catena-Poly[[diaqua­cadmium(II)]bis­(μ-2,2-dimethyl­butane­dioato-κ4 O,O′:O′′,O′′′)[diaqua­cadmium(II)]-μ-1,4-bis­(3-pyridylmeth­yl)piperazine-κ2 N 3:N 3′]

Amy L Pochodylo; Robert L LaDuca

doi:10.1107/S1600536810018799

. 2010 May 26;66(Pt 6):m708. doi: 10.1107/S1600536810018799

catena-Poly[[diaquacadmium(II)]bis(μ-2,2-dimethylbutanedioato-κ⁴ O,O′:O′′,O′′′)[diaquacadmium(II)]-μ-1,4-bis(3-pyridylmethyl)piperazine-κ² N ³:N ^3′]

Amy L Pochodylo ^a, Robert L LaDuca ^a,^*

PMCID: PMC2979442 PMID: 21579341

Abstract

In the title compound, [Cd₂(C₆H₈O₄)₂(C₁₆H₂₀N₄)(H₂O)₄]_n, pentagonal-bipyramidally coordinated Cd^II ions are connected into {Cd₂(2,2-dimethylsuccinate)₂(H₂O)₄} centrosymmetric dimeric clusters. In turn, these clusters are linked by tethering 1,4-bis(3-pyridylmethyl)piperazine (3-bpmp) ligands into [Cd₂(2,2-dimethylsuccinate)₂(3-bpmp)(H₂O)₄]_n coordination polymer chains. The chain motifs are oriented parallel to [1 Inline graphic 0]. Individual chains are connected into supramolecular layers via O—H⋯N and O—H⋯O hydrogen-bonding mechanisms.

Related literature

For other dicarboxylate coordination polymers containing 3-bpmp ligands, see: Johnston et al. (2008 ▶). For the preparation of 3-bpmp, see: Niu et al. (2001 ▶).

Experimental

Crystal data

[Cd₂(C₆H₈O₄)₂(C₁₆H₂₀N₄)(H₂O)₄]
M _r = 426.74
Triclinic,
a = 9.275 (3) Å
b = 10.378 (3) Å
c = 10.625 (5) Å
α = 114.461 (3)°
β = 101.274 (3)°
γ = 106.687 (2)°
V = 831.6 (5) Å³
Z = 2
Mo Kα radiation
μ = 1.34 mm⁻¹
T = 173 K
0.26 × 0.18 × 0.13 mm

Data collection

Bruker APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.723, T _max = 0.840
12027 measured reflections
3047 independent reflections
2909 reflections with I > 2σ(I)
R _int = 0.058

Refinement

R[F ² > 2σ(F ²)] = 0.035
wR(F ²) = 0.099
S = 1.16
3047 reflections
222 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.65 e Å⁻³
Δρ_min = −1.07 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2006 ▶); 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/S1600536810018799/lh5049sup1.cif

e-66-0m708-sup1.cif^{(22.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810018799/lh5049Isup2.hkl

e-66-0m708-Isup2.hkl^{(149.5KB, 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
O5—H5C⋯O4	0.84 (4)	1.93 (2)	2.705 (3)	154 (4)
O5—H5D⋯O1ⁱ	0.83 (2)	1.99 (2)	2.744 (3)	152 (3)
O6—H6C⋯O3ⁱⁱ	0.85 (2)	1.84 (2)	2.679 (3)	171 (4)
O6—H6D⋯N2ⁱⁱⁱ	0.83 (2)	2.03 (2)	2.851 (4)	173 (4)

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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. We also thank Anthony H. LaDuca for experimental assistance.

supplementary crystallographic information

Comment

Recently we have been investigating bis(3-pyridylmethyl)piperazine (3-bpmp) as a neutral dipodal tethering ligand for the construction of divalent metal coordination polymers in tandem with aromatic dicarboxylate ligands (Johnston et al., 2008). This chemistry has been extended into an aliphatic dicarboxylate system with the synthesis of the title compound.

The asymmetric unit of the title compound contains a Cd^II ion, one 2,2-dimethylsuccinate ligand, two aqua ligands, and one-half of a 3-bpmp ligand whose central piperazinyl ring is situated over a crystallographic inversion centre. The Cd^II ion is pentagonal bipyramidally coordinated in a {CdO₆N} environment, with its apical positions occupied by aqua ligands. Its basal plane consists of two chelating carboxylate groups from two 2,2-dimethylsuccinate ligands and one pyridyl N donor atom from a 3-bpmp ligand. A pair of Cd^II ions is aggregated into a centrosymmetric {Cd₂(H₂O)₄(2,2-dimethylsuccinate)₂} dinuclear cluster (Fig. 1) by two bis(chelating) 2,2-dimethylsuccinate ligands, which adopt a gauche conformation.

{Cd₂(H₂O)₄(2,2-dimethylsuccinate)₂} dinuclear clusters are connected by tethering 3-bpmp ligands into one-dimensional [Cd₂(2,2-dimethylsuccinate)₂(H₂O)₄(3-bpmp)]_n coordination polymer chains, which are oriented parallel to the (1 1 0) crystal direction (Fig. 2). The through-ligand Cd···Cd contact distance is 13.381 (6) Å. Individual chains are connected into supramolecular pseudo layers (Fig. 3) via O—H···N and O—H···O interactions (Table 1). Within the pseudo layers, aqua ligands (O6) donate hydrogen bonds to piperazinyl N atoms of 3-bpmp ligands and ligated 2,2-dimethylsuccinate carboxylate O atoms in neighboring chains. Neighboring pseudo layers stack into the three-dimensional crystal structure (Fig. 4) of the title compound by crystal packing forces.

Experimental

All starting materials were obtained commercially, except for 3-bpmp, which was prepared by a published procedure (Niu et al., 2001). A mixture of cadmium nitrate tetrahydrate (114 mg, 0.37 mmol), 2,2-dimethylsuccinic acid (54 mg, 0.37 mmol), 3-bpmp (199 mg, 0.742 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 72 h. Colourless blocks of the title compound (57 mg, 26% yield) were isolated after washing with distilled water and acetone, and drying in air.