2-Amino-5-iodo­pyridinium bromide hemihydrate and 2-amino-5-iodo­pyridinium chloride monohydrate

The hydro­bromide and hydro­chloride salts of 2-amino-5-iodo­pyridine were prepared from aqueous solutions. The hydro­bromide salt, C₅H₆IN₂⁺·Br^-·0.5H₂O, crystallizes as a hemihydrate, and exhibits hydrogen bonding and [pi]-stacking which stabilize the crystal structure. The hydro­chloride salt, C₅H₆IN₂⁺·Cl^-·H₂O·0.375HCl, crystallized as the hydrate and exhibits similar hydrogen bonding and [pi]-stacking in the lattice. The most interesting feature of the hydrochloride salt is the presence of an additional fractional HCl molecule which introduces disorder in the location of the water molecule. The additional proton from the fractional HCl molecule is accounted for by the presence of a partial hydronium ion on one of the water sites.

S1. Introduction

We have been inter­ested in the synthesis and analysis of tetra­halocuprate complexes of substituted pyridinium cations in order to study the nature of the magnetic inter­actions in such materials (Gale et al., 2013; Solomon et al., 2013; Wikaira et al., 2013). Magnetic exchange in such materials is propagated by non-bonding contacts between the halide anions, which are in turn controlled by the nature of the counterions, in some cases leading to highly unusual structural motifs (Abdalrahman et al., 2013). As such, we are inter­ested in the inter­actions within and between the pyridinium ions and have undertaken the study of the title hydro­chloride and hydro­bromide salts of 2-amino-5-iodo­pyridine (hence 5IAP) (see scheme). The two salts crystallize as hydrates, but with distinctly different structures.

S2. Experimental

S2.1. Synthesis and crystallization

For the preparation of 2-amino-5-iodo­pyridinium bromide hemihydrate, (1), 2-amino-5-iodo­pyridine (0.44 g, 2.0 mmol) was dissolved in 6 M HCl (10 ml) with warming. The resulting solution was left to evaporate in air until the total volume had reduced to near 6 ml. The solution was then transferred to a desiccator, where colourless crystals (needles) appeared. The crystals were recovered by filtration and dried under vacuum (yield 0.26 g, 46%). Analysis, calculated for C₅H_9.25Cl_1.25IN₂ (found) (%): C 20.52 (20.62), H 3.18 (2.98), N 9.57 (9.22).

For the preparation of 2-amino-5-iodo­pyridinium chloride sesquihydrate, (2), 2-amino-5-iodo­pyridine (0.44 g, 2.0 mmol) was dissolved in 4.5 M HBr (10 ml) with warming. The resulting solution was left to evaporate in air until the total volume had reduced to near 5 ml. The solution was then transferred to a desiccator, where colourless crystals (blocks) appeared. The crystals were recovered by filtration and dried under vacuum (yield 0.21 g, 34%). Analysis, calculated for C₅H₇N₂OBrI (found) (%): C 19.38 (19.14), H 2.27 (3.52), N 9.04 (8.82).

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms bound to C atoms were refined using a riding model, with U_iso(H) = 1.2U_eq(C). H atoms bonded to N atoms were located in a difference map and their positions refined using fixed U_iso values [U_iso(H) = 1.2U_eq(N)].

For compound (1), H atoms bonded to O atoms were also located in the difference map and their positions allowed to refine using anti­bumping restraints (0.9 Å for O—H distances and 1.7 Å for H···H distances) and fixed U_iso values [U_iso(H) = 1.2U_eq(O)].

For compound (2), atoms O1, O2, Cl2, and Cl3 were refined anisotropically with fixed occupancies of 0.875, 0.125, 0.25 and 0.125, respectively. Atoms H1A, H1B, H1C and H2A were refined with distance restraints (O—H = 0.86 Å) and fixed U_iso values [U_iso(H) = 1.2U_eq(O)], with occupancies of 0.875, 0.875, 0.5 and 0.125, respectively.

