The title compound, C
14H
15ClN
4O
2+·C
2O
42−, was obtained as a 1:1 binary ionic compound. Two cations and two anions are connected
via ionic N—H
O hydrogen bonds to form an annulus with internal dimensions of about 8.5 × 9.5 Å, and these units are connected through O—H
O hydrogen bonds to form a two-dimensional porous layer. Weak C—H
π and C—Cl
π [Cl
centroid = 3.575 (2) and 3.598 (2) Å] interactions, together with strong π–π stacking interactions [centroid-to-centroid distance = 3.429 (3) Å], contribute to the stability of the structure.
Supporting information
CCDC reference: 672793
Key indicators
- Single-crystal X-ray study
- T = 294 K
- Mean (C-C) = 0.005 Å
- R factor = 0.069
- wR factor = 0.201
- Data-to-parameter ratio = 12.5
checkCIF/PLATON results
No syntax errors found
Alert level C
WEIGH01_ALERT_1_C Extra text has been found in the
_refine_ls_weighting_scheme field. This should be in the
_refine_ls_weighting_details field.
Weighting scheme given as calc w=1/[\s^2^(Fo^2^)+(0.1334P)^2^] where
Weighting scheme identified as calc
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.35
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ... 6
PLAT369_ALERT_2_C Long C(sp2)-C(sp2) Bond C15 - C16 ... 1.56 Ang.
PLAT432_ALERT_2_C Short Inter X...Y Contact O3 .. C14 .. 3.00 Ang.
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 1
C14 H15 Cl N4 O
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 2
C2 O4
0 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
7 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
3 ALERT type 2 Indicator that the structure model may be wrong or deficient
1 ALERT type 3 Indicator that the structure quality may be low
2 ALERT type 4 Improvement, methodology, query or suggestion
0 ALERT type 5 Informative message, check
2,6-Bis[(imidazol-1-yl)methyl]-4-chlorophenol (0.05 mmol, 14.4 mg) in methanol
(8 ml) and oxalic acid (0.05 mmol, 4.5 mg) in methanol (2 ml) and water (0.5 ml) were mixed and left to stand at room temperature. Colorless block crystals
were obtained by slow evaporation of the solution after 8 days. Yield, 60%;
1H NMR (400 MHz, DMSO-d6): δ 5.25 (s, 4H), 7.08 (s, 2H), 7.10 (s, 2H), 7.30
(s, 2H), 8.09 (s, 2H).
H1O, H2N and H4N were observed in difference electron density maps and refined
with isotropic displacement parameters. All other hydrogen atoms were
positioned geometrically and refined in the riding model approximation with
C—H = 0.93 or 0.97 Å and Uiso(H) = 1.2Ueq(C).
Data collection: DIFRAC (Gabe & White, 1993); cell refinement: DIFRAC (Gabe & White, 1993); data reduction: NRCVAX (Gabe et al., 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and
Mercury (Version 1.2; Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
3,3'-(5-Chloro-2-hydroxy-
m-phenylenedimethylene)diimidazolium oxalate
top
Crystal data top
C14H15ClN4O2+·C2O42− | F(000) = 784 |
