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Homopiperazinium 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 17 May 2006; accepted 22 May 2006; online 26 May 2006)

The crystal packing in the title compound, C5H14N22+·2H2AsO4, involves anion-to-anion O—H⋯O hydrogen bonds, resulting in double chains of dihydrogenarsenate tetra­hedra. The double chains are crosslinked by further O—H⋯O bonds to result in a three-dimensional framework that accommodates the organic cations in large cavities. The cations inter­act with the framework by way of N—H⋯O bonds.

Comment

The title compound, (I)[link] (Fig. 1[link]), was prepared as part of our ongoing structural studies of hydrogen-bonding inter­actions in protonated-amine (di)hydrogen arsenates (Wilkinson & Harrison, 2005a[Wilkinson, H. S. & Harrison, W. T. A. (2005a). Acta Cryst. E61, m1228-m1230.],b[Wilkinson, H. S. & Harrison, W. T. A. (2005b). Acta Cryst. E61, m1289-m1291.]; Todd & Harrison, 2005[Todd, M. J. & Harrison, W. T. A. (2005). Acta Cryst. E61, m1024-m1026.]). These simple organic salts show inter­esting packing motifs, strongly influenced by the inter­play of N—H⋯O and O—H⋯O hydrogen bonds.

[Scheme 1]

Both the (H2AsO4) dihydrogenarsenate groups in (I)[link] show their normal tetra­hedral geometry [mean As—O = 1.677 (2) Å], with the protonated As—OH vertices showing their expected lengthening relative to the unprotonated As—O bonds, which have formal partial double-bond character (Table 1[link]). The homopiperazinium cation adopts a chair conformation, with atoms N1, C1, C3 and C4 almost coplanar (r.m.s. deviation from the mean plane = 0.029 Å) and atoms C5, C2 and N2 displaced from the plane by 0.667 (3), −1.186 (3) and −1.045 (3) Å, respectively.

As well as electrostatic attractions, the component species in (I)[link] inter­act by means of a network of cation-to-anion N—H⋯O and anion-to-anion O—H⋯O hydrogen bonds (Table 2[link]). The (H2AsO4) units are linked into polymeric double chains (Fig. 2[link]) propagating along [100]. Each strand of the chain consists of alternating As1- and As2-centred groups, with O3—H1⋯O5i and O7—H3⋯O1iii providing the hydrogen-bond links (see Table 2[link] for symmetry codes). The two strands are then crosslinked by the O8—H4⋯O2 inter­action. The graph-set notation (Bernstein et al., 1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]) for this hydrogen-bonding pattern within the double chain is an R44(16) loop. The As1⋯As2i and As1⋯As2iii intra-strand separations are 4.7032 (3) and 4.7531 (3) Å, respectively, and the As1⋯As2 inter-strand separation is 5.0014 (3) Å. Finally, the [100] double chains are crosslinked in [001] by the O4—H2⋯O6ii bonds [with As1⋯As2ii = 4.5461 (3) Å], to result in a very open three-dimensional network of dihydrogenarsenate groups, delimiting inter­secting channels that propagate in [100] and [010] (Figs. 3[link] and 4[link]). The organic cations occupy the large eight-membered ring (i.e. eight H2AsO4 tetra­hedra) [100] channels in the framework and inter­act with them by way of the four N—H⋯O bonds. It should be noted that the mean H⋯O contact distance for the O—H⋯O bonds (1.71 Å) is significantly smaller than the mean H⋯O distance (1.84 Å) for the N—H⋯O bonds. The graph-set notation for the eight-membered ring loop is R88(32).

The situation in (I)[link] of a hydrogen-bonded array of tetra­hedral anions encompassing a network of channels occupied by organic cations is similar to that of α-C5H7N2·H2PO4 (C5H7N2 is the 2-amino­pyridinium cation; Czapla et al., 2003[Czapla, Z., Dacko, S. & Waskowska, A. (2003). J. Phys. Condens. Matter, 15, 3793-3803.]). In the phosphate, symmetrical O⋯H⋯O hydrogen bonds appear to be present at room temperature, and a paraelectric-to-ferroelectric phase transition occurs on cooling below 104 K.

[Figure 1]
Figure 1
The asymmetric unit of (I)[link], showing 50% displacement ellipsoids (arbitrary spheres for H atoms). Hydrogen bonds are indicated by dashed lines.
[Figure 2]
Figure 2
Detail of a hydrogen-bonded (dashed lines) dihydrogenarsenate double chain in (I)[link]. Symmetry codes are as in Table 2[link].
[Figure 3]
Figure 3
The packing in (I)[link], viewed down [100], with the dihydrogenarsenate groups represented by polyhedra. Colour key: H2AsO4 groups yellow, O atoms red, N dark blue, C grey, H pale blue, H⋯O portions of the O—H⋯O hydrogen bonds green.
[Figure 4]
Figure 4
The packing in (I)[link], viewed down [010]. Drawing conventions as in Fig. 3[link].

