Piperazinium bis­(dihydrogenarsenate)

Wilkinson, H.S.; Harrison, W.T.A.

doi:10.1107/S160053680605118X

metal-organic compounds

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ISSN: 2056-9890

Volume 63| Part 1| January 2007| Pages m26-m28

https://doi.org/10.1107/S160053680605118X

Piperazinium bis(dihydrogenarsenate)

Hazel S. Wilkinson ^a and William T. A. Harrison ^a ^*

^aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
^*Correspondence e-mail: w.harrison@abdn.ac.uk

(Received 14 November 2006; accepted 27 November 2006; online 6 December 2006)

The title compound, C₄H₁₂N₂²⁺·2H₂AsO₄⁻, contains a network of doubly protonated piperazinium cations (lying on centres of inversion) and dihydogenarsenate anions. The component species interact by way of cation-to-anion N—H⋯O and anion-to-anion O—H⋯O hydrogen bonds, the latter leading to infinite sheets of (H₂AsO₄)⁻ anions.

Comment

The title compound, (I) (Fig. 1), was prepared as part of our ongoing studies of hydrogen-bonding interactions in the molecular salts of oxo-anions (Wilkinson & Harrison, 2004 ). Such materials show interesting crystal structures arising from the interplay of cation-to-anion N—H⋯O and anion-to-anion O—H⋯O hydrogen bonds (Lee & Harrison, 2003 ).

The (H₂AsO₄)⁻ anion in (I) shows its normal tetrahedral geometry about As, with the usual distinction (Table 1) between protonated and unprotonated As—O bond lengths (Wilkinson & Harrison, 2004). The piperazinium dication lies on a centre of inversion and adopts a typical chair conformation.

As well as coulombic forces, the component species in (I) interact by way of a network of N—H⋯O and O—H⋯O hydrogen bonds (Table 2). The (H₂AsO₄)⁻ units are linked into infinite sheets (Fig. 2) by the O—H⋯O hydrogen bonds. The O3—H1⋯O2ⁱ interaction (see Table 2 for symmetry codes) results in centrosymmetric dimeric pairs of (H₂AsO₄)⁻ tetrahedra linked by pairs of O—H⋯O hydrogen bonds. The O4—H2⋯O1ⁱⁱ hydrogen bond links these dimers into an infinite sheet (Fig. 3) lying parallel to (100). The As⋯Asⁱ and As⋯Asⁱⁱ separations are 4.0148 (3) and 5.0190 (3) Å, respectively. The topological connectivity of the As atoms defines a 6³ sheet (O'Keeffe & Hyde, 1996 ), i.e. every As node participates in three polyhedral six-ring loops.

The anionic sheets are bridged by piperazinium cations, each of which participates in two N—H⋯O interactions from each of its NH₂ groups to nearby dihydrogenarsenate tetrahedra. This results (Fig. 3) in organic and inorganic layers that alternate along the a axis. A similar layered structure has been reported for guanidinium dihydrogenarsenate, CH₆N₃·H₂AsO₄ (Wilkinson & Harrison, 2005 ), despite the different cation:anion ratios in the two compounds. Other ammonium hydrogenarsenate salts contain isolated pairs of tetrahedra (Todd & Harrison, 2005 ) or polymeric chains of anions (Wilkinson & Harrison, 2004).

Figure 1
The molecular structure of (I)

(50% displacement ellipsoids and H atoms are drawn as spheres of arbitrary radius). The hydrogen bond is indicated by a dashed line. [Symmetry code: (i) −x, −y, 1 − z.]

Figure 2
Detail of a part of a (100) hydrogen-bonded sheet of (H₂AsO₄)⁻ groups in (I)

in polyhedral representation, with the H⋯O parts of the hydrogen bonds coloured yellow. [Symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) 1 − x, − $[{1\over 2}]$ + y, $[{1\over 2}]$ − z.]

Figure 3
The packing in (I)

, showing the (100) dihydrogenarsenate layers mediated by the organic cations. The H⋯O parts of the N—H⋯O and O—H⋯O hydrogen bonds are coloured blue and yellow, respectively. H atoms bound to C atoms are omitted for clarity.

Experimental

A 0.5 M aqueous piperazine solution (10 ml) was added to a 0.5 M aqueous H₃AsO₄ solution (10 ml) to give a clear solution. Crystals of (I) were obtained as the water evaporated over the course of a few days.