Mr = 378.77 | Dx = 1.464 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 28 reflections |
a = 7.3158 (18) Å | θ = 4.6–9.5° |
b = 19.824 (4) Å | µ = 0.26 mm−1 |
c = 11.901 (2) Å | T = 294 K |
β = 95.18 (2)° | Block, colourless |
V = 1719.0 (6) Å3 | 0.30 × 0.26 × 0.20 mm |
Z = 4 | |
Data collection top
Enraf–Nonius CAD-4 diffractometer | Rint = 0.007 |
Radiation source: fine-focus sealed tube | θmax = 25.5°, θmin = 2.0° |
Graphite monochromator | h = −8→8 |
ω/2θ scans | k = 0→23 |
4162 measured reflections | l = −7→14 |
3122 independent reflections | 3 standard reflections every 300 reflections |
1789 reflections with I > 2σ(I) | intensity decay: 3.7% |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.070 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.201 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.96 | Calculated w = 1/[σ2(Fo2) + (0.1334P)2] where P = (Fo2 + 2Fc2)/3 |
3122 reflections | (Δ/σ)max < 0.001 |
249 parameters | Δρmax = 0.53 e Å−3 |
0 restraints | Δρmin = −0.39 e Å−3 |
Crystal data top
C14H15ClN4O2+·C2O42− | V = 1719.0 (6) Å3 |
Mr = 378.77 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.3158 (18) Å | µ = 0.26 mm−1 |
b = 19.824 (4) Å | T = 294 K |
c = 11.901 (2) Å | 0.30 × 0.26 × 0.20 mm |
β = 95.18 (2)° | |
Data collection top
Enraf–Nonius CAD-4 diffractometer | Rint = 0.007 |
4162 measured reflections | 3 standard reflections every 300 reflections |
3122 independent reflections | intensity decay: 3.7% |
1789 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.070 | 0 restraints |
wR(F2) = 0.201 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.96 | Δρmax = 0.53 e Å−3 |
3122 reflections | Δρmin = −0.39 e Å−3 |
249 parameters | |
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 | x | y | z | Uiso*/Ueq | |
Cl1 | 0.74430 (17) | 0.05960 (6) | 0.08437 (11) | 0.0619 (4) | |
O1 | 0.7766 (4) | −0.17156 (15) | −0.2216 (2) | 0.0429 (7) | |
O2 | 0.4825 (4) | 0.08021 (14) | −0.4268 (3) | 0.0468 (8) | |
O3 | 0.7050 (3) | 0.13828 (14) | −0.3313 (3) | 0.0482 (8) | |
O4 | 0.4533 (4) | 0.22842 (13) | −0.2732 (3) | 0.0503 (8) | |
O5 | 0.2327 (4) | 0.15468 (14) | −0.3234 (3) | 0.0510 (8) | |
N1 | 0.9367 (4) | −0.03705 (14) | −0.3488 (3) | 0.0328 (7) | |
N2 | 1.1907 (5) | 0.00811 (19) | −0.3871 (3) | 0.0427 (9) | |
N3 | 0.9597 (4) | −0.21898 (15) | 0.0491 (3) | 0.0364 (8) | |
N4 | 1.2236 (5) | −0.22666 (19) | 0.1424 (3) | 0.0481 (10) | |
C1 | 0.7455 (5) | −0.0099 (2) | −0.0058 (4) | 0.0406 (9) | |
C2 | 0.7426 (5) | 0.0001 (2) | −0.1197 (3) | 0.0395 (9) | |
H2 | 0.7378 | 0.0438 | −0.1484 | 0.047* | |
C3 | 0.7466 (4) | −0.05428 (18) | −0.1930 (3) | 0.0329 (9) | |
C4 | 0.7551 (4) | −0.12011 (19) | −0.1478 (3) | 0.0322 (8) | |
C5 | 0.7528 (5) | −0.1295 (2) | −0.0318 (3) | 0.0358 (9) | |
C6 | 0.7471 (5) | −0.0742 (2) | 0.0388 (4) | 0.0417 (10) | |
H6 | 0.7443 | −0.0803 | 0.1161 | 0.050* | |
C7 | 0.7489 (5) | −0.04358 (19) | −0.3167 (3) | 0.0358 (9) | |
