Poly[[di­aqua­[μ-1,4-bis(pyridin-4-ylmeth­yl)piperazine-κ2 N:N′]{μ-2,2′-[(1,4-phenyl­ene)bis(­oxy)]di­acetato-κ2 O:O′}cobalt(II)] penta­hydrate]

Alexander D Sample; Robert L LaDuca

doi:10.1107/S1600536814008745

. 2014 May 3;70(Pt 6):m198–m199. doi: 10.1107/S1600536814008745

Poly[[diaqua[μ-1,4-bis(pyridin-4-ylmethyl)piperazine-κ² N:N′]{μ-2,2′-[(1,4-phenylene)bis(oxy)]diacetato-κ² O:O′}cobalt(II)] pentahydrate]

Alexander D Sample ^a, Robert L LaDuca ^a,^*

PMCID: PMC4051029 PMID: 24940193

Abstract

In the title compound, {[Co(C₁₀H₈O₆)(C₁₆H₂₀N₄)(H₂O)₂]·5H₂O}_n, octahedrally coordinated Co^II ions on crystallographic inversion centres are bound by trans O atoms belonging to two hydroquinone-O,O′-diacetate (hqda) anions {systematic name: 2,2′-[(1,4-phenylene)bis(oxy)]diacetate}, two trans-pyridine N-donor atoms from two bis(pyridin-4-ylmethyl)piperazine (4-bpmp) ligands, and two trans aqua ligands. The exobidentate hqda and 4-bpmp ligands form [Co(hqda)(4-bpmp)(H₂O)₂]_n coordination polymer layers parallel to (110) that are anchored into the full crystal structure by O—H⋯O hydrogen bonding between aqua ligands and ligated hqda O atoms. Disordered water molecules of crystallization occupy incipient channels along [100]. However, these could not modeled reliably and so they were treated with SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the crystal data take the presence of these molecules into account. The crystal under investigation was twinned by non-merohedry, the twin fraction of the components being 53.3% and 46.7%. Only data from the major twin component were used in the refinement.

Related literature

For the preparation of bis(4-pyridymethyl)piperazine, see: Niu et al. (2001 ▶). For the preparation of divalent metal terephthalate coordination polymers containing 4-bpmp, see: Farnum et al. (2013 ▶). graphic file with name e-70-0m198-scheme1.jpg

Experimental

Crystal data

[Co(C₁₀H₈O₆)(C₁₆H₂₀N₄)(H₂O)₂]·5H₂O
M _r = 677.57
Triclinic,
a = 5.7727 (8) Å
b = 10.3421 (15) Å
c = 13.1675 (19) Å
α = 87.175 (2)°
β = 78.856 (2)°
γ = 81.474 (2)°
V = 762.61 (19) Å³
Z = 1
Mo Kα radiation
μ = 0.63 mm⁻¹
T = 173 K
0.19 × 0.17 × 0.05 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (TWINABS; Sheldrick, 2003 ▶) T _min = 0.676, T _max = 0.745
13385 measured reflections
2786 independent reflections
2032 reflections with I > 2σ(I)
R _int = 0.053

Refinement

R[F ² > 2σ(F ²)] = 0.093
wR(F ²) = 0.228
S = 1.10
2786 reflections
179 parameters
H-atom parameters constrained
Δρ_max = 0.71 e Å⁻³
Δρ_min = −0.89 e Å⁻³

Data collection: APEX2 (Bruker, 2012 ▶); cell refinement: SAINT (Bruker, 2012 ▶); data reduction: SAINT (Bruker, 2012 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: OLEX2 (Dolomanov et al., 2009 ▶); software used to prepare material for publication: OLEX2.