Crystal data

C₄H₁₂N₂²⁺·2H₂AsO₄⁻
M_r = 370.02
Monoclinic, P 2₁ /c
a = 5.8208 (3) Å
b = 8.9966 (4) Å
c = 11.0369 (5) Å
β = 95.126 (1)°
V = 575.66 (5) Å³
Z = 2
D_x = 2.135 Mg m⁻³
Mo Kα radiation
μ = 5.84 mm⁻¹
T = 293 (2) K
Block, colourless
0.44 × 0.41 × 0.22 mm

Data collection

Bruker SMART1000 CCD diffractometer
ω scans
Absorption correction: multi-scan (SADABS; Bruker, 1999 ) T_min = 0.141, T_max = 0.277
5723 measured reflections
2081 independent reflections
1843 reflections with I > 2σ(I)
R_int = 0.019
θ_max = 32.5°

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.018
wR(F²) = 0.050
S = 1.05
2081 reflections
74 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0302P)² + 0.0622P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max = 0.001
Δρ_max = 0.54 e Å⁻³
Δρ_min = −0.50 e Å⁻³
Extinction correction: SHELXL97
Extinction coefficient: 0.061 (2)

Table 1
Selected geometric parameters (Å, °)

As1—O1	1.6633 (11)
As1—O2	1.6577 (11)
As1—O3	1.7214 (11)
As1—O4	1.7095 (11)

O1—As1—O2	115.12 (6)
O1—As1—O3	110.51 (5)
O1—As1—O4	106.14 (6)
O2—As1—O3	111.08 (6)
O2—As1—O4	110.53 (6)
O3—As1—O4	102.62 (5)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1⋯O2ⁱ	0.83	1.82	2.6211 (16)	161
O4—H2⋯O1ⁱⁱ	0.84	1.72	2.5533 (16)	170
N1—H3⋯O2	0.90	1.86	2.7163 (16)	158
N1—H4⋯O1ⁱⁱⁱ	0.90	1.87	2.7617 (16)	173
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

H atoms bound to O atoms were found in difference Fourier maps and refined as riding on their carrier O atoms in their as-found relative positions. H atoms bound to N and C atoms were placed in idealized positions (C—H = 0.97 Å and N—H = 0.90 Å) and refined as riding. The constraint U_iso(H) = 1.2U_eq(carrier) was applied in all cases.

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997 ) and ATOMS (Shape Software, 2004 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S160053680605118X/bi2109sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053680605118X/bi2109Isup2.hkl

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software, 2004); software used to prepare material for publication: SHELXL97.

Piperazinium bis(dihydrogenarsenate) top

Crystal data top

C₄H₁₂N₂²⁺·2H₂AsO₄⁻	F(000) = 368
M_r = 370.02	D_x = 2.135 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4016 reflections
a = 5.8208 (3) Å	θ = 2.3–32.5°
b = 8.9966 (4) Å	µ = 5.84 mm⁻¹
c = 11.0369 (5) Å	T = 293 K
β = 95.126 (1)°	Block, colourless
V = 575.66 (5) Å³	0.44 × 0.41 × 0.22 mm
Z = 2

Data collection top

Bruker SMART1000 CCD diffractometer	2081 independent reflections
Radiation source: fine-focus sealed tube	1843 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
ω scans	θ_max = 32.5°, θ_min = 2.9°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −8→8
T_min = 0.141, T_max = 0.277	k = −8→13
5723 measured reflections	l = −16→16

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.018	H-atom parameters constrained
wR(F²) = 0.050	w = 1/[σ²(F_o²) + (0.0302P)² + 0.0622P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max = 0.001
2081 reflections	Δρ_max = 0.54 e Å⁻³
74 parameters	Δρ_min = −0.50 e Å⁻³
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.061 (2)

