The asymmetric unit of the title compound, C
12H
17N
4OS
+·I
−·1.25H
2O, contains two crystallographically independent molecules. Both formula units assume the usual
F conformation and have the hydroxyethyl group disordered over two sites, each with half occupation. Two thiamine cations are linked by hydrogen bonds into a cyclic dimer. These dimers are further connected by base-pairing hydrogen bonds into a chain along [010]. The stacked dimers form channels, which are occupied by iodide anions. The cations and anions are associated by N—H
I hydrogen bonds, C—H
I interactions and I
thiazolium ring close contacts. The interactions between thiamine and the iodide anions are similar to those observed in monoclinic thiamine iodide 1.5-hydrate [Hu & Zhang (1993).
J. Inclusion Phenom. Mol. Recognit. Chem. 16, 273–281].
Supporting information
CCDC reference: 810013
Compound (I) was prepared by reacting thiamine nitrate (0.065 g, 0.2 mmol) and
zinc iodide (0.064 g, 0.2 mmol) in water (20 ml). The solution was set aside
to crystallize at ambient temperature. Colourless crystals of (I) suitable for
X-ray analysis were obtained after two weeks, and washed with water and
methanol.
The hydroxyethyl groups of the molecules A and B are disordered,
each over two positions. Three of the four water sites are also disordered.
From the hydrogen-bonding scheme, atoms O41 and O51 belong to the same
disorder group as atoms O21 and O11 (referred to as the first disordered part
in the Comment), while atom O52 is occupied simultaneously with atom
O12 in the second disorder group. (We use the term `disorder group' as
defined in the CIF dictionary.) The occupancy factors were refined to 0.474 (7)
and 0.536 (7) for parts 1 and 2, respectively, and they were fixed at 0.50 in
the final refinement. C-bound H atoms were positioned geometrically and
refined as riding atoms, with C—H = 0.93 (CH), 0.97 (CH2) and 0.96 Å
(CH3) and N—H = 0.86 Å, and with Uiso(H) =
1.2Ueq(C,N). H aroms of the hydroxy group and water molecules were
located from difference Fourier maps and were restrained in the refinements,
with Uiso(H) = 1.2Ueq(O). The highest residual electron
density was found 0.91 Å from I2 and the deepest hole 0.75 Å from I2.
Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-5-(2-hydroxyethyl)-4-methyl-
1,3-thiazol-3-ium iodide 1.25-hydrate
top
Crystal data top
C12H17N4OS+·I−·1.25H2O | Z = 4 |
Mr = 414.78 | F(000) = 826 |
Triclinic, P1 | Dx = 1.606 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 11.9437 (10) Å | Cell parameters from 4302 reflections |
b = 12.5913 (12) Å | θ = 2.5–26.0° |
c = 13.8768 (13) Å | µ = 2.00 mm−1 |
α = 104.900 (1)° | T = 293 K |
β = 100.968 (2)° | Plate, colourless |
γ = 115.129 (1)° | 0.21 × 0.17 × 0.05 mm |
V = 1715.6 (3) Å3 | |
Data collection top
Bruker APEX CCD area-detector diffractometer | 6271 independent reflections |
Radiation source: sealed tube | 5141 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.015 |
ϕ and ω scans | θmax = 25.5°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −14→8 |
Tmin = 0.679, Tmax = 0.907 | k = −14→15 |
9403 measured reflections | l = −16→16 |
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)] = 0.053 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.156 | H-atom parameters constrained |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0816P)2 + 2.7224P] where P = (Fo2 + 2Fc2)/3 |
6271 reflections | (Δ/σ)max = 0.004 |
418 parameters | Δρmax = 1.62 e Å−3 |
8 restraints | Δρmin = −0.98 e Å−3 |
Crystal data top
C12H17N4OS+·I−·1.25H2O | γ = 115.129 (1)° |
Mr = 414.78 | V = 1715.6 (3) Å3 |
Triclinic, P1 | Z = 4 |
a = 11.9437 (10) Å | Mo Kα radiation |
b = 12.5913 (12) Å | µ = 2.00 mm−1 |
c = 13.8768 (13) Å | T = 293 K |
α = 104.900 (1)° | 0.21 × 0.17 × 0.05 mm |
β = 100.968 (2)° | |
Data collection top
Bruker APEX CCD area-detector diffractometer | 6271 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 5141 reflections with I > 2σ(I) |
