organic compounds
2-[(E)-(6-Amino-1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)iminomethyl]pyridinium bromide
aUniversity of Kwazulu-Natal, School of Chemistry, Private Bag X01, Scottsville 3209, Pietermaritzburg, South Africa, and bNelson Mandela Metropolitan University, Summerstrand Campus, Department of Chemistry, University Way, Summerstrand, PO Box 77000, Port Elizabeth 6031, South Africa
*Correspondence e-mail: richard.betz@webmail.co.za
The title compound, C12H14N5O2+·Br−, is the hydrobromide salt of a Schiff base in which protonation has taken place at the pyridine N atom. This organic cation is essentially planar (r.m.s. of all fitted non-H atoms = 0.0448 Å). In the crystal, N—H⋯Br hydrogen bonds as well as C—H⋯O and C–H⋯Br interactions connect the molecules, forming a three-dimensional network.
Related literature
For the development of radiopharmaceuticals, see: Gerber et al. (2011). For the of the neutral organic parent molecule, see: Booysen et al. (2011a). For the crystal structures of polymorphs of 6-amino-1,3-dimethyl-5-[(E-2-(methylsulfanyl)benzylideneamino]pyrimidine-2,4(1H,3H)-dione, see: Booysen et al. (2011b,c). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990); Bernstein et al. (1995).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2010); cell SAINT (Bruker, 2010); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
10.1107/S1600536811033290/su2307sup1.cif
contains datablocks I, global. DOI:Supporting information file. DOI: 10.1107/S1600536811033290/su2307Isup2.cdx
Structure factors: contains datablock I. DOI: 10.1107/S1600536811033290/su2307Isup3.hkl
Supporting information file. DOI: 10.1107/S1600536811033290/su2307Isup4.cml
The title compound was prepared by the reaction of (E)-6-amino-1,3- dimethyl-5-(pyridin-2-ylmethyleneamino)pyrimidine-2,4(1H,3H)- dione and trans-[ReOBr3(PPh3)2] in methanol. The solution was filtered and single crystals suitable for the X-ray analysis were obtained from the mother liquor which was left in a fridge for several days.
Carbon-bound H atoms were placed in calculated positions (C—H 0.95 Å) and were included in the
in the riding model approximation, with U(H) set to 1.2Ueq(C). The H atoms of the methyl groups were allowed to rotate with a fixed angle around the C—C bond to best fit the experimental electron density (HFIX 137 in the SHELX program suite (Sheldrick, 2008)), with U(H) set to 1.5Ueq(C). All nitrogen-bound H atoms were located on a difference Fourier map and refined freely.Data collection: APEX2 (Bruker, 2010); cell
