Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270108039504/sk3264sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270108039504/sk3264Isup2.hkl |
CCDC reference: 718161
The title compound was prepared according to the literature method (Hoskins et al., 1997b). A 30.0 mg sample was sealed in a 23 ml Teflon-lined stainless steel autoclave, heated at 400 K for 2 d under autogenous pressure and cooled slowly to room temperature. Plate-shaped single crystals suitable for X-ray diffraction were obtained at the bottom of the autoclave.
In polymorph (II), the water molecules were both disordered over two positions. Because of the existence of the discrete hydrogen-bonding networks, the disorder parameters of O1 and O2 were coupled and their final occupancies were refined to be 0.59 (1):0.41 (1) for the major and minor components, respectively. All H atoms bonded to C atoms were positioned geometrically, with C—H distances of 0.93 (aromatic) and 0.97 Å (methylene), and treated as riding, with Uiso(H) set at 1.2Ueq(C). H atoms bonded to water O atoms were found in difference maps and refined with the constraints O—H = 0.82 (1) Å, H—H = 1.35 (1) Å and Uiso(H) = 1.5Ueq(O).
Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003), Mercury (Version 1.4; Bruno et al., 2002) and DIAMOND (Brandenburg, 2004); software used to prepare material for publication: PLATON (Spek, 2003).
C14H14N4·2H2O | F(000) = 1168 |
Mr = 274.32 | Dx = 1.233 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 2032 reflections |
a = 10.7178 (8) Å | θ = 2.3–23.8° |
b = 17.9925 (14) Å | µ = 0.09 mm−1 |
c = 15.3662 (12) Å | T = 299 K |
β = 94.006 (2)° | Prism, colorless |
V = 2956.0 (4) Å3 | 0.30 × 0.20 × 0.20 mm |
Z = 8 |
Bruker SMART APEX CCD area-detector diffractometer | 3369 independent reflections |
Radiation source: fine focus sealed Siemens Mo tube | 2237 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.026 |
0.3° wide ω exposures scans | θmax = 27.5°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | h = −13→13 |
Tmin = 0.965, Tmax = 0.983 | k = −18→23 |
9245 measured reflections | l = −19→19 |
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)] = 0.057 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.140 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0555P)2 + 0.7501P] where P = (Fo2 + 2Fc2)/3 |
3369 reflections | (Δ/σ)max < 0.001 |
224 parameters | Δρmax = 0.17 e Å−3 |
12 restraints | Δρmin = −0.13 e Å−3 |
C14H14N4·2H2O | V = 2956.0 (4) Å3 |
Mr = 274.32 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 10.7178 (8) Å | µ = 0.09 mm−1 |
b = 17.9925 (14) Å | T = 299 K |
c = 15.3662 (12) Å | 0.30 × 0.20 × 0.20 mm |
β = 94.006 (2)° |
