Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103005857/tr1047sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103005857/tr1047Isup2.hkl |
CCDC reference: 214165
The title compound was obtained from Clariant GmbH, Germany. Colourless crystals were obtained by slow evaporation of water from a concentrated solution. In the 13C{1H}-NMR spectra, (I) shows three signals. The two singlets at δ of 155.5 and 156.2 p.p.m. can be assigned to the carbamoyl and guanidinium C atoms of the cation. The chemical shifts are in good agreement with the values reported by Hesse et al. (1991), Kalinowski et al. (1984a) and Machnitzki et al. (2000).
The signal at δ of 15.3 p.p.m., showing a doublet fine structure (1J(PC) = 135.3 Hz), corresponds to the C atom of the methylphosphonate anion. The chemical shift and coupling constant agree well with those reported by Berger et al. (1993) and Kalinowski et al. (1984b) for diethyl methylphosphonate and related compounds. The 13C{1H}-NMR spectrum was recorded on a Bruker ARX 400 spectrometer at 100.6 MHz using d6-dimethylsulfoxide as solvent.
H atom positions were located from difference Fourier maps and were individually refined, as were their respective Ueq values.
Data collection: P3/PC (Siemens, 1993); cell refinement: P3/PC; data reduction: XDISK Version 4.20.2 (Siemens, 1991); program(s) used to solve structure: SHELXS93 (Sheldrick, 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP, Version 5.03. (Siemens, 1994); software used to prepare material for publication: SHELXL97.
C2H7N4O+·CH4O3P−·H2O | F(000) = 456 |
Mr = 216.14 | Dx = 1.436 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 50 reflections |
a = 11.9081 (18) Å | θ = 10.8–14.4° |
b = 6.4458 (7) Å | µ = 0.28 mm−1 |
c = 13.996 (3) Å | T = 295 K |
β = 111.440 (16)° | Prism, colourless |
V = 999.9 (3) Å3 | 0.46 × 0.29 × 0.28 mm |
Z = 4 |
Siemens P3 diffractometer | 1467 reflections with I > 2σ(I) |
Radiation source: normal-focus sealed tube | Rint = 0.025 |
Graphite monochromator | θmax = 27.5°, θmin = 3.0° |
ω scans | h = 0→15 |
Absorption correction: ψ scan North, Phillips & Mathews, 1968 | k = 0→8 |
Tmin = 0.883, Tmax = 0.926 | l = −18→16 |
2400 measured reflections | 3 standard reflections every 100 reflections |
2293 independent reflections | intensity decay: none |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.037 | All H-atom parameters refined |
wR(F2) = 0.085 | w = 1/[σ2(Fo2) + (0.0403P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.83 | (Δ/σ)max < 0.001 |
2293 reflections | Δρmax = 0.28 e Å−3 |
171 parameters | Δρmin = −0.23 e Å−3 |
