^i—Cu1—N2	98.33 (10)	C8—C7—C6	118.9 (3)
O3—Cu1—N1	96.71 (9)	C8—C7—H7	120.6
O2^i—Cu1—N1	156.50 (9)	C6—C7—H7	120.6
N2—Cu1—N1	81.80 (10)	C7—C8—C9	119.4 (3)
C15—O2—Cu1^i	105.94 (18)	C7—C8—H8	120.3
C11—O3—Cu1	102.07 (18)	C9—C8—H8	120.3
C1—N1—C5	119.4 (3)	C10—C9—C8	119.0 (3)
C1—N1—Cu1	126.3 (2)	C10—C9—H9	120.5
C5—N1—Cu1	114.28 (19)	C8—C9—H9	120.5
C10—N2—C6	119.6 (3)	N2—C10—C9	122.2 (3)
C10—N2—Cu1	125.5 (2)	N2—C10—H10	118.9
C6—N2—Cu1	114.88 (19)	C9—C10—H10	118.9
N1—C1—C2	121.6 (3)	O4—C11—O3	123.7 (3)
N1—C1—H1	119.2	O4—C11—C12	119.3 (3)
C2—C1—H1	119.2	O3—C11—C12	116.7 (2)
C3—C2—C1	119.5 (3)	C13—C12—C14^ii	118.9 (3)
C3—C2—H2	120.3	C13—C12—C11	116.8 (2)
C1—C2—H2	120.3	C14^ii—C12—C11	123.9 (3)
C2—C3—C4	119.3 (3)	C14—C13—C12	122.1 (3)
C2—C3—H3	120.3	C14—C13—H13	118.9
C4—C3—H3	120.3	C12—C13—H13	118.9
C3—C4—C5	118.8 (3)	C13—C14—C12^ii	119.0 (3)
C3—C4—H4	120.6	C13—C14—C15	118.7 (2)
C5—C4—H4	120.6	C12^ii—C14—C15	122.2 (2)
N1—C5—C4	121.4 (3)	O1—C15—O2	124.0 (3)
N1—C5—C6	114.6 (2)	O1—C15—C14	119.4 (2)
C4—C5—C6	123.9 (3)	O2—C15—C14	116.4 (2)
N2—C6—C7	120.9 (3)

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