metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Piperazinium bis­­(di­hydrogenarsenate)

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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)[link] (Fig. 1[link]), was prepared as part of our ongoing studies of hydrogen-bonding inter­actions in the mol­ecular salts of oxo-anions (Wilkinson & Harrison, 2004[Wilkinson, H. S. & Harrison, W. T. A. (2004). Acta Cryst. E60, m1359-m1361.]). 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[Lee, C. & Harrison, W. T. A. (2003). Acta Cryst. E59, m739-m741.]).

[Scheme 1]

The (H2AsO4) anion in (I)[link] shows its normal tetra­hedral geometry about As, with the usual distinction (Table 1[link]) between protonated and unpro­ton­ated As—O bond lengths (Wilkinson & Harrison, 2004[Wilkinson, H. S. & Harrison, W. T. A. (2004). Acta Cryst. E60, m1359-m1361.]). 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)[link] inter­act by way of a network of N—H⋯O and O—H⋯O hydrogen bonds (Table 2[link]). The (H2AsO4) units are linked into infinite sheets (Fig. 2[link]) by the O—H⋯O hydrogen bonds. The O3—H1⋯O2i inter­action (see Table 2[link] 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[link]) 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[O'Keeffe, M. & Hyde, B. G. (1996). Crystal Structures 1. Patterns and Symmetry, p. 357. Washington, DC: Mineralogical Society of America.]), 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[link]) 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[Wilkinson, H. S. & Harrison, W. T. A. (2005). Acta Cryst. E61, m2023-m2025.]), despite the different cation:anion ratios in the two compounds. Other ammonium hydrogenarsenate salts contain isolated pairs of tetra­hedra (Todd & Harrison, 2005[Todd, M. J. & Harrison, W. T. A. (2005). Acta Cryst. E61, m1024-m1026.]) or polymeric chains of anions (Wilkinson & Harrison, 2004[Wilkinson, H. S. & Harrison, W. T. A. (2004). Acta Cryst. E60, m1359-m1361.]).

[Figure 1]
Figure 1
The mol­ecular structure of (I)[link] (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]
Figure 2
Detail of a part of a (100) hydrogen-bonded sheet of (H2AsO4) groups in (I)[link] 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]
Figure 3
The packing in (I)[link], 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)[link] were obtained as the water evaporated over the course of a few days.

Crystal data
  • C4H12N22+·2H2AsO4

  • Mr = 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

  • Dx = 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[Bruker (1999). SMART (Version 5.624), SAINT (Version 6.02A) and SADABS (Version 6.02). Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.141, Tmax = 0.277

  • 5723 measured reflections

  • 2081 independent reflections

  • 1843 reflections with I > 2σ(I)

  • Rint = 0.019

  • θmax = 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(Fo2) + (0.0302P)2 + 0.0622P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 0.54 e Å−3

  • Δρmin = −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 DA 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 Uiso(H) = 1.2Ueq(carrier) was applied in all cases.

Data collection: SMART (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT (Version 6.02A) and SADABS (Version 6.02). Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT (Version 6.02A) and SADABS (Version 6.02). Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and ATOMS (Shape Software, 2004[Shape Software (2004). ATOMS. Shape Software, Kingsport, Tennessee, USA.]); software used to prepare material for publication: SHELXL97.