Bruker SMART APEX CCD area-detector diffractometer | 3369 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | 2237 reflections with I > 2σ(I) |
Tmin = 0.965, Tmax = 0.983 | Rint = 0.026 |
9245 measured reflections |
R[F2 > 2σ(F2)] = 0.057 | 12 restraints |
wR(F2) = 0.140 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.17 e Å−3 |
3369 reflections | Δρmin = −0.13 e Å−3 |
224 parameters |
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 | Occ. (<1) | |
C1 | 0.53974 (17) | 0.42695 (9) | −0.00846 (10) | 0.0546 (4) | |
C2 | 0.42190 (18) | 0.44231 (10) | 0.01619 (12) | 0.0630 (5) | |
H2 | 0.3681 | 0.4034 | 0.0273 | 0.076* | |
C3 | 0.61776 (17) | 0.48557 (11) | −0.02467 (12) | 0.0616 (5) | |
H3 | 0.6979 | 0.4762 | −0.0415 | 0.074* | |
C4 | 0.5846 (2) | 0.34798 (10) | −0.01634 (12) | 0.0721 (6) | |
H4A | 0.5131 | 0.3149 | −0.0213 | 0.087* | |
H4B | 0.6289 | 0.3431 | −0.0690 | 0.087* | |
C5 | 0.6319 (2) | 0.30087 (11) | 0.13498 (14) | 0.0743 (6) | |
H5 | 0.5491 | 0.2917 | 0.1461 | 0.089* | |
C6 | 0.8285 (2) | 0.31079 (12) | 0.14960 (16) | 0.0814 (6) | |
H6 | 0.9106 | 0.3097 | 0.1735 | 0.098* | |
C7 | 0.7936 (2) | 0.33287 (11) | 0.06809 (14) | 0.0727 (5) | |
H7 | 0.8456 | 0.3495 | 0.0261 | 0.087* | |
C8 | 1.37872 (15) | 0.45287 (11) | 0.77603 (10) | 0.0551 (4) | |
C9 | 1.43993 (17) | 0.51832 (11) | 0.76292 (14) | 0.0716 (6) | |
H9 | 1.3997 | 0.5632 | 0.7716 | 0.086* | |
C10 | 1.43998 (16) | 0.38752 (11) | 0.76313 (12) | 0.0624 (5) | |
H10 | 1.4000 | 0.3426 | 0.7722 | 0.075* | |
C11 | 1.24523 (17) | 0.45326 (14) | 0.80100 (12) | 0.0757 (6) | |
H11A | 1.2279 | 0.4075 | 0.8313 | 0.091* | |
H11B | 1.2330 | 0.4944 | 0.8403 | 0.091* | |
C12 | 1.12161 (18) | 0.52399 (12) | 0.68190 (13) | 0.0668 (5) | |
H12 | 1.1415 | 0.5722 | 0.6997 | 0.080* | |
C13 | 1.05094 (18) | 0.50388 (12) | 0.61061 (13) | 0.0685 (5) | |
H13 | 1.0128 | 0.5368 | 0.5703 | 0.082* | |
C14 | 1.10934 (17) | 0.40531 (11) | 0.67441 (13) | 0.0645 (5) | |
H14 | 1.1211 | 0.3553 | 0.6880 | 0.077* | |
N1 | 0.66770 (15) | 0.32609 (8) | 0.05926 (9) | 0.0606 (4) | |
N2 | 0.7272 (2) | 0.29034 (10) | 0.19224 (12) | 0.0840 (6) | |
N3 | 1.15841 (12) | 0.46048 (9) | 0.72304 (9) | 0.0569 (4) | |
N4 | 1.04272 (14) | 0.42884 (10) | 0.60531 (10) | 0.0693 (5) | |
O1 | 0.716 (2) | 0.2775 (11) | 0.3763 (4) | 0.115 (4) | 0.59 (1) |
H1A | 0.717 (7) | 0.277 (5) | 0.3227 (8) | 0.172* | 0.59 (1) |
H1B | 0.786 (4) | 0.276 (6) | 0.402 (4) | 0.172* | 0.59 (1) |
O2 | 0.8981 (14) | 0.3183 (8) | 0.5088 (10) | 0.102 (2) | 0.59 (1) |
H2A | 0.923 (8) | 0.358 (3) | 0.530 (4) | 0.152* | 0.59 (1) |
H2B | 0.847 (8) | 0.296 (4) | 0.537 (5) | 0.152* | 0.59 (1) |
O1' | 0.779 (3) | 0.2557 (8) | 0.3734 (5) | 0.108 (5) | 0.41 (1) |
H1C | 0.756 (10) | 0.262 (6) | 0.3217 (17) | 0.162* | 0.41 (1) |
H1D | 0.776 (13) | 0.293 (4) | 0.404 (5) | 0.162* | 0.41 (1) |
