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n-Heptyl­ammonium di­hydrogenarsenate, (C7H18N)[As(O)2(OH)2] (C7ADA), is ferroelastic at room temperature and isostructural with n-heptyl­ammonium di­hydrogenphosphate (C7ADP). In contrast to the other known n-alkyl­ammonium di­hydrogenphosphates (CnADP) and di­hydrogenarsenates (CnADA), two independent anions in the present structure are substantially disordered (∼88 and ∼12%, respectively). There are strong hydrogen bonds between the di­hydrogenarsenates themselves, and moderate hydrogen bonds between the di­hydrogenarsenates and the n-alkyl­ammonium groups. The hydrogen-bond distances correspond well to those observed in the di­hydrogenphosphates. There are two H atoms in the structure which are involved in asymmetric hydrogen bonds between respective oxy­gen pairs. These H atoms jump from the donor to the acceptor O atoms during ferroelastic switching.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100020850/av1066sup1.cif
Contains datablocks global, C7ADA

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100020850/av1066C7ADAsup2.hkl
Contains datablock C7ADA

CCDC reference: 163903

Computing details top

Data collection: COLLECT (Nonius BV, 1997-2000); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to refine structure: JANA2000 (Petříček & Dušek, 2000); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: JANA2000.

n-heptylammonium dihydrogenarsenate top
Crystal data top
C7H18N+·[As(O)2(OH)2]F(000) = 1072
Mr = 257.16Dx = 1.510 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 9.3261 (3) ÅCell parameters from 24037 reflections
b = 32.34003 (14) Åθ = 1.0–27.5°
c = 7.5005 (3) ŵ = 2.99 mm1
β = 90.595 (2)°T = 290 K
V = 2262.1 (1) Å3Prism, colourless
Z = 80.22 × 0.12 × 0.05 mm
Data collection top
Nonius KappaCCD
diffractometer
4974 independent reflections
Radiation source: fine-focus sealed X-ray tube2700 reflections with I > 3σ(I)
Graphite monochromatorRint = 0.052
CCD scansθmax = 27.5°, θmin = 1.3°
Absorption correction: integration
Gaussian integration (Coppens et al., 1965)
h = 1212
Tmin = 0.614, Tmax = 0.860k = 4241
13013 measured reflectionsl = 09
Refinement top
Refinement on F65 restraints
Least-squares matrix: full with fixed elements per cycle27 constraints
R[F > 3σ(F)] = 0.044H atoms treated by a mixture of independent and constrained refinement
wR(F) = 0.053Weighting scheme based on measured s.u.'s w = [σ2(Fo) + 0.0001(Fo)2]-1
S = 1.46(Δ/σ)max = 0.001
4972 reflectionsΔρmax = 1.22 e Å3
369 parametersΔρmin = 1.07 e Å3
Special details top

Experimental. rotation scans: 10 images collected by ω scans, rotation per image 10°, 202 s exposure, crystal to detector distance 35 mm.

Refinement. Though the structure was intended to be refined as a twin the trial measurement on a 4-dircle diffractometer with a point detector did not indicate existence of a second domain.

Nevertheless the twinning was evidenced on other sample. The twinning matrix is given in _diffrn_reflns_transf_matrix_ items

The H atoms except of those which are bonded to the O atoms were restrained by the distfix and anglefix functions of JANA2000: The values for distfix were 0.85(0.021) Å for O—H distances. The values for distfix were 0.90(0.022) Å for N—H distances. The values for distfix were 0.9(0.022) Å for methyl-H distances. The values for distfix were 0.95(0.013) Å for methylene-H distances. The values for anglefix were 109.47(1.00) ° for all H—N—H; H—C—H angles, and 170 (2) ° for O11—HO11···O32 {1_455}.

