catena-Poly[bis­[(1,10-phenanthroline)cobalt(II)]-μ4-3,6-dicarb­oxy­cyclo­hexane-1,2,4,5-tetra­carboxyl­ato]

Wei Xu

doi:10.1107/S1600536811019970

. 2011 Jun 4;67(Pt 7):m832–m833. doi: 10.1107/S1600536811019970

catena-Poly[bis[(1,10-phenanthroline)cobalt(II)]-μ₄-3,6-dicarboxycyclohexane-1,2,4,5-tetracarboxylato]

Wei Xu ^a,^*

PMCID: PMC3151899 PMID: 21836841

Abstract

In the title compound, [Co₂(C₁₂H₈O₁₂)(C₁₂H₈N₂)₂]_n, each 3,6-dicarboxycyclohexane-1,2,4,5-tetracarboxylate (H₂chhc⁴⁻) anion has crystallographically imposed C ₂ symmetry and bridges four six-coordinate Co atoms, generating polymeric chains running along [010]. These chains are further extended into a three-dimensional network via O—H⋯O hydrogen-bonding interactions and interchain π–π stacking interactions [centroid–centroid distance = 3.662 (2) Å].

Related literature

For the design and synthesis of coordination polymer complexes and their potential applications, see: Biradha et al. (2006 ▶); Bauer et al. (2007 ▶); Zacher et al. (2011 ▶). For the 1,2,3,4,5,6-cyclohexanehexacarboxylate ligand, see: Li et al. (2006 ▶); Wang et al. (2008 ▶); Thuéry & Masci (2010 ▶). For related structures, see: Konar et al. (2004 ▶); Li et al. (2006 ▶).

Experimental

Crystal data

[Co₂(C₁₂H₈O₁₂)(C₁₂H₈N₂)₂]
M _r = 822.46
Monoclinic,
a = 22.180 (4) Å
b = 8.9520 (18) Å
c = 16.426 (3) Å
β = 93.33 (3)°
V = 3256.0 (11) Å³
Z = 4
Mo Kα radiation
μ = 1.10 mm⁻¹
T = 295 K
0.31 × 0.23 × 0.15 mm

Data collection

Siemens P4 diffractometer
Absorption correction: ψ scan (XSCANS; Siemens, 1996 ▶) T _min = 0.702, T _max = 0.784
4566 measured reflections
3753 independent reflections
3312 reflections with I > 2σ(I)
R _int = 0.022
3 standard reflections every 97 reflections intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.083
S = 1.03
3753 reflections
248 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Data collection: XSCANS (Siemens, 1996 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811019970/sj5153sup1.cif

e-67-0m832-sup1.cif^{(19KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811019970/sj5153Isup2.hkl

e-67-0m832-Isup2.hkl^{(184.1KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Co1—O1	2.2002 (13)
Co1—O2	2.0890 (13)
Co1—O5ⁱ	2.1211 (13)
Co1—O6ⁱ	2.1519 (13)
Co1—N1	2.1012 (15)
Co1—N2	2.1016 (15)

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Symmetry code: (i) Inline graphic .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H4A⋯O2ⁱⁱ	0.79 (3)	1.89 (3)	2.627 (2)	156 (2)

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Symmetry code: (ii) Inline graphic .

Acknowledgments

This project was supported by the Scientific Research Fund of the Zhejiang Provincial Education Department (grant No. Y201017782) and the Scientific Research Fund of Ningbo University (grant No. XKL09078). Grateful thanks are also extended to the K. C. Wong Magna Fund in Ningbo University.

supplementary crystallographic information

Comment

The rational design and construction of metal-organic coordination polymers with flexible multidentate ligands have received more and more attention due to their intriguing structural topologies and novel properties for potential applications (Biradha, et al., 2006; Bauer, et al., 2007; Zacher, et al., 2011). As a typical flexible cycloalkane polycarboxylic acid ligand, we have focused on the 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H₆chhc) whose coordination chemistry remains practically unexplored. We were particularly aware that the greater flexibility of this ligand would make the prediction and control of the final coordination networks that it generates more difficult. (Wang, et al., 2008; Thuéry & Masci, 2010). Herein, we report a new cobalt coordination polymer, [Co₂(phen)₂(H₂chhc)]_n, resulting from reaction of Co²⁺ cations, phen and H₆chhc under hydrothermal conditions. It is isostructural with the previously reported [Ni₂(phen)₂(H₂chhc)]_n complex (Li, et al., 2006).

The asymmetric unit of the title compound consists of one Co²⁺ cation, one phen ligand and one-half of a H₂chhc^4- anion lying across a twofold rotation axis. The Co atoms are each in an octahedral environment defined by two N atoms of one phen ligand and four O atoms of two carboxylate groups from different H₂chhc^4- anions. The Co-O bond lengths fall in the range 2.089 (1)-2.200 (1) Å and the two Co-N distances are 2.101 (2) and 2.102 (2) Å (Table 1), thus falling in the expected region (Konar, et al., 2004). The octahedral coordination around the Co atoms are strongly distorted since the diametrical and non-diametrical bond angles indicate signficant deviations from 180° and 90°, respectively. The H₂chhc^4- ligands assume an e,e,e,e,e,e-conformation with the central ring adopting a chair-shaped configuration, the carboxylate and carboxyl groups being located at the equatorical sites. Each carboxylate group of the H₂chhc^4- anion chelates one Co atom. As a result, the H₂chhc^4- anions are each coordinated to four [Co(phen)]²⁺ units, leading to polymeric chains [Co₂(phen)₂(H₂chhc)]_n running along the [010] direction with the phen ligands exo-orientated (Fig. 1). The phen ligands of two adjacent supramolecular chains are stacked via the quinoline fragments (centroid-centroid distance = 3.662 (2) Å). Obviously, such π-π stacking interactions are responsible for the supramolecular assembly of the one-dimensional chains into two-dimensional layers parallel to (001) (Fig. 2). The layers are further connected to form a three-dimensional framework via interlayer O-H···O hydrogen bonds (d(O4···O2^#1 = 2.627 (2) Å, <O4-H4A···O2^#1 = 156 (2)°, #1 = -x, 2-y, -z).

Experimental

CoCl₂.6H₂O (0.238 g, 1.0 mmol), H₆chhc (0.173 g, 0.5 mmol), phen (0.200 g, 1.0 mmol) and NaOH 1.5 mL (1 M) were stirred in 20 mL H₂O. The resulting mixture was placed in a 23 mL Teflon-lined autoclave and heated at 170 °C for 3 days. The reaction system was cooled to room temperature at a rate of 20 °C/h, and small amount of pink crystals of the title complex was obtained.