O2' | 0.869 (2) | 0.3192 (12) | 0.5294 (16) | 0.113 (4) | 0.41 (1) |
H2C | 0.921 (10) | 0.350 (6) | 0.546 (6) | 0.169* | 0.41 (1) |
H2D | 0.831 (10) | 0.299 (6) | 0.567 (5) | 0.169* | 0.41 (1) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0723 (12) | 0.0509 (10) | 0.0390 (9) | 0.0055 (9) | −0.0087 (8) | 0.0010 (7) |
C2 | 0.0679 (12) | 0.0560 (11) | 0.0642 (11) | −0.0079 (9) | −0.0020 (9) | 0.0129 (9) |
C3 | 0.0609 (11) | 0.0673 (12) | 0.0568 (11) | 0.0079 (9) | 0.0061 (8) | 0.0083 (9) |
C4 | 0.0997 (15) | 0.0580 (12) | 0.0554 (11) | 0.0141 (10) | −0.0174 (10) | −0.0065 (9) |
C5 | 0.0941 (15) | 0.0609 (12) | 0.0672 (13) | 0.0047 (11) | 0.0011 (11) | 0.0089 (10) |
C6 | 0.0914 (16) | 0.0671 (14) | 0.0817 (16) | 0.0108 (12) | −0.0214 (13) | −0.0054 (11) |
C7 | 0.0808 (14) | 0.0658 (13) | 0.0709 (13) | 0.0088 (10) | 0.0017 (11) | 0.0025 (10) |
C8 | 0.0477 (9) | 0.0769 (12) | 0.0392 (9) | 0.0028 (9) | −0.0074 (7) | −0.0025 (8) |
C9 | 0.0575 (10) | 0.0633 (12) | 0.0910 (15) | 0.0105 (9) | −0.0159 (10) | −0.0108 (11) |
C10 | 0.0575 (10) | 0.0627 (12) | 0.0659 (12) | −0.0080 (9) | −0.0042 (9) | 0.0073 (9) |
C11 | 0.0524 (11) | 0.1278 (19) | 0.0459 (10) | 0.0071 (11) | −0.0029 (8) | −0.0009 (11) |
C12 | 0.0650 (12) | 0.0681 (12) | 0.0664 (12) | 0.0042 (10) | −0.0025 (9) | −0.0081 (10) |
C13 | 0.0630 (12) | 0.0832 (15) | 0.0580 (12) | 0.0108 (10) | −0.0046 (9) | 0.0029 (10) |
C14 | 0.0600 (11) | 0.0670 (12) | 0.0664 (12) | −0.0036 (9) | 0.0035 (9) | 0.0015 (10) |
N1 | 0.0847 (11) | 0.0452 (8) | 0.0503 (9) | 0.0111 (7) | −0.0064 (8) | −0.0004 (7) |
N2 | 0.1220 (16) | 0.0694 (11) | 0.0581 (10) | 0.0145 (11) | −0.0109 (11) | 0.0079 (8) |
N3 | 0.0441 (8) | 0.0784 (11) | 0.0476 (8) | 0.0012 (7) | −0.0013 (6) | −0.0043 (7) |
N4 | 0.0614 (10) | 0.0872 (13) | 0.0579 (10) | −0.0058 (8) | −0.0058 (8) | −0.0086 (9) |
O1 | 0.123 (7) | 0.153 (7) | 0.068 (3) | −0.010 (6) | 0.004 (3) | 0.004 (3) |
O2 | 0.095 (5) | 0.119 (4) | 0.092 (5) | −0.035 (3) | 0.017 (3) | −0.009 (3) |
O1' | 0.137 (12) | 0.134 (6) | 0.052 (3) | 0.012 (6) | 0.001 (4) | −0.002 (3) |
O2' | 0.103 (8) | 0.140 (7) | 0.097 (8) | −0.071 (6) | 0.017 (5) | −0.029 (6) |
C1—C2 | 1.372 (3) | C11—N3 | 1.470 (2) |
C1—C3 | 1.379 (2) | C11—H11A | 0.9700 |
C1—C4 | 1.508 (2) | C11—H11B | 0.9700 |
C2—C3i | 1.375 (3) | C12—C13 | 1.337 (3) |
C2—H2 | 0.9300 | C12—N3 | 1.351 (2) |
C3—C2i | 1.374 (3) | C12—H12 | 0.9300 |
C3—H3 | 0.9300 | C13—N4 | 1.355 (3) |
C4—N1 | 1.467 (2) | C13—H13 | 0.9300 |
C4—H4A | 0.9700 | C14—N4 | 1.308 (2) |
C4—H4B | 0.9700 | C14—N3 | 1.329 (2) |
C5—N2 | 1.314 (3) | C14—H14 | 0.9300 |
C5—N1 | 1.330 (2) | O1—H1A | 0.824 (10) |
C5—H5 | 0.9300 | O1—H1B | 0.822 (10) |
C6—C7 | 1.342 (3) | O1—H1C | 1.01 (7) |
C6—N2 | 1.358 (3) | O1—H1D | 0.80 (11) |
