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metal-organic compounds
Homopiperazinium bis(dihydrogenarsenate)
aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
*Correspondence e-mail: w.harrison@abdn.ac.uk
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) (Fig. 1
), was prepared as part of our ongoing structural studies of hydrogen-bonding interactions in protonated-amine (di)hydrogen arsenates (Wilkinson & Harrison, 2005a
,b
; Todd & Harrison, 2005
). These simple organic salts show interesting packing motifs, strongly influenced by the interplay of N—H⋯O and O—H⋯O hydrogen bonds.
Both the (H2AsO4)− dihydrogenarsenate groups in (I) 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
). 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) interact by means of a network of cation-to-anion N—H⋯O and anion-to-anion O—H⋯O hydrogen bonds (Table 2
). The (H2AsO4)− units are linked into polymeric double chains (Fig. 2
) 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
for symmetry codes). The two strands are then crosslinked by the O8—H4⋯O2 interaction. The graph-set notation (Bernstein et al., 1995
) 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
and 4
). 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) 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
). In the phosphate, symmetrical O⋯H⋯O hydrogen bonds appear to be present at room temperature, and a paraelectric-to-ferroelectric occurs on cooling below 104 K.
![]() | Figure 1 The asymmetric unit of (I) ![]() |
![]() | Figure 2 Detail of a hydrogen-bonded (dashed lines) dihydrogenarsenate double chain in (I) ![]() ![]() |
![]() | Figure 3 The packing in (I) ![]() |
![]() | Figure 4 The packing in (I) ![]() ![]() |
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) grew as the water evaporated over the course of a few days.
Crystal data
|
Refinement
|
|
|
The initial R(F) ≃ 0.20. The pseudo-orthorhombic with β ≃ 90° suggested the possibility of Inserting a mirror plane perpendicular to the a axis as a with the aid of the twin matrix ( 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
).
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); cell 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.
Supporting information
https://doi.org/10.1107/S1600536806018897/hg2038sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536806018897/hg2038Isup2.hkl
Data collection: SMART (Bruker, 1999); cell
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.C5H14N22+·2AsH2O4− | F(000) = 768 |
Mr = 384.05 | Dx = 1.968 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 6614 reflections |
a = 8.1495 (3) Å | θ = 2.3–32.5° |
b = 11.7163 (4) Å | µ = 5.19 mm−1 |
c = 13.5730 (5) Å | T = 293 K |
β = 90.234 (1)° | Block, colourless |
V = 1295.97 (8) Å3 | 0.32 × 0.19 × 0.16 mm |
Z = 4 |
Bruker SMART1000 CCD area-detector diffractometer | 4639 independent reflections |
Radiation source: fine-focus sealed tube | 3760 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.025 |
ω scans | θmax = 32.5°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | h = −12→10 |
Tmin = 0.288, Tmax = 0.491 | k = −17→16 |
