Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803006287/bt6254sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803006287/bt6254Isup2.hkl |
CCDC reference: 209989
Crystals of compound (1H+·Cl−) (Brown & Kirby, 1997) were grown from a saturated solution in ethanol.
H atoms bonded to N and O atoms were identified in a difference synthesis and refined freely. Methyl H atoms were similarly identified, the methyl groups then idealized (C—H = 0.98 Å, all angles 109.5°) and refined as rigid groups allowed to rotate but not tip. Other H atoms were included using a riding model with fixed C—H bond lengths of 1.00 Å; Uiso(H) values were fixed at 1.2Ueq of the parent atom. The structure is pseudo-A-centred; the higher symmetry cell, corresponding after reorientation to space group C2/m, would however require the cation to display mirror symmetry, which is only approximate in the true structure (cf. Fig. 2). Furthermore, a large number of highly significant reflections are observed that do not correspond to a centred lattice.
Data collection: DIF4 (Stoe & Cie, 1992); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.
C11H21N2O4+·Cl− | F(000) = 600 |
Mr = 280.75 | Dx = 1.432 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 9.804 (2) Å | Cell parameters from 52 reflections |
b = 9.730 (2) Å | θ = 10–11.5° |
c = 13.896 (3) Å | µ = 0.30 mm−1 |
β = 100.82 (2)° | T = 143 K |
V = 1302.1 (5) Å3 | Tablet, colourless |
Z = 4 | 0.50 × 0.40 × 0.15 mm |
Stoe STADI-4 diffractometer | Rint = 0.021 |
Radiation source: fine-focus sealed tube | θmax = 27.5°, θmin = 3.2° |
Graphite monochromator | h = −12→1 |
ω/θ scans | k = 0→12 |
3416 measured reflections | l = −17→18 |
2977 independent reflections | 3 standard reflections every 60 min |
2090 reflections with I > 2σ(I) | intensity decay: none |
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)] = 0.050 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.135 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0544P)2 + 0.641P] where P = (Fo2 + 2Fc2)/3 |
2977 reflections | (Δ/σ)max < 0.001 |
175 parameters | Δρmax = 0.35 e Å−3 |
0 restraints | Δρmin = −0.33 e Å−3 |
C11H21N2O4+·Cl− | V = 1302.1 (5) Å3 |
Mr = 280.75 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.804 (2) Å | µ = 0.30 mm−1 |
b = 9.730 (2) Å | T = 143 K |
c = 13.896 (3) Å | 0.50 × 0.40 × 0.15 mm |
β = 100.82 (2)° |
Stoe STADI-4 diffractometer | Rint = 0.021 |
3416 measured reflections | 3 standard reflections every 60 min |
2977 independent reflections | intensity decay: none |
2090 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.050 | 0 restraints |
wR(F2) = 0.135 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.35 e Å−3 |
2977 reflections | Δρmin = −0.33 e Å−3 |
175 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. Non-bonded distances: 2.8633 (0.0025) O1 - N1 2.9794 (0.0026) O1 - N2 2.5615 (0.0032) C8 - C9 2.5547 (0.0030) C6 - C9 2.5840 (0.0032) C6 - C8 |