Tmin = 0.679, Tmax = 0.907 | Rint = 0.015 |
9403 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.053 | 8 restraints |
wR(F2) = 0.156 | H-atom parameters constrained |
S = 1.09 | Δρmax = 1.62 e Å−3 |
6271 reflections | Δρmin = −0.98 e Å−3 |
418 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
I1 | 0.71720 (4) | 0.46470 (4) | 0.43520 (3) | 0.06377 (17) | |
I2 | 0.49286 (6) | 0.77149 (5) | 0.11844 (3) | 0.0793 (2) | |
S1 | 0.3254 (2) | 0.41301 (17) | 0.29637 (17) | 0.0825 (6) | |
O11 | 0.1852 (14) | 0.1485 (13) | 0.1563 (11) | 0.120 (5) | 0.50 |
H1A | 0.2101 | 0.1360 | 0.2120 | 0.144* | 0.50 |
O12 | 0.1357 (11) | 0.2533 (16) | 0.0662 (11) | 0.127 (5) | 0.50 |
H12 | 0.0821 | 0.1789 | 0.0442 | 0.153* | 0.50 |
N1 | 0.5361 (5) | 0.6006 (4) | 0.3243 (4) | 0.0502 (11) | |
N2 | 0.7423 (6) | 0.8898 (5) | 0.6678 (4) | 0.0634 (13) | |
N3 | 0.6008 (5) | 0.9473 (4) | 0.5783 (4) | 0.0544 (11) | |
N4 | 0.5181 (5) | 0.8742 (5) | 0.3979 (4) | 0.0629 (13) | |
H4A | 0.4781 | 0.9171 | 0.4050 | 0.075* | |
H4B | 0.5098 | 0.8301 | 0.3356 | 0.075* | |
C1 | 0.4464 (6) | 0.5616 (6) | 0.3687 (5) | 0.0588 (15) | |
H1 | 0.4500 | 0.6112 | 0.4331 | 0.071* | |
C2 | 0.5116 (6) | 0.5101 (6) | 0.2288 (5) | 0.0562 (14) | |
C3 | 0.3989 (7) | 0.4036 (7) | 0.2004 (6) | 0.078 (2) | |
C4 | 0.6101 (8) | 0.5371 (7) | 0.1731 (6) | 0.0717 (18) | |
H4C | 0.5774 | 0.4657 | 0.1083 | 0.086* | |
H4D | 0.6916 | 0.5523 | 0.2179 | 0.086* | |
H4E | 0.6246 | 0.6108 | 0.1572 | 0.086* | |
C5 | 0.3410 (10) | 0.2843 (8) | 0.1036 (8) | 0.122 (4) | |
H5A | 0.2728 | 0.2845 | 0.0530 | 0.146* | 0.50 |
H5B | 0.4096 | 0.2933 | 0.0732 | 0.146* | 0.50 |
H5C | 0.4100 | 0.2844 | 0.0763 | 0.146* | 0.50 |
H5D | 0.3064 | 0.2116 | 0.1237 | 0.146* | 0.50 |
C61 | 0.283 (2) | 0.1551 (16) | 0.1068 (18) | 0.138 (9) | 0.50 |
H6A | 0.2425 | 0.0903 | 0.0358 | 0.165* | 0.50 |
H6B | 0.3495 | 0.1444 | 0.1484 | 0.165* | 0.50 |
C62 | 0.2346 (13) | 0.2716 (16) | 0.0190 (10) | 0.088 (5) | 0.50 |
H6C | 0.2621 | 0.3477 | 0.0032 | 0.105* | 0.50 |
H6D | 0.2048 | 0.1993 | −0.0455 | 0.105* | 0.50 |
C7 | 0.6571 (6) | 0.7268 (5) | 0.3755 (5) | 0.0528 (13) | |
H7A | 0.6632 | 0.7707 | 0.3269 | 0.063* | |
H7B | 0.7331 | 0.7154 | 0.3891 | 0.063* | |
C8 | 0.6753 (6) | 0.9517 (5) | 0.6658 (5) | 0.0549 (14) | |
C9 | 0.5919 (6) | 0.8759 (5) | 0.4825 (4) | 0.0488 (12) | |
C10 | 0.6609 (6) | 0.8075 (5) | 0.4774 (4) | 0.0499 (13) | |
C11 | 0.7328 (6) | 0.8178 (5) | 0.5713 (5) | 0.0575 (14) | |
H11 | 0.7782 | 0.7732 | 0.5697 | 0.069* | |
C12 | 0.6836 (8) | 1.0319 (7) | 0.7700 (5) | 0.0750 (19) | |
H12A | 0.7393 | 1.0271 | 0.8267 | 0.090* | |
H12B | 0.5968 | 1.0009 | 0.7751 | 0.090* | |
H12C | 0.7187 | 1.1180 | 0.7758 | 0.090* | |
S2 | 1.01658 (16) | 0.41512 (19) | 0.30887 (15) | 0.0726 (5) | |
O21 | 1.0241 (13) | 0.3624 (12) | 0.0769 (10) | 0.096 (3) | 0.50 |
H21 | 1.0643 | 0.4401 | 0.1022 | 0.115* | 0.50 |
O22 | 1.0497 (12) | 0.5528 (12) | 0.1665 (9) | 0.099 (4) | 0.50 |
H22 | 1.0839 | 0.6280 | 0.2029 | 0.119* | 0.50 |
N5 | 0.8249 (5) | 0.2441 (4) | 0.3255 (4) | 0.0524 (11) | |
N6 | 0.8830 (6) | 0.2498 (5) | 0.6642 (5) | 0.0723 (15) | |
N7 | 0.9590 (5) | 0.1186 (5) | 0.5783 (5) | 0.0657 (14) | |
N8 | 0.9046 (6) | 0.0376 (6) | 0.3984 (5) | 0.0749 (16) | |
H8A | 0.9520 | 0.0029 | 0.4074 | 0.090* | |
H8B | 0.8647 | 0.0275 | 0.3354 | 0.090* | |
C13 | 0.9506 (6) | 0.3282 (6) | 0.3766 (5) | 0.0549 (14) | |
H13 | 0.9974 | 0.3379 | 0.4431 | 0.066* | |
C14 | 0.7743 (6) | 0.2479 (6) | 0.2291 (5) | 0.0665 (17) | |
C15 | 0.8669 (7) | 0.3354 (8) | 0.2065 (6) | 0.079 (2) | |
C16 | 0.6316 (7) | 0.1645 (8) | 0.1653 (6) | 0.090 (3) | |
H16A | 0.6111 | 0.1876 | 0.1063 | 0.108* | |
H16B | 0.5805 | 0.1743 | 0.2090 | 0.108* | |
H16C | 0.6113 | 0.0777 | 0.1395 | 0.108* | |
C17 | 0.8522 (10) | 0.3704 (11) | 0.1122 (9) | 0.139 (5) | |
H17A | 0.7607 | 0.3467 | 0.0830 | 0.167* | 0.50 |