C6—H6 | 0.9300 | O2—H2A | 0.823 (10) |
C7—N1 | 1.353 (2) | O2—H2B | 0.822 (10) |
C7—H7 | 0.9300 | O2—H2C | 0.84 (7) |
C8—C10 | 1.368 (2) | O2—H2D | 1.24 (4) |
C8—C9 | 1.370 (3) | O1'—H1B | 0.58 (8) |
C8—C11 | 1.507 (2) | O1'—H1C | 0.822 (10) |
C9—C9ii | 1.374 (4) | O1'—H1D | 0.820 (10) |
C9—H9 | 0.9300 | O2'—H2A | 0.91 (5) |
C10—C10ii | 1.375 (3) | O2'—H2C | 0.818 (10) |
C10—H10 | 0.9300 | O2'—H2D | 0.820 (10) |
C2—C1—C3 | 118.51 (16) | N3—C11—H11A | 109.5 |
C2—C1—C4 | 121.14 (17) | C8—C11—H11A | 109.5 |
C3—C1—C4 | 120.35 (18) | N3—C11—H11B | 109.5 |
C1—C2—C3i | 120.87 (17) | C8—C11—H11B | 109.5 |
C1—C2—H2 | 119.6 | H11A—C11—H11B | 108.1 |
C3i—C2—H2 | 119.6 | C13—C12—N3 | 106.53 (18) |
C2i—C3—C1 | 120.62 (17) | C13—C12—H12 | 126.7 |
C2i—C3—H3 | 119.7 | N3—C12—H12 | 126.7 |
C1—C3—H3 | 119.7 | C12—C13—N4 | 110.46 (18) |
N1—C4—C1 | 111.64 (14) | C12—C13—H13 | 124.8 |
N1—C4—H4A | 109.3 | N4—C13—H13 | 124.8 |
C1—C4—H4A | 109.3 | N4—C14—N3 | 112.77 (18) |
N1—C4—H4B | 109.3 | N4—C14—H14 | 123.6 |
C1—C4—H4B | 109.3 | N3—C14—H14 | 123.6 |
H4A—C4—H4B | 108.0 | C5—N1—C7 | 106.85 (17) |
N2—C5—N1 | 112.1 (2) | C5—N1—C4 | 126.02 (19) |
N2—C5—H5 | 123.9 | C7—N1—C4 | 126.96 (18) |
N1—C5—H5 | 123.9 | C5—N2—C6 | 104.38 (18) |
C7—C6—N2 | 110.5 (2) | C14—N3—C12 | 106.11 (16) |
C7—C6—H6 | 124.7 | C14—N3—C11 | 126.53 (17) |
N2—C6—H6 | 124.7 | C12—N3—C11 | 127.10 (17) |
C6—C7—N1 | 106.1 (2) | C14—N4—C13 | 104.13 (16) |
C6—C7—H7 | 126.9 | H1A—O1—H1B | 114 (2) |
N1—C7—H7 | 126.9 | H1A—O1—H1D | 119 (10) |
C10—C8—C9 | 118.55 (17) | H1C—O1—H1D | 100 (9) |
C10—C8—C11 | 120.99 (18) | H2A—O2—H2B | 115 (2) |
C9—C8—C11 | 120.42 (18) | H1A—O1'—H1B | 112 (9) |
C8—C9—C9ii | 120.72 (11) | H1B—O1'—H1C | 132 (10) |
C8—C9—H9 | 119.6 | H1C—O1'—H1D | 115 (2) |
C9ii—C9—H9 | 119.6 | H2A—O2'—H2B | 162 (10) |
C8—C10—C10ii | 120.73 (11) | H2B—O2'—H2C | 144 (10) |
C8—C10—H10 | 119.6 | H2A—O2'—H2D | 133 (10) |
C10ii—C10—H10 | 119.6 | H2C—O2'—H2D | 116 (2) |
N3—C11—C8 | 110.55 (14) | ||
C3—C1—C2—C3i | −0.1 (3) | N2—C5—N1—C4 | −175.90 (16) |
C4—C1—C2—C3i | 178.90 (16) | C6—C7—N1—C5 | 0.3 (2) |
C2—C1—C3—C2i | 0.1 (3) | C6—C7—N1—C4 | 175.69 (16) |
C4—C1—C3—C2i | −178.90 (16) | C1—C4—N1—C5 | 84.0 (2) |
C2—C1—C4—N1 | −101.9 (2) | C1—C4—N1—C7 | −90.5 (2) |
C3—C1—C4—N1 | 77.0 (2) | N1—C5—N2—C6 | 0.4 (2) |
N2—C6—C7—N1 | −0.1 (2) | C7—C6—N2—C5 | −0.2 (2) |
C10—C8—C9—C9ii | 0.2 (3) | N4—C14—N3—C12 | −0.6 (2) |
C11—C8—C9—C9ii | −177.6 (2) | N4—C14—N3—C11 | −175.09 (16) |
C9—C8—C10—C10ii | −0.5 (3) | C13—C12—N3—C14 | 0.6 (2) |
C11—C8—C10—C10ii | 177.3 (2) | C13—C12—N3—C11 | 175.05 (16) |
C10—C8—C11—N3 | −94.3 (2) | C8—C11—N3—C14 | 89.2 (2) |
C9—C8—C11—N3 | 83.5 (2) | C8—C11—N3—C12 | −84.2 (2) |
N3—C12—C13—N4 | −0.4 (2) | N3—C14—N4—C13 | 0.3 (2) |