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 | ||
C1 | 0.6876 (2) | 0.3646 (3) | 0.29236 (15) | 0.0243 (5) | |
H1 | 0.6376 | 0.2747 | 0.2808 | 0.029* | |
C3 | 0.8165 (2) | 0.5056 (2) | 0.41368 (15) | 0.0257 (5) | |
H3 | 0.8524 | 0.5111 | 0.4858 | 0.031* | |
C5 | 0.6682 (2) | 0.6162 (3) | 0.28395 (15) | 0.0249 (5) | |
H5 | 0.6041 | 0.6962 | 0.2676 | 0.030* | |
C6 | 0.5866 (2) | 0.4825 (3) | 0.26452 (15) | 0.0273 (5) | |
H6 | 0.5161 | 0.4795 | 0.3079 | 0.033* | |
C7 | 0.8862 (2) | 0.5063 (2) | 0.26162 (14) | 0.0187 (4) | |
H7 | 0.9688 | 0.5106 | 0.2290 | 0.022* | |
C8 | 0.7914 (2) | 0.6299 (2) | 0.23015 (15) | 0.0214 (5) | |
H8 | 0.8436 | 0.7158 | 0.2532 | 0.026* | |
C9 | 0.8109 (2) | 0.3675 (2) | 0.23805 (14) | 0.0185 (4) | |
H9 | 0.8766 | 0.2921 | 0.2647 | 0.022* | |
C11 | 0.8924 (2) | 0.3255 (3) | 0.08160 (16) | 0.0264 (5) | |
H11A | 0.9642 | 0.3933 | 0.1068 | 0.032* | |
H11B | 0.8647 | 0.3363 | 0.0105 | 0.032* | |
H11C | 0.9291 | 0.2327 | 0.0966 | 0.032* | |
C12 | 0.6720 (2) | 0.2289 (3) | 0.10228 (17) | 0.0319 (6) | |
H12A | 0.7109 | 0.1470 | 0.1383 | 0.038* | |
H12B | 0.6599 | 0.2115 | 0.0317 | 0.038* | |
H12C | 0.5818 | 0.2505 | 0.1193 | 0.038* | |
C13 | 0.6369 (3) | 0.7297 (3) | 0.08771 (18) | 0.0381 (7) | |
H13A | 0.5518 | 0.6936 | 0.1058 | 0.046* | |
H13B | 0.6234 | 0.7387 | 0.0163 | 0.046* | |
H13C | 0.6583 | 0.8199 | 0.1181 | 0.046* | |
C14 | 0.8720 (2) | 0.6830 (3) | 0.08041 (17) | 0.0294 (5) | |
H14A | 0.8909 | 0.7796 | 0.0981 | 0.035* | |
H14B | 0.8506 | 0.6741 | 0.0089 | 0.035* | |
H14C | 0.9538 | 0.6274 | 0.1067 | 0.035* | |
N1 | 0.76874 (18) | 0.3475 (2) | 0.12896 (13) | 0.0207 (4) | |
H02 | 0.732 (3) | 0.438 (3) | 0.103 (2) | 0.054 (9)* | |
N2 | 0.75245 (18) | 0.6348 (2) | 0.12195 (12) | 0.0220 (4) | |
O2 | 0.74755 (16) | 0.37942 (17) | 0.39475 (10) | 0.0264 (4) | |
H01 | 0.431 (5) | 0.481 (4) | 0.163 (3) | 0.087 (14)* | |
O4 | 0.72744 (17) | 0.61697 (18) | 0.38783 (11) | 0.0293 (4) | |
O10 | 0.93126 (15) | 0.51173 (16) | 0.36659 (10) | 0.0241 (4) | |
O1 | 0.51722 (17) | 0.4677 (2) | 0.16633 (12) | 0.0357 (5) | |
Cl | 0.22043 (5) | 0.50808 (7) | 0.18133 (5) | 0.03420 (19) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0248 (10) | 0.0350 (13) | 0.0139 (10) | −0.0068 (10) | 0.0061 (8) | −0.0025 (9) |
C3 | 0.0324 (11) | 0.0289 (12) | 0.0158 (9) | 0.0006 (10) | 0.0047 (8) | −0.0007 (9) |
C5 | 0.0234 (10) | 0.0349 (13) | 0.0173 (10) | 0.0102 (10) | 0.0060 (8) | 0.0010 (9) |
C6 | 0.0192 (10) | 0.0472 (15) | 0.0177 (10) | 0.0025 (10) | 0.0092 (8) | 0.0000 (10) |
C7 | 0.0179 (9) | 0.0243 (11) | 0.0137 (9) | 0.0005 (8) | 0.0023 (7) | 0.0013 (8) |
C8 | 0.0216 (10) | 0.0238 (12) | 0.0192 (10) | 0.0029 (8) | 0.0049 (8) | 0.0022 (9) |
C9 | 0.0181 (9) | 0.0251 (11) | 0.0122 (9) | 0.0005 (8) | 0.0025 (7) | −0.0016 (8) |
C11 | 0.0234 (11) | 0.0344 (13) | 0.0239 (11) | 0.0012 (10) | 0.0108 (9) | −0.0055 (10) |