0 restraints | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0119 (12) |
C2H7N4O+·CH4O3P−·H2O | V = 999.9 (3) Å3 |
Mr = 216.14 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 11.9081 (18) Å | µ = 0.28 mm−1 |
b = 6.4458 (7) Å | T = 295 K |
c = 13.996 (3) Å | 0.46 × 0.29 × 0.28 mm |
β = 111.440 (16)° |
Siemens P3 diffractometer | 1467 reflections with I > 2σ(I) |
Absorption correction: ψ scan North, Phillips & Mathews, 1968 | Rint = 0.025 |
Tmin = 0.883, Tmax = 0.926 | 3 standard reflections every 100 reflections |
2400 measured reflections | intensity decay: none |
2293 independent reflections |
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.085 | All H-atom parameters refined |
S = 0.83 | Δρmax = 0.28 e Å−3 |
2293 reflections | Δρmin = −0.23 e Å−3 |
171 parameters |
Geometry. Mean-plane data from final SHELXL refinement run:- Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) 0.5957 (0.0159) x + 6.4323 (0.0019) y − 0.7913 (0.0155) z = 1.4787 (0.0152) * −0.0005 (0.0007) O1 * −0.0004 (0.0006) N1 * −0.0004 (0.0005) N2 * 0.0013 (0.0018) C1 − 0.0790 (0.0037) C2 − 0.0963 (0.0048) N3 − 0.1338 (0.0041) N4 0.0049 (0.0046) O3 − 0.2265 (0.0047) O4 Rms deviation of fitted atoms = 0.0008 1.2969 (0.0136) x + 6.4033 (0.0020) y − 1.0220 (0.0181) z = 1.8807 (0.0166) Angle to previous plane (with approximate e.s.d.) = 3.40(0.04) * 0.0002 (0.0006) N2 * 0.0002 (0.0006) N3 * 0.0002 (0.0006) N4 * −0.0007 (0.0018) C2 − 0.0297 (0.0036) C1 0.0113 (0.0039) O1 − 0.1098 (0.0048) N1 − 0.0630 (0.0044) O3 − 0.4124 (0.0053) O4 Rms deviation of fitted atoms = 0.0004 0.9913 (0.0083) x + 6.4170 (0.0018) y − 1.0064 (0.0085) z = 1.5955 (0.0122) Angle to previous plane (with approximate e.s.d.) = 1.56(0.03) * −0.0365 (0.0013) N1 * 0.0089 (0.0018) C1 * 0.0244 (0.0012) O1 * 0.0331 (0.0017) N2 * −0.0004 (0.0018) C2 * 0.0007 (0.0012) N3 * −0.0303 (0.0012) N4 0.0181 (0.0035) O3 − 0.2886 (0.0039) O4 Rms deviation of fitted atoms = 0.0240 |
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 | ||
P | 0.59655 (5) | 0.17680 (9) | 0.69649 (4) | 0.03592 (17) | |
O2 | 0.59588 (15) | −0.0661 (3) | 0.68696 (14) | 0.0517 (4) | |
H6 | 0.546 (2) | −0.127 (5) | 0.698 (2) | 0.075 (10)* | |
O3 | 0.71415 (13) | 0.2495 (2) | 0.69094 (12) | 0.0486 (4) | |
O4 | 0.57926 (13) | 0.2387 (2) | 0.79384 (11) | 0.0472 (4) | |
C3 | 0.4724 (3) | 0.2675 (6) | 0.5896 (2) | 0.0618 (7) | |
H5A | 0.481 (2) | 0.226 (4) | 0.530 (2) | 0.077 (9)* | |
H5B | 0.402 (3) | 0.214 (5) | 0.599 (2) | 0.096 (11)* | |
H5C | 0.472 (3) | 0.412 (5) | 0.588 (2) | 0.092 (11)* | |
O5 | 0.76682 (17) | −0.3379 (4) | 0.66069 (17) | 0.0680 (6) | |
H7A | 0.719 (3) | −0.262 (5) | 0.681 (3) | 0.120 (14)* | |