SAINT (Bruker, 2010); data reduction: SAINT (Bruker, 2010); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. The molecular structure of the title compound, with atom labels and displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. A view along the b-axis of the intermolecular contacts in the crystal of the title compound [Blue dashed lines indicate N-H···Br hydrogen bonds, green dashed lines C–H···O contacts and yellow dashed lines C–H···Br contacts; see Table 1 for details; Symmetry operators: (i) x - 1, y - 2, z; (ii) -x + 2, y - 1/2, -z + 1/2; (iii) -x + 3, y - 1/2,-z + 1/2; (iv) x + 1, y + 2, z; (v) -x + 2, -y + 1, -z; (vi) x, y - 1, z]. | |
Fig. 3. The crystal packing of the title compound, viewed along the b-axis. The N-H···Br, C-H···Br and C-H···O interactions are shown as dashed cyan lines - see Table 1 for details. |
C12H14N5O2+·Br− | F(000) = 688 |
Mr = 340.19 | Dx = 1.706 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2ybc | Cell parameters from 7045 reflections |
a = 8.9520 (2) Å | θ = 2.7–28.3° |
b = 4.9630 (1) Å | µ = 3.11 mm−1 |
c = 30.9123 (6) Å | T = 200 K |
β = 105.391 (1)° | Plate, orange |
V = 1324.14 (5) Å3 | 0.55 × 0.28 × 0.12 mm |
Z = 4 |
Bruker APEXII CCD diffractometer | 3277 independent reflections |
Radiation source: fine-focus sealed tube | 2998 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.017 |
ϕ and ω scans | θmax = 28.3°, θmin = 2.4° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −11→11 |
Tmin = 0.660, Tmax = 1.000 | k = −6→6 |
10606 measured reflections | l = −41→38 |
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)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.068 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.16 | w = 1/[σ2(Fo2) + (0.0154P)2 + 1.8033P] where P = (Fo2 + 2Fc2)/3 |
3277 reflections | (Δ/σ)max < 0.001 |
195 parameters | Δρmax = 0.42 e Å−3 |
0 restraints | Δρmin = −0.36 e Å−3 |
C12H14N5O2+·Br− | V = 1324.14 (5) Å3 |
Mr = 340.19 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.9520 (2) Å | µ = 3.11 mm−1 |
b = 4.9630 (1) Å | T = 200 K |
c = 30.9123 (6) Å | 0.55 × 0.28 × 0.12 mm |
β = 105.391 (1)° |
Bruker APEXII CCD diffractometer | 3277 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 2998 reflections with I > 2σ(I) |
Tmin = 0.660, Tmax = 1.000 | Rint = 0.017 |
10606 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.068 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.16 | Δρmax = 0.42 e Å−3 |
3277 reflections | Δρmin = −0.36 e Å−3 |
195 parameters |
x | y | z | Uiso*/Ueq | ||
O1 | 1.37652 (19) | 0.7382 (4) | 0.17215 (6) | 0.0318 (4) | |
O2 | 1.1136 (2) | 0.0840 (3) | 0.22406 (5) | 0.0308 (4) | |
N1 | 1.2019 (2) | 0.4910 (4) | 0.12052 (6) | 0.0207 (4) | |
N2 | 1.2433 (2) | 0.4126 (4) | 0.19775 (6) | 0.0231 (4) | |
N3 | 0.94690 (19) | −0.0572 (4) | 0.13177 (6) | 0.0190 (3) | |
N4 | 1.0173 (2) | 0.2538 (4) | 0.06812 (6) | 0.0242 (4) | |
H741 | 1.053 (3) | 0.317 (6) | 0.0469 (10) | 0.039 (8)* | |
H742 | 0.950 (3) | 0.138 (6) | 0.0608 (9) | 0.026 (7)* | |