H71 | 0.6892 | −0.0813 | −0.3568 | 0.043* | |
H72 | 0.6804 | −0.0030 | −0.3386 | 0.043* | |
C8 | 1.0552 (6) | −0.0889 (2) | −0.3687 (4) | 0.0451 (10) | |
H8 | 1.0305 | −0.1349 | −0.3652 | 0.054* | |
C9 | 1.2137 (6) | −0.0604 (2) | −0.3942 (4) | 0.0470 (10) | |
H9 | 1.3183 | −0.0828 | −0.4131 | 0.056* | |
C10 | 1.0253 (5) | 0.02073 (19) | −0.3585 (3) | 0.0368 (9) | |
H10 | 0.9776 | 0.0634 | −0.3469 | 0.044* | |
C11 | 0.7680 (5) | −0.1998 (2) | 0.0192 (4) | 0.0433 (10) | |
H11A | 0.7019 | −0.2012 | 0.0863 | 0.052* | |
H11B | 0.7115 | −0.2321 | −0.0344 | 0.052* | |
C12 | 1.0751 (6) | −0.2505 (2) | −0.0185 (4) | 0.0507 (11) | |
H12 | 1.0452 | −0.2660 | −0.0916 | 0.061* | |
C13 | 1.2387 (6) | −0.2548 (2) | 0.0404 (4) | 0.0562 (12) | |
H13 | 1.3442 | −0.2737 | 0.0157 | 0.067* | |
C14 | 1.0532 (6) | −0.2052 (2) | 0.1469 (3) | 0.0409 (10) | |
H14 | 1.0070 | −0.1842 | 0.2082 | 0.049* | |
C15 | 0.3939 (5) | 0.17246 (18) | −0.3160 (3) | 0.0325 (8) | |
C16 | 0.5419 (5) | 0.12589 (17) | −0.3614 (3) | 0.0318 (8) | |
H1O | 0.711 (7) | −0.203 (3) | −0.226 (4) | 0.063 (16)* | |
H2N | 1.270 (8) | 0.035 (3) | −0.394 (5) | 0.079 (18)* | |
H4N | 1.312 (7) | −0.222 (2) | 0.196 (4) | 0.055 (13)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cl1 | 0.0567 (7) | 0.0605 (8) | 0.0677 (8) | 0.0019 (6) | 0.0008 (6) | −0.0262 (6) |
O1 | 0.0453 (17) | 0.0360 (16) | 0.0483 (18) | −0.0147 (14) | 0.0097 (13) | −0.0047 (13) |
O2 | 0.0307 (15) | 0.0506 (17) | 0.0604 (19) | −0.0080 (13) | 0.0115 (13) | −0.0209 (14) |
O3 | 0.0237 (14) | 0.0511 (17) | 0.069 (2) | 0.0019 (12) | −0.0003 (12) | −0.0134 (15) |
O4 | 0.0319 (15) | 0.0374 (16) | 0.079 (2) | 0.0125 (12) | −0.0116 (14) | −0.0118 (14) |
O5 | 0.0290 (15) | 0.0453 (16) | 0.079 (2) | 0.0083 (13) | 0.0075 (14) | −0.0029 (15) |
N1 | 0.0313 (16) | 0.0319 (16) | 0.0346 (18) | −0.0020 (13) | 0.0006 (13) | 0.0008 (13) |
N2 | 0.037 (2) | 0.045 (2) | 0.046 (2) | −0.0123 (17) | 0.0044 (15) | −0.0011 (16) |
N3 | 0.0323 (17) | 0.0364 (17) | 0.0395 (19) | −0.0050 (14) | −0.0019 (14) | −0.0009 (14) |
N4 | 0.0336 (19) | 0.051 (2) | 0.057 (2) | −0.0017 (16) | −0.0115 (17) | −0.0116 (18) |
C1 | 0.0270 (19) | 0.044 (2) | 0.050 (3) | −0.0021 (17) | −0.0012 (17) | −0.0095 (19) |
C2 | 0.0286 (19) | 0.037 (2) | 0.052 (3) | −0.0009 (16) | −0.0033 (17) | 0.0011 (18) |
C3 | 0.0141 (16) | 0.038 (2) | 0.046 (2) | 0.0003 (14) | −0.0025 (15) | 0.0015 (17) |
C4 | 0.0160 (16) | 0.037 (2) | 0.043 (2) | −0.0090 (14) | −0.0020 (14) | −0.0018 (16) |
C5 | 0.0228 (18) | 0.046 (2) | 0.037 (2) | −0.0080 (16) | −0.0034 (15) | 0.0052 (17) |
C6 | 0.034 (2) | 0.052 (2) | 0.039 (2) | −0.0021 (18) | −0.0012 (17) | −0.0040 (18) |
C7 | 0.0267 (19) | 0.036 (2) | 0.043 (2) | −0.0021 (15) | −0.0029 (16) | 0.0076 (17) |
C8 | 0.042 (2) | 0.036 (2) | 0.058 (3) | 0.0021 (18) | 0.0097 (19) | −0.0064 (19) |
C9 | 0.038 (2) | 0.054 (3) | 0.050 (3) | 0.0035 (19) | 0.0081 (19) | −0.001 (2) |