Supplementary Material

Crystal structure: contains datablock(s) I, pub. DOI: 10.1107/S1600536814008745/tk5308sup1.cif

e-70-0m198-sup1.cif^{(19.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814008745/tk5308Isup2.hkl

e-70-0m198-Isup2.hkl^{(136.8KB, hkl)}

CCDC reference: 997809

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H4A⋯O1ⁱ	0.91	2.28	2.945 (7)	130
O4—H4B⋯O2	0.91	1.85	2.636 (7)	143

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Symmetry code: (i) Inline graphic .

Acknowledgments

We gratefully acknowledge Lyman Briggs College of Michigan State University for funding this work.

supplementary crystallographic information

1. Chemical context

Some divalent metal terephthalate coordination polymers with bis(pyridin-4-ylmethyl)piperazine (4-bpmp) coligands show intriguing entangled topologies. (Farnum et al., 2013). We hoped to expand the scope of these materials by using a para aromatic dicarboxylate with longer pendant arms, such as hydroquinone-O,O'-diacetic acid (H₂hqda). The title compound was obtained as pink crystals through the hydrothermal reaction of cobalt nitrate, H₂hqda, and 4-bpmp.

2. Structural commentary

The asymmetric unit of the title compound contains a divalent cobalt atom on a crystallographic inversion centre, an aqua ligand, half of a hqda ligand whose centroid rests on another crystallographic inversion centre, and one half of a 4-bpmp ligand whose centroid rests on a third crystallographic inversion centre.

The cobalt atom is octahedrally coordinated (Fig. 1), with the equatorial plane containing trans pyridyl N atom donors from two 4-bpmp ligands and trans O atom donors from monodentate carboxylate groups belonging to two hqda ligands. The aqua ligands are located in the axial positions.

The Co atoms are connected by exobidentate, bis(monodentate) hqda ligands to form [Co(hqda)(H₂O)₂]_n coordination polymer chains that are oriented parallel to [0 1 0]. Each individual chain is linked to two others by tethering 4-bpmp ligands, to construct [Co(hqda)(4-bpmp)(H₂O)₂]_n coordination polymer layers parallel to (110) (Fig. 2). As each cobalt atom is connected to four others, the underlying topology of the layer is a (4,4) rectangular grid. The internuclear Co···Co through-space distances across the grid apertures are 13.17 Å and 25.14 Å.

3. Supramolecular features

Individual [Co(hqda)(4-bpmp)(H₂O)₂]_n layers stack in a AAA pattern along the a crystal direction (Fig. 3). The supramolecular O—H···O hydrogen bonding between aqua ligands in one layer and ligated hqda O atoms in two others provides the impetus for the formation of the three-dimensional crystal structure of the title compound.

Disordered water molecules of crystallization occupy incipient channels along [1 0 0]. These could not be refined well, and thus their electron density was modeled using the SQUEEZE subroutine of PLATON (Spek, 2009). The resulting analysis indicated the presence of approximately five water molecules per unit cell, in a region comprising 20.6% of the total unit cell volume.

4. Database survey

This compound was not previously reported in the CCDC.

5. Synthesis and crystallization

Cobalt(II) nitrate hexahydrate and hydroquinone-O,O'-diacetic acid (H₂hqda) were obtained commercially. Bis(4-pyridymethyl)piperazine (4-bpmp) was prepared via a published procedure (Niu et al., 2001). A mixture of cobalt(II) nitrate hexahydrate (68 mg, 0.23 mmol), H₂hqda (84 mg, 0.37 mmol), 4-bpmp (99 mg, 0.37 mmol), 0.25 ml of a 1.0 M NaOH solution and 10.0 g water (550 mmol) was placed into a 23 ml Teflon-lined Parr acid digestion bomb, which was then heated under autogenous pressure at 393 K for 24 h. Pink plates of the title compound were obtained in a multi-phase mixture.

6. Refinement

All H atoms bound to C atoms were placed in calculated positions, with C—H = 0.95–0.99 Å, and refined in riding mode with U_iso = 1.2U_eq(C). The H atoms within the aqua ligand were found in a difference Fourier map, restrained with O—H = 0.85 Å and refined with U_iso = 1.5U_eq(O).