N5 | 0.7294 (2) | −0.4378 (4) | 0.09421 (6) | 0.0222 (4) | |
H751 | 0.763 (3) | −0.333 (6) | 0.0774 (9) | 0.030 (7)* | |
C1 | 1.0559 (2) | 0.1427 (4) | 0.14542 (6) | 0.0189 (4) | |
C2 | 1.0908 (2) | 0.2922 (4) | 0.11067 (7) | 0.0188 (4) | |
C3 | 1.2809 (2) | 0.5581 (4) | 0.16435 (7) | 0.0226 (4) | |
C4 | 1.1344 (2) | 0.2018 (4) | 0.19125 (7) | 0.0212 (4) | |
C5 | 1.2294 (3) | 0.6593 (5) | 0.08419 (8) | 0.0292 (5) | |
H5A | 1.2784 | 0.5504 | 0.0653 | 0.044* | |
H5B | 1.2977 | 0.8096 | 0.0971 | 0.044* | |
H5C | 1.1304 | 0.7298 | 0.0659 | 0.044* | |
C6 | 1.3189 (3) | 0.4895 (6) | 0.24431 (8) | 0.0354 (6) | |
H6A | 1.4077 | 0.3709 | 0.2564 | 0.053* | |
H6B | 1.2448 | 0.4724 | 0.2625 | 0.053* | |
H6C | 1.3546 | 0.6766 | 0.2451 | 0.053* | |
C7 | 0.8975 (2) | −0.2117 (4) | 0.15854 (7) | 0.0201 (4) | |
H7 | 0.9368 | −0.1947 | 0.1901 | 0.024* | |
C8 | 0.7801 (2) | −0.4132 (4) | 0.13933 (7) | 0.0194 (4) | |
C9 | 0.7160 (2) | −0.5808 (4) | 0.16555 (7) | 0.0235 (4) | |
H9 | 0.7485 | −0.5673 | 0.1973 | 0.028* | |
C10 | 0.6044 (3) | −0.7680 (5) | 0.14522 (8) | 0.0269 (5) | |
H10 | 0.5598 | −0.8822 | 0.1631 | 0.032* | |
C11 | 0.5580 (3) | −0.7884 (5) | 0.09892 (8) | 0.0287 (5) | |
H11 | 0.4823 | −0.9173 | 0.0847 | 0.034* | |
C12 | 0.6233 (2) | −0.6188 (5) | 0.07375 (7) | 0.0269 (5) | |
H12 | 0.5930 | −0.6304 | 0.0419 | 0.032* | |
Br1 | 0.75392 (3) | 0.85034 (5) | 0.004599 (7) | 0.03093 (8) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0294 (8) | 0.0307 (9) | 0.0339 (9) | −0.0127 (7) | 0.0057 (7) | −0.0055 (7) |
O2 | 0.0388 (9) | 0.0325 (9) | 0.0189 (7) | −0.0090 (7) | 0.0039 (6) | 0.0023 (7) |
N1 | 0.0219 (8) | 0.0197 (9) | 0.0213 (8) | −0.0046 (7) | 0.0073 (7) | −0.0011 (7) |
N2 | 0.0253 (9) | 0.0225 (9) | 0.0190 (8) | −0.0031 (7) | 0.0013 (7) | −0.0029 (7) |
N3 | 0.0189 (8) | 0.0183 (8) | 0.0200 (8) | −0.0004 (7) | 0.0054 (6) | −0.0006 (7) |
N4 | 0.0271 (9) | 0.0271 (10) | 0.0182 (8) | −0.0072 (8) | 0.0056 (7) | 0.0012 (7) |
N5 | 0.0228 (8) | 0.0245 (9) | 0.0197 (8) | −0.0040 (7) | 0.0067 (7) | 0.0021 (7) |
C1 | 0.0192 (9) | 0.0187 (10) | 0.0186 (9) | −0.0003 (8) | 0.0047 (7) | −0.0009 (8) |
C2 | 0.0185 (9) | 0.0171 (10) | 0.0207 (9) | 0.0012 (7) | 0.0052 (7) | −0.0008 (8) |
C3 | 0.0193 (9) | 0.0227 (10) | 0.0250 (10) | 0.0000 (8) | 0.0042 (8) | −0.0026 (8) |
C4 | 0.0224 (9) | 0.0192 (10) | 0.0209 (10) | 0.0008 (8) | 0.0035 (8) | −0.0008 (8) |
C5 | 0.0359 (12) | 0.0257 (11) | 0.0290 (11) | −0.0091 (10) | 0.0138 (9) | 0.0017 (10) |
C6 | 0.0413 (13) | 0.0355 (14) | 0.0223 (11) | −0.0073 (11) | −0.0038 (10) | −0.0053 (10) |
C7 | 0.0211 (9) | 0.0205 (10) | 0.0188 (9) | −0.0001 (8) | 0.0055 (7) | −0.0003 (8) |
C8 | 0.0194 (9) | 0.0199 (10) | 0.0192 (9) | 0.0012 (8) | 0.0055 (7) | 0.0002 (8) |
