A three-dimensional supramolecular network built with the zigzag chain complex bis(5-carboxy-1H-imidazole-4-carboxyl­ato)copper(II)

In the title complex, poly[copper(II)-di-μ-5-carboxy-1H-imidazole-4-carboxyl­ato], [Cu(C₅H₃N₂O₄)₂]_n or [Cu(H₂Imda)₂]_n, each imidazole moiety is bonded to the Cu atom via O and N atoms to give a square-planar coordination [Cu—O = 2.014 (2) and 2.016 (2) Å, and Cu—N = 1.982 (3) and 1.992 (2) Å]. The distorted square-pyramidal geometry at the Cu atom results from coordination to an adjacent O atom [Cu—O = 2.305 (2) Å], which generates zigzag chains. There is a sixth, weaker, octahedral coordination to the Cu atom from an inversion-related O atom [Cu—O = 3.090 (2) Å], which links the chains into sheets in the (100) plane. Imidazole moieties in the sheets are linked in the [100] direction by pairs of N—H...O and C—H...O hydrogen bonds, thus generating a three-dimensional network.

S1. Comment

4,5-Imidazoledicarboxylic acid (H₃Imda) can form three types of anions, namely Imda³⁻, HImda²⁻ and H₂Imda⁻, while interacting with metal ions. In the crystal structure of a mixed-valence Co^II,III complex, Na₂[Co₄(Imda)₄(2,2'-bipy)₄].12H₂O (2,2'-bipy is 2,2'-bipyridine; Wang et al., 2004), the Imda³⁻ trianion links adjacent Co atoms through both bidentate CO₂ groups and an imidazole entity into a square plane, which is capped at each corner by 2,2'-bipy ligands; adjacent square planes are linked by water- and CO₂-bound Na⁺ cations into a one-dimensional motif. The dinuclear mixed-valence Mn^III,IV complex Mn₂(dtbsalpn)₂(Imda) {H₂dtbsalpn is 1,3-tris[(3,5-di-tert-butylsalicylidene)amino]propane} follows a similar coordination pattern (Rajendiran et al., 2003). Recently, the crystal structures of M(H₂Imda)₂(H₂O)₂ (M = Co, Cu and Zn), in which the H₂Imda⁻ monoanion coordinates to the metal ion via only one N atom and one O atom of the monodentate CO₂ group, have been reported (Shimizu et al., 2004).

We have obtained metal-cluster complexes by using mixed N– and O-atom ligands under hydrothermal conditions (Yin et al., 2004). We employed the ligand H₃Imda to react with Cu^II in the presence of NaOH in the hope of synthesizing a new metal-cluster complex, but this reaction resulted in the complex [Cu(H₂Imda)₂]_n, (I), being obtained serendipitously.

The title complex is shown in Fig. 1, with selected geometric parameters listed in Table 1. Both H₂Imda⁻ monoanions chelate the Cu atom in a syn mode, which does not resemble that found in M(H₂Imda)₂(H₂O)₂ (M = Co, Cu and Zn) complexes (Shimizu et al., 2004). In the asymmetric unit, the coordination geometry of the Cu atom may be described as slightly distorted square pyramidal, with two O atoms (O1 and O11) of monodentate CO₂ groups and two N atoms (N3 and N13) of two H₂Imda⁻ imidazole moieties in the basal plane, and an O atom (O4ⁱ) of a monodentate CO₂ group of an adjacent H₂Imda⁻ species occupying the apical position. There is a sixth, weaker, Cu1···O coordination to atom O1ⁱⁱ in the inversion-related complex at (1 − x, 1 − y, 1 − z). Such [4 + 1+1]-coordination is not uncommon; a search of the current (July 2004) release of the Cambridge Structural Database (Allen, 2002) for compounds with octahedral coordination at the Cu atom in compounds with a CuN₂O₄ moiety and the sixth Cu—O coordination in the ranges 2.6–2.8, 2.8–3.0, 3.0–3.2 and 3.2–3.4 Å yielded 51, 72, 62 and 61 hits, respectively. Atoms O1, O11, N3 and N13 form a plane with a mean deviation of 0.009 Å; atom Cu1 lies +0.1218 (13) Å from this plane and the remaining two atoms, O4B and O1C (see the Fig. 1 caption for symmetry codes), lie +2.419 (3) and −2.873 (4) Å, respectively, from the basal plane. The two carboxylic acid hydroxy groups form intramolecular O—H···O hydrogen bonds to adjacent carboxyl O atoms (Table 2).