The dihydrogenarsenates are disordered (there are two independent dihydrogenarsenates in the structure). There were made two refinements which described the disorder. One, whose results are listed in the tables below, is based on the assumption of the stacking faults (1/2,0,0). The second one expressed disorder of dihydrogenarsenates which were disordered in two sites. The geometry of the disordered molecules which were displaced by [1/2, 0, 0] was considered to be the same, the sum in each site was supposed to equal to 1. The occupancy of the disordered molecules in each site equalled to 0.883 (1) and its complement to 1.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
As10.06360 (3)0.298272 (15)0.25206 (5)0.02414 (17)
O110.0637 (2)0.33579 (11)0.2237 (4)0.0426 (13)
O210.0972 (2)0.28957 (9)0.4659 (3)0.0367 (11)
O310.2013 (2)0.31177 (9)0.1279 (3)0.0343 (10)
O410.0084 (3)0.25314 (9)0.1745 (4)0.0355 (11)
As20.55964 (4)0.295829 (15)0.26254 (5)0.02436 (17)
O120.4441 (2)0.33554 (10)0.2642 (4)0.0412 (13)
O220.5958 (3)0.28693 (11)0.0428 (3)0.0411 (12)
O320.7032 (2)0.31035 (9)0.3735 (3)0.0349 (11)
O420.4876 (2)0.25269 (9)0.3404 (3)0.0308 (10)
N10.2172 (3)0.69637 (11)0.2682 (4)0.0300 (14)
C110.1382 (4)0.65713 (16)0.2479 (6)0.0336 (18)
C210.2357 (4)0.61974 (17)0.2575 (6)0.0380 (19)
C310.1529 (4)0.57983 (16)0.2468 (6)0.038 (2)
C410.2446 (4)0.54138 (16)0.2510 (6)0.0378 (19)
C510.1619 (4)0.50152 (17)0.2502 (6)0.039 (2)
C610.2510 (5)0.46284 (18)0.2553 (6)0.047 (2)
C710.1678 (5)0.42272 (18)0.2568 (7)0.061 (2)
N20.7241 (3)0.69623 (11)0.2298 (4)0.0310 (14)
C120.6425 (4)0.65681 (16)0.2504 (6)0.0327 (18)
C220.7371 (4)0.62007 (15)0.2438 (6)0.0332 (17)
C320.6541 (4)0.57942 (17)0.2508 (7)0.041 (2)
C420.7455 (5)0.54140 (16)0.2482 (6)0.0362 (18)
C520.6610 (4)0.50092 (17)0.2473 (7)0.042 (2)
C620.7525 (5)0.46253 (17)0.2457 (7)0.042 (2)
C720.6649 (5)0.42279 (17)0.2445 (7)0.058 (2)
H1n10.245 (3)0.6968 (11)0.384 (2)0.044 (8)*
H2n10.170 (3)0.7180 (8)0.245 (3)0.044 (8)*
H3n10.293 (2)0.6959 (10)0.199 (3)0.044 (8)*
H1c110.084 (2)0.6558 (13)0.352 (2)0.047 (6)*
H2c110.079 (2)0.6512 (13)0.148 (2)0.047 (6)*
H1c210.294 (3)0.6238 (14)0.156 (2)0.058 (7)*
H2c210.295 (3)0.6198 (14)0.359 (2)0.058 (7)*
H1c310.092 (2)0.5789 (14)0.348 (2)0.048 (6)*
H2c310.097 (2)0.5760 (13)0.141 (2)0.048 (6)*
H1c410.308 (2)0.5418 (13)0.152 (2)0.048 (6)*
H2c410.301 (2)0.5402 (13)0.359 (2)0.048 (6)*
H1c510.105 (2)0.5037 (12)0.145 (2)0.038 (5)*
H2c510.101 (2)0.5025 (13)0.350 (2)0.038 (5)*
H1c610.300 (3)0.4616 (13)0.145 (2)0.049 (7)*
H2c610.319 (2)0.4656 (14)0.349 (2)0.049 (7)*
