Di-μ-chlorido-bis­{[2-(8-quinol­yloxy)­acetato-κ3 N,O 1,O 2]copper(II)}

Zhi-hong Wang; Jun Fan; Wei-guang Zhang; Jun Wang

doi:10.1107/S1600536808031656

. 2008 Oct 18;64(Pt 11):m1446. doi: 10.1107/S1600536808031656

Di-μ-chlorido-bis{[2-(8-quinolyloxy)acetato-κ³ N,O ¹,O ²]copper(II)}

Zhi-hong Wang ^a, Jun Fan ^a, Wei-guang Zhang ^a,^*, Jun Wang ^a

PMCID: PMC2959508 PMID: 21580885

Abstract

The title compound, [Cu₂(C₁₁H₈NO₃)₂Cl₂], is a bicopper(II) complex. Each Cu^II ion is five-coordinated by two O atoms and one N atom from the (8-quinolyloxy)acetate ligand, and by two μ₂-chloride ligands, thus exhibiting a distorted square-pyramidal CuCl₂NO₂ coordination environment. Each (8-quinolyloxy)acetate anion acts as a tridentate chelating ligand. In the crystal structure, adjacent quinolyl rings are involved in strong π–π stacking interactions, with interplanar distances of 3.549 (5) and 3.763 (5) Å, thereby forming a two-dimensional planar network perpendicular to the ab plane. Furthermore, a weak interaction [2.750 (4) Å] is observed within these planes between one Cu^II ion and a carboxylate O atom from a ligand in an adjacent molecule, which also contributes to the stability of the structure.

Related literature

For general background, see: Hong et al. (2006 ▶); Sudik et al. (2005 ▶); Dong et al. (2007 ▶); Tong et al., 1999 ▶. For related structures, see: Wang & Lu (2004 ▶); Wang et al. (2005 ▶). Koelsch (1931 ▶) reports the synthesis of the (8-quinolyloxy)acetate ligand.

Experimental

Crystal data

[Cu₂(C₁₁H₈NO₃)₂Cl₂]
M _r = 602.35
Monoclinic,
a = 8.3796 (17) Å
b = 19.195 (4) Å
c = 13.392 (3) Å
β = 98.85 (3)°
V = 2128.4 (8) Å³
Z = 4
Mo Kα radiation
μ = 2.29 mm⁻¹
T = 298 (2) K
0.36 × 0.30 × 0.24 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.462, T _max = 0.582
11625 measured reflections
4179 independent reflections
2737 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.087
S = 1.01
4179 reflections
307 parameters
H-atom parameters constrained
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.47 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 1999 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶) and ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808031656/zl2140sup1.cif

e-64-m1446-sup1.cif^{(23.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808031656/zl2140Isup2.hkl

e-64-m1446-Isup2.hkl^{(204.8KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

This work has been supported by the National Natural Science Foundation of China (grant No. 20771040).

supplementary crystallographic information

Comment

Metal–polycarboxylate coordination polymers have attracted considerable attention in past decades, owing to their fascinating architectures and potential applications as new materials in gas absorption, catalysis and luminescence (Dong et al., 2007; Sudik et al., 2005). However, only a limited amount of work has been reported on the use of benzene polycarboxylate ligands that combine characteristics of both flexibility and rigidity (Hong et al., 2006; Wang & Lu, 2004; Wang et al., 2005).

Herein, we report the crystal structure of the title compound, (I). A perspective view of the binuclear copper complex (I), showing the atomic numbering scheme, is depicted in Fig. 1. The coordination geometry around the Cu^II ion may be described as a slightly distorted square pyramid, the basal plane being defined by one N atom, two O atoms from (8-quinolyloxy)acetate and one chloride anion; the apical position is occupied by another bridging chloride anion from the adjacent copper(II) unit, this atom being coordinated at a longer distance [Cu1—Cl2 = 2.823 (14) Å and Cu2—Cl1 = 2.776 (12) Å]. Thus, two chlorides form bi-bridges between two Cu^II ions, which link two Cu^II units to generate a binuclear complex. Each (8-quinolyloxy)acetate molecule acts as a tridentate chelating ligand. The inequivalence of the carboxylate C—O distances may be correlated with their involvement in bonding with the Cu^II centres.

In the crystal structure, adjacent quinolinyl rings are involved in strong π-π stacking attractions by partial overlapping of π-electron densities (Tong et al., 1999). The centroid-centroid separation between rings A (atoms N1/C1—C4/C9) and Bⁱ [atoms C15—C20; symmetry code: (i): - x, 1/2 + y, 1/2 - z] is 3.763 (5) Å, and the other between rings C (atoms C4—C9) and D^j [atoms N2/C12—C15/C20; symmetry code: (j): 1- x, 1/2 + y, 1/2 - z] is 3.549 (5) Å. Considering these π-π intermolecular attractions, they imply the formation of a two-dimensional planar network perpendicular to the ab plane (Fig. 2). Furthermore, a weak interaction [2.750 (4) Å] is observed between the atom Cu1 and carboxylate oxygen atom O6^k [symmetry code: (k): -1+x,y,z] from the ligand in adjacent Cu^II unit, thus contributing to the two-dimensional network's stability (Fig. 2).

Experimental

The ligand quinolin-8-yloxyacetic acid was prepared according to the general procedure reported by Koelsch (1931). An aqueous solution of CuCl₂.2 H₂O (0.057 g, 0.33 mmol) was added dropwise to the mixture of Y(NO₃)₃.6 H₂O (0.064 g, 0.17 mmol) and quinolin-8-yloxyacetic acid (0.103 g, 0.50 mmol) in aqueous solution at 343 K, and the pH value was adjusted to be about 5 with NaOH. After stirring for 0.5 h, the resulting green solution was filtered. Slow evaporation from the filtrate for several weeks yielded green block-like crystals suitable for X-ray analysis. IR (KBr pellet, cm^-1): 3051, 1650, 1628, 1505, 1429, 1379, 1317, 1263, 1115, 837, 772.