One H₂Imda⁻ monoanion (containing atoms N3, O1 and O4) uses both CO₂ groups and an imidazole N atom to link to adjacent Cu atoms to form a zigzag chain via an n-glide operation, both CO₂ groups being monodentate. Adjacent chains are then linked by inversion-related pairs of the weaker Cu···O1C and O1···CuC interactions [the suffix C corresponds to the symmetry operation (1 − x, 1 − y, 1 − z)] to generate a sheet in the (100) plane, as shown in Fig. 2. These sheets are linked by pairs of N—H···O and C—H···O hydrogen bonds (Table 2), which link the Cu(H₂Imda)₂ moieties into chains extending along [100] (Fig. 3). The combination of these hydrogen bonds and the Cu—O bonds shown in Fig. 2 then develops a three-dimensional network.

S2. Experimental

An aqueous solution (10 ml) of 4,5-imidazoledicarboxylic acid (0.078 g 0.5 mmol) was adjusted to a pH of 5 with 1 M NaOH solution at 333 K. The solution was then transferred to 25 ml Teflon-lined stainless vessel that contained Cu(NO₃)₂·3H₂O (0.182 g 0.75 mmol). The vessel was sealed and heated to 413 K for 12 d, and then cooled at 5 K h⁻¹ to 373 K. The vessel was kept at 373 K for 10 h before being cooled to room temperature. Blue long parallelepiped crystals were separated by hand (yield 13%).

S3. Refinement

All H atoms were found in difference maps and subsequently allowed for in the refinements as riding atoms [C—H = 0.93 Å, N—H = 0.86 Å, O—H = 0.82 Å and U_iso(H) = 1.2U_eq(parent atom)].

Computing details

Data collection: PROCESS-AUTO (Rigaku Corporation, 1998); cell refinement: PROCESS-AUTO; data reduction: TEXSAN (Molecular Structure Corporation & Rigaku Corporation, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997) in WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. A segment of the structure of the title complex, with displacement ellipsoids drawn at the 30% probability level. [Symmetry codes: (A) −1/2 + x, 3/2 − y, −1/2 + z; (B) 1/2 + x, 3/2 − y, 1/2 + z; (C) 1 − x, 1 − y, 1 − z; (D) 3/2 − x, −1/2 + y, 3/2 − z; (E) 1/2 − x, −1/2 + y, 1/2 − z.]
	Fig. 2. A view of the two-dimensional network in the (100) plane. Atoms labeled with an asterisk (*) or a hash (#) are at symmetry positions (1 − x, 1 − y, 1 − z) and (−1/2 + x, 3/2 − y, −1/2 + z), respectively.
	Fig. 3. A view showing the chain of Cu(H2Imda)2 moieties along [100] linked by pairs of N—H···O and C—H···O hydrogen bonds. Atoms labeled with an asterisk (*) are at symmetry position (−1 + x, y, z).