N2—C5—N1—C7 | −0.5 (2) | C12—C13—N4—C14 | 0.1 (2) |
Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+3, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···N2 | 0.82 (1) | 2.03 (2) | 2.848 (7) | 172 (9) |
O1—H1B···O2 | 0.82 (1) | 2.10 (5) | 2.815 (16) | 145 (8) |
O2—H2A···N4 | 0.82 (1) | 2.10 (4) | 2.869 (13) | 157 (9) |
O2—H2B···O1iii | 0.82 (1) | 2.03 (5) | 2.811 (17) | 158 (11) |
O1′—H1C···N2 | 0.82 (1) | 2.06 (3) | 2.868 (10) | 170 (13) |
O1′—H1D···O2′ | 0.82 (1) | 2.15 (7) | 2.77 (2) | 132 (8) |
O2′—H2C···N4 | 0.82 (1) | 2.09 (2) | 2.902 (17) | 172 (11) |
O2′—H2D···O1′iii | 0.82 (1) | 1.82 (3) | 2.625 (17) | 165 (11) |
Symmetry code: (iii) −x+3/2, −y+1/2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C14H14N4·2H2O |
Mr | 274.32 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 299 |
a, b, c (Å) | 10.7178 (8), 17.9925 (14), 15.3662 (12) |
β (°) | 94.006 (2) |
V (Å3) | 2956.0 (4) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.30 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1997) |
Tmin, Tmax | 0.965, 0.983 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9245, 3369, 2237 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.140, 1.04 |
No. of reflections | 3369 |
No. of parameters | 224 |
No. of restraints | 12 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.17, −0.13 |
Computer programs: SMART (Bruker, 2001), SAINT-Plus (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2003), Mercury (Version 1.4; Bruno et al., 2002) and DIAMOND (Brandenburg, 2004), PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···N2 | 0.824 (10) | 2.030 (18) | 2.848 (7) | 172 (9) |
O1—H1B···O2 | 0.822 (10) | 2.10 (5) | 2.815 (16) | 145 (8) |
O2—H2A···N4 | 0.823 (10) | 2.10 (4) | 2.869 (13) | 157 (9) |
O2—H2B···O1i | 0.822 (10) | 2.03 (5) | 2.811 (17) | 158 (11) |
O1'—H1C···N2 | 0.822 (10) | 2.06 (3) | 2.868 (10) | 170 (13) |
O1'—H1D···O2' | 0.820 (10) | 2.15 (7) | 2.77 (2) | 132 (8) |
O2'—H2C···N4 | 0.818 (10) | 2.09 (2) | 2.902 (17) | 172 (11) |
O2'—H2D···O1'i | 0.820 (10) | 1.82 (3) | 2.625 (17) | 165 (11) |
Symmetry code: (i) −x+3/2, −y+1/2, −z+1. |
The crystal structure of another polymorph of the title compound (bix.2H2O) has been reported previously [Cambridge Strcutural Database (Allen, 2002) refcode PUVQIG (Hoskins et al., 1997b; Abrahams et al., 1998). Interestingly, crystallization of bix via the hydrothermal method leads to a structure in the monoclinic space group C2/c with Z = 8 [polymorph (II)], in contrast to the previously reported structure [polymorph (I)] in space group P21/n with Z = 2, which was obtained by recrystallization from water. In this communication, we report the differences between these two polymorphs and give an illustration of their topological classification.