C9 | 0.0254 (10) | 0.0245 (11) | 0.0213 (10) | −0.0004 (9) | 0.0075 (8) | 0.0024 (8) |
C10 | 0.0245 (10) | 0.0271 (11) | 0.0301 (11) | −0.0033 (9) | 0.0089 (9) | 0.0055 (9) |
C11 | 0.0232 (10) | 0.0287 (12) | 0.0318 (12) | −0.0068 (9) | 0.0030 (9) | 0.0010 (9) |
C12 | 0.0246 (10) | 0.0310 (12) | 0.0223 (10) | −0.0043 (9) | 0.0015 (8) | −0.0004 (9) |
Br1 | 0.03684 (13) | 0.03914 (14) | 0.01623 (10) | −0.01255 (11) | 0.00606 (8) | −0.00141 (10) |
O1—C3 | 1.217 (3) | C1—C4 | 1.435 (3) |
O2—C4 | 1.227 (3) | C5—H5A | 0.9800 |
N1—C2 | 1.377 (3) | C5—H5B | 0.9800 |
N1—C3 | 1.392 (3) | C5—H5C | 0.9800 |
N1—C5 | 1.471 (3) | C6—H6A | 0.9800 |
N2—C3 | 1.373 (3) | C6—H6B | 0.9800 |
N2—C4 | 1.407 (3) | C6—H6C | 0.9800 |
N2—C6 | 1.469 (3) | C7—C8 | 1.458 (3) |
N3—C7 | 1.290 (3) | C7—H7 | 0.9500 |
N3—C1 | 1.377 (3) | C8—C9 | 1.387 (3) |
N4—C2 | 1.319 (3) | C9—C10 | 1.387 (3) |
N4—H741 | 0.87 (3) | C9—H9 | 0.9500 |
N4—H742 | 0.82 (3) | C10—C11 | 1.384 (3) |
N5—C12 | 1.338 (3) | C10—H10 | 0.9500 |
N5—C8 | 1.353 (3) | C11—C12 | 1.377 (3) |
N5—H751 | 0.85 (3) | C11—H11 | 0.9500 |
C1—C2 | 1.407 (3) | C12—H12 | 0.9500 |
C2—N1—C3 | 122.47 (17) | N1—C5—H5C | 109.5 |
C2—N1—C5 | 119.69 (18) | H5A—C5—H5C | 109.5 |
C3—N1—C5 | 117.56 (18) | H5B—C5—H5C | 109.5 |
C3—N2—C4 | 125.60 (18) | N2—C6—H6A | 109.5 |
C3—N2—C6 | 117.31 (19) | N2—C6—H6B | 109.5 |
C4—N2—C6 | 117.04 (18) | H6A—C6—H6B | 109.5 |
C7—N3—C1 | 124.61 (18) | N2—C6—H6C | 109.5 |
C2—N4—H741 | 121 (2) | H6A—C6—H6C | 109.5 |
C2—N4—H742 | 120.8 (18) | H6B—C6—H6C | 109.5 |
H741—N4—H742 | 116 (3) | N3—C7—C8 | 118.67 (18) |
C12—N5—C8 | 123.33 (19) | N3—C7—H7 | 120.7 |
C12—N5—H751 | 116.5 (18) | C8—C7—H7 | 120.7 |
C8—N5—H751 | 120.1 (18) | N5—C8—C9 | 118.09 (19) |
N3—C1—C2 | 115.38 (17) | N5—C8—C7 | 119.33 (18) |
N3—C1—C4 | 124.84 (18) | C9—C8—C7 | 122.58 (19) |
C2—C1—C4 | 119.77 (18) | C10—C9—C8 | 119.8 (2) |
N4—C2—N1 | 117.62 (19) | C10—C9—H9 | 120.1 |
N4—C2—C1 | 122.17 (19) | C8—C9—H9 | 120.1 |
N1—C2—C1 | 120.19 (18) | C11—C10—C9 | 120.0 (2) |
O1—C3—N2 | 122.5 (2) | C11—C10—H10 | 120.0 |
O1—C3—N1 | 121.2 (2) | C9—C10—H10 | 120.0 |
N2—C3—N1 | 116.34 (18) | C12—C11—C10 | 118.9 (2) |
O2—C4—N2 | 119.16 (19) | C12—C11—H11 | 120.5 |
O2—C4—C1 | 125.2 (2) | C10—C11—H11 | 120.5 |
N2—C4—C1 | 115.60 (18) | N5—C12—C11 | 119.8 (2) |
N1—C5—H5A | 109.5 | N5—C12—H12 | 120.1 |
N1—C5—H5B | 109.5 | C11—C12—H12 | 120.1 |
H5A—C5—H5B | 109.5 | ||
C7—N3—C1—C2 | −178.59 (19) | C6—N2—C4—O2 | −3.8 (3) |
C7—N3—C1—C4 | 2.4 (3) | C3—N2—C4—C1 | −1.3 (3) |
C3—N1—C2—N4 | 176.60 (19) | C6—N2—C4—C1 | 176.35 (19) |
C5—N1—C2—N4 | 2.8 (3) | N3—C1—C4—O2 | −0.7 (3) |
C3—N1—C2—C1 | −1.7 (3) | C2—C1—C4—O2 | −179.7 (2) |
C5—N1—C2—C1 | −175.54 (19) | N3—C1—C4—N2 | 179.18 (18) |
N3—C1—C2—N4 | 3.9 (3) | C2—C1—C4—N2 | 0.2 (3) |