C12 | 0.0303 (12) | 0.0428 (15) | 0.0235 (11) | −0.0116 (11) | 0.0070 (10) | −0.0109 (11) |
C13 | 0.0337 (13) | 0.0528 (18) | 0.0285 (12) | 0.0181 (12) | 0.0075 (11) | 0.0150 (12) |
C14 | 0.0282 (12) | 0.0342 (14) | 0.0269 (12) | 0.0010 (10) | 0.0083 (10) | 0.0106 (10) |
N1 | 0.0175 (8) | 0.0293 (11) | 0.0159 (8) | −0.0008 (8) | 0.0049 (7) | −0.0030 (8) |
N2 | 0.0205 (8) | 0.0304 (11) | 0.0159 (8) | 0.0065 (8) | 0.0051 (7) | 0.0067 (8) |
O2 | 0.0363 (9) | 0.0298 (9) | 0.0142 (7) | −0.0038 (7) | 0.0078 (6) | 0.0016 (6) |
O4 | 0.0382 (9) | 0.0342 (10) | 0.0168 (7) | 0.0065 (8) | 0.0086 (7) | −0.0031 (7) |
O10 | 0.0250 (7) | 0.0310 (9) | 0.0147 (7) | −0.0002 (7) | −0.0005 (6) | −0.0005 (6) |
O1 | 0.0157 (7) | 0.0703 (14) | 0.0211 (8) | 0.0022 (8) | 0.0038 (6) | −0.0019 (8) |
Cl | 0.0178 (3) | 0.0400 (4) | 0.0451 (4) | 0.0018 (2) | 0.0067 (2) | −0.0049 (3) |
C1—O2 | 1.441 (2) | C9—N1 | 1.507 (2) |
C1—C6 | 1.517 (3) | C9—H9 | 1.0000 |
C1—C9 | 1.541 (3) | C11—N1 | 1.499 (3) |
C1—H1 | 1.0000 | C11—H11A | 0.9800 |
C3—O4 | 1.396 (3) | C11—H11B | 0.9800 |
C3—O2 | 1.402 (3) | C11—H11C | 0.9800 |
C3—O10 | 1.405 (3) | C12—N1 | 1.495 (3) |
C3—H3 | 1.0000 | C12—H12A | 0.9800 |
C5—O4 | 1.451 (3) | C12—H12B | 0.9800 |
C5—C6 | 1.524 (3) | C12—H12C | 0.9800 |
C5—C8 | 1.541 (3) | C13—N2 | 1.470 (3) |
C5—H5 | 1.0000 | C13—H13A | 0.9800 |
C6—O1 | 1.413 (3) | C13—H13B | 0.9800 |
C6—H6 | 1.0000 | C13—H13C | 0.9800 |
C7—O10 | 1.444 (2) | C14—N2 | 1.477 (3) |
C7—C8 | 1.533 (3) | C14—H14A | 0.9800 |
C7—C9 | 1.544 (3) | C14—H14B | 0.9800 |
C7—H7 | 1.0000 | C14—H14C | 0.9800 |
C8—N2 | 1.481 (3) | N1—H02 | 0.99 (3) |
C8—H8 | 1.0000 | O1—H01 | 0.85 (4) |
O2—C1—C6 | 107.55 (18) | C1—C9—H9 | 108.3 |
O2—C1—C9 | 105.64 (16) | C7—C9—H9 | 108.3 |
C6—C1—C9 | 113.29 (18) | N1—C11—H11A | 109.5 |
O2—C1—H1 | 110.1 | N1—C11—H11B | 109.5 |
C6—C1—H1 | 110.1 | H11A—C11—H11B | 109.5 |
C9—C1—H1 | 110.1 | N1—C11—H11C | 109.5 |
O4—C3—O2 | 112.06 (18) | H11A—C11—H11C | 109.5 |
O4—C3—O10 | 111.32 (18) | H11B—C11—H11C | 109.5 |
O2—C3—O10 | 110.48 (18) | N1—C12—H12A | 109.5 |
O4—C3—H3 | 107.6 | N1—C12—H12B | 109.5 |
O2—C3—H3 | 107.6 | H12A—C12—H12B | 109.5 |
O10—C3—H3 | 107.6 | N1—C12—H12C | 109.5 |
O4—C5—C6 | 106.23 (18) | H12A—C12—H12C | 109.5 |
O4—C5—C8 | 106.16 (17) | H12B—C12—H12C | 109.5 |
C6—C5—C8 | 114.91 (18) | N2—C13—H13A | 109.5 |
O4—C5—H5 | 109.8 | N2—C13—H13B | 109.5 |
C6—C5—H5 | 109.8 | H13A—C13—H13B | 109.5 |
C8—C5—H5 | 109.8 | N2—C13—H13C | 109.5 |
O1—C6—C1 | 110.02 (19) | H13A—C13—H13C | 109.5 |
O1—C6—C5 | 113.54 (19) | H13B—C13—H13C | 109.5 |
C1—C6—C5 | 107.73 (17) | N2—C14—H14A | 109.5 |
O1—C6—H6 | 108.5 | N2—C14—H14B | 109.5 |
C1—C6—H6 | 108.5 | H14A—C14—H14B | 109.5 |
C5—C6—H6 | 108.5 | N2—C14—H14C | 109.5 |
O10—C7—C8 | 108.26 (16) | H14A—C14—H14C | 109.5 |
O10—C7—C9 | 106.86 (16) | H14B—C14—H14C | 109.5 |
C8—C7—C9 | 112.68 (17) | C12—N1—C11 | 107.97 (17) |
O10—C7—H7 | 109.7 | C12—N1—C9 | 112.99 (17) |
