Poly[bis­(piperazine-1,4-diium) [(μ4-cyclo-hexa­phosphato)dilithium] tetra­hydrate]

Iness Ameur; Sonia Abid; Salem S Al-Deyab; Mohamed Rzaigui

doi:10.1107/S1600536813011756

. 2013 May 11;69(Pt 6):m305–m306. doi: 10.1107/S1600536813011756

Poly[bis(piperazine-1,4-diium) [(μ₄-cyclo-hexaphosphato)dilithium] tetrahydrate]

Iness Ameur ^a, Sonia Abid ^a,^*, Salem S Al-Deyab ^b, Mohamed Rzaigui ^a

PMCID: PMC3684873 PMID: 23794975

Abstract

In the title compound, {(C₄H₁₂N₂)₂[Li₂(P₆O₁₈)]·4H₂O}_n, the phosphate ring anion, located around an inversion center, adopts a chair conformation. Adjacent P₆O₁₈ rings are linked via corner-sharing by LiO₄ tetrahedra, generating anionic porous {[Li₂(P₆O₁₈)]⁴⁻}_n layers parallel to (101). The piperazine-1,4-diium cations occupy the pores and develop hydrogen bonds with the inorganic framework. An extensive network of N—H⋯O and O—H⋯O hydrogen-bonding interactions link the components into a three-dimensional network and additional stabilization is provided by weak C—H⋯O hydrogen bonds.

Related literature

For applications of compounds with open-framework structures, see: Assani et al. (2012 ▶); Mahesh et al. (2002 ▶); Natarajan (2000 ▶). For related structures with cyclohexaphosphate rings, see: Abid et al. (2011 ▶), Amri et al. (2009 ▶); Marouani et al. (2010 ▶); For related structures with piperazine rings, see: Essid et al. (2010 ▶), Xu et al. (2007 ▶). For the synthesis of the precursor, see: Schülke & Kayser (1985 ▶).

Experimental

Crystal data

(C₄H₁₂N₂)₂[Li₂(P₆O₁₈)]·4H₂O
M _r = 736.08
Monoclinic,
a = 10.245 (3) Å
b = 12.966 (4) Å
c = 10.910 (4) Å
β = 111.00 (3)°
V = 1352.8 (7) Å³
Z = 2
Ag Kα radiation
λ = 0.56085 Å
μ = 0.26 mm⁻¹
T = 293 K
0.50 × 0.40 × 0.30 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
7884 measured reflections
6469 independent reflections
3904 reflections with I > 2σ(I)
R _int = 0.038
2 standard reflections every 120 min intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.128
S = 1.00
6469 reflections
202 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.57 e Å⁻³
Δρ_min = −0.47 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶); software used to prepare material for publication: WinGX (Farrugia, 2012 ▶).

Supplementary Material

Click here for additional data file.^{(23.7KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813011756/pk2476sup1.cif

e-69-0m305-sup1.cif^{(23.7KB, cif)}

Click here for additional data file.^{(310.2KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813011756/pk2476Isup2.hkl

e-69-0m305-Isup2.hkl^{(310.2KB, 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
N1—H2A⋯O8	0.90	1.99	2.792 (3)	147
N1—H2B⋯O7ⁱ	0.90	1.88	2.763 (3)	166
N2—H3A⋯O11	0.90	1.83	2.707 (4)	165
N2—H3B⋯O4ⁱⁱ	0.90	1.91	2.802 (2)	168
O10—H110⋯O1ⁱⁱⁱ	0.84 (4)	1.99 (4)	2.792 (4)	159 (5)
O11—H111⋯O5ⁱⁱⁱ	0.84 (3)	2.49 (4)	3.001 (3)	120 (3)
O11—H111⋯O8ⁱⁱⁱ	0.84 (3)	2.07 (3)	2.826 (3)	150 (4)
O10—H210⋯O5ⁱ	0.82 (4)	1.95 (4)	2.764 (3)	170 (4)
O11—H211⋯O10ⁱⁱⁱ	0.86 (4)	1.87 (4)	2.720 (4)	170 (4)
C1—H1A⋯O6^iv	0.97	2.51	3.273 (4)	135
C4—H1D⋯O10	0.97	2.56	3.227 (4)	126
C2—H2C⋯O2^v	0.97	2.29	3.078 (3)	137
C3—H4B⋯O5ⁱⁱⁱ	0.97	2.46	3.324 (4)	148