H17B | 0.9036 | 0.4621 | 0.1372 | 0.167* | 0.50 |
H17C | 0.8812 | 0.3252 | 0.0647 | 0.167* | 0.50 |
H17D | 0.7583 | 0.3328 | 0.0775 | 0.167* | 0.50 |
C181 | 0.8894 (14) | 0.3177 (16) | 0.0248 (11) | 0.100 (6) | 0.50 |
H18A | 0.8390 | 0.2257 | −0.0053 | 0.120* | 0.50 |
H18B | 0.8779 | 0.3496 | −0.0308 | 0.120* | 0.50 |
C182 | 0.9126 (14) | 0.5010 (14) | 0.1131 (18) | 0.129 (8) | 0.50 |
H18C | 0.8961 | 0.4996 | 0.0415 | 0.154* | 0.50 |
H18D | 0.8787 | 0.5495 | 0.1512 | 0.154* | 0.50 |
C19 | 0.7412 (6) | 0.1590 (6) | 0.3703 (5) | 0.0570 (14) | |
H19A | 0.6973 | 0.0721 | 0.3200 | 0.068* | |
H19B | 0.6741 | 0.1802 | 0.3806 | 0.068* | |
C20 | 0.9517 (7) | 0.1888 (7) | 0.6632 (6) | 0.0695 (18) | |
C21 | 0.8931 (6) | 0.1073 (6) | 0.4820 (5) | 0.0586 (15) | |
C22 | 0.8195 (6) | 0.1692 (6) | 0.4747 (5) | 0.0574 (15) | |
C23 | 0.8182 (7) | 0.2380 (6) | 0.5677 (5) | 0.0626 (16) | |
H23 | 0.7697 | 0.2793 | 0.5643 | 0.075* | |
C24 | 1.0256 (8) | 0.2015 (8) | 0.7703 (6) | 0.085 (2) | |
H24A | 1.0117 | 0.2548 | 0.8244 | 0.102* | |
H24B | 1.1174 | 0.2388 | 0.7802 | 0.102* | |
H24C | 0.9932 | 0.1193 | 0.7738 | 0.102* | |
O3 | 0.8210 (8) | 0.0114 (8) | 0.1872 (6) | 0.138 (3) | |
H3A | 0.7482 | −0.0544 | 0.1586 | 0.165* | |
H3B | 0.8671 | 0.0074 | 0.1509 | 0.165* | |
O41 | 1.1893 (15) | 0.6083 (13) | 0.1754 (11) | 0.141 (6) | 0.50 |
H41A | 1.2025 | 0.6667 | 0.2274 | 0.170* | 0.50 |
H41B | 1.2349 | 0.5771 | 0.1905 | 0.170* | 0.50 |
O51 | −0.0605 (19) | 0.0937 (18) | 0.0465 (18) | 0.172 (8) | 0.50 |
H51A | 0.0023 | 0.0954 | 0.0811 | 0.207* | 0.50 |
H51B | −0.0417 | 0.1681 | 0.0592 | 0.207* | 0.50 |
O52 | 0.0411 (17) | 0.0647 (16) | 0.1534 (15) | 0.176 (9) | 0.50 |
H52A | 0.1009 | 0.0779 | 0.2037 | 0.211* | 0.50 |
H52B | 0.0345 | 0.0106 | 0.1013 | 0.211* | 0.50 |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
I1 | 0.0655 (3) | 0.0780 (3) | 0.0656 (3) | 0.0469 (2) | 0.0252 (2) | 0.0319 (2) |
I2 | 0.1060 (4) | 0.0987 (4) | 0.0506 (3) | 0.0668 (3) | 0.0297 (3) | 0.0244 (2) |
S1 | 0.0727 (12) | 0.0618 (10) | 0.0854 (13) | 0.0169 (9) | 0.0441 (10) | 0.0041 (9) |
O11 | 0.118 (11) | 0.101 (9) | 0.094 (9) | 0.025 (8) | 0.017 (8) | 0.035 (7) |
O12 | 0.065 (7) | 0.172 (14) | 0.109 (10) | 0.054 (8) | 0.004 (7) | 0.029 (10) |
N1 | 0.060 (3) | 0.046 (2) | 0.050 (3) | 0.030 (2) | 0.026 (2) | 0.016 (2) |
N2 | 0.085 (4) | 0.058 (3) | 0.049 (3) | 0.039 (3) | 0.020 (3) | 0.021 (2) |
N3 | 0.063 (3) | 0.048 (2) | 0.050 (3) | 0.027 (2) | 0.023 (2) | 0.013 (2) |
N4 | 0.081 (4) | 0.069 (3) | 0.048 (3) | 0.050 (3) | 0.021 (3) | 0.013 (2) |
C1 | 0.067 (4) | 0.056 (3) | 0.054 (3) | 0.031 (3) | 0.031 (3) | 0.013 (3) |
C2 | 0.065 (4) | 0.057 (3) | 0.048 (3) | 0.035 (3) | 0.027 (3) | 0.011 (3) |
C3 | 0.075 (5) | 0.066 (4) | 0.066 (4) | 0.024 (4) | 0.033 (4) | −0.003 (3) |
C4 | 0.088 (5) | 0.073 (4) | 0.065 (4) | 0.044 (4) | 0.046 (4) | 0.021 (3) |
C5 | 0.130 (9) | 0.072 (5) | 0.098 (7) | 0.014 (5) | 0.059 (7) | −0.017 (5) |
C61 | 0.15 (2) | 0.22 (3) | 0.089 (14) | 0.12 (2) | 0.057 (15) | 0.068 (17) |
C62 | 0.070 (9) | 0.091 (11) | 0.045 (7) | 0.020 (8) | −0.001 (7) | −0.006 (7) |
C7 | 0.061 (3) | 0.050 (3) | 0.054 (3) | 0.032 (3) | 0.027 (3) | 0.018 (3) |
C8 | 0.062 (4) | 0.046 (3) | 0.048 (3) | 0.020 (3) | 0.022 (3) | 0.017 (3) |
C9 | 0.055 (3) | 0.044 (3) | 0.047 (3) | 0.024 (3) | 0.022 (3) | 0.016 (2) |
C10 | 0.059 (3) | 0.043 (3) | 0.048 (3) | 0.024 (3) | 0.023 (3) | 0.016 (2) |
C11 | 0.067 (4) | 0.050 (3) | 0.059 (4) | 0.033 (3) | 0.023 (3) | 0.017 (3) |
C12 | 0.092 (5) | 0.075 (4) | 0.054 (4) | 0.041 (4) | 0.029 (4) | 0.015 (3) |
S2 | 0.0493 (9) | 0.0872 (12) | 0.0770 (11) | 0.0206 (8) | 0.0160 (8) | 0.0525 (10) |
O21 | 0.117 (10) | 0.109 (8) | 0.099 (9) | 0.072 (8) | 0.066 (8) | 0.045 (8) |
O22 | 0.091 (8) | 0.110 (9) | 0.079 (7) | 0.029 (7) | 0.039 (7) | 0.041 (7) |
N5 | 0.050 (3) | 0.049 (2) | 0.058 (3) | 0.022 (2) | 0.014 (2) | 0.029 (2) |