C4—C1—C2—N4 | −177.0 (2) | C1—N3—C7—C8 | 179.27 (18) |
N3—C1—C2—N1 | −177.84 (17) | C12—N5—C8—C9 | −1.5 (3) |
C4—C1—C2—N1 | 1.3 (3) | C12—N5—C8—C7 | 179.3 (2) |
C4—N2—C3—O1 | −179.9 (2) | N3—C7—C8—N5 | 1.8 (3) |
C6—N2—C3—O1 | 2.5 (3) | N3—C7—C8—C9 | −177.43 (19) |
C4—N2—C3—N1 | 0.9 (3) | N5—C8—C9—C10 | 0.6 (3) |
C6—N2—C3—N1 | −176.75 (19) | C7—C8—C9—C10 | 179.8 (2) |
C2—N1—C3—O1 | −178.6 (2) | C8—C9—C10—C11 | 0.4 (3) |
C5—N1—C3—O1 | −4.7 (3) | C9—C10—C11—C12 | −0.6 (4) |
C2—N1—C3—N2 | 0.7 (3) | C8—N5—C12—C11 | 1.3 (3) |
C5—N1—C3—N2 | 174.62 (19) | C10—C11—C12—N5 | −0.2 (4) |
C3—N2—C4—O2 | 178.6 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H741···Br1i | 0.87 (3) | 2.77 (3) | 3.4584 (19) | 138 (2) |
N4—H742···Br1ii | 0.82 (3) | 2.55 (3) | 3.312 (2) | 154 (2) |
N5—H751···Br1ii | 0.85 (3) | 2.41 (3) | 3.1763 (18) | 151 (2) |
C5—H5A···Br1i | 0.98 | 2.89 | 3.764 (2) | 148 |
C6—H6A···O1iii | 0.98 | 2.60 | 3.453 (3) | 145 |
C9—H9···O2iv | 0.95 | 2.53 | 3.446 (3) | 162 |
C10—H10···O1v | 0.95 | 2.56 | 3.429 (3) | 152 |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x, y−1, z; (iii) −x+3, y−1/2, −z+1/2; (iv) −x+2, y−1/2, −z+1/2; (v) x−1, y−2, z. |
Experimental details
Crystal data | |
Chemical formula | C12H14N5O2+·Br− |
Mr | 340.19 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 200 |
a, b, c (Å) | 8.9520 (2), 4.9630 (1), 30.9123 (6) |
β (°) | 105.391 (1) |
V (Å3) | 1324.14 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 3.11 |
Crystal size (mm) | 0.55 × 0.28 × 0.12 |
Data collection | |
Diffractometer | Bruker APEXII CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2008) |
Tmin, Tmax | 0.660, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10606, 3277, 2998 |
Rint | 0.017 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.068, 1.16 |
No. of reflections | 3277 |
No. of parameters | 195 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.42, −0.36 |
Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SIR97 (Altomare et al., 1999), ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H741···Br1i | 0.87 (3) | 2.77 (3) | 3.4584 (19) | 138 (2) |
N4—H742···Br1ii | 0.82 (3) | 2.55 (3) | 3.312 (2) | 154 (2) |
N5—H751···Br1ii | 0.85 (3) | 2.41 (3) | 3.1763 (18) | 151 (2) |
C5—H5A···Br1i | 0.98 | 2.89 | 3.764 (2) | 148.4 |
C6—H6A···O1iii | 0.98 | 2.60 | 3.453 (3) | 145.0 |
C9—H9···O2iv | 0.95 | 2.53 | 3.446 (3) | 162.1 |
C10—H10···O1v | 0.95 | 2.56 | 3.429 (3) | 152.0 |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x, y−1, z; (iii) −x+3, y−1/2, −z+1/2; (iv) −x+2, y−1/2, −z+1/2; (v) x−1, y−2, z. |
Acknowledgements
The authors thank Ms Dakota Neale-Shutte for helpful discussions.
References