S3. Results and discussion

2-Amino-5-iodo­pyridinium bromide hemihydrate, (5IAPH)Br.0.5H₂O, (1), crystallizes in the monoclinic space group P2₁/n with two pyridinium bromide salts and one water molecule in the asymmetric unit (Fig. 1). Bond lengths and angles within the pyridinium cation are the same as found in the literature, within experimental error (Landee et al., 2001; Giantsidis et al., 2002). The bromide anions are linked by hydrogen bonding to both amino and pyridinium H atoms (Fig. 2), and are further stabilized via halogen bonds to the pyridinium I atoms [Br1ⁱ···I1 = 3.417 Å and C15—I1···Br1ⁱ = 177.9°, and Br1ⁱⁱ···I2 = 3.448 Å and C25—I2···Br1ⁱⁱ = 174.7°; symmetry codes: (i) x + 1/2, -y + 3/2, z - 1/2; (ii) x - 1/2, -y + 1/2, z + 1/2] (Fig. 3). Such halogen bonding has been observed previously in a variety of compounds (Abdalrahman et al. 2013; Awwadi et al., 2007; Espallargas et al., 2006, 2009).

π-stacking inter­actions are seen between 5-IAPH cations (Fig. 3). The distance between ring centroids is 3.78 Å, with a slippage angle of 20.8° and an inter­planar distance near 3.5 Å. The I atoms are separated by 4.215 Å, which is within the sum of the van der Waals radii [Standard reference?], suggesting an inter­action of some type, but the C—I···I angles are too small for a typical halogen bond.

The asymmetric unit of (1) also contains one water molecule which is disordered over two sites, with occupancies of 0.62 and 0.38 for atoms O1 and O2, respectively. The water molecules are held in the lattice by hydrogen bonding, in this case to both bromide anions (as hydrogen-bond donors) and to the N22 amino group (as hydrogen-bond acceptor) (Fig. 4). The disorder of the water molecule may be a result of the difference in the hydrogen-bonding character, as position O1 shows stronger hydrogen bonding to the bromide anions, whereas position O2 shows stronger hydrogen bonding to the amino group.

2-Amino-5-iodo­pyridinium chloride sesquihydrate, (5IAPH)Cl.1.5 H₂O, (2), crystallizes in the monoclinic space group P2₁/c but, in contrast with (1), the asymmetric unit contains only a single pyridinium–chloride ion pair, as well as one full-occupancy water molecule. In addition, (2) exhibits an unusual disorder between another water molecule and a second chloride anion. The asymmetric unit is shown in Fig. 5. As observed for (1), the bond lengths and angles within the pyridinium ring are the same as those reported in the literature (Landee et al., 2001; Giantsidis et al., 2002). Water molecule O1 serves as a hydrogen-bond acceptor to the amino N atom, while anion Cl1 serves as an acceptor for the pyridinium N atom.

Salt (2) shows similar, albeit weaker, π-stacking inter­actions to those observed in (1) (see Fig. 3). The distance between ring centroids is 4.18 Å, with a slippage angle of 33.3° and an inter­planar distance near 3.5 Å. The I atoms are also separated by 4.18 Å, again within the sum of the van der Waals radii. An I···Cl halogen bond [I1···Cl1ⁱⁱⁱ = 3.35 Å and C15—I1···Cl1ⁱⁱⁱ = 171°; symmetry code: (iii) x, -y + 1/2, z + 1/2] mimics the I···Br halogen bond in (1). The resulting lattice stabilization is shown in Fig. 6.