C10 | 0.040 (2) | 0.033 (2) | 0.037 (2) | −0.0086 (18) | −0.0006 (17) | 0.0017 (16) |
C11 | 0.028 (2) | 0.053 (2) | 0.048 (2) | −0.0075 (18) | −0.0022 (17) | 0.005 (2) |
C12 | 0.043 (2) | 0.056 (3) | 0.054 (3) | −0.002 (2) | 0.003 (2) | −0.017 (2) |
C13 | 0.036 (2) | 0.058 (3) | 0.074 (3) | 0.005 (2) | 0.006 (2) | −0.011 (2) |
C14 | 0.043 (2) | 0.042 (2) | 0.037 (2) | −0.0015 (18) | 0.0009 (18) | −0.0073 (18) |
C15 | 0.0278 (19) | 0.034 (2) | 0.035 (2) | 0.0053 (16) | −0.0002 (15) | 0.0072 (16) |
C16 | 0.0242 (18) | 0.0286 (18) | 0.043 (2) | 0.0010 (15) | 0.0024 (15) | 0.0041 (16) |
Geometric parameters (Å, º) top
Cl1—C1 | 1.747 (4) | C2—C3 | 1.389 (5) |
O1—C4 | 1.364 (5) | C2—H2 | 0.930 |
O1—H1O | 0.79 (5) | C3—C4 | 1.411 (5) |
O2—C16 | 1.247 (4) | C3—C7 | 1.489 (5) |
O3—C16 | 1.239 (4) | C4—C5 | 1.395 (5) |
O4—C15 | 1.280 (4) | C5—C6 | 1.385 (6) |
O5—C15 | 1.227 (4) | C5—C11 | 1.520 (5) |
N1—C10 | 1.326 (4) | C6—H6 | 0.930 |
N1—C8 | 1.380 (5) | C7—H71 | 0.970 |
N1—C7 | 1.464 (5) | C7—H72 | 0.970 |
N2—C10 | 1.310 (5) | C8—C9 | 1.349 (6) |
N2—C9 | 1.372 (6) | C8—H8 | 0.930 |
N2—H2N | 0.80 (5) | C9—H9 | 0.930 |
N3—C14 | 1.325 (5) | C10—H10 | 0.930 |
N3—C12 | 1.369 (5) | C11—H11A | 0.970 |
N3—C11 | 1.465 (5) | C11—H11B | 0.970 |
N4—C14 | 1.323 (5) | C12—C13 | 1.334 (6) |
N4—C13 | 1.348 (6) | C12—H12 | 0.930 |
N4—H4N | 0.87 (5) | C13—H13 | 0.930 |
C1—C2 | 1.369 (6) | C14—H14 | 0.930 |
C1—C6 | 1.380 (6) | C15—C16 | 1.556 (5) |
| | | |
C4—O1—H1O | 122 (4) | N1—C7—H72 | 109.3 |
C10—N1—C8 | 108.0 (3) | C3—C7—H72 | 109.3 |
C10—N1—C7 | 125.2 (3) | H71—C7—H72 | 108.0 |
C8—N1—C7 | 126.7 (3) | C9—C8—N1 | 107.0 (4) |
C10—N2—C9 | 109.0 (4) | C9—C8—H8 | 126.5 |
C10—N2—H2N | 126 (4) | N1—C8—H8 | 126.5 |
C9—N2—H2N | 124 (4) | C8—C9—N2 | 106.8 (4) |
C14—N3—C12 | 108.3 (3) | C8—C9—H9 | 126.6 |
C14—N3—C11 | 124.5 (4) | N2—C9—H9 | 126.6 |
C12—N3—C11 | 127.1 (3) | N2—C10—N1 | 109.1 (4) |
C14—N4—C13 | 108.9 (4) | N2—C10—H10 | 125.4 |
C14—N4—H4N | 125 (3) | N1—C10—H10 | 125.4 |
C13—N4—H4N | 126 (3) | N3—C11—C5 | 111.6 (3) |
C2—C1—C6 | 120.9 (4) | N3—C11—H11A | 109.3 |
C2—C1—Cl1 | 119.6 (3) | C5—C11—H11A | 109.3 |
C6—C1—Cl1 | 119.5 (3) | N3—C11—H11B | 109.3 |
C1—C2—C3 | 120.6 (4) | C5—C11—H11B | 109.3 |
C1—C2—H2 | 119.7 | H11A—C11—H11B | 108.0 |
C3—C2—H2 | 119.7 | C13—C12—N3 | 107.0 (4) |
C2—C3—C4 | 118.8 (4) | C13—C12—H12 | 126.5 |
C2—C3—C7 | 120.8 (3) | N3—C12—H12 | 126.5 |
C4—C3—C7 | 120.3 (3) | C12—C13—N4 | 107.7 (4) |
O1—C4—C5 | 123.3 (3) | C12—C13—H13 | 126.1 |
O1—C4—C3 | 116.7 (3) | N4—C13—H13 | 126.1 |
C5—C4—C3 | 119.8 (3) | N4—C14—N3 | 108.2 (4) |
C6—C5—C4 | 119.9 (4) | N4—C14—H14 | 125.9 |
C6—C5—C11 | 119.3 (4) | N3—C14—H14 | 125.9 |
C4—C5—C11 | 120.8 (3) | O5—C15—O4 | 124.5 (3) |
C1—C6—C5 | 119.8 (4) | O5—C15—C16 | 119.9 (3) |
C1—C6—H6 | 120.1 | O4—C15—C16 | 115.5 (3) |
C5—C6—H6 | 120.1 | O3—C16—O2 | 126.6 (3) |