H7B | 0.745 (3) | −0.453 (5) | 0.672 (2) | 0.096 (13)* | |
O1 | 0.95809 (14) | 0.2744 (2) | 1.08370 (10) | 0.0472 (4) | |
N1 | 0.75668 (18) | 0.2823 (4) | 0.99593 (17) | 0.0558 (6) | |
H1A | 0.700 (2) | 0.263 (4) | 0.936 (2) | 0.063 (8)* | |
H1B | 0.7411 (19) | 0.285 (3) | 1.0504 (18) | 0.047 (7)* | |
N2 | 0.88367 (17) | 0.2597 (3) | 0.90780 (13) | 0.0416 (4) | |
H2 | 0.821 (2) | 0.262 (3) | 0.8512 (19) | 0.057 (7)* | |
N3 | 0.9825 (2) | 0.2220 (3) | 0.79735 (16) | 0.0522 (5) | |
H3A | 0.914 (2) | 0.225 (4) | 0.7536 (19) | 0.056 (8)* | |
H3B | 1.049 (2) | 0.209 (4) | 0.7864 (18) | 0.059 (8)* | |
N4 | 1.09290 (17) | 0.2272 (3) | 0.96957 (16) | 0.0456 (5) | |
H4A | 1.159 (3) | 0.211 (4) | 0.951 (2) | 0.083 (9)* | |
H4B | 1.0917 (19) | 0.243 (3) | 1.0289 (17) | 0.038 (6)* | |
C1 | 0.8706 (2) | 0.2729 (3) | 1.00319 (16) | 0.0402 (5) | |
C2 | 0.98832 (19) | 0.2359 (3) | 0.89232 (15) | 0.0374 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
P | 0.0320 (3) | 0.0408 (3) | 0.0385 (3) | 0.0003 (3) | 0.0171 (2) | −0.0008 (3) |
O2 | 0.0547 (10) | 0.0416 (9) | 0.0764 (12) | −0.0050 (8) | 0.0449 (9) | −0.0063 (9) |
O3 | 0.0390 (8) | 0.0522 (10) | 0.0604 (10) | −0.0048 (7) | 0.0251 (7) | 0.0039 (7) |
O4 | 0.0479 (9) | 0.0570 (10) | 0.0396 (8) | 0.0105 (7) | 0.0193 (7) | −0.0013 (7) |
C3 | 0.0539 (16) | 0.078 (2) | 0.0441 (15) | 0.0078 (15) | 0.0065 (12) | −0.0025 (14) |
O5 | 0.0593 (12) | 0.0540 (12) | 0.1066 (16) | 0.0042 (11) | 0.0493 (12) | 0.0061 (13) |
O1 | 0.0463 (9) | 0.0625 (11) | 0.0301 (8) | −0.0001 (7) | 0.0108 (7) | −0.0031 (7) |
N1 | 0.0443 (12) | 0.0867 (18) | 0.0393 (12) | 0.0000 (11) | 0.0187 (10) | −0.0021 (11) |
N2 | 0.0391 (10) | 0.0552 (12) | 0.0276 (9) | −0.0008 (9) | 0.0087 (8) | 0.0002 (8) |
N3 | 0.0591 (14) | 0.0642 (15) | 0.0390 (11) | 0.0047 (12) | 0.0246 (11) | 0.0024 (10) |
N4 | 0.0409 (11) | 0.0542 (13) | 0.0430 (11) | 0.0001 (9) | 0.0168 (9) | −0.0015 (9) |
C1 | 0.0474 (12) | 0.0392 (13) | 0.0351 (11) | 0.0000 (10) | 0.0162 (10) | 0.0012 (9) |
C2 | 0.0465 (12) | 0.0319 (11) | 0.0360 (11) | −0.0002 (9) | 0.0178 (10) | 0.0009 (9) |
P—O2 | 1.5714 (17) | N1—H1A | 0.87 (3) |
P—O3 | 1.5055 (14) | N1—H1B | 0.85 (2) |
P—O4 | 1.5042 (15) | N2—C1 | 1.402 (3) |
P—C3 | 1.774 (3) | N2—C2 | 1.349 (3) |
O2—H6 | 0.78 (3) | N2—H2 | 0.86 (2) |
C3—H5A | 0.92 (3) | N3—C2 | 1.309 (3) |
C3—H5B | 0.96 (3) | N3—H3A | 0.83 (2) |
C3—H5C | 0.93 (3) | N3—H3B | 0.87 (3) |
O5—H7A | 0.88 (4) | N4—C2 | 1.319 (3) |
O5—H7B | 0.82 (3) | N4—H4A | 0.92 (3) |
O1—C1 | 1.224 (2) | N4—H4B | 0.84 (2) |
N1—C1 | 1.324 (3) | ||
O2—P—O3 | 106.36 (9) | H1A—N1—H1B | 122 (2) |
