Bis(3-azoniapentane-1,5-diaminium) cyclo­hexa­phosphate dihydrate: a monoclinic polymorph

Lamia Khedhiri; Samah Akriche; Salem S Al-Deyab; Mohamed Rzaigui

doi:10.1107/S1600536812025172

. 2012 Jun 13;68(Pt 7):o2038–o2039. doi: 10.1107/S1600536812025172

Bis(3-azoniapentane-1,5-diaminium) cyclohexaphosphate dihydrate: a monoclinic polymorph

Lamia Khedhiri ^a,^*, Samah Akriche ^a, Salem S Al-Deyab ^b, Mohamed Rzaigui ^a

PMCID: PMC3393307 PMID: 22807864

Abstract

In the title hydrated molecular salt, 2C₄H₁₆N₃ ³⁺·P₆O₁₈ ⁶⁻·2H₂O, the complete cyclohexaphosphate anion is generated by crystallographic inversion symmetry. The six P atoms of the P₆O₁₈ ⁶⁻ anion form a chair conformation and the organic cation has a corrugated linear geometry. In the crystal, the cations and the anions are connected by N—H⋯O hydrogen bonds into slabs propagating in the ac plane. The water molecules link the slabs by accepting N—H⋯O links and forming O—H⋯O links. The triclinic polymorph was reported by Gharbi et al. [(1995). J. Solid State Chem. 114, 42–51].

Related literature

For the triclinic polymorph of the title compound, see: Gharbi et al. (1995 ▶). For related structures, see: Averbuch-Pouchot & Durif (1991 ▶); Bridi & Jouini (1989 ▶); Kamoun et al. (1990 ▶); Khedhiri et al. (2007 ▶); Schülke & Kayser (1985 ▶); Khedhiri et al. (2003 ▶).

Experimental

Crystal data

2C₄H₁₆N₃ ³⁺·P₆O₁₈ ⁶⁻·2H₂O
M _r = 722.25
Monoclinic,
a = 10.033 (4) Å
b = 16.597 (2) Å
c = 8.007 (3) Å
β = 105.07 (2)°
V = 1287.6 (7) Å³
Z = 2
Ag Kα radiation
λ = 0.56087 Å
μ = 0.27 mm⁻¹
T = 293 K
0.32 × 0.27 × 0.21 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
9091 measured reflections
6303 independent reflections
5211 reflections with I > 2σ(I)
R _int = 0.014
2 standard reflections every 120 min intensity decay: 2%

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.099
S = 1.07
6303 reflections
189 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.47 e Å⁻³
Δρ_min = −0.97 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: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812025172/hb6809sup1.cif

e-68-o2038-sup1.cif^{(18.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812025172/hb6809Isup2.hkl

e-68-o2038-Isup2.hkl^{(302.3KB, 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—H1W1⋯O5	0.84 (1)	2.12 (1)	2.9274 (17)	163 (2)
O1W—H2W1⋯O2ⁱ	0.85 (1)	1.85 (1)	2.6938 (16)	175 (2)
N1—H1B⋯O1W ⁱⁱ	0.89	1.99	2.7817 (15)	147
N1—H1C⋯O1	0.89	1.96	2.8054 (14)	159
N1—H1A⋯O6ⁱⁱⁱ	0.89	1.96	2.8013 (15)	156
N2—H2A⋯O8ⁱⁱⁱ	0.90	2.10	2.8049 (16)	135
N2—H2A⋯O9ⁱⁱ	0.90	2.36	3.0891 (15)	138
N2—H2B⋯O9	0.90	2.14	2.7973 (16)	130
N2—H2B⋯O8ⁱⁱ	0.90	2.15	2.8706 (13)	137
N3—H3B⋯O5^iv	0.89	1.99	2.8414 (17)	159
N3—H3C⋯O1^v	0.89	1.93	2.7973 (16)	164
N3—H3A⋯O6^vi	0.89	1.96	2.8008 (16)	157

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

Acknowledgments

The authors extend their appreciation to the Deanship of Scientific Research at King Saud University.

supplementary crystallographic information

Comment

The title compound (I), was prepared as part of our ongoing structural studies of inorganic-organic cyclohexaphosphates systems. Its chemical composition includes three entities, P₆O₁₈ ring, water molecules and organic cations [C₄N₃H₁₆]³⁺ and is polymorphic with a previously described triclinic phase (Gharbi et al., 1995). The geometrical configuration of these entities is depicted in Figure 1, whereas Figure 2 shows the complete atomic arrangement.