poly[copper(II)-µ-5-carboxy-1H-imidazole-4-carboxylato],

Crystal data

[Cu(C10H6N4O8)]	F(000) = 748
Mr = 373.73	Dx = 1.972 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2318 reflections
a = 7.112 (1) Å	θ = 3.2–28°
b = 14.676 (3) Å	µ = 1.79 mm^−1
c = 12.145 (2) Å	T = 293 K
β = 96.65 (3)°	Parallelepiped, blue
V = 1259.1 (4) Å^3	0.30 × 0.10 × 0.06 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID imaging plate diffractometer	3038 independent reflections
Radiation source: fine-focus sealed tube	2318 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
Detector resolution: 10.00 pixels mm^-1	θmax = 28.0°, θmin = 3.2°
ω scans	h = 0→9
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = 0→19
Tmin = 0.807, Tmax = 0.898	l = −16→15
4554 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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.101	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0536P)^2 + 0.1086P] where P = (Fo^2 + 2Fc^2)/3
3038 reflections	(Δ/σ)max = 0.001
210 parameters	Δρmax = 0.57 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
Cu1	0.38859 (5)	0.57768 (3)	0.61124 (3)	0.02405 (12)
O1	0.5549 (3)	0.61073 (16)	0.49365 (17)	0.0271 (5)
O2	0.5450 (3)	0.69413 (16)	0.33820 (17)	0.0297 (5)
O3	0.2731 (3)	0.77558 (18)	0.20750 (19)	0.0373 (6)
H3	0.3585	0.7533	0.2502	0.045*
O4	−0.0463 (3)	0.78344 (16)	0.19586 (19)	0.0364 (6)
N1	−0.0564 (3)	0.67896 (18)	0.3874 (2)	0.0271 (6)
H1	−0.1691	0.6935	0.3595	0.033*
N3	0.1800 (3)	0.62062 (19)	0.4997 (2)	0.0259 (5)
C2	−0.0097 (4)	0.6333 (2)	0.4825 (2)	0.0292 (7)
H2	−0.0952	0.6134	0.5296	0.035*
C4	0.2560 (4)	0.6611 (2)	0.4129 (2)	0.0222 (6)
C5	0.1096 (4)	0.6985 (2)	0.3421 (2)	0.0233 (6)
C6	0.4674 (4)	0.6563 (2)	0.4138 (2)	0.0233 (6)
C7	0.1067 (4)	0.7553 (2)	0.2418 (3)	0.0298 (7)
O11	0.6017 (3)	0.51959 (15)	0.71053 (16)	0.0275 (5)
O12	0.6598 (3)	0.44032 (16)	0.86885 (18)	0.0322 (5)
O13	0.4420 (4)	0.3655 (2)	1.0074 (2)	0.0453 (7)
H13	0.5063	0.3800	0.9583	0.054*
O14	0.1284 (4)	0.3671 (2)	1.0292 (2)	0.0488 (7)
N11	0.0408 (4)	0.47378 (19)	0.8368 (2)	0.0307 (6)
H11	−0.0599	0.4608	0.8665	0.037*
N13	0.2295 (3)	0.52994 (18)	0.7218 (2)	0.0257 (5)
C12	0.0488 (4)	0.5242 (2)	0.7457 (3)	0.0320 (7)
H12	−0.0548	0.5514	0.7048	0.038*
C14	0.3387 (4)	0.4817 (2)	0.8027 (2)	0.0233 (6)
C15	0.2235 (4)	0.4461 (2)	0.8752 (2)	0.0247 (6)
C16	0.5482 (4)	0.4798 (2)	0.7956 (2)	0.0246 (6)
C17	0.2592 (5)	0.3895 (3)	0.9771 (3)	0.0348 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.01924 (17)	0.0319 (2)	0.02083 (18)	0.00016 (16)	0.00162 (12)	0.00426 (16)
O1	0.0190 (9)	0.0388 (12)	0.0235 (10)	0.0021 (9)	0.0021 (8)	0.0045 (9)
O2	0.0232 (10)	0.0376 (12)	0.0291 (11)	0.0017 (9)	0.0065 (9)	0.0075 (10)
O3	0.0306 (11)	0.0443 (15)	0.0371 (12)	0.0041 (11)	0.0045 (10)	0.0181 (11)
O4	0.0289 (11)	0.0389 (14)	0.0397 (13)	0.0039 (10)	−0.0038 (10)	0.0150 (11)
N1	0.0207 (11)	0.0307 (14)	0.0298 (13)	0.0006 (10)	0.0024 (10)	0.0020 (11)
N3	0.0194 (11)	0.0352 (15)	0.0234 (12)	0.0009 (11)	0.0035 (9)	0.0037 (11)
C2	0.0222 (14)	0.0395 (18)	0.0259 (15)	−0.0001 (13)	0.0027 (12)	0.0075 (14)
C4	0.0206 (13)	0.0235 (15)	0.0223 (13)	0.0003 (11)	0.0023 (10)	0.0004 (12)
C5	0.0213 (13)	0.0253 (15)	0.0237 (13)	0.0000 (11)	0.0048 (11)	−0.0009 (12)
C6	0.0212 (13)	0.0246 (15)	0.0243 (13)	0.0005 (12)	0.0034 (11)	−0.0022 (12)
C7	0.0328 (16)	0.0265 (16)	0.0302 (15)	0.0008 (13)	0.0040 (13)	0.0023 (13)
O11	0.0213 (10)	0.0348 (12)	0.0266 (10)	−0.0008 (9)	0.0036 (8)	0.0062 (9)
O12	0.0220 (10)	0.0420 (14)	0.0324 (11)	0.0020 (10)	0.0018 (8)	0.0112 (10)
O13	0.0416 (14)	0.0533 (17)	0.0425 (14)	0.0078 (12)	0.0112 (11)	0.0247 (13)
O14	0.0460 (15)	0.0536 (17)	0.0504 (15)	0.0041 (13)	0.0210 (12)	0.0188 (14)
N11	0.0239 (12)	0.0385 (16)	0.0309 (13)	−0.0008 (11)	0.0076 (10)	0.0012 (12)
N13	0.0207 (12)	0.0317 (15)	0.0248 (12)	0.0009 (10)	0.0037 (9)	0.0039 (11)
C12	0.0230 (14)	0.0401 (19)	0.0330 (16)	0.0025 (14)	0.0037 (12)	0.0057 (15)
C14	0.0222 (13)	0.0248 (15)	0.0231 (13)	−0.0004 (12)	0.0034 (11)	0.0017 (12)
C15	0.0214 (13)	0.0279 (16)	0.0256 (14)	−0.0013 (12)	0.0064 (11)	−0.0007 (12)
C16	0.0231 (14)	0.0264 (16)	0.0238 (14)	−0.0002 (12)	0.0008 (11)	−0.0002 (13)
C17	0.0357 (17)	0.0341 (17)	0.0361 (17)	0.0033 (15)	0.0106 (14)	0.0071 (15)