O2—P—O4 | 110.07 (9) | C2—N2—C1 | 126.19 (18) |
O3—P—O4 | 113.70 (10) | C2—N2—H2 | 112.8 (16) |
O2—P—C3 | 106.26 (15) | C1—N2—H2 | 121.0 (16) |
O3—P—C3 | 110.98 (14) | C2—N3—H3A | 114.8 (17) |
O4—P—C3 | 109.18 (12) | C2—N3—H3B | 118.4 (17) |
P—O2—H6 | 118 (2) | H3A—N3—H3B | 127 (2) |
P—C3—H5A | 109.5 (17) | C2—N4—H4A | 114.8 (17) |
P—C3—H5B | 105.8 (19) | C2—N4—H4B | 116.9 (15) |
H5A—C3—H5B | 114 (3) | H4A—N4—H4B | 128 (2) |
P—C3—H5C | 110.0 (18) | O1—C1—N1 | 125.0 (2) |
H5A—C3—H5C | 106 (2) | O1—C1—N2 | 121.6 (2) |
H5B—C3—H5C | 111 (2) | N1—C1—N2 | 113.4 (2) |
H7A—O5—H7B | 99 (3) | N2—C2—N3 | 117.5 (2) |
C1—N1—H1A | 118.2 (16) | N2—C2—N4 | 121.60 (19) |
C1—N1—H1B | 119.1 (15) | N3—C2—N4 | 120.9 (2) |
C2—N2—C1—O1 | 3.9 (3) | C1—N2—C2—N3 | 178.5 (2) |
C2—N2—C1—N1 | −175.8 (2) | C1—N2—C2—N4 | −1.6 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H6···O4i | 0.78 (3) | 1.76 (3) | 2.533 (2) | 172 (3) |
O5—H7A···O2 | 0.88 (4) | 1.96 (4) | 2.810 (3) | 164 (3) |
O5—H7B···O3ii | 0.82 (3) | 1.99 (3) | 2.800 (3) | 170 (3) |
N1—H1A···O4 | 0.87 (3) | 1.99 (3) | 2.859 (3) | 175 (2) |
N1iii—H1Biii···O3 | 0.85 (2) | 2.12 (2) | 2.959 (3) | 172 (2) |
N2—H2···O3 | 0.86 (2) | 2.14 (3) | 2.969 (3) | 161 (2) |
N3—H3A···O3 | 0.83 (2) | 2.22 (3) | 2.997 (3) | 158 (2) |
N3—H3B···O5iv | 0.87 (3) | 2.06 (3) | 2.850 (3) | 151 (2) |
N4—H4A···O5iv | 0.92 (3) | 2.08 (3) | 2.918 (3) | 151 (2) |
N4—H4B···O1 | 0.84 (2) | 2.01 (2) | 2.664 (3) | 134 (2) |
N3—H3A···O1iii | 0.83 (2) | 2.62 (2) | 2.897 (2) | 101 (2) |
N3—H3B···O1iii | 0.87 (3) | 2.64 (2) | 2.897 (2) | 98 (2) |
Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) x, y−1, z; (iii) x, −y+1/2, z−1/2; (iv) −x+2, y+1/2, −z+3/2. |
Experimental details
Crystal data | |
Chemical formula | C2H7N4O+·CH4O3P−·H2O |
Mr | 216.14 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 295 |
a, b, c (Å) | 11.9081 (18), 6.4458 (7), 13.996 (3) |
β (°) | 111.440 (16) |
V (Å3) | 999.9 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.28 |
Crystal size (mm) | 0.46 × 0.29 × 0.28 |
Data collection | |
Diffractometer | Siemens P3 diffractometer |
Absorption correction | ψ scan North, Phillips & Mathews, 1968 |
Tmin, Tmax | 0.883, 0.926 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2400, 2293, 1467 |
Rint | 0.025 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.085, 0.83 |
No. of reflections | 2293 |
No. of parameters | 171 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.28, −0.23 |
Computer programs: P3/PC (Siemens, 1993), P3/PC, XDISK Version 4.20.2 (Siemens, 1991), SHELXS93 (Sheldrick, 1993), SHELXL97 (Sheldrick, 1997), XP, Version 5.03. (Siemens, 1994), SHELXL97.