Supporting information


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+·2H2AsO4F(000) = 368
Mr = 370.02Dx = 2.135 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 4016 reflections
a = 5.8208 (3) Åθ = 2.3–32.5°
b = 8.9966 (4) ŵ = 5.84 mm1
c = 11.0369 (5) ÅT = 293 K
β = 95.126 (1)°Block, colourless
V = 575.66 (5) Å30.44 × 0.41 × 0.22 mm
Z = 2
Data collection top
Bruker SMART1000 CCD
diffractometer
2081 independent reflections
Radiation source: fine-focus sealed tube1843 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.019
ω scansθmax = 32.5°, θmin = 2.9°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 88
Tmin = 0.141, Tmax = 0.277k = 813
5723 measured reflectionsl = 1616
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.018H-atom parameters constrained
wR(F2) = 0.050 w = 1/[σ2(Fo2) + (0.0302P)2 + 0.0622P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
2081 reflectionsΔρmax = 0.54 e Å3
74 parametersΔρmin = 0.50 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction 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
xyzUiso*/Ueq
As10.40499 (2)0.436013 (14)0.326653 (11)0.01998 (6)
O10.32761 (19)0.59593 (12)0.25923 (11)0.0300 (2)
O20.2595 (2)0.39073 (14)0.44371 (10)0.0345 (2)
O30.69769 (19)0.43297 (12)0.36654 (11)0.0328 (2)
H10.74280.48750.42440.039*
O40.3715 (2)0.30278 (13)0.21605 (11)0.0369 (3)
H20.47330.23760.23240.044*
N10.0005 (2)0.13912 (13)0.43416 (10)0.0232 (2)
H30.05270.23280.42800.028*
H40.09790.12040.36840.028*
C10.1992 (2)0.03324 (17)0.43684 (15)0.0276 (3)
H1A0.31310.06030.50270.033*
H1B0.27130.04090.36120.033*
C20.1233 (2)0.12533 (16)0.54583 (13)0.0258 (3)
H2A0.25720.19000.53930.031*
H2B0.02260.15640.61600.031*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
As10.02492 (8)0.01499 (8)0.01921 (8)0.00073 (4)0.00256 (5)0.00057 (4)
O10.0350 (5)0.0189 (4)0.0342 (5)0.0005 (4)0.0069 (4)0.0071 (4)
O20.0452 (6)0.0322 (6)0.0266 (5)0.0180 (5)0.0054 (5)0.0009 (4)
O30.0270 (5)0.0352 (6)0.0343 (6)0.0026 (4)0.0070 (4)0.0072 (4)
O40.0439 (6)0.0293 (6)0.0342 (5)0.0107 (5)0.0146 (5)0.0142 (4)
N10.0260 (5)0.0193 (5)0.0242 (5)0.0031 (4)0.0009 (4)0.0030 (4)
C10.0233 (6)0.0267 (7)0.0339 (7)0.0014 (5)0.0095 (5)0.0030 (5)
C20.0284 (6)0.0217 (6)0.0279 (6)0.0011 (5)0.0065 (5)0.0026 (5)
Geometric parameters (Å, º) top
As1—O11.6633 (11)N1—H30.900
As1—O21.6577 (11)N1—H40.900
As1—O31.7214 (11)C1—C2i1.511 (2)
As1—O41.7095 (11)C1—H1A0.970
O3—H10.829C1—H1B0.970
O4—H20.842C2—C1i1.511 (2)
N1—C21.4877 (17)C2—H2A0.970
N1—C11.4966 (18)C2—H2B0.970
O1—As1—O2115.12 (6)H3—N1—H4108.0
O1—As1—O3110.51 (5)N1—C1—C2i111.68 (11)
O1—As1—O4106.14 (6)N1—C1—H1A109.3
O2—As1—O3111.08 (6)C2i—C1—H1A109.3
O2—As1—O4110.53 (6)N1—C1—H1B109.3
O3—As1—O4102.62 (5)C2i—C1—H1B109.3
As1—O3—H1115.2H1A—C1—H1B107.9
As1—O4—H2107.6N1—C2—C1i110.64 (11)
C2—N1—C1111.19 (11)N1—C2—H2A109.5
C2—N1—H3109.4C1i—C2—H2A109.5
C1—N1—H3109.4N1—C2—H2B109.5
C2—N1—H4109.4C1i—C2—H2B109.5
C1—N1—H4109.4H2A—C2—H2B108.1
Symmetry code: (i) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H1···O2ii0.831.822.6211 (16)161
O4—H2···O1iii0.841.722.5533 (16)170
N1—H3···O20.901.862.7163 (16)158
N1—H4···O1iv0.901.872.7617 (16)173
Symmetry codes: (ii) x+1, y+1, z+1; (iii) x+1, y1/2, z+1/2; (iv) x, y1/2, z+1/2.
 

Acknowledgements

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

References

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