N6 | 0.085 (4) | 0.063 (3) | 0.062 (3) | 0.030 (3) | 0.020 (3) | 0.030 (3) |
N7 | 0.066 (3) | 0.076 (3) | 0.066 (3) | 0.036 (3) | 0.021 (3) | 0.045 (3) |
N8 | 0.087 (4) | 0.099 (4) | 0.066 (4) | 0.062 (4) | 0.025 (3) | 0.045 (3) |
C13 | 0.049 (3) | 0.063 (3) | 0.057 (3) | 0.027 (3) | 0.015 (3) | 0.034 (3) |
C14 | 0.054 (4) | 0.071 (4) | 0.065 (4) | 0.022 (3) | 0.008 (3) | 0.038 (3) |
C15 | 0.059 (4) | 0.094 (5) | 0.073 (4) | 0.021 (4) | 0.009 (3) | 0.055 (4) |
C16 | 0.065 (4) | 0.093 (5) | 0.081 (5) | 0.015 (4) | −0.002 (4) | 0.051 (5) |
C17 | 0.082 (6) | 0.168 (10) | 0.134 (9) | 0.017 (7) | −0.003 (6) | 0.118 (9) |
C181 | 0.110 (15) | 0.107 (13) | 0.078 (11) | 0.036 (11) | 0.041 (11) | 0.055 (10) |
C182 | 0.115 (17) | 0.18 (2) | 0.114 (17) | 0.089 (18) | 0.045 (14) | 0.068 (17) |
C19 | 0.050 (3) | 0.057 (3) | 0.066 (4) | 0.023 (3) | 0.017 (3) | 0.034 (3) |
C20 | 0.064 (4) | 0.066 (4) | 0.070 (4) | 0.020 (3) | 0.016 (3) | 0.039 (4) |
C21 | 0.061 (4) | 0.058 (3) | 0.062 (4) | 0.027 (3) | 0.019 (3) | 0.035 (3) |
C22 | 0.054 (3) | 0.053 (3) | 0.065 (4) | 0.021 (3) | 0.016 (3) | 0.037 (3) |
C23 | 0.069 (4) | 0.056 (3) | 0.065 (4) | 0.029 (3) | 0.021 (3) | 0.030 (3) |
C24 | 0.086 (5) | 0.096 (5) | 0.066 (4) | 0.035 (5) | 0.017 (4) | 0.045 (4) |
O3 | 0.150 (7) | 0.160 (7) | 0.097 (5) | 0.089 (6) | 0.032 (5) | 0.028 (5) |
O41 | 0.138 (12) | 0.096 (9) | 0.112 (11) | 0.004 (8) | 0.068 (10) | 0.000 (8) |
O51 | 0.153 (16) | 0.144 (14) | 0.22 (2) | 0.063 (13) | 0.088 (16) | 0.078 (15) |
O52 | 0.131 (13) | 0.122 (12) | 0.157 (15) | −0.003 (10) | −0.051 (11) | 0.067 (11) |
Geometric parameters (Å, º) top
S1—C1 | 1.668 (6) | O22—H22 | 0.8164 |
S1—C3 | 1.736 (7) | N5—C13 | 1.318 (7) |
O11—C61 | 1.446 (10) | N5—C14 | 1.381 (8) |
O11—H1A | 0.8522 | N5—C19 | 1.484 (7) |
O11—H52A | 1.4254 | N6—C20 | 1.340 (10) |
O12—C62 | 1.421 (9) | N6—C23 | 1.349 (9) |
O12—H12 | 0.8061 | N7—C20 | 1.322 (9) |
N1—C1 | 1.315 (7) | N7—C21 | 1.353 (8) |
N1—C2 | 1.390 (7) | N8—C21 | 1.332 (9) |
N1—C7 | 1.482 (7) | N8—H8A | 0.8600 |
N2—C8 | 1.335 (8) | N8—H8B | 0.8600 |
N2—C11 | 1.362 (8) | C13—H13 | 0.9300 |
N3—C8 | 1.335 (8) | C14—C15 | 1.345 (9) |
N3—C9 | 1.356 (7) | C14—C16 | 1.490 (9) |
N4—C9 | 1.316 (8) | C15—C17 | 1.487 (10) |
N4—H4A | 0.8600 | C16—H16A | 0.9600 |
N4—H4B | 0.8600 | C16—H16B | 0.9600 |
C1—H1 | 0.9300 | C16—H16C | 0.9600 |
C2—C3 | 1.326 (9) | C17—C181 | 1.467 (9) |
C2—C4 | 1.497 (8) | C17—C182 | 1.484 (10) |
C3—C5 | 1.504 (9) | C17—H17A | 0.9700 |
C4—H4C | 0.9600 | C17—H17B | 0.9700 |
C4—H4D | 0.9600 | C17—H17C | 0.9700 |
C4—H4E | 0.9600 | C17—H17D | 0.9700 |
C5—C62 | 1.478 (9) | C181—H18A | 0.9700 |
C5—C61 | 1.491 (10) | C181—H18B | 0.9700 |
C5—H5A | 0.9700 | C182—H18C | 0.9700 |
C5—H5B | 0.9700 | C182—H18D | 0.9700 |
C5—H5C | 0.9700 | C19—C22 | 1.509 (8) |
C5—H5D | 0.9700 | C19—H19A | 0.9700 |
C61—H6A | 0.9700 | C19—H19B | 0.9700 |
C61—H6B | 0.9700 | C20—C24 | 1.507 (10) |
C62—H6C | 0.9700 | C21—C22 | 1.406 (9) |
C62—H6D | 0.9700 | C22—C23 | 1.363 (9) |
C7—C10 | 1.493 (7) | C23—H23 | 0.9300 |
C7—H7A | 0.9700 | C24—H24A | 0.9616 |
C7—H7B | 0.9700 | C24—H24B | 0.9563 |
C8—C12 | 1.493 (8) | C24—H24C | 0.9570 |
C9—C10 | 1.421 (8) | O3—H3A | 0.8296 |
C10—C11 | 1.359 (9) | O3—H3B | 0.8237 |
C11—H11 | 0.9300 | O41—H22 | 1.4804 |
C12—H12A | 0.9608 | O41—H41A | 0.8194 |
C12—H12B | 0.9647 | O41—H41B | 0.8221 |
C12—H12C | 0.9564 | O51—H51A | 0.7978 |
S2—C13 | 1.668 (6) | O51—H51B | 0.8249 |
S2—C15 | 1.731 (7) | O52—H51A | 1.2440 |
O21—C181 | 1.416 (9) | O52—H52A | 0.8216 |
O21—H21 | 0.8200 | O52—H52B | 0.8206 |
O22—C182 | 1.428 (10) | | |
| | | |
C1—S1—C3 | 90.9 (3) | C13—N5—C14 | 114.2 (5) |
C61—O11—H1A | 104.4 | C13—N5—C19 | 123.5 (5) |
C62—O12—H12 | 109.9 | C14—N5—C19 | 122.2 (5) |
C1—N1—C2 | 114.0 (5) | C20—N6—C23 | 114.9 (6) |
C1—N1—C7 | 122.7 (5) | C20—N7—C21 | 118.0 (6) |
C2—N1—C7 | 123.1 (5) | C21—N8—H8A | 120.0 |
C8—N2—C11 | 115.9 (5) | C21—N8—H8B | 120.0 |
C8—N3—C9 | 118.7 (5) | H8A—N8—H8B | 120.0 |