P—O2 | 1.5714 (17) | P—O4 | 1.5042 (15) |
P—O3 | 1.5055 (14) | P—C3 | 1.774 (3) |
O2—P—O3 | 106.36 (9) | O1—C1—N1 | 125.0 (2) |
O2—P—O4 | 110.07 (9) | O1—C1—N2 | 121.6 (2) |
O3—P—O4 | 113.70 (10) | N1—C1—N2 | 113.4 (2) |
O2—P—C3 | 106.26 (15) | N2—C2—N3 | 117.5 (2) |
O3—P—C3 | 110.98 (14) | N2—C2—N4 | 121.60 (19) |
O4—P—C3 | 109.18 (12) | N3—C2—N4 | 120.9 (2) |
C2—N2—C1 | 126.19 (18) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H6···O4i | 0.78 (3) | 1.76 (3) | 2.533 (2) | 172 (3) |
O5—H7A···O2 | 0.88 (4) | 1.96 (4) | 2.810 (3) | 164 (3) |
O5—H7B···O3ii | 0.82 (3) | 1.99 (3) | 2.800 (3) | 170 (3) |
N1—H1A···O4 | 0.87 (3) | 1.99 (3) | 2.859 (3) | 175 (2) |
N1iii—H1Biii···O3 | 0.85 (2) | 2.12 (2) | 2.959 (3) | 172 (2) |
N2—H2···O3 | 0.86 (2) | 2.14 (3) | 2.969 (3) | 161 (2) |
N3—H3A···O3 | 0.83 (2) | 2.22 (3) | 2.997 (3) | 158 (2) |
N3—H3B···O5iv | 0.87 (3) | 2.06 (3) | 2.850 (3) | 151 (2) |
N4—H4A···O5iv | 0.92 (3) | 2.08 (3) | 2.918 (3) | 151 (2) |
N4—H4B···O1 | 0.84 (2) | 2.01 (2) | 2.664 (3) | 134 (2) |
N3—H3A···O1iii | 0.83 (2) | 2.62 (2) | 2.897 (2) | 101 (2) |
N3—H3B···O1iii | 0.87 (3) | 2.64 (2) | 2.897 (2) | 98 (2) |
Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) x, y−1, z; (iii) x, −y+1/2, z−1/2; (iv) −x+2, y+1/2, −z+3/2. |
Reference | C1—O | C1—N1 | C1—N2 | C2—N2 | C2—N3 | C2—N4 |
(I)a | 1.224 (2) | 1.324 (3) | 1.402 (3) | 1.349 (3) | 1.309 (3) | 1.319 (3) |
DIVVEJb | 1.225 (3) | 1.326 (4) | 1.392 (4) | 1.358 (4) | 1.318 (3) | 1.313 (3) |
DUNHIDc | 1.217 (3) | 1.329 (3) | 1.399 (3) | 1.358 (3) | 1.319 (3) | 1.320 (3) |
GADWUDd | 1.233 (5) | 1.319 (5) | 1.390 (4) | 1.355 (4) | 1.323 (5) | 1.304 (5) |
JODZOR1e | 1.221 (3) | 1.326 (3) | 1.395 (3) | 1.356 (3) | 1.322 (3) | 1.313 (3) |
JODZOR2e | 1.225 (3) | 1.319 (3) | 1.394 (2) | 1.356 (3) | 1.318 (2) | 1.304 (3) |
QIRGIHf | 1.236 (2) | 1.336 (2) | 1.415 (2) | 1.371 (2) | 1.331 (2) | 1.323 (2) |
Notes: (a) This work; (b) Begley et al., (1985); (c) Zaman & Darlow, (1986); (d) Begley et al., (1988); (e) Scoponi et al., (1991); (f) Bemm, (2000). |
The present study was undertaken in order to reveal the nature of the title compound, (I). The asymmetric unit was found to contain one carbamoylguanidinium (CG) cation, one methylphosphonate (MP) anion and one water molecule. These are shown in Fig. 1, in which the atom-numbering scheme is also defined.