As a flexible ligand, bix has been often used in the synthesis of metal–organic frameworks as a linker molecule (Hoskins et al., 1997a; Abrahams et al., 2002; Carculli et al., 2005; Wen et al., 2005, Zhang et al., 2005) and in the construction of hydrogen-bonded supramolecular assemblies as hydrogen-bonding acceptors (Ma & Coppens, 2004; Ma et al., 2004; Shen et al., 2004; Aakeröy et al., 2005, 2006; Zhang et al., 2007). Recently, as a result of our interest in exploring the self-assembling nature of carboxylic acids with Lewis bases (Meng et al., 2007; Meng, Lin & Li, 2008; Meng, Xiao, Wang & Liu, 2008; Meng, Xiao, Zhang & Zhou, 2008), we have re-synthesized the N-containing Lewis base bix by the standard procedure (Hoskins et al., 1997b).
Single-crystal X-ray diffraction reveals that there are two independent half-bix molecules and two water molecules in the selected asymmetric unit of polymorph (II) (Fig. 1). In the N1-containing bix molecule, its two halves are related by an inversion center at (1/2, 1/2, 0). However, the two halves in the N2-containing bix molecule are related by a twofold axis. By comparison, the asymmetric unit of polymorph (I) consists of only one water molecule and half a bix molecule whose two halves are related by an inversion center at (0, 1, 1/2). Besides this, the cell volume (2956.0 Å3) in polymorph (II) expands to ca four times of that in polymorph (I) (733.4 Å3). The water molecules in (II) are linked into a discrete tetrameric R44(8) water ring (Fig. 2) by O—H···O hydrogen bonds. Conversely, water molecules in (I) are linked into one-dimensional water chains [O···O = 2.728 (2) and 2.782 (2) Å; symmetry codes: -x, -y + 2, -z; -x - 1, -y + 2, -z] running parallel to the [100] direction (Fig. 2). These apparent differences may mainly be attributed to (i) the crystallized [cystallization?] conditions, i.e. temperature and pressure, and (ii) the flexibility stemming from the –CH2– group (Zhang et al., 2007).
The crystal packings of polymorphs (I) and (II) are also very different from each other. In (II), bix and water molecules are linked by O—H···O and N—H···O hydrogen bonds (Table 1) into a continuous three-dimensional network. Two types of hydrogen-bonded rings are formed; one is the R44(8) ring as mentioned above and the other is a very large R1420(106) hydrogen-bond ring (Bernstein et al., 1995), which is constructed via N—H···O hydrogen bonds. Topological analysis indicates that if one considers the tetrameric water units to be four-connected nodes and the bix molecules to be bridges (Fig. 3a), one single net can then be rationalized as a three-dimensional net with CdSO4 (cds) topology. Fig. 3(b) reveals the topology displayed by this structure with short and long Schläfli symbols 65.8 and 6.6.6.6.62.*, respectively (* means there are no rings for this angle; Batten, 2001; Batten & Robson, 1998). Further analysis indicates that five independent three-dimensional networks of this type related by a translation vector of ca 2.1436 Å along the [100] direction make up the final fivefold interpenetrated network (Fig. 3b). These interpenetrated networks are strengthened by π–π and C—H···π interactions [Cg1···Cg2ii = 3.934 (2) Å, Cg3···Cg3iii = 3.593 (2) Å, and H3···Cg3iv = 2.95 Å, C3···Cg3iv = 3.829 (2) Å and C3—H3···Cg3iv = 158°; Cg1, Cg2 and Cg3 are the centroids of the rings involving C1, C8 and N4, respectively; symmetry codes: (ii) x - 1, y, z - 1, (iii) -x + 2, y, -z + 3/2; (iv) -x + 2, y, -z + 1/2]. By contrast, bix molecules in polymorph (I) are joined together by the only Owater···Nimidazole [2.821 (2) Å] hydrogen bond, which originates from two sides of the one-dimensional water chain, resulting in a simple two-dimensional sheet running parallel to the (010) plane (Fig. 4a). We can regard the two-dimensional sheet as a Shubnikov hexagonal plane (hcb) net with a total Schläfli symbol of 63 (Fig. 4b). The neighbouring sheets are linked by C1—H1···O1(-x - 1/2, y - 1/2, -z + 1/2) interactions into a simple three-dimensional network. No other interactions are observed in polymorph (I).