C9—N4—H4A | 120.0 | N5—C13—S2 | 112.5 (4) |
C9—N4—H4B | 120.0 | N5—C13—H13 | 123.7 |
H4A—N4—H4B | 120.0 | S2—C13—H13 | 123.7 |
N1—C1—S1 | 112.3 (4) | C15—C14—N5 | 111.9 (6) |
N1—C1—H1 | 123.9 | C15—C14—C16 | 127.6 (6) |
S1—C1—H1 | 123.9 | N5—C14—C16 | 120.5 (6) |
C3—C2—N1 | 112.1 (5) | C14—C15—C17 | 128.6 (7) |
C3—C2—C4 | 127.6 (6) | C14—C15—S2 | 110.5 (5) |
N1—C2—C4 | 120.2 (6) | C17—C15—S2 | 120.8 (6) |
C2—C3—C5 | 127.4 (7) | C14—C16—H16A | 109.5 |
C2—C3—S1 | 110.6 (5) | C14—C16—H16B | 109.5 |
C5—C3—S1 | 121.8 (6) | H16A—C16—H16B | 109.5 |
C2—C4—H4C | 109.5 | C14—C16—H16C | 109.5 |
C2—C4—H4D | 109.5 | H16A—C16—H16C | 109.5 |
H4C—C4—H4D | 109.5 | H16B—C16—H16C | 109.5 |
C2—C4—H4E | 109.5 | C181—C17—C15 | 119.3 (11) |
H4C—C4—H4E | 109.5 | C182—C17—C15 | 126.1 (12) |
H4D—C4—H4E | 109.5 | C181—C17—H17A | 107.5 |
C62—C5—C3 | 112.6 (10) | C15—C17—H17A | 107.5 |
C61—C5—C3 | 123.2 (12) | C181—C17—H17B | 107.5 |
C61—C5—H5A | 106.5 | C15—C17—H17B | 107.5 |
C3—C5—H5A | 106.5 | H17A—C17—H17B | 107.0 |
C61—C5—H5B | 106.5 | C182—C17—H17C | 105.8 |
C3—C5—H5B | 106.5 | C15—C17—H17C | 105.8 |
H5A—C5—H5B | 106.5 | C182—C17—H17D | 105.8 |
C62—C5—H5C | 109.1 | C15—C17—H17D | 105.8 |
C3—C5—H5C | 109.1 | H17C—C17—H17D | 106.2 |
C62—C5—H5D | 109.1 | O21—C181—C17 | 101.7 (11) |
C3—C5—H5D | 109.1 | O21—C181—H18A | 111.4 |
H5C—C5—H5D | 107.8 | C17—C181—H18A | 111.4 |
O11—C61—C5 | 104.3 (12) | O21—C181—H18B | 111.4 |
O11—C61—H6A | 110.9 | C17—C181—H18B | 111.4 |
C5—C61—H6A | 110.9 | H18A—C181—H18B | 109.3 |
O11—C61—H6B | 110.9 | O22—C182—C17 | 103.6 (11) |
C5—C61—H6B | 110.9 | O22—C182—H18C | 111.1 |
H6A—C61—H6B | 108.9 | C17—C182—H18C | 111.1 |
O12—C62—C5 | 101.4 (10) | O22—C182—H18D | 111.0 |
O12—C62—H6C | 111.5 | C17—C182—H18D | 111.0 |
C5—C62—H6C | 111.5 | H18C—C182—H18D | 109.0 |
O12—C62—H6D | 111.5 | N5—C19—C22 | 112.4 (5) |
C5—C62—H6D | 111.5 | N5—C19—H19A | 109.1 |
H6C—C62—H6D | 109.3 | C22—C19—H19A | 109.1 |
N1—C7—C10 | 113.2 (5) | N5—C19—H19B | 109.1 |
N1—C7—H7A | 108.9 | C22—C19—H19B | 109.1 |
C10—C7—H7A | 108.9 | H19A—C19—H19B | 107.9 |
N1—C7—H7B | 108.9 | N7—C20—N6 | 126.4 (6) |
C10—C7—H7B | 108.9 | N7—C20—C24 | 117.8 (7) |
H7A—C7—H7B | 107.7 | N6—C20—C24 | 115.7 (7) |
N3—C8—N2 | 125.3 (5) | N8—C21—N7 | 116.3 (6) |
N3—C8—C12 | 117.3 (6) | N8—C21—C22 | 123.8 (6) |
N2—C8—C12 | 117.4 (6) | N7—C21—C22 | 119.9 (6) |
N4—C9—N3 | 117.0 (5) | C23—C22—C21 | 116.9 (6) |
N4—C9—C10 | 123.3 (5) | C23—C22—C19 | 120.1 (6) |
N3—C9—C10 | 119.6 (5) | C21—C22—C19 | 123.0 (6) |
C11—C10—C9 | 116.8 (5) | N6—C23—C22 | 123.9 (6) |
C11—C10—C7 | 119.9 (5) | N6—C23—H23 | 118.1 |
C9—C10—C7 | 123.3 (5) | C22—C23—H23 | 118.1 |
C10—C11—N2 | 123.7 (6) | C20—C24—H24A | 108.9 |
C10—C11—H11 | 118.2 | C20—C24—H24B | 109.4 |
N2—C11—H11 | 118.2 | H24A—C24—H24B | 109.6 |
C8—C12—H12A | 109.6 | C20—C24—H24C | 109.3 |
C8—C12—H12B | 109.3 | H24A—C24—H24C | 109.6 |
H12A—C12—H12B | 109.0 | H24B—C24—H24C | 110.0 |
C8—C12—H12C | 109.9 | H3A—O3—H3B | 108.4 |
H12A—C12—H12C | 109.7 | H41A—O41—H41B | 111.1 |
H12B—C12—H12C | 109.4 | H51A—O51—H51B | 106.7 |
C13—S2—C15 | 90.9 (3) | H52A—O52—H52B | 107.2 |
C182—O22—H22 | 110.5 | | |
| | | |
C2—N1—C1—S1 | −0.8 (7) | C14—N5—C13—S2 | −1.5 (7) |
C7—N1—C1—S1 | −176.8 (4) | C19—N5—C13—S2 | −176.9 (5) |
C3—S1—C1—N1 | −0.6 (6) | C15—S2—C13—N5 | 0.5 (6) |
C1—N1—C2—C3 | 2.3 (9) | C13—N5—C14—C15 | 1.9 (9) |
C7—N1—C2—C3 | 178.2 (6) | C19—N5—C14—C15 | 177.4 (7) |
C1—N1—C2—C4 | −175.3 (6) | C13—N5—C14—C16 | −176.0 (7) |
C7—N1—C2—C4 | 0.7 (9) | C19—N5—C14—C16 | −0.5 (10) |
N1—C2—C3—C5 | −178.8 (9) | N5—C14—C15—C17 | −178.8 (10) |
C4—C2—C3—C5 | −1.5 (15) | C16—C14—C15—C17 | −1.1 (17) |
N1—C2—C3—S1 | −2.6 (8) | N5—C14—C15—S2 | −1.4 (9) |
C4—C2—C3—S1 | 174.7 (6) | C16—C14—C15—S2 | 176.3 (7) |
C1—S1—C3—C2 | 1.8 (7) | C13—S2—C15—C14 | 0.6 (7) |
C1—S1—C3—C5 | 178.3 (9) | C13—S2—C15—C17 | 178.2 (9) |
C2—C3—C5—C62 | −102.0 (12) | C14—C15—C17—C181 | −99.1 (13) |