Experimental

An aqueous homopiperazine solution (10 ml, 0.5 M) was added to an aqueous H3AsO4 solution (10 ml, 0.5 M), giving a clear solution. A mass of plate- and slab-like crystals of (I)[link] grew as the water evaporated over the course of a few days.

Crystal data
  • C5H14N22+·2AsH2O4

  • Mr = 384.05

  • Monoclinic, P 21 /n

  • a = 8.1495 (3) Å

  • b = 11.7163 (4) Å

  • c = 13.5730 (5) Å

  • β = 90.234 (1)°

  • V = 1295.97 (8) Å3

  • Z = 4

  • Dx = 1.968 Mg m−3

  • Mo Kα radiation

  • μ = 5.19 mm−1

  • T = 293 (2) K

  • Block cut from slab, colourless

  • 0.32 × 0.19 × 0.16 mm

Data collection
  • Bruker SMART1000 CCD area-detector diffractometer

  • ω scans

  • Absorption correction: multi-scan (SADABS; Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT (Version 6.02a) and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.288, Tmax = 0.491

  • 14796 measured reflections

  • 4639 independent reflections

  • 3760 reflections with I > 2σ(I)

  • Rint = 0.025

  • θmax = 32.5°

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.024

  • wR(F2) = 0.057

  • S = 0.95

  • 4639 reflections

  • 156 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0308P)2] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 0.40 e Å−3

  • Δρmin = −0.41 e Å−3

  • Extinction correction: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.])

  • Extinction coefficient: 0.0013 (3)

Table 1
Selected geometric parameters (Å, °)

As1—O1 1.6530 (14)
As1—O2 1.6543 (15)
As1—O4 1.7001 (15)
As1—O3 1.7053 (14)
As2—O5 1.6492 (14)
As2—O6 1.6516 (15)
As2—O7 1.6973 (16)
As2—O8 1.7072 (13)
N1—C1—C2—N2 −77.8 (2)
C1—C2—N2—C3 15.0 (3)
C2—N2—C3—C4 55.6 (3)
N2—C3—C4—C5 −85.6 (2)
C3—C4—C5—N1 65.9 (3)
C4—C5—N1—C1 −59.7 (2)
C5—N1—C1—C2 83.3 (2)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H1⋯O5i 0.90 1.65 2.555 (2) 178
O4—H2⋯O6ii 0.86 1.73 2.579 (2) 165
O7—H3⋯O1iii 0.89 1.76 2.600 (2) 156
O8—H4⋯O2 0.88 1.70 2.567 (2) 169
N1—H5⋯O2 0.90 1.82 2.716 (2) 174
N1—H6⋯O1i 0.90 1.91 2.802 (2) 171
N2—H2A⋯O6iv 0.90 1.80 2.698 (2) 174
N2—H2B⋯O5v 0.90 1.83 2.721 (2) 173
Symmetry codes: (i) -x+1, -y+1, -z; (ii) [-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iii) -x+2, -y+1, -z; (iv) x-1, y, z; (v) [-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].

The initial refinement stalled with R(F) ≃ 0.20. The pseudo-ortho­rhom­bic unit cell with β ≃ 90° suggested the possibility of twinning. Inserting a mirror plane perpendicular to the a axis as a twinning operation with the aid of the twin matrix ([\overline{1}] 0 0, 0 1 0, 0 0 1) led to a straightforward convergence to the final answer, with volume fractions of 0.875 (6):0.125 (6) for the two components. For a similar case, see Pompetzki et al. (2003[Pompetzki, M., Friese, K. & Jansen, M. (2003). Acta Cryst. C59, i117-i119.]).