14796 measured reflections | l = −19→20 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difmap (O-H) and geom (others) |
R[F2 > 2σ(F2)] = 0.024 | H-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 reflections | Δρmax = 0.40 e Å−3 |
156 parameters | Δρmin = −0.41 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0013 (3) |
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. |
x | y | z | Uiso*/Ueq | ||
As1 | 0.68569 (2) | 0.303928 (15) | 0.034816 (14) | 0.02193 (5) | |
O1 | 0.76061 (19) | 0.32062 (13) | −0.07725 (10) | 0.0314 (3) | |
O2 | 0.6564 (2) | 0.42518 (14) | 0.09465 (14) | 0.0511 (5) | |
O3 | 0.50652 (19) | 0.22875 (14) | 0.03389 (11) | 0.0341 (3) | |
H1 | 0.4560 | 0.2282 | −0.0254 | 0.041* | |
O4 | 0.8174 (2) | 0.21845 (14) | 0.09834 (12) | 0.0399 (4) | |
H2 | 0.7830 | 0.1909 | 0.1536 | 0.048* | |
As2 | 0.81196 (2) | 0.702982 (15) | 0.141776 (14) | 0.02319 (5) | |
O5 | 0.64072 (19) | 0.77730 (14) | 0.13254 (12) | 0.0383 (4) | |
O6 | 0.8354 (2) | 0.64027 (14) | 0.24990 (10) | 0.0415 (4) | |
O7 | 0.9719 (2) | 0.79097 (13) | 0.11673 (15) | 0.0475 (5) | |
H3 | 1.0517 | 0.7524 | 0.0866 | 0.057* | |
O8 | 0.8236 (2) | 0.60340 (12) | 0.05025 (10) | 0.0334 (3) | |
H4 | 0.7680 | 0.5397 | 0.0579 | 0.040* | |
C1 | 0.2683 (3) | 0.39324 (17) | 0.18419 (15) | 0.0293 (4) | |
H1A | 0.2968 | 0.3474 | 0.2412 | 0.035* | |
H1B | 0.2899 | 0.3479 | 0.1259 | 0.035* | |
C2 | 0.0894 (3) | 0.4205 (2) | 0.18770 (17) | 0.0360 (5) | |
H2C | 0.0288 | 0.3538 | 0.1658 | 0.043* | |
H2D | 0.0674 | 0.4813 | 0.1411 | 0.043* | |
N1 | 0.3756 (2) | 0.49654 (14) | 0.18250 (13) | 0.0293 (4) | |
H5 | 0.4714 | 0.4778 | 0.1541 | 0.035* | |
H6 | 0.3274 | 0.5499 | 0.1445 | 0.035* | |
C3 | 0.1419 (3) | 0.48886 (19) | 0.36471 (16) | 0.0387 (5) | |
H3A | 0.2062 | 0.4225 | 0.3832 | 0.046* | |
H3B | 0.0810 | 0.5132 | 0.4223 | 0.046* | |
C4 | 0.2583 (3) | 0.58472 (19) | 0.33405 (17) | 0.0375 (5) | |
H4A | 0.1984 | 0.6375 | 0.2922 | 0.045* | |
H4B | 0.2915 | 0.6262 | 0.3927 | 0.045* | |
C5 | 0.4107 (3) | 0.54720 (19) | 0.28025 (17) | 0.0345 (5) | |
H5A | 0.4823 | 0.6125 | 0.2718 | 0.041* | |
H5B | 0.4686 | 0.4916 | 0.3203 | 0.041* | |
N2 | 0.0242 (2) | 0.45573 (15) | 0.28616 (15) | 0.0351 (4) | |
H2A | −0.0442 | 0.5150 | 0.2763 | 0.042* | |
H2B | −0.0368 | 0.3977 | 0.3094 | 0.042* |
U11 | U22 | U33 | U12 | U13 | U23 | |
As1 | 0.02024 (9) | 0.02205 (9) | 0.02354 (9) | −0.00063 (7) | 0.00305 (7) | 0.00010 (7) |
O1 | 0.0299 (7) | 0.0391 (8) | 0.0253 (7) | 0.0027 (6) | 0.0061 (6) | 0.0103 (6) |
O2 | 0.0463 (10) | 0.0324 (8) | 0.0749 (13) | −0.0089 (7) | 0.0309 (9) | −0.0224 (8) |
O3 | 0.0252 (7) | 0.0476 (9) | 0.0295 (7) | −0.0123 (7) | −0.0023 (6) | 0.0063 (7) |
O4 | 0.0291 (8) | 0.0560 (10) | 0.0346 (8) | 0.0050 (7) | −0.0018 (7) | 0.0176 (7) |
As2 | 0.02066 (9) | 0.02539 (9) | 0.02351 (9) | 0.00275 (7) | −0.00057 (7) | −0.00614 (7) |
O5 | 0.0277 (8) | 0.0512 (9) | 0.0360 (8) | 0.0179 (7) | −0.0075 (6) | −0.0145 (7) |
O6 | 0.0559 (11) | 0.0449 (9) | 0.0237 (7) | 0.0201 (8) | −0.0018 (7) | −0.0036 (6) |
O7 | 0.0350 (9) | 0.0323 (9) | 0.0754 (14) | −0.0087 (7) | 0.0180 (9) | −0.0190 (8) |