S1—C3—C5—C62 | 82.2 (11) | S2—C15—C17—C181 | 83.8 (12) |
C2—C3—C5—C61 | 134.8 (13) | C14—C15—C17—C182 | 137.6 (13) |
S1—C3—C5—C61 | −41.0 (16) | S2—C15—C17—C182 | −39.5 (17) |
C3—C5—C61—O11 | 55 (2) | C15—C17—C181—O21 | −59.4 (15) |
C3—C5—C62—O12 | −67.5 (14) | C15—C17—C182—O22 | 55 (2) |
C1—N1—C7—C10 | −4.4 (8) | C13—N5—C19—C22 | −6.6 (8) |
C2—N1—C7—C10 | 179.9 (5) | C14—N5—C19—C22 | 178.3 (6) |
C9—N3—C8—N2 | −0.9 (9) | C21—N7—C20—N6 | 1.1 (10) |
C9—N3—C8—C12 | 179.6 (5) | C21—N7—C20—C24 | −179.8 (6) |
C11—N2—C8—N3 | 0.6 (9) | C23—N6—C20—N7 | −1.3 (10) |
C11—N2—C8—C12 | −179.8 (6) | C23—N6—C20—C24 | 179.6 (6) |
C8—N3—C9—N4 | −179.7 (5) | C20—N7—C21—N8 | 178.8 (6) |
C8—N3—C9—C10 | 0.4 (8) | C20—N7—C21—C22 | −0.1 (9) |
N4—C9—C10—C11 | −179.7 (6) | N8—C21—C22—C23 | −179.4 (6) |
N3—C9—C10—C11 | 0.2 (8) | N7—C21—C22—C23 | −0.5 (9) |
N4—C9—C10—C7 | 0.2 (9) | N8—C21—C22—C19 | 2.4 (10) |
N3—C9—C10—C7 | −179.9 (5) | N7—C21—C22—C19 | −178.7 (5) |
N1—C7—C10—C11 | 100.3 (6) | N5—C19—C22—C23 | 101.7 (7) |
N1—C7—C10—C9 | −79.6 (7) | N5—C19—C22—C21 | −80.1 (7) |
C9—C10—C11—N2 | −0.5 (9) | C20—N6—C23—C22 | 0.6 (9) |
C7—C10—C11—N2 | 179.6 (5) | C21—C22—C23—N6 | 0.3 (9) |
C8—N2—C11—C10 | 0.1 (9) | C19—C22—C23—N6 | 178.6 (6) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1···I1i | 0.93 | 2.98 | 3.643 (6) | 129 |
C13—H13···I1ii | 0.93 | 3.02 | 3.623 (6) | 124 |
N4—H4A···N3iii | 0.86 | 2.26 | 3.112 (7) | 172 |
N4—H4B···I2 | 0.86 | 2.86 | 3.667 (5) | 158 |
N8—H8A···N7iv | 0.86 | 2.23 | 3.079 (8) | 170 |
N8—H8B···O3 | 0.86 | 1.96 | 2.793 (9) | 164 |
O11—H1A···N2i | 0.85 | 1.81 | 2.665 (15) | 178 |
O12—H12···O52 | 0.81 | 2.33 | 2.85 (2) | 123 |
O21—H21···O41 | 0.82 | 1.84 | 2.637 (18) | 165 |
O22—H22···N6ii | 0.82 | 1.92 | 2.632 (14) | 146 |
O3—H3A···I2v | 0.83 | 2.73 | 3.526 (9) | 161 |
O3—H3B···O51vi | 0.82 | 2.12 | 2.78 (2) | 137 |
O3—H3B···O52vi | 0.82 | 1.88 | 2.59 (2) | 144 |
O41—H41A···N6ii | 0.82 | 2.26 | 2.982 (16) | 148 |
O51—H51A···O11 | 0.80 | 1.96 | 2.73 (3) | 162 |
O51—H51B···O21vii | 0.82 | 2.16 | 2.97 (2) | 172 |
O52—H52A···N2i | 0.82 | 2.14 | 2.957 (16) | 179 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+2, −y+1, −z+1; (iii) −x+1, −y+2, −z+1; (iv) −x+2, −y, −z+1; (v) x, y−1, z; (vi) x+1, y, z; (vii) x−1, y, z. |
Experimental details
Crystal data |
Chemical formula | C12H17N4OS+·I−·1.25H2O |
Mr | 414.78 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 11.9437 (10), 12.5913 (12), 13.8768 (13) |
α, β, γ (°) | 104.900 (1), 100.968 (2), 115.129 (1) |
V (Å3) | 1715.6 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.00 |
Crystal size (mm) | 0.21 × 0.17 × 0.05 |
|
Data collection |
Diffractometer | Bruker APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.679, 0.907 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9403, 6271, 5141 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.606 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.053, 0.156, 1.09 |
No. of reflections | 6271 |
No. of parameters | 418 |
No. of restraints | 8 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.62, −0.98 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1···I1i | 0.93 | 2.98 | 3.643 (6) | 129 |
C13—H13···I1ii | 0.93 | 3.02 | 3.623 (6) | 124 |
N4—H4A···N3iii | 0.86 | 2.26 | 3.112 (7) | 172 |
N4—H4B···I2 | 0.86 | 2.86 | 3.667 (5) | 158 |
N8—H8A···N7iv | 0.86 | 2.23 | 3.079 (8) | 170 |
N8—H8B···O3 | 0.86 | 1.96 | 2.793 (9) | 164 |
O11—H1A···N2i | 0.85 | 1.81 | 2.665 (15) | 178 |
O12—H12···O52 | 0.81 | 2.33 | 2.85 (2) | 123 |
O21—H21···O41 | 0.82 | 1.84 | 2.637 (18) | 165 |
O22—H22···N6ii | 0.82 | 1.92 | 2.632 (14) | 146 |
O3—H3A···I2v | 0.83 | 2.73 | 3.526 (9) | 161 |
O3—H3B···O51vi | 0.82 | 2.12 | 2.78 (2) | 137 |
O3—H3B···O52vi | 0.82 | 1.88 | 2.59 (2) | 144 |
O41—H41A···N6ii | 0.82 | 2.26 | 2.982 (16) | 148 |
O51—H51A···O11 | 0.80 | 1.96 | 2.73 (3) | 162 |
O51—H51B···O21vii | 0.82 | 2.16 | 2.97 (2) | 172 |