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

Acknowledgments

This work was supported by the Tunisian Ministry of HEScR and the Deanship of Scientific Research at King Saud University (research group project No. RGP-VPP-089).

supplementary crystallographic information

Comment

The area of framework materials continues to be of interest not only because of the wide variety of structures but also due to their potential applications in the areas of catalysis, sorption and separation processes (Mahesh et al., 2002) Natarajan, 2000). Much attention has been devoted to the synthesis of open-framework phosphates which exhibit a rich structural diversity and have been widely studied as catalysts, ion-exchangers and as positive electrode in the lithium and sodium batteries (Assani et al., 2012). Within this family of compounds, the resulting anionic frameworks, generally constructed from PO₄ tetrahedra that are vertex linked with MO_n polyhedra (with n = 4, 5 and 6), generate pores and channels offering suitable environment to accommodate different other cations. The piperazine (C₄N₂H₁₀), which is a common heterocyclic nitrogen compound, has been indicated as excellent template for preparing microporous materials (Xu et al., 2007). The crystal structure reported here gives another illustration of this type of material. The corresponding compound, (C₄H₁₂N₂)₂Li₂P₆O₁₈.4H₂O (I), is an organic-inorganic hybrid built of two main cyclic components, C₄H₁₂N₂ and P₆O₁₈ (Fig. 1). The phosphoric rings are interconnected by the Li⁺ cations via LiO₄ tetrahedra sharing corners to form a two-dimensional inorganic framework extending along the (101) plane as shown in Fig. 2. The diprotonated (C₄H₁₂N₂)²⁺ cations are trapped within the 10-membered ring pore of the layer, whereas the water molecules are located in the interlayer region and are grafted onto the framework oxygen atoms through hydrogen bonds (Fig. 3). The asymmetric unit of this atomic arrangement is built of one half of the P₆O₁₈ ring lying on an inversion center (1/2, 1/2, 1/2), one Li⁺ cation, two water molecules and one piperazine-1,4-diium cation. The organic and inorganic rings adopt a chair conformation with different geometrical characteristics due to their different size and flexibility. However, the P₆O₁₈ ring has (P–O and O–O) distances and (O–P–O, P–O–P and P–P–P angles) comparable to those observed in other cyclohexaphosphates having the same internal inversion symmetry (Abid et al., 2011; Amri et al., 2009; Marouani et al., 2010). The LiO₄ tetrahedra is slightly distorted with Li–O distances ranging from 1.877 (4) to 1.969 (4) Å. The smallest distance between two tetrahedral centers is 5.548 (2) Å. The organic ring has for carbon atoms (C1, C2, C3 and C4) almost coplanar (r.m.s. deviation from the mean plane = 0.014 Å) and N1 and N2 displaced from the plane by 0.672 (2) and -0.663 (2) Å, respectively. These characteristics do not differ from those particular values observed in other compounds of the piperazinium despite the different constraints of their solid states (Essid et al., 2010).

Experimental

Crystals of the title compound were prepared by adding dropwise and stirring an ethanolic solution (5 mL) of piperazine (10 mmol) then an aquous solution (10 mL) of KOH (10 mmol) to an aqueous solution (10 mL) of cyclohexaphosphoric acid (5 mmol). Colourless prismatic crystals were obtained after a slow evaporation over a few days at ambient temperature. The cyclohexaphosphoric acid H₆P₆O₁₈,was produced from Li₆P₆O₁₈.6H₂O, prepared according to the procedure of Schülke and Kayser (Schülke & Kayser, 1985), through an ion-exchange resin in H-state (Amberlite IR 120).