H1c710.097 (3)0.4245 (13)0.353 (3)0.079 (6)*
H2c710.219 (4)0.3977 (10)0.267 (4)0.079 (6)*
H3c710.119 (3)0.4232 (13)0.144 (3)0.079 (6)*
H1n20.782 (2)0.6946 (9)0.319 (3)0.034 (7)*
H2n20.664 (3)0.7180 (8)0.246 (3)0.034 (7)*
H3n20.775 (2)0.7002 (9)0.130 (2)0.034 (7)*
H1c120.588 (2)0.6588 (13)0.355 (2)0.047 (6)*
H2c120.581 (2)0.6578 (13)0.151 (2)0.047 (6)*
H1c220.787 (3)0.6211 (14)0.136 (2)0.058 (7)*
H2c220.804 (2)0.6199 (14)0.341 (3)0.058 (7)*
H1c320.591 (2)0.5774 (14)0.349 (2)0.048 (6)*
H2c320.602 (2)0.5769 (14)0.144 (2)0.048 (6)*
H1c420.792 (2)0.5416 (13)0.136 (2)0.048 (6)*
H2c420.817 (2)0.5417 (13)0.340 (2)0.048 (6)*
H1c520.600 (2)0.5016 (12)0.143 (2)0.038 (5)*
H2c520.604 (2)0.5005 (13)0.350 (2)0.038 (5)*
H1c620.820 (2)0.4658 (14)0.153 (2)0.049 (7)*
H2c620.802 (3)0.4617 (13)0.358 (2)0.049 (7)*
H1c720.597 (3)0.4203 (13)0.346 (3)0.079 (6)*
H2c720.731 (4)0.4004 (11)0.248 (4)0.079 (6)*
H3c720.612 (3)0.4222 (13)0.136 (3)0.079 (6)*
Ho120.360 (2)0.3273 (11)0.240 (4)0.018 (11)*
Ho220.611 (6)0.2631 (10)0.009 (6)0.13 (2)*
Ho410.002 (4)0.2451 (14)0.063 (3)0.065 (16)*
Ho110.131 (2)0.3247 (11)0.282 (5)0.064 (17)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
As10.0220 (2)0.0281 (3)0.0226 (2)0.0013 (2)0.00170 (18)0.0029 (2)
O110.0260 (16)0.041 (2)0.061 (2)0.0058 (16)0.0077 (15)0.0180 (17)
O210.0491 (17)0.041 (2)0.0203 (16)0.0029 (14)0.0037 (13)0.0063 (13)
O310.0236 (14)0.048 (2)0.0314 (17)0.0088 (14)0.0065 (12)0.0016 (14)
O410.0472 (16)0.030 (2)0.0292 (19)0.0120 (15)0.0065 (14)0.0019 (14)
As20.0227 (2)0.0284 (3)0.0222 (2)0.0014 (2)0.00044 (18)0.0013 (2)
O120.0298 (18)0.027 (2)0.067 (2)0.0009 (16)0.0076 (15)0.0059 (16)
O220.063 (2)0.039 (2)0.0217 (17)0.0042 (17)0.0081 (14)0.0011 (15)
O320.0227 (14)0.049 (2)0.0330 (18)0.0075 (14)0.0055 (12)0.0010 (14)
O420.0375 (15)0.029 (2)0.0256 (17)0.0084 (14)0.0006 (12)0.0023 (13)
N10.0227 (18)0.032 (3)0.035 (2)0.0039 (18)0.0040 (15)0.0010 (17)
C110.030 (2)0.033 (3)0.038 (3)0.006 (2)0.004 (2)0.002 (2)
C210.030 (2)0.034 (3)0.050 (3)0.002 (2)0.001 (2)0.004 (2)
C310.036 (2)0.026 (3)0.051 (3)0.003 (2)0.002 (2)0.000 (2)
C410.038 (2)0.030 (3)0.045 (3)0.010 (2)0.001 (2)0.001 (2)
C510.043 (2)0.032 (3)0.043 (3)0.003 (2)0.004 (2)0.004 (2)
C610.057 (3)0.041 (4)0.042 (3)0.006 (3)0.003 (2)0.002 (2)
C710.081 (4)0.029 (4)0.072 (4)0.003 (3)0.006 (3)0.003 (2)
N20.035 (2)0.028 (2)0.030 (2)0.006 (2)0.0004 (16)0.0025 (17)
C120.027 (2)0.030 (3)0.042 (3)0.003 (2)0.006 (2)0.000 (2)
C220.033 (2)0.027 (3)0.040 (3)0.002 (2)0.001 (2)0.000 (2)
C320.037 (2)0.033 (4)0.054 (3)0.006 (2)0.000 (2)0.002 (2)