The MP anion has a distorted tetrahedral geometry (Table 2), with bond angles between 106.3 (2)° and 113.7 (1)°. The P—C3 bond length is in good agreement with the phosphorous–carbon distances of dimethylphosphinic acid as reported by Giordano & Ripamonti (1967). The O2—H6 hydroxyl group of the MP anion acts as donor to O4i, in a screw-related anion to form an endless N1 = C11(4) chain (Bernstein et al., 1995), and as an acceptor of H7A of the water molecule (Fig. 2). This water molecule donates its second H atom to the O3ii atom of an anion displaced by −b from that of the asymmetric unit, thus forming an N2 = C22(6) chain. Both chains run parallel to the b axis. The combination of both chains generates a column built from N3 = R44(12) rings (E).
The non-H-atom skeleton of the cation is nearly planar. A dihedral angle of 3.40 (4)° is formed by the normals to the planes of the ureic (C1, N1, N2, O1) and guanidinium (C2, N2, N3, N4) fragments, each of which is planar to within experimental error. The bond lengths found in the cation are compared in Table 1 with those reported previously for this moiety; references are indicated by their Cambridge Structural Database codes (Allen, 2002). In general, excellent agreement is found, except that the bond lengths deposited for the low-temperature structure (QIRGIH) tend to be 0.01–0.02 Å longer. The trend in the bond lengths such that N2—C1 > N2—C2 > N1—C1 = N3—C2 = N4—C2 is well established and is consistent with a low degree of conjugation between the ureic and guanidinium fragments as noted by Scoponi et al. (1991). These authors mentioned that nitrogen–carbon multiple bonding will place formal positive charge on the N atoms and thus enhance their ability to form hydrogen bonds. Indeed previous studies of the CG cation have shown that all N—H bonds act as proton donors, and this behaviour is also found in the present study.
The CG cation is connected to the MP anion via three NH···O hydrogen bonds to generate two condensed rings [C, N2 = R21(6)] and [D, N2 = R22(8)]. Two of the contacts involve atom O3, which is approximately equidistant from atoms H2 and H3A. This situation differs from that described by Zaman & Darlow (1986), in which the corresponding O atom is 0.6 Å closer to H2 than to H3A.
Atom O3 also accepts atom H1Biii (cf. Table 3) of a c-glide-related cation. Furthermore, the water molecule accepts atoms H3B and H4A to form a six-membered ring [B, N2 = R21(6)]. These two protons are often donated to a common acceptor, such as a Cl− ion or an MO2 fragment of a dinitroamide, phosphate or perchlorate ion. The MO2 fragments act as bidentate acceptors, forming N2 = R22(8) rings.
A strong intramolecular NH···O hydrogen bond (H4B···O1) closes a six-membered [A, N1 = S(6)] ring. This motif of intramolecular hydrogen bridging has been frequently encountered (Bilton et al., 2000) and has always been found in structure determinations of the CG cation (Begley et al., 1985; Begley et al., 1988; Bemm, 2000; Scoponi et al., 1991; Zaman & Darlow, 1986).
In addition to these strong interactions, O1iii (Table 3) makes two weak contacts with H3A and H3B to build a four-membered [F, N2 = R21(4)] and a six-membered [G, N3 = R22(6)] ring. In more than half of the reported structures of the CG cation, intermolecular O1···H3A hydrogen bonding strongly links the cations to chains in a head-to-tail fashion. In (I) this motif is disrupted by the strong interaction with the anion. Details of the hydrogen bonding are collected in Table 3.