N1—C7—C3 | 111.4 (3) | O3—C16—C15 | 117.6 (3) |
N1—C7—H71 | 109.3 | O2—C16—C15 | 115.7 (3) |
C3—C7—H71 | 109.3 | | |
| | | |
C6—C1—C2—C3 | −1.9 (6) | C7—N1—C8—C9 | −179.2 (3) |
Cl1—C1—C2—C3 | 178.9 (3) | N1—C8—C9—N2 | 1.3 (5) |
C1—C2—C3—C4 | −0.4 (5) | C10—N2—C9—C8 | 0.0 (5) |
C1—C2—C3—C7 | −178.2 (3) | C9—N2—C10—N1 | −1.3 (5) |
C2—C3—C4—O1 | −173.9 (3) | C8—N1—C10—N2 | 2.1 (4) |
C7—C3—C4—O1 | 3.9 (4) | C7—N1—C10—N2 | 179.3 (3) |
C2—C3—C4—C5 | 2.3 (5) | C14—N3—C11—C5 | 87.6 (5) |
C7—C3—C4—C5 | −180.0 (3) | C12—N3—C11—C5 | −89.1 (5) |
O1—C4—C5—C6 | 174.1 (3) | C6—C5—C11—N3 | −87.1 (4) |
C3—C4—C5—C6 | −1.7 (5) | C4—C5—C11—N3 | 89.2 (4) |
O1—C4—C5—C11 | −2.1 (5) | C14—N3—C12—C13 | −0.5 (5) |
C3—C4—C5—C11 | −178.0 (3) | C11—N3—C12—C13 | 176.6 (4) |
C2—C1—C6—C5 | 2.5 (6) | N3—C12—C13—N4 | 0.3 (5) |
Cl1—C1—C6—C5 | −178.4 (3) | C14—N4—C13—C12 | 0.0 (5) |
C4—C5—C6—C1 | −0.6 (5) | C13—N4—C14—N3 | −0.3 (5) |
C11—C5—C6—C1 | 175.7 (3) | C12—N3—C14—N4 | 0.5 (5) |
C10—N1—C7—C3 | −93.7 (4) | C11—N3—C14—N4 | −176.7 (3) |
C8—N1—C7—C3 | 83.0 (5) | O5—C15—C16—O3 | −164.8 (3) |
C2—C3—C7—N1 | 88.7 (4) | O4—C15—C16—O3 | 15.6 (5) |
C4—C3—C7—N1 | −89.1 (4) | O5—C15—C16—O2 | 16.5 (5) |
C10—N1—C8—C9 | −2.1 (5) | O4—C15—C16—O2 | −163.0 (3) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···O4i | 0.79 (5) | 1.81 (5) | 2.597 (4) | 174 (5) |
N2—H2N···O2ii | 0.80 (5) | 1.86 (6) | 2.647 (4) | 166 (6) |
N2—H2N···O5ii | 0.80 (5) | 2.53 (6) | 3.012 (5) | 119 (5) |
N4—H4N···O3iii | 0.87 (5) | 2.33 (5) | 2.861 (5) | 120 (4) |
N4—H4N···O4iii | 0.87 (5) | 1.88 (5) | 2.710 (4) | 160 (4) |
C8—H8···Cg2 | 0.93 | 2.83 | 3.664 (4) | 149 |
Symmetry codes: (i) −x+1, y−1/2, −z−1/2; (ii) x+1, y, z; (iii) −x+2, −y, −z. |
Experimental details
Crystal data |
Chemical formula | C14H15ClN4O2+·C2O42− |
Mr | 378.77 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 294 |
a, b, c (Å) | 7.3158 (18), 19.824 (4), 11.901 (2) |
β (°) | 95.18 (2) |
V (Å3) | 1719.0 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.26 |
Crystal size (mm) | 0.30 × 0.26 × 0.20 |
|
Data collection |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4162, 3122, 1789 |
Rint | 0.007 |
(sin θ/λ)max (Å−1) | 0.605 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.070, 0.201, 0.96 |
No. of reflections | 3122 |
No. of parameters | 249 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.53, −0.39 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···O4i | 0.79 (5) | 1.81 (5) | 2.597 (4) | 174 (5) |
N2—H2N···O2ii | 0.80 (5) | 1.86 (6) | 2.647 (4) | 166 (6) |
N2—H2N···O5ii | 0.80 (5) | 2.53 (6) | 3.012 (5) | 119 (5) |
N4—H4N···O3iii | 0.87 (5) | 2.33 (5) | 2.861 (5) | 120 (4) |
N4—H4N···O4iii | 0.87 (5) | 1.88 (5) | 2.710 (4) | 160 (4) |
C8—H8···Cg2 | 0.93 | 2.83 | 3.664 (4) | 149 |
Symmetry codes: (i) −x+1, y−1/2, −z−1/2; (ii) x+1, y, z; (iii) −x+2, −y, −z. |