C420.041 (2)0.031 (3)0.036 (3)0.003 (2)0.003 (2)0.002 (2)
C520.040 (2)0.031 (4)0.056 (3)0.002 (2)0.006 (2)0.001 (2)
C620.049 (2)0.033 (3)0.045 (3)0.000 (3)0.002 (2)0.004 (2)
C720.080 (4)0.031 (4)0.065 (4)0.007 (3)0.007 (3)0.008 (2)
Geometric parameters (Å, º) top
As1—O111.709 (3)C61—H2c610.95 (2)
As1—O211.655 (2)C71—H1c710.98 (3)
As1—O311.653 (2)C71—H2c710.94 (3)
As1—O411.707 (3)C71—H3c710.96 (2)
As2—O121.677 (3)O11—Ho110.84 (3)
As2—O221.710 (3)O41—Ho410.88 (2)
As2—O321.638 (2)O12—Ho120.84 (2)
As2—O421.657 (2)O22—Ho220.88 (4)
N1—C111.475 (6)N2—H1n20.86 (2)
C11—C211.514 (7)N2—H2n20.91 (2)
C21—C311.506 (7)N2—H3n20.90 (2)
C31—C411.509 (7)C12—H1c120.95 (2)
C41—C511.502 (7)C12—H2c120.94 (2)
C51—C611.502 (7)C22—H1c220.94 (2)
C61—C711.512 (8)C22—H2c220.95 (2)
N2—C121.493 (6)C32—H1c320.95 (2)
C12—C221.481 (6)C32—H2c320.94 (2)
C22—C321.527 (7)C42—H1c420.95 (2)
C32—C421.496 (7)C42—H2c420.95 (2)
C42—C521.528 (7)C52—H1c520.96 (2)
C52—C621.506 (7)C52—H2c520.94 (2)
C62—C721.523 (7)C62—H1c620.95 (2)
N1—H1n10.90 (2)C62—H2c620.96 (2)
N1—H2n10.84 (2)C72—H1c721.00 (3)
N1—H3n10.88 (2)C72—H2c720.95 (3)
C11—H1c110.94 (2)C72—H3c720.95 (2)
C11—H2c110.95 (2)O11—O32i2.592 (4)
C21—H1c210.95 (2)O21—O22ii2.541 (5)
C21—H2c210.94 (2)O31—O122.591 (4)
C31—H1c310.95 (2)O41—O42iii2.513 (4)
C31—H2c310.95 (2)N1—O22iv2.976 (5)
C41—H1c410.95 (2)N1—O32v2.789 (4)
C41—H2c410.96 (2)N1—O42vi2.756 (4)
C51—H1c510.95 (2)N2—O21v2.850 (4)
C51—H2c510.94 (2)N2—O31iv2.791 (4)
C61—H1c610.95 (2)N2—O41vi2.824 (5)
O11—As1—O21111.45 (15)O12—As2—O22105.62 (16)
O11—As1—O31106.57 (15)O12—As2—O32107.37 (15)
O11—As1—O41107.11 (14)O12—As2—O42112.28 (14)
O21—As1—O31116.75 (13)O22—As2—O32111.70 (14)
O21—As1—O41104.77 (15)O22—As2—O42106.42 (15)
O31—As1—O41109.84 (15)O32—As2—O42113.24 (14)
Symmetry codes: (i) x1, y, z; (ii) x1/2, y+1/2, z+1/2; (iii) x1/2, y+1/2, z1/2; (iv) x+1, y+1, z; (v) x+1, y+1, z+1; (vi) x+1/2, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HD···AD—H···A
O11—HO11···O32i0.84 (3)2.592 (4)166 (3)
O41—HO41···O42iii0.88 (3)2.513 (4)159 (4)
O12—HO12···O310.84 (2)2.591 (4)164 (3)
O22—HO22···O21vii0.88 (4)2.541 (5)155 (5)
N1—H3n1···O22iv0.88 (3)2.976 (5)152 (3)
N1—H1n1···O32v0.90 (2)2.789 (4)172 (3)
N1—H2n1···O42vi0.84 (3)2.756 (4)159 (3)
N2—H1n2···O21v0.86 (2)2.850 (4)161 (3)
N2—H3n2···O31iv0.90 (2)2.791 (4)148 (2)
N2—H2n2···O41vi0.91 (3)2.824 (5)164 (3)
Symmetry codes: (i) x1, y, z; (iii) x1/2, y+1/2, z1/2; (iv) x+1, y+1, z; (v) x+1, y+1, z+1; (vi) x+1/2, y+1/2, z+1/2; (vii) x+1/2, y+1/2, z1/2.
 

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