O52—H52A···N2i | 0.82 | 2.14 | 2.957 (16) | 179 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+2, −y+1, −z+1; (iii) −x+1, −y+2, −z+1; (iv) −x+2, −y, −z+1; (v) x, y−1, z; (vi) x+1, y, z; (vii) x−1, y, z. |
Distances between the anion and the pyrimidine or thiazolium ring in the anion
bridges I (C1—H···A···P) and II (N4—H···A···T) (Å)a topCompound | A | P | A···P | A | T | A···T | Reference |
(Hth)Cl2.H2O | Cl | N2 | 3.484 | Cl | C2 | 3.369 | Kraut & Reed (1962) |
(th)Cl.H2O | Cl | C9 | 4.414 | O(water) | N1 | 3.125 | Pletcher et al. (1972) |
(Hth)Br2.0.5H2O | Br | C8 | 3.601 | Br | C2 | 3.509 | Thompson & Richardson (1977) |
(th)Br.1.5H2O | Br | C9 | 4.806 | Br | N1 | 3.991 | Hu & Zhang (1992) |
(Hth)I2 | I | N2 | 3.857 | I | N1 | 3.683 | Lee & Richardson (1976) |
(th)I.1.5H2O | I | C9 | 4.910 | I | C2 | 4.083 | Hu & Zhang (1993b) |
(th)I.1.25H2O | I1 | N3 | 4.885 (5) | I2 | C2 | 4.039 (8) | This work |
| I1 | C21 | 5.050 (6) | O3(water) | N5 | 3.038 (11) | |
(a) A refers to the anion, T to one of the atoms in the thiazolium ring and
P to one of the atoms in the pyrimidine ring. |
Thiamine (vitamin B1) in the form of pyrophosphate is a coenzyme for a number of enzyme systems catalysing the transfer of acyl or aldehyde groups and the decarboxylation of α-keto acids (Krampitz, 1969). The catalytic processes involve the recognition and reaction of a substrate anion such as pyruvate at the C1 site of the thiazolium group (refer to molecule A in Fig. 1 for atomic numbering, unless otherwise indicated). Structural studies of thiamine–anion compounds as models of host–guest interactions have revealed two distinct types of interaction between thiamine and anions (Aoki et al., 1993; Cramer et al., 1988). One of these is of the form C1—H···anion···pyrimidine ring, i.e. an anion accepts a hydrogen bond from atom C1 of the thiazolium group and makes a close contact with the pyrimidine ring of the same molecule, and the other is of the form N4—H···anion···thiazolium ring, where an anion accepts a hydrogen bond from the amine group and forms an electrostatic contact with the thiazolium ring. These two interactions have been defined as type I and II anion bridges, respectively (Hu et al., 1999). Thiamine interacts with an anionic group near the active C1 position through a type I anion bridge, serving as a model for thiamine–substrate interactions based on the fact that the enzymatic reactions proceed through C1-substituted thiamine intermediates (Breslow, 1958).
The construction of host frameworks, which trap anionic or neutral guests through the use of hydrogen bonding, electrostatic and π–π interactions, is one of the goals of organic crystal engineering (Beatty, 2003; Biradha, 2003; Desiraju, 1995; Etter, 1991; Videnova-Adrabińska, 1996). Thiamine, as a naturally occurring cationic host, provides multiple sites that serve as hydrogen-bonding donors or acceptors to form various hydrogen-bonded supramolecular arrays on which anion guests are adsorbed (Aoki et al., 1993; Hu et al., 2001b). For example, one-dimensional chains in the ClO4- (Aoki et al., 1988; Kozioł et al., 1987) and BF4- salts (Aoki et al., 1990; Hu et al., 2001a) of thiamine, a triple helical chain in the SCN- salt (Hu & Zhang, 1993a) and a two-dimensional network in the tetraphenylborate salt (Hu et al., 2005) have all been observed to date. In this regard, we are interested in how anions interact with supramolecular assemblies of thiamine. Generally, thiamine–anion compounds can be isolated in two forms, the protonated form (Hth), with a proton on the pyrimidine N2 atom, and the unprotonated form (th). The structures of a protonated compound, (Hth)I2 (Lee & Richardson, 1976), and an unprotonated compound, (th)I.1.5H2O, (II), in the monoclinic form (Hu & Zhang, 1993b) have been reported. We report here an unprotonated triclinic form, the title compound, (th)I.1.25H2O, (I).