The O-bound H atoms were found in difference maps and refined as riding in their as-found relative positions. The C– and N-bound H 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. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT (Version 6.02a) and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990[Sheldrick, G. M. (1990). Acta Cryst. A46, 467-473.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); 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, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Homopiperizinium bis(dihydrogenarsenate) top
Crystal data top
C5H14N22+·2AsH2O4F(000) = 768
Mr = 384.05Dx = 1.968 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 6614 reflections
a = 8.1495 (3) Åθ = 2.3–32.5°
b = 11.7163 (4) ŵ = 5.19 mm1
c = 13.5730 (5) ÅT = 293 K
β = 90.234 (1)°Block, colourless
V = 1295.97 (8) Å30.32 × 0.19 × 0.16 mm
Z = 4
Data collection top
Bruker SMART1000 CCD area-detector
diffractometer
4639 independent reflections
Radiation source: fine-focus sealed tube3760 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
ω scansθmax = 32.5°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 1210
Tmin = 0.288, Tmax = 0.491k = 1716
14796 measured reflectionsl = 1920
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difmap (O-H) and geom (others)
R[F2 > 2σ(F2)] = 0.024H-atom parameters constrained
wR(F2) = 0.057 w = 1/[σ2(Fo2) + (0.0308P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.95(Δ/σ)max = 0.001
4639 reflectionsΔρmax = 0.40 e Å3
156 parametersΔρmin = 0.41 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0013 (3)
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
As10.68569 (2)0.303928 (15)0.034816 (14)0.02193 (5)
O10.76061 (19)0.32062 (13)0.07725 (10)0.0314 (3)
O20.6564 (2)0.42518 (14)0.09465 (14)0.0511 (5)
O30.50652 (19)0.22875 (14)0.03389 (11)0.0341 (3)
H10.45600.22820.02540.041*
O40.8174 (2)0.21845 (14)0.09834 (12)0.0399 (4)
H20.78300.19090.15360.048*
As20.81196 (2)0.702982 (15)0.141776 (14)0.02319 (5)
O50.64072 (19)0.77730 (14)0.13254 (12)0.0383 (4)
O60.8354 (2)0.64027 (14)0.24990 (10)0.0415 (4)
O70.9719 (2)0.79097 (13)0.11673 (15)0.0475 (5)
H31.05170.75240.08660.057*
O80.8236 (2)0.60340 (12)0.05025 (10)0.0334 (3)
H40.76800.53970.05790.040*
C10.2683 (3)0.39324 (17)0.18419 (15)0.0293 (4)
H1A0.29680.34740.24120.035*
H1B0.28990.34790.12590.035*
C20.0894 (3)0.4205 (2)0.18770 (17)0.0360 (5)
H2C0.02880.35380.16580.043*
H2D0.06740.48130.14110.043*
N10.3756 (2)0.49654 (14)0.18250 (13)0.0293 (4)
H50.47140.47780.15410.035*
H60.32740.54990.14450.035*
C30.1419 (3)0.48886 (19)0.36471 (16)0.0387 (5)
H3A0.20620.42250.38320.046*
H3B0.08100.51320.42230.046*
C40.2583 (3)0.58472 (19)0.33405 (17)0.0375 (5)
H4A0.19840.63750.29220.045*
H4B0.29150.62620.39270.045*
C50.4107 (3)0.54720 (19)0.28025 (17)0.0345 (5)
H5A0.48230.61250.27180.041*
H5B0.46860.49160.32030.041*
N20.0242 (2)0.45573 (15)0.28616 (15)0.0351 (4)
H2A0.04420.51500.27630.042*
H2B0.03680.39770.30940.042*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
As10.02024 (9)0.02205 (9)0.02354 (9)0.00063 (7)0.00305 (7)0.00010 (7)
O10.0299 (7)0.0391 (8)0.0253 (7)0.0027 (6)0.0061 (6)0.0103 (6)