C8—C7—H7 | 109.7 | C11—N1—C9 | 111.58 (16) |
C9—C7—H7 | 109.7 | C12—N1—H02 | 114.9 (18) |
N2—C8—C7 | 109.97 (17) | C11—N1—H02 | 104.0 (18) |
N2—C8—C5 | 114.78 (17) | C9—N1—H02 | 105.1 (18) |
C7—C8—C5 | 106.38 (17) | C13—N2—C14 | 107.11 (18) |
N2—C8—H8 | 108.5 | C13—N2—C8 | 112.64 (17) |
C7—C8—H8 | 108.5 | C14—N2—C8 | 109.56 (17) |
C5—C8—H8 | 108.5 | C3—O2—C1 | 111.47 (16) |
N1—C9—C1 | 113.43 (16) | C3—O4—C5 | 111.46 (16) |
N1—C9—C7 | 110.88 (17) | C3—O10—C7 | 110.44 (15) |
C1—C9—C7 | 107.47 (17) | C6—O1—H01 | 109 (3) |
N1—C9—H9 | 108.3 | ||
O2—C1—C6—O1 | −175.87 (17) | O10—C7—C9—C1 | 59.6 (2) |
C9—C1—C6—O1 | 67.8 (2) | C8—C7—C9—C1 | −59.2 (2) |
O2—C1—C6—C5 | 59.9 (2) | C1—C9—N1—C12 | −47.8 (3) |
C9—C1—C6—C5 | −56.5 (2) | C7—C9—N1—C12 | −168.80 (18) |
O4—C5—C6—O1 | 177.72 (16) | C1—C9—N1—C11 | −169.66 (19) |
C8—C5—C6—O1 | −65.2 (2) | C7—C9—N1—C11 | 69.3 (2) |
O4—C5—C6—C1 | −60.2 (2) | C7—C8—N2—C13 | 166.40 (19) |
C8—C5—C6—C1 | 56.9 (2) | C5—C8—N2—C13 | 46.5 (3) |
O10—C7—C8—N2 | 175.20 (16) | C7—C8—N2—C14 | −74.5 (2) |
C9—C7—C8—N2 | −66.8 (2) | C5—C8—N2—C14 | 165.63 (19) |
O10—C7—C8—C5 | −59.9 (2) | O4—C3—O2—C1 | 59.9 (2) |
C9—C7—C8—C5 | 58.0 (2) | O10—C3—O2—C1 | −64.9 (2) |
O4—C5—C8—N2 | −178.51 (18) | C6—C1—O2—C3 | −59.1 (2) |
C6—C5—C8—N2 | 64.4 (2) | C9—C1—O2—C3 | 62.2 (2) |
O4—C5—C8—C7 | 59.6 (2) | O2—C3—O4—C5 | −61.0 (2) |
C6—C5—C8—C7 | −57.5 (2) | O10—C3—O4—C5 | 63.3 (2) |
O2—C1—C9—N1 | 177.73 (17) | C6—C5—O4—C3 | 60.7 (2) |
C6—C1—C9—N1 | −64.8 (2) | C8—C5—O4—C3 | −62.1 (2) |
O2—C1—C9—C7 | −59.4 (2) | O4—C3—O10—C7 | −61.5 (2) |
C6—C1—C9—C7 | 58.1 (2) | O2—C3—O10—C7 | 63.7 (2) |
O10—C7—C9—N1 | −175.92 (15) | C8—C7—O10—C3 | 60.5 (2) |
C8—C7—C9—N1 | 65.3 (2) | C9—C7—O10—C3 | −61.2 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H01···Cl | 0.85 (4) | 2.14 (5) | 2.9821 (18) | 170 (4) |
N1—H02···N2 | 0.99 (3) | 1.94 (3) | 2.801 (3) | 144 (3) |
N1—H02···O1 | 0.99 (3) | 2.44 (3) | 2.863 (2) | 105 (2) |
C12—H12B···O2i | 0.98 | 2.40 | 3.283 (3) | 150 |
C13—H13B···O4ii | 0.98 | 2.62 | 3.414 (3) | 138 |
C3—H3···O10iii | 1.00 | 2.67 | 3.555 (3) | 148 |
C11—H11C···O10iv | 0.98 | 2.55 | 3.516 (3) | 169 |
C7—H7···Clv | 1.00 | 2.67 | 3.654 (2) | 167 |
C11—H11A···Clv | 0.98 | 2.77 | 3.708 (2) | 161 |
C14—H14C···Clv | 0.98 | 2.87 | 3.839 (2) | 170 |
C12—H12A···Clvi | 0.98 | 2.82 | 3.685 (3) | 148 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) x, −y+3/2, z−1/2; (iii) −x+2, −y+1, −z+1; (iv) −x+2, y−1/2, −z+1/2; (v) x+1, y, z; (vi) −x+1, y−1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C11H21N2O4+·Cl− |
Mr | 280.75 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 143 |
a, b, c (Å) | 9.804 (2), 9.730 (2), 13.896 (3) |
β (°) | 100.82 (2) |
V (Å3) | 1302.1 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.30 |
Crystal size (mm) | 0.50 × 0.40 × 0.15 |
Data collection | |