Geometric parameters (Å, º)

Cu1—N13	1.982 (3)	C4—C5	1.385 (4)
Cu1—N3	1.992 (2)	C4—C6	1.505 (4)
Cu1—O11	2.014 (2)	C5—C7	1.475 (4)
Cu1—O1	2.016 (2)	O11—C16	1.283 (4)
Cu1—O4^i	2.305 (2)	O12—C16	1.262 (3)
Cu1—O1^ii	3.090 (2)	O13—C17	1.356 (4)
O1—C6	1.279 (4)	O13—H13	0.82
O2—C6	1.254 (4)	O14—C17	1.229 (4)
O3—C7	1.333 (4)	N11—C12	1.338 (4)
O3—H3	0.82	N11—C15	1.389 (4)
O4—C7	1.235 (4)	N11—H11	0.86
O4—Cu1^iii	2.305 (2)	N13—C12	1.352 (4)
N1—C2	1.343 (4)	N13—C14	1.376 (4)
N1—C5	1.389 (4)	C12—H12	0.93
N1—H1	0.86	C14—C15	1.374 (4)
N3—C2	1.354 (4)	C14—C16	1.502 (4)
N3—C4	1.374 (4)	C15—C17	1.487 (4)
C2—H2	0.93
N13—Cu1—N3	97.68 (10)	O2—C6—O1	124.8 (3)
N13—Cu1—O11	83.90 (9)	O2—C6—C4	119.9 (3)
N3—Cu1—O11	172.26 (10)	O1—C6—C4	115.3 (2)
N13—Cu1—O1	173.20 (10)	O4—C7—O3	123.5 (3)
N3—Cu1—O1	83.93 (9)	O4—C7—C5	119.3 (3)
O11—Cu1—O1	93.64 (8)	O3—C7—C5	117.2 (3)
N13—Cu1—O4^i	96.40 (10)	C16—O11—Cu1	113.71 (18)
N3—Cu1—O4^i	96.82 (10)	C17—O13—H13	109.5
O11—Cu1—O4^i	90.51 (9)	C12—N11—C15	108.2 (2)
O1—Cu1—O4^i	89.95 (9)	C12—N11—H11	125.9
O1^ii—Cu1—O4^i	161.07 (9)	C15—N11—H11	125.9
C6—O1—Cu1	112.91 (18)	C12—N13—C14	106.7 (2)
C7—O3—H3	109.5	C12—N13—Cu1	143.0 (2)
C7—O4—Cu1^iii	128.2 (2)	C14—N13—Cu1	110.26 (18)
C2—N1—C5	107.8 (2)	N11—C12—N13	110.2 (3)
C2—N1—H1	126.1	N11—C12—H12	124.9
C5—N1—H1	126.1	N13—C12—H12	124.9
C2—N3—C4	107.2 (2)	C15—C14—N13	108.9 (2)
C2—N3—Cu1	143.1 (2)	C15—C14—C16	134.4 (3)
C4—N3—Cu1	109.27 (18)	N13—C14—C16	116.7 (2)
N1—C2—N3	110.2 (3)	C14—C15—N11	106.1 (3)
N1—C2—H2	124.9	C14—C15—C17	133.5 (3)
N3—C2—H2	124.9	N11—C15—C17	120.4 (3)
N3—C4—C5	108.3 (2)	O12—C16—O11	123.7 (3)
N3—C4—C6	117.2 (2)	O12—C16—C14	121.0 (3)
C5—C4—C6	134.6 (3)	O11—C16—C14	115.3 (2)
C4—C5—N1	106.5 (2)	O14—C17—O13	123.4 (3)
C4—C5—C7	132.5 (3)	O14—C17—C15	120.7 (3)
N1—C5—C7	120.9 (3)	O13—C17—C15	115.9 (3)
N3—Cu1—O1—C6	11.1 (2)	N1—C5—C7—O3	176.0 (3)