The construction of organic crystals based on the hydrogen-bond interactions of organic ligands and various hydrogen bonding donors has been rapidly developed because of their fascinating structural diversity and potential applications for functional materials (MacGillivray & Atwood, 1997; Corna et al., 2004). In particular, intermolecular hydrogen bonds have been proven to be ideal and efficient tools in the design and construction of organic crystals because of their strength and directional properties (Aakeröy & Seddon, 1993). Dicarboxylic acids which can form strong and directional hydrogen bonds are frequently chosen as building blocks for crystal engineering, and a variety of cocrystals have been synthesized by assembling dicarboxylic acids and organic ligands bearing N-donors, such as pyridine-based ligands (Bhogala, 2003; Sarkar & Biradha, 2006). Imidazoles, which are also to N-donor compounds, have attracted attentions in the construction of some metal–organic frameworks in recent years (Dobrzanska et al., 2006; Zou et al., 2006; Wang et al., 2006), but only a few reports describing organic crystals composed of dicarboxylic acids and diimidazole compounds have appeared in the literature to date (Aakeröy et al., 2006; Van Roey et al., 1991; Wang et al., 2007). In further development of such interesting hydrogen-bonding supramolecular systems and as a continuation of our research in this area, we report here the crystal structure of an imidazolium oxalate salt, viz. the title compound, (I).
As depicted in Figure 1, the carboxyl protons H2N and H4N of oxalic acid have completely transferred to N2 and N4 of BICP, resulting in the formation of an imidazolium oxalate salt. Two cations and two anions form an annulus with internal dimensions of about 8.5 Å × 9.5 Å via N—H···O hydrogen bonds as illustrated in Figure 2 and Table 1. These units are further connected by O—H···O hydrogen bonds involving the hydroxy groups of the cation and the carbonyl group of oxalate to result in a 2-D porous layer as shown in Figure 3.
A network of intermolecular π–π and C—H···π interactions, as well as C–Cl···π interactions (Spek, 2003), provide strong packing forces in the structure of (I). A comparatively strong π–π interaction between an imidazole ring and another symmetry-related imidazole ring at (2 - x, -y, -1 - z), with their centroids separated by 3.429 (3) Å, plays an important part in the connection of adjacent porous layers. Weak C—H···π interactions also contribute to the interaction of neighboring layers. In addition, chlorine is involved in two separate C—Cl···π interactions, with C1···Cg1 = 4.623 (5) Å, Cl1···Cg1 = 3.575 (2) Å and C1—Cl1···Cg1 = 116°, and C1···Cg3 = 4.103 (4) Å, Cl1···Cg3 = 3.598 (2) Å and C1—Cl1···Cg3 = 94°, where Cg1 is the centroid of the imidazole ring of the molecule at (2 - x, -y, -z) and Cg3 is the centroid of the phenyl ring of the molecule at (1 - x, -y, -z).