Diffractometer | Stoe STADI-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3416, 2977, 2090 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.651 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.050, 0.135, 1.05 |
No. of reflections | 2977 |
No. of parameters | 175 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.35, −0.33 |
Computer programs: DIF4 (Stoe & Cie, 1992), DIF4, REDU4 (Stoe & Cie, 1992), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP (Siemens, 1994), SHELXL97.
C8—N2 | 1.481 (3) | C12—N1 | 1.495 (3) |
C9—N1 | 1.507 (2) | C13—N2 | 1.470 (3) |
C11—N1 | 1.499 (3) | C14—N2 | 1.477 (3) |
C12—N1—C11 | 107.97 (17) | C13—N2—C14 | 107.11 (18) |
C12—N1—C9 | 112.99 (17) | C13—N2—C8 | 112.64 (17) |
C11—N1—C9 | 111.58 (16) | C14—N2—C8 | 109.56 (17) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H01···Cl | 0.85 (4) | 2.14 (5) | 2.9821 (18) | 170 (4) |
N1—H02···N2 | 0.99 (3) | 1.94 (3) | 2.801 (3) | 144 (3) |
N1—H02···O1 | 0.99 (3) | 2.44 (3) | 2.863 (2) | 105 (2) |
C12—H12B···O2i | 0.98 | 2.40 | 3.283 (3) | 150 |
C13—H13B···O4ii | 0.98 | 2.62 | 3.414 (3) | 138 |
C3—H3···O10iii | 1.00 | 2.67 | 3.555 (3) | 148 |
C11—H11C···O10iv | 0.98 | 2.55 | 3.516 (3) | 169 |
C7—H7···Clv | 1.00 | 2.67 | 3.654 (2) | 167 |
C11—H11A···Clv | 0.98 | 2.77 | 3.708 (2) | 161 |
C14—H14C···Clv | 0.98 | 2.87 | 3.839 (2) | 170 |
C12—H12A···Clvi | 0.98 | 2.82 | 3.685 (3) | 148 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) x, −y+3/2, z−1/2; (iii) −x+2, −y+1, −z+1; (iv) −x+2, y−1/2, −z+1/2; (v) x+1, y, z; (vi) −x+1, y−1/2, −z+1/2. |
We have studied the reactions of a number of derivatives of the synaxial diaminoalcohol (1) (Beckmann, 1998; Dean, 2000). The system is of interest in the context of enzyme mechanism and efficiency because of the close and fixed geometrical relationship between the two amino groups and the axial oxygen centre, and we have reported the crystal and molecular structure of (1) in the previous paper (Beckmann et al., 2003). We report here the structure of the chloride of the conjugate acid, (1H+·Cl−), and the different hydrogen-bonding arrangement in the ammonium cation.
In contrast to the diaminoalcohol (1), which has an internal hydrogen bond between the alcohol OH group and one of the dimethylamino groups, the intramolecular hydrogen bond in the conjugate acid (1H+) is unsymmetrically shared (Table 2 and Fig. 1) between the two amino groups. The angle N—H···N is 146° and the H atom is also relatively close to the neighbouring axial hydroxy-group O atom [H···O = 2.44 (3) Å]. Despite the narrow N—H···O angle, this could be regarded as the minor component of a highly asymmetric three-centre hydrogen bond. The hydroxy group is itself involved in a hydrogen bond to the chloride anion. An extensive system of non-classical hydrogen bonds (Table 2) links the residues to form a three-dimensional network (Fig. 2).
The bond lengths at the protonated nitrogen N1 are as expected longer than those at N2 (Table 1).