O11—Cu1—O1—C6	−176.2 (2)	N13—Cu1—O11—C16	0.0 (2)
O4^i—Cu1—O1—C6	−85.7 (2)	O1—Cu1—O11—C16	−173.6 (2)
N13—Cu1—N3—C2	7.7 (4)	O4^i—Cu1—O11—C16	96.4 (2)
O1—Cu1—N3—C2	−179.0 (4)	N3—Cu1—N13—C12	−6.2 (4)
O4^i—Cu1—N3—C2	−89.7 (4)	O11—Cu1—N13—C12	−178.5 (4)
N13—Cu1—N3—C4	177.9 (2)	O4^i—Cu1—N13—C12	91.6 (4)
O1—Cu1—N3—C4	−8.8 (2)	N3—Cu1—N13—C14	170.3 (2)
O4^i—Cu1—N3—C4	80.4 (2)	O11—Cu1—N13—C14	−2.0 (2)
C5—N1—C2—N3	−1.4 (4)	O4^i—Cu1—N13—C14	−91.9 (2)
C4—N3—C2—N1	1.0 (4)	C15—N11—C12—N13	0.7 (4)
Cu1—N3—C2—N1	171.2 (3)	C14—N13—C12—N11	−0.7 (4)
C2—N3—C4—C5	−0.2 (3)	Cu1—N13—C12—N11	175.8 (3)
Cu1—N3—C4—C5	−174.0 (2)	C12—N13—C14—C15	0.5 (4)
C2—N3—C4—C6	179.8 (3)	Cu1—N13—C14—C15	−177.3 (2)
Cu1—N3—C4—C6	5.9 (3)	C12—N13—C14—C16	−178.6 (3)
N3—C4—C5—N1	−0.6 (3)	Cu1—N13—C14—C16	3.6 (3)
C6—C4—C5—N1	179.5 (3)	N13—C14—C15—N11	−0.1 (3)
N3—C4—C5—C7	174.6 (3)	C16—C14—C15—N11	178.8 (3)
C6—C4—C5—C7	−5.3 (6)	N13—C14—C15—C17	−179.7 (3)
C2—N1—C5—C4	1.2 (4)	C16—C14—C15—C17	−0.8 (6)
C2—N1—C5—C7	−174.7 (3)	C12—N11—C15—C14	−0.4 (4)
Cu1—O1—C6—O2	170.8 (2)	C12—N11—C15—C17	179.3 (3)
Cu1—O1—C6—C4	−10.6 (3)	Cu1—O11—C16—O12	−179.1 (2)
N3—C4—C6—O2	−178.1 (3)	Cu1—O11—C16—C14	1.9 (3)
C5—C4—C6—O2	1.8 (5)	C15—C14—C16—O12	−1.7 (6)
N3—C4—C6—O1	3.2 (4)	N13—C14—C16—O12	177.1 (3)
C5—C4—C6—O1	−176.9 (3)	C15—C14—C16—O11	177.4 (3)
Cu1^iii—O4—C7—O3	−34.9 (5)	N13—C14—C16—O11	−3.7 (4)
Cu1^iii—O4—C7—C5	143.2 (2)	C14—C15—C17—O14	179.0 (4)
C4—C5—C7—O4	−176.8 (3)	N11—C15—C17—O14	−0.6 (5)
N1—C5—C7—O4	−2.2 (5)	C14—C15—C17—O13	−0.9 (6)
C4—C5—C7—O3	1.3 (5)	N11—C15—C17—O13	179.6 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	0.82	1.82	2.642 (3)	175
O13—H13···O12	0.82	1.85	2.653 (3)	165
N1—H1···O2^iv	0.86	2.02	2.837 (3)	158
N11—H11···O12^iv	0.86	2.02	2.825 (3)	156
C2—H2···O1^iv	0.93	2.48	3.133 (4)	128
C12—H12···O11^iv	0.93	2.50	3.160 (4)	129

Symmetry code: (iv) x−1, y, z.