O8 | 0.0436 (9) | 0.0294 (7) | 0.0271 (7) | −0.0041 (7) | 0.0047 (7) | −0.0092 (6) |
C1 | 0.0353 (11) | 0.0238 (9) | 0.0287 (9) | 0.0041 (8) | 0.0010 (8) | −0.0031 (8) |
C2 | 0.0287 (11) | 0.0394 (12) | 0.0400 (12) | −0.0041 (9) | −0.0013 (9) | −0.0004 (9) |
N1 | 0.0259 (8) | 0.0301 (9) | 0.0322 (9) | 0.0045 (7) | 0.0074 (7) | 0.0058 (7) |
C3 | 0.0494 (14) | 0.0342 (11) | 0.0326 (11) | 0.0016 (10) | 0.0135 (10) | 0.0013 (9) |
C4 | 0.0451 (13) | 0.0277 (10) | 0.0396 (12) | −0.0009 (9) | 0.0066 (10) | −0.0077 (9) |
C5 | 0.0298 (11) | 0.0296 (11) | 0.0441 (12) | −0.0033 (8) | −0.0020 (9) | −0.0014 (9) |
N2 | 0.0273 (9) | 0.0292 (9) | 0.0488 (11) | 0.0024 (7) | 0.0115 (8) | 0.0103 (8) |
As1—O1 | 1.6530 (14) | C2—H2C | 0.9700 |
As1—O2 | 1.6543 (15) | C2—H2D | 0.9700 |
As1—O4 | 1.7001 (15) | N1—C5 | 1.480 (3) |
As1—O3 | 1.7053 (14) | N1—H5 | 0.9000 |
O3—H1 | 0.9028 | N1—H6 | 0.9000 |
O4—H2 | 0.8642 | C3—N2 | 1.483 (3) |
As2—O5 | 1.6492 (14) | C3—C4 | 1.529 (3) |
As2—O6 | 1.6516 (15) | C3—H3A | 0.9700 |
As2—O7 | 1.6973 (16) | C3—H3B | 0.9700 |
As2—O8 | 1.7072 (13) | C4—C5 | 1.509 (3) |
O7—H3 | 0.8921 | C4—H4A | 0.9700 |
O8—H4 | 0.8799 | C4—H4B | 0.9700 |
C1—N1 | 1.493 (3) | C5—H5A | 0.9700 |
C1—C2 | 1.494 (3) | C5—H5B | 0.9700 |
C1—H1A | 0.9700 | N2—H2A | 0.9000 |
C1—H1B | 0.9700 | N2—H2B | 0.9000 |
C2—N2 | 1.498 (3) | ||
O1—As1—O2 | 113.88 (8) | C5—N1—H5 | 108.5 |
O1—As1—O4 | 107.56 (8) | C1—N1—H5 | 108.5 |
O2—As1—O4 | 110.43 (9) | C5—N1—H6 | 108.5 |
O1—As1—O3 | 111.95 (8) | C1—N1—H6 | 108.5 |
O2—As1—O3 | 108.77 (8) | H5—N1—H6 | 107.5 |
O4—As1—O3 | 103.78 (8) | N2—C3—C4 | 113.39 (18) |
As1—O3—H1 | 113.4 | N2—C3—H3A | 108.9 |
As1—O4—H2 | 117.0 | C4—C3—H3A | 108.9 |
O5—As2—O6 | 113.40 (8) | N2—C3—H3B | 108.9 |
O5—As2—O7 | 108.32 (9) | C4—C3—H3B | 108.9 |
O6—As2—O7 | 111.23 (10) | H3A—C3—H3B | 107.7 |
O5—As2—O8 | 110.81 (8) | C5—C4—C3 | 115.50 (18) |
O6—As2—O8 | 109.63 (7) | C5—C4—H4A | 108.4 |
O7—As2—O8 | 102.95 (8) | C3—C4—H4A | 108.4 |
As2—O7—H3 | 110.2 | C5—C4—H4B | 108.4 |
As2—O8—H4 | 117.6 | C3—C4—H4B | 108.4 |
N1—C1—C2 | 113.53 (17) | H4A—C4—H4B | 107.5 |
N1—C1—H1A | 108.9 | N1—C5—C4 | 113.23 (18) |
C2—C1—H1A | 108.9 | N1—C5—H5A | 108.9 |
N1—C1—H1B | 108.9 | C4—C5—H5A | 108.9 |
C2—C1—H1B | 108.9 | N1—C5—H5B | 108.9 |
H1A—C1—H1B | 107.7 | C4—C5—H5B | 108.9 |
C1—C2—N2 | 115.93 (19) | H5A—C5—H5B | 107.7 |
C1—C2—H2C | 108.3 | C3—N2—C2 | 118.85 (17) |
N2—C2—H2C | 108.3 | C3—N2—H2A | 107.6 |
C1—C2—H2D | 108.3 | C2—N2—H2A | 107.6 |
N2—C2—H2D | 108.3 | C3—N2—H2B | 107.6 |
H2C—C2—H2D | 107.4 | C2—N2—H2B | 107.6 |
C5—N1—C1 | 114.97 (16) | H2A—N2—H2B | 107.0 |
N1—C1—C2—N2 | −77.8 (2) | C3—C4—C5—N1 | 65.9 (3) |
C1—C2—N2—C3 | 15.0 (3) | C4—C5—N1—C1 | −59.7 (2) |
C2—N2—C3—C4 | 55.6 (3) | C5—N1—C1—C2 | 83.3 (2) |
N2—C3—C4—C5 | −85.6 (2) |
D—H···A | D—H | H···A | D···A | 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+3/2, y−1/2, −z+1/2; (iii) −x+2, −y+1, −z; (iv) x−1, y, z; (v) −x+1/2, y−1/2, −z+1/2. |
Acknowledgements
HSW thanks the Carnegie Trust for the Universities of Scotland for an undergraduate vacation studentship.
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