Poly[1,4-bis­(4-pyridylmeth­yl)piperazine­diium [[tetra­aqua­cobaltate(II)]-μ-pyromellitato-κ2 O 1:O 4] dihydrate]

Laura K Sposato; Robert L LaDuca

doi:10.1107/S1600536809051101

. 2009 Nov 28;65(Pt 12):m1709. doi: 10.1107/S1600536809051101

Poly[1,4-bis(4-pyridylmethyl)piperazinediium [[tetraaquacobaltate(II)]-μ-pyromellitato-κ² O ¹:O ⁴] dihydrate]

Laura K Sposato ^a, Robert L LaDuca ^b,^*

PMCID: PMC2972020 PMID: 21578710

Abstract

In the title compound, {(C₁₆H₂₂N₄)[Co(C₁₀H₂O₈)(H₂O)₄]·2H₂O}_n, the octahedrally coordinated Co^II atom is situated on an inversion center and possesses four aqua ligands. The Co atoms are linked into an anionic coordination polymer chain by bis-monodentate pyromellitate ligands. The chain motifs are connected into a supramolecular layer by hydrogen bonding mediated by uncoordinated water molecules. Charge balance is provided by doubly protonated bis(4-pyridylmethyl)piperazine units, which are anchored to the coordination polymer chain motifs by N—H⋯O hydrogen bonding.

Related literature

For some divalent cobalt pyromellitate coordination polymers containing dipyridyl ligands, see: Majumder et al. (2006 ▶). For the preparation of bis(4-pyridylmethyl)piperazine, see: Pocic et al. (2005 ▶). graphic file with name e-65-m1709-scheme1.jpg

Experimental

Crystal data

(C₁₆H₂₂N₄)[Co(C₁₀H₂O₈)(H₂O)₄]·2H₂O
M _r = 687.52
Triclinic,
a = 7.278 (2) Å
b = 9.752 (3) Å
c = 11.257 (3) Å
α = 66.733 (3)°
β = 75.168 (3)°
γ = 83.359 (3)°
V = 709.5 (3) Å³
Z = 1
Mo Kα radiation
μ = 0.69 mm⁻¹
T = 173 K
0.24 × 0.14 × 0.10 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.853, T _max = 0.933
11370 measured reflections
2908 independent reflections
2511 reflections with I > 2σ(I)
R _int = 0.058

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.153
S = 1.05
2908 reflections
226 parameters
10 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.23 e Å⁻³
Δρ_min = −0.91 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: CrystalMaker (Palmer, 2007 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809051101/hy2258sup1.cif

e-65-m1709-sup1.cif^{(18.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809051101/hy2258Isup2.hkl

e-65-m1709-Isup2.hkl^{(142.7KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1WA⋯O6ⁱ	0.88 (2)	2.38 (3)	2.997 (3)	128 (3)
O1W—H1WB⋯O1ⁱ	0.89 (2)	1.88 (2)	2.764 (3)	174 (3)
O5—H5A⋯N1	0.88 (2)	1.87 (2)	2.739 (3)	177 (3)
O5—H5B⋯O4	0.85 (2)	1.87 (2)	2.697 (3)	163 (3)
O6—H6C⋯O1W	0.86 (2)	1.92 (2)	2.753 (3)	165 (3)
O6—H6D⋯O2ⁱⁱ	0.86 (2)	1.81 (2)	2.624 (3)	158 (3)
N2—H2N⋯O3ⁱⁱⁱ	0.91 (2)	1.73 (2)	2.630 (3)	171 (3)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

We gratefully acknowledge the donors of the American Chemical Society Petroleum Research Fund for funding this work.

supplementary crystallographic information

Comment

The diverse possible binding modes of the pyromellitate ligand (1,2,4,5-benzenetetracarboxylate) has allowed formation of a wide variety of cobalt-containing coordination polymers, especially in the presence of dipyridyl neutral co-ligands (Majumder et al., 2006). This chemistry was further developed by the synthesis of the title compound, which incorporates the long-spanning hydrogen-bonding capable dipyridyl ligand bis(4-pyridylmethyl)piperazine (bpmp).

The asymmetric unit of the title compound consists of a divalent Co^II atom on a crystallographic inversion center, one-half of a pyromellitate tetraanion situated across another crystallographic inversion center, one-half of a (H₂bpmp)²⁺ dication (protonated at each of the two piperazinyl N atoms) sited across another crystallographic inversion center, and one water molecule of crystallization. The local coordination and surrounding supramolecular environment is illustrated in Fig. 1.

Adjacent Co^II ions are linked into [Co(H₂O)₄(pyromellitate)]_n^2n- anionic one-dimensional coordination polymer motifs, via symmetrically related monodentate carboxylate termini of the pyromellitate ligands. These chain motifs are oriented parallel to the [1 1 0] direction; the Co···Co distance along the chain is 11.474 (3) Å. Two of the pyromellitate carboxylate groups do not ligate to Co^II ions. Neighboring chain motifs aggregate into supramolecular layers coincident with the ab planes (Fig. 2), established by hydrogen-bonding patterns between the co-crystallized water molecules, aqua ligands, and ligated pyromellitate carboxylate O atoms (Table 1). In turn, the supramolecular layers stack in an AAA pattern along the c axis, with charge-balancing (H₂bpmp)²⁺ dications situated in the interlamellar regions (Fig. 3), thus forming the three-dimensional crystal structure of the title compound. The closest Co···Co contact distance between neighboring layers is 11.257 (3) Å, which defines the c lattice parameter.

Experimental

All starting materials were obtained commercially, except for bpmp, which was prepared by a published procedure (Pocic et al., 2005). A mixture of cobalt nitrate hexahydrate (108 mg, 0.37 mmol), pyromellitic acid (94 mg, 0.37 mmol), bpmp (99 mg, 0.37 mmol) 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 48 h. After cooling to 293 K, orange blocks of the title compound were obtained along with a white powder.