The packing of (I) consists of hybrid layers where the organic and inorganic species are alternated. Theses layers, extended perpendicularly to the b axis, are also connected between them in the two other directions via H-bonds assuring the cohesion of the network. The P₆O₁₈ rings are located around the inversion centers (0, 0, 0) and (1/2, 1/2, 1/2) and are built up by only three independent PO₄ tetrahedra. The P—P—P angles of 98.85 (1), 109.09 (1) and 138.42 (1)° show that the rings are significantly distorted from the ideal threefold symmetry. It should be noted that these large deviations are commonly observed in cyclohexaphosphates with a ring of low local symmetry (Khedhiri et al., 2003, Khedhiri et al., 2007), as in the title compound. Nevertheless, this distortion is comparatively less important than that observed in Cs₆P₆O₁₈.6H₂O, which shows the greatest distortion for the same angles, ranging between 93.2 and 145.5° (Averbuch-Pouchot and Durif, 1991). The great flexibility of the hexamembered P₆O₁₈ rings can probably explain the pronounced distortion observed for the big rings compared with their smaller ring analogues. Examination of the main geometrical features of the three independent PO₄ tetrahedra (P—O and P–P distances as well as P–O–P or O–P–O angles) shows clearly that, in spite of the P–P–P angles deformation, they are in accordance with values generally observed in condensed phosphate anions.

In the organic entity, N–C and C–C distances and N–C–C and C–N–C angles, spreading within the respective ranges 1.477 (1) - 1.512 (2) Å and 109 (1) -111.5 (9)°, are similar to those observed in others compounds (Kamoun et al., 1990; Bridi et al., 1989). All nitrogen atoms of the used amine are protonated and so it is formulated by [C₄N₃H₁₆]³⁺. Among the eight hydrogen atoms of this group, only one, H1B, establishes a hydrogen bond with a water molecule, the remaining ones are connected to the external oxygen atoms of three phosphoric rings to form an anionic entity of formula [C₄N₃H₁₆(P₆O₁₈)₃]^15-. The two hydrogen atoms of the water molecule act as a link between successive anions. A three dimensional network of N–H···O and O–H···O hydrogen bonds interconnects the structural arrangement.

This study shows that (I) is a polymorph of the triclinic structure published elsewhere (Gharbi et al., 1995). Both phases have the same chemical formula and some structural analogeous but they present several differences in their crystal data, H-bonding scheme, internal symmetry of the cyclohexaphosphoric anions and particularly the aza-3 pentanediyl-1,5 diaminium which has different conformations where the torsion angles N2–C3–C4–N3, C2–N2–C3–C4, N1–C1–C2–N2 and C3–N2–C2–C1 exhibit the following values -175.34 (9)°, -178.34 (9)°, 171.15 (9)° and 177.79 (9)° in the title compound and 177.67°, 175.32°, 66.45° and -69.92° in the bibliography one.

Experimental

Single crystals of the title compound were prepared in two steps. In the first one, 50 ml of an aqueous solution of cyclohexaphosphoric acid was prepared by protonation of 4 g of Li₆P₆O₁₈.6H₂O, obtained by the Schülke process (Schülke et al., 1985), with an ion-exchange resin (Amberlite IR 120). In the second one, the frech acidic solution (20 ml, 2.6 mmol) was immediately neutralized with a solution of aza-3 pentanediyl-1,5 diamine (2.8 mmol in 10 ml of ehanol) under continuous stirring. Good quality of prismatic-shaped crystals were obtained after a slow evaporation during few days at ambient temperature