The asymmetric unit of (I) contains two crystallographically independent thiamine molecules, A (containing atom S1) and B (containing atom S2) (Fig. 1), two I- ions and 2.5 water molecules. The thiamine molecules occur as monovalent cations with an unprotonated pyrimidine ring (atoms N2 of A and N6 of B are unprotonated). The dimensions of the pyrimidine groups are in agreement with those found in the unprotonated monoclinic compound, (II). The C8—N2—C11 and C20—N6—C23 bond angles are 115.9 (5) and 114.9 (6)° in (I), comparable with the values of 115.4 (7) and 115.9 (8)° in (II) but smaller than that of 119.0° in protonated (Hth)I2. Both thiamine molecules A and B adopt an F conformation in terms of the torsion angles: ϕT = -4.4 (8) and ϕP = -79.6 (7)° for A, and -6.6 (8) and -80.1 (7)°, respectively, for B [ϕT = C10—C7—N1—C1 (or C22—C19—N5—C13) ≈ 0° and ϕP = N1—C7—C10—C9 (or N5—C19—C22—C21) ≈ ±90° for the F conformation; Blank et al., 1976].
The hydroxyethyl side chains of both A and B are disordered, each over two half-occupied positions, and fold back toward the thiazolium groups to make a close contact between S and hydroxy O atoms (values for B in square brackets?): S1···O11 [O12] = 2.893 (13) [3.075 (12)] and S2···O21 [O22] = 3.142 (15) [2.923 (15)] Å. This close contact is a common feature in thiamine structures.
A water molecule (O3) acts as a type II anion bridge to link the two aromatic rings of B by accepting a hydrogen bond from atom N8 (Table 1) and making a close contact with the thiazolium ring [closest distance O3···N5 = 3.038 (11) Å]. Atom I2 accepts a hydrogen bond from atom N4 of A but is involved in a quite loose contact with the thiazolium ring, where the closest distance between atom I2 and the thiazolium ring is I2···C2 = 4.039 (8) Å. In a rigorous sense, the type II anion bridge does not exist for A in (I). This is also the case with monoclinic (II) [closest distance I···C2 = 4.083 (7) Å]. In contrast, the type II anion bridge is active in (Hth)I2 (Lee & Richardson, 1976).
It is noteworthy that the I···thiazolium distance in protonated Hth.I2 [closest distance I···N1 = 3.68 Å] is evidently shorter than those in (I) and (II). A similar situation has been also observed in the bromide salts, unprotonated (th)Br.1.5H2O (Hu & Zhang, 1992) and protonated (Hth)Br2.0.5H2O (Thompson & Richardson, 1977) (Table 2). As to the type I anion bridge, atom I1 simultaneously forms two C—H···I interactions with C1—H1 of A at (1 - x, 1 - y, 1 - z) and C13—H13 of B at (2 - x, 1 - y, 1 - z) (Table 1), but the distances between I1 and the pyrimidine rings are too long to be considered as significant interactions [closest distances I1···N3i = 4.885 (5) for A and I1···C21ii = 5.050 (6) Å for B; symmetry codes: (i) 1 - x, 1 - y, 1 - z; (ii) 2 - x, 1 - y, 1 - z]. Thus, a type I anion bridge does not form in (I). Interestingly, a type I anion bridge is present in the protonated Cl, Br and I salts, but is also absent in the unprotonated Cl and Br salts and in (II), as indicated by the long anion···pyrimidine distances listed in Table 2. However, an inspection of the other thiamine salts with various inorganic anions, including NO3- (Ishida et al., 1984; Yang et al., 1987), ClO4- (Aoki et al., 1988; Kozioł et al., 1987), BF4- (Aoki et al., 1990; Hu et al., 2001a) and PF6- (Aoki et al., 1988), shows the common existence of type I anion bridges in these compounds, regardless of whether the thiamine has a protonated or unprotonated pyrimidine ring.
The crystal packing in (I) is dominated by intermolecular hydrogen bonds involving thiamine and water molecules (Table 1). For the first part of the disorder (atoms C61/O11/C181/O21/O41/O51), a cyclic dimeric unit is constructed by self-association of molecule A and its centrosymmetric partner through O11—H···N2i hydrogen bonds (Fig. 2). Molecules B also form a centrosymmetric cyclic dimer through the intervention of water molecules via O21—H···O41—H···N6ii hydrogen bonds. These cyclic dimers are further linked by a self-complementary pyrimidine···pyrimidine interaction involving a pair of N4—H···N3iii hydrogen bonds for A (or N8—H···N7iv for B), which is a supramolecular synthon frequently observed in thiamine structures [symmetry codes: (iii) 1 - x, 2 - y, 1 - z; (iv) 2 - x, -y, 1 - z]. These base-pairing interactions connect the cyclic dimers into chains extending along [010]. The chains formed by molecules A and B, respectively, are arranged alternately with the cyclic dimers aligned, thus forming a channel along [100] (Fig. 3). This arrangement of the A and B chains is stabilized by π–π interactions between the pyrimidine rings of molecules A and B at (x, 1 + y, z), with a centroid-to-centroid distance of 3.554 (1) Å, and by O11···H—O51—H···O21v hydrogen bonds [symmetry code: (v) x - 1, y, z].
The thiamine molecules are self-associated into a similar chain structure for the second disorder group (atoms C62/O12/C182/O22/O52). One difference from the first disorder group is that now cyclic dimer A is mediated by water molecules (O12—H···O52—H···N2i), while cyclic dimer B is formed directly by hydrogen bonds between the hydroxy group and a pyrimidine N atom (O22—H···N6ii). It is interesting to note that the channel formed by the stacking of the cyclic dimers serves as an anion tunnel, with I atoms arranged through it. As shown in Fig. 3, atom I1, lying in a cavity surrounded by four thiazolium rings, is involved in two C—H···I interactions with two thiazolium groups, as mentioned above, and two electrostatic interactions with the other two thiazolium groups, with I1 located over the ring planes. The distances between I1 and the centroids of the thiazolium rings are 3.7759 (6) and 3.8252 (6) Å. This binding mode of an I- anion to thiamine molecules is similar to that found in monoclinic (II). A major difference is that the cyclic dimer consists of molecules A and B in (II) and thus is noncentrosymmetric.
In summary, although two types of anion bridges have frequently been observed in thiamine compounds, halogen anions do not follow this rule. A similar hydrogen-bonded network of thiamine molecules, which captures I- anions in a unique mode, has been observed in both triclinic (I) and monoclinic (II), indicating the robustness of these supramolecular synthons. The results could be helpful for understanding the interactions between thiamine and anions in enzyme systems, and may also provide useful information for developing supramolecular host frameworks that selectively adsorb anionic guests.