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Next to cardiovascular diseases, cancer has become one of the main fatal diseases in industrialized countries. Apart from classical surgery, chemo- and radiotherapeutic treatments have entered the arsenal of possible cures for certain types of cancer. All methods, however, suffer from their own set of problematic side-effects and, as a consequence, the development of radiopharmaceuticals – combining the advantages of chemotherapy as well as radiation methods while at the same time avoiding their unique respective undesired side-effects – has been a topic of research (Gerber et al., 2011). Tailoring and fine-tuning of the envisioned radiopharmaceuticals' properties such as lipophilicity and, in particular, inertness is of paramount importance with respect to possible future in vivo applications in contemporary medicine and requires sound knowledge about structural parameters of the ligands applied if a more heuristic approach in the synthesis is to triumph over pure trial-and-error as it is encountered in this specific field of coordination chemistry up to the present day. To allow for an assessment of changes in structural features upon coordination, the molecular and crystal structure of the title compound has been determined. The crystal structure of the neutral compound (Booysen et al., 2011a), and other 6-amino-1,3-dimethyl-2,4(1H,3H)-dione-derived Schiff-base ligands (Booysen et al., 2011b,c), have been described previously.
The molecular structure of the title molecule is illustrated in Fig. 1. Protonation of the neutral organic ligand took place on the nitrogen atom, N5, of the pyridine moiety. The molecule has the E configuration about the C=N bond. As expected the intracyclic angles in the protonated pyridine moiety cover a range of 118.09 (19)–123.33 (19) °, with the largest angle on the protonated nitrogen atom, N, and the smallest angle on the carbon atom, C , bonded to the exocyclic substituent. The organic cation is essentially planar (r.m.s. for all its fitted non-hydrogen atoms = 0.0448 Å).
In the crystal, N-H···Br hydrogen bonds as well as C–H···O and C–H···Br contacts are observed (Table 1). While the hydrogen bonds are formed between the nitrogen-bonded hydrogen atoms and the bromide anion exclusively, the C–H···O contacts involve the hydrogen atoms of the pyridine moiety and one of the nitrogen-bonded methyl groups as donors and both oxygen atoms as acceptors. The C–H···Br contact is supported by one of the hydrogen atoms of the second nitrogen-bonded methyl group. In terms of graph-set analysis (Etter et al., 1990; Bernstein et al., 1995), the descriptor for the classical hydrogen bonds is DDD on the unitary level, whereas the C–H···O contacts necessitate a C(5)C(8)C(11) on the same level. In total, these contact result in the formation of a three-dimensional network (Fig. 3).