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
As1	0.40499 (2)	0.436013 (14)	0.326653 (11)	0.01998 (6)
O1	0.32761 (19)	0.59593 (12)	0.25923 (11)	0.0300 (2)
O2	0.2595 (2)	0.39073 (14)	0.44371 (10)	0.0345 (2)
O3	0.69769 (19)	0.43297 (12)	0.36654 (11)	0.0328 (2)
H1	0.7428	0.4875	0.4244	0.039*
O4	0.3715 (2)	0.30278 (13)	0.21605 (11)	0.0369 (3)
H2	0.4733	0.2376	0.2324	0.044*
N1	0.0005 (2)	0.13912 (13)	0.43416 (10)	0.0232 (2)
H3	0.0527	0.2328	0.4280	0.028*
H4	−0.0979	0.1204	0.3684	0.028*
C1	0.1992 (2)	0.03324 (17)	0.43684 (15)	0.0276 (3)
H1A	0.3131	0.0603	0.5027	0.033*
H1B	0.2713	0.0409	0.3612	0.033*
C2	−0.1233 (2)	0.12533 (16)	0.54583 (13)	0.0258 (3)
H2A	−0.2572	0.1900	0.5393	0.031*
H2B	−0.0226	0.1564	0.6160	0.031*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
As1	0.02492 (8)	0.01499 (8)	0.01921 (8)	−0.00073 (4)	−0.00256 (5)	0.00057 (4)
O1	0.0350 (5)	0.0189 (4)	0.0342 (5)	−0.0005 (4)	−0.0069 (4)	0.0071 (4)
O2	0.0452 (6)	0.0322 (6)	0.0266 (5)	−0.0180 (5)	0.0054 (5)	−0.0009 (4)
O3	0.0270 (5)	0.0352 (6)	0.0343 (6)	0.0026 (4)	−0.0070 (4)	−0.0072 (4)
O4	0.0439 (6)	0.0293 (6)	0.0342 (5)	0.0107 (5)	−0.0146 (5)	−0.0142 (4)
N1	0.0260 (5)	0.0193 (5)	0.0242 (5)	−0.0031 (4)	0.0009 (4)	0.0030 (4)
C1	0.0233 (6)	0.0267 (7)	0.0339 (7)	−0.0014 (5)	0.0095 (5)	0.0030 (5)
C2	0.0284 (6)	0.0217 (6)	0.0279 (6)	0.0011 (5)	0.0065 (5)	−0.0026 (5)

Geometric parameters (Å, º) top

As1—O1	1.6633 (11)	N1—H3	0.900
As1—O2	1.6577 (11)	N1—H4	0.900
As1—O3	1.7214 (11)	C1—C2ⁱ	1.511 (2)
As1—O4	1.7095 (11)	C1—H1A	0.970
O3—H1	0.829	C1—H1B	0.970
O4—H2	0.842	C2—C1ⁱ	1.511 (2)
N1—C2	1.4877 (17)	C2—H2A	0.970
N1—C1	1.4966 (18)	C2—H2B	0.970

O1—As1—O2	115.12 (6)	H3—N1—H4	108.0
O1—As1—O3	110.51 (5)	N1—C1—C2ⁱ	111.68 (11)
O1—As1—O4	106.14 (6)	N1—C1—H1A	109.3
O2—As1—O3	111.08 (6)	C2ⁱ—C1—H1A	109.3
O2—As1—O4	110.53 (6)	N1—C1—H1B	109.3
O3—As1—O4	102.62 (5)	C2ⁱ—C1—H1B	109.3
As1—O3—H1	115.2	H1A—C1—H1B	107.9
As1—O4—H2	107.6	N1—C2—C1ⁱ	110.64 (11)
C2—N1—C1	111.19 (11)	N1—C2—H2A	109.5
C2—N1—H3	109.4	C1ⁱ—C2—H2A	109.5
C1—N1—H3	109.4	N1—C2—H2B	109.5
C2—N1—H4	109.4	C1ⁱ—C2—H2B	109.5
C1—N1—H4	109.4	H2A—C2—H2B	108.1

Symmetry code: (i) −x, −y, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1···O2ⁱⁱ	0.83	1.82	2.6211 (16)	161
O4—H2···O1ⁱⁱⁱ	0.84	1.72	2.5533 (16)	170
N1—H3···O2	0.90	1.86	2.7163 (16)	158
N1—H4···O1^iv	0.90	1.87	2.7617 (16)	173

Symmetry codes: (ii) −x+1, −y+1, −z+1; (iii) −x+1, y−1/2, −z+1/2; (iv) −x, y−1/2, −z+1/2.

Acknowledgements

HSW thanks the Carnegie Trust for the Universities of Scotland for an undergraduate vacation studentship.

References

Bruker (1999). SMART (Version 5.624), SAINT (Version 6.02A) and SADABS (Version 6.02). Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Lee, C. & Harrison, W. T. A. (2003). Acta Cryst. E59, m739–m741. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
O'Keeffe, M. & Hyde, B. G. (1996). Crystal Structures 1. Patterns and Symmetry, p. 357. Washington, DC: Mineralogical Society of America. Google Scholar
Shape Software (2004). ATOMS. Shape Software, Kingsport, Tennessee, USA. Google Scholar
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany. Google Scholar
Todd, M. J. & Harrison, W. T. A. (2005). Acta Cryst. E61, m1024–m1026. Web of Science CSD CrossRef IUCr Journals Google Scholar
Wilkinson, H. S. & Harrison, W. T. A. (2004). Acta Cryst. E60, m1359–m1361. Web of Science CSD CrossRef IUCr Journals Google Scholar
Wilkinson, H. S. & Harrison, W. T. A. (2005). Acta Cryst. E61, m2023–m2025. Web of Science CSD CrossRef IUCr Journals Google Scholar

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