O20.0463 (10)0.0324 (8)0.0749 (13)0.0089 (7)0.0309 (9)0.0224 (8)
O30.0252 (7)0.0476 (9)0.0295 (7)0.0123 (7)0.0023 (6)0.0063 (7)
O40.0291 (8)0.0560 (10)0.0346 (8)0.0050 (7)0.0018 (7)0.0176 (7)
As20.02066 (9)0.02539 (9)0.02351 (9)0.00275 (7)0.00057 (7)0.00614 (7)
O50.0277 (8)0.0512 (9)0.0360 (8)0.0179 (7)0.0075 (6)0.0145 (7)
O60.0559 (11)0.0449 (9)0.0237 (7)0.0201 (8)0.0018 (7)0.0036 (6)
O70.0350 (9)0.0323 (9)0.0754 (14)0.0087 (7)0.0180 (9)0.0190 (8)
O80.0436 (9)0.0294 (7)0.0271 (7)0.0041 (7)0.0047 (7)0.0092 (6)
C10.0353 (11)0.0238 (9)0.0287 (9)0.0041 (8)0.0010 (8)0.0031 (8)
C20.0287 (11)0.0394 (12)0.0400 (12)0.0041 (9)0.0013 (9)0.0004 (9)
N10.0259 (8)0.0301 (9)0.0322 (9)0.0045 (7)0.0074 (7)0.0058 (7)
C30.0494 (14)0.0342 (11)0.0326 (11)0.0016 (10)0.0135 (10)0.0013 (9)
C40.0451 (13)0.0277 (10)0.0396 (12)0.0009 (9)0.0066 (10)0.0077 (9)
C50.0298 (11)0.0296 (11)0.0441 (12)0.0033 (8)0.0020 (9)0.0014 (9)
N20.0273 (9)0.0292 (9)0.0488 (11)0.0024 (7)0.0115 (8)0.0103 (8)
Geometric parameters (Å, º) top
As1—O11.6530 (14)C2—H2C0.9700
As1—O21.6543 (15)C2—H2D0.9700
As1—O41.7001 (15)N1—C51.480 (3)
As1—O31.7053 (14)N1—H50.9000
O3—H10.9028N1—H60.9000
O4—H20.8642C3—N21.483 (3)
As2—O51.6492 (14)C3—C41.529 (3)
As2—O61.6516 (15)C3—H3A0.9700
As2—O71.6973 (16)C3—H3B0.9700
As2—O81.7072 (13)C4—C51.509 (3)
O7—H30.8921C4—H4A0.9700
O8—H40.8799C4—H4B0.9700
C1—N11.493 (3)C5—H5A0.9700
C1—C21.494 (3)C5—H5B0.9700
C1—H1A0.9700N2—H2A0.9000
C1—H1B0.9700N2—H2B0.9000
C2—N21.498 (3)
O1—As1—O2113.88 (8)C5—N1—H5108.5
O1—As1—O4107.56 (8)C1—N1—H5108.5
O2—As1—O4110.43 (9)C5—N1—H6108.5
O1—As1—O3111.95 (8)C1—N1—H6108.5
O2—As1—O3108.77 (8)H5—N1—H6107.5
O4—As1—O3103.78 (8)N2—C3—C4113.39 (18)
As1—O3—H1113.4N2—C3—H3A108.9
As1—O4—H2117.0C4—C3—H3A108.9
O5—As2—O6113.40 (8)N2—C3—H3B108.9
O5—As2—O7108.32 (9)C4—C3—H3B108.9
O6—As2—O7111.23 (10)H3A—C3—H3B107.7
O5—As2—O8110.81 (8)C5—C4—C3115.50 (18)
O6—As2—O8109.63 (7)C5—C4—H4A108.4
O7—As2—O8102.95 (8)C3—C4—H4A108.4
As2—O7—H3110.2C5—C4—H4B108.4
As2—O8—H4117.6C3—C4—H4B108.4
N1—C1—C2113.53 (17)H4A—C4—H4B107.5
N1—C1—H1A108.9N1—C5—C4113.23 (18)
C2—C1—H1A108.9N1—C5—H5A108.9
N1—C1—H1B108.9C4—C5—H5A108.9
C2—C1—H1B108.9N1—C5—H5B108.9
H1A—C1—H1B107.7C4—C5—H5B108.9
C1—C2—N2115.93 (19)H5A—C5—H5B107.7
C1—C2—H2C108.3C3—N2—C2118.85 (17)
N2—C2—H2C108.3C3—N2—H2A107.6
C1—C2—H2D108.3C2—N2—H2A107.6
N2—C2—H2D108.3C3—N2—H2B107.6
H2C—C2—H2D107.4C2—N2—H2B107.6
C5—N1—C1114.97 (16)H2A—N2—H2B107.0
N1—C1—C2—N277.8 (2)C3—C4—C5—N165.9 (3)
C1—C2—N2—C315.0 (3)C4—C5—N1—C159.7 (2)
C2—N2—C3—C455.6 (3)C5—N1—C1—C283.3 (2)
N2—C3—C4—C585.6 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H1···O5i0.901.652.555 (2)178
O4—H2···O6ii0.861.732.579 (2)165
O7—H3···O1iii0.891.762.600 (2)156
O8—H4···O20.881.702.567 (2)169
N1—H5···O20.901.822.716 (2)174
N1—H6···O1i0.901.912.802 (2)171
N2—H2A···O6iv0.901.802.698 (2)174
N2—H2B···O5v0.901.832.721 (2)173
Symmetry codes: (i) x+1, y+1, z; (ii) x+3/2, y1/2, z+1/2; (iii) x+2, y+1, z; (iv) x1, y, z; (v) x+1/2, y1/2, z+1/2.
 

Acknowledgements

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

References

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