Initially unaccounted-for electron density near (0.5, 0.5, 0) was resolved as a disorder involving a partial-occupancy chloride ion (Cl2) in that position and a partial-occupancy water molecule (O2) nearby, which refined to 50% each and led to an R1 value of 0.0207. However, this resulted in unacceptably short contacts between symmetry-related O2 water molecules, suggesting that the problem was with the O2 molecules. The electron density at the O2 site could be accounted for and the potential atom collisions avoided by reducing the O2 occupancy to 0.125 and allowing for a partial chloride ion (Cl3) on the same site, also with an occupancy of 0.125. Cl3 would then be too close to O1 [2.486 (6) Å] so the occupancy of O1 was reduced to 0.875 to avoid the collision and making one full water molecule per asymmetric unit. The result of this disorder is shown in Fig. 7. Although this final resulted produced a refinement with a slightly higher R1 (0.0224), the final resolution of atomic positions is highly preferable. The final occupancy of H1B of 0.5 accounts for the partial occupancy of an extra chloride ion (Cl3 = 0.125 and Cl2 = 0.25) and the provides the additional proton occupation for O2 (0.125). Although H2A is included in the final refinement, the electron density is low enough to make its position uncertain, and in fact, the final R value remains unchanged if it is removed entirely. The apparent poor geometry of the H-atom positions in the area of the disordered atoms likely occurs because they are affected by the presence of slightly displaced disordered congeners.

The alternative possibility that the additional proton density required for charge balance could be located on the amino N atom can be readily discounted. Only two H atoms were located in the difference map bonded to N12, and the sum of the three angles around N12 is 360 (4)°, precluding a tetra­hedral geometry for that atom. Attempts to resolve the disorder by modeling the electron density at (0.5,0.5,0) as a partially occupancy water molecule were also unsuccessful, leading to a greater than 1.0 occupancy for the O atom and refining with unrealistic displacement parameters (non-positive definite).

The hydrogen- and halogen-bonding inter­actions seen in both (1) and (2) provide structural motifs that can stabilize the positions of metal ions in the crystal structure, as demonstrated successfully in the reported copper(II) complexes (Landee et al., 2001; Giantsidis et al., 2002). Efforts to exploit this phenomenon with other metal ions are in progress.

Related literature

For related literature, see: Abdalrahman et al. (2013); Awwadi et al. (2007); Espallargas et al. (2006, 2009); Gale et al. (2013); Giantsidis et al. (2002); Landee et al. (2001); Solomon et al. (2013); Wikaira et al. (2013).

Computing details

For both compounds, data collection: SMART (Siemens, 1996); cell refinement: SMART (Siemens, 1996); data reduction: SHELXTL (Sheldrick, 2008); program(s) used to solve structure: SHELXTL97 (Sheldrick, 2008); program(s) used to refine structure: SHELXTL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008), enCIFer (Allen et al., 2004) and publCIF (Westrip, 2010).

Figures

	Fig. 1. The asymmetric unit of (1), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Only those H atoms whose positions were refined are labelled. Both positions for the disordered water molecule are shown.
	Fig. 2. A packing diagram for (1), viewed parallel to the ac face diagonal, showing the formation of layers. Dashed lines represent hydrogen and halogen bonds.
	Fig. 3. A view of the π-stacking and I···I bonding (dashed line) in (1).
	Fig. 4. A packing diagram for (1),viewed parallel to the hydrogen/halogen-bonded layers. Dashed lines represent hydrogen and halogen bonds.
	Fig. 5. The asymmetric unit of (2), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Only those H atoms whose positions were refined are labelled. The partial-occupancy chloride anion is shown as a dotted ellipse.
	Fig. 6. A packing diagram for (2), viewed parallel to the a axis. Dashed lines represent hydrogen and halogen bonds.
	Fig. 7. A diagram showing the result of the disorder between water molecules O1 and O2, and chloride ions Cl2 and Cl3 viewed parallel to the b-axis. Occupancies for the disordered atoms are given in [···]. Dashed lines represent hydrogen bonds and short interatomic distances which are avoided by the partial occupancies. O1 and Cl3 are not present coincidentally, nor are O2 and Cl2, nor O2 and Cl3. The occupancies of O1 and O2 total to one full water molecule. [Symmetry codes: (A) -x-1, -y+1, -z; (B) x-1, y, z; (C) -x, -y+1, -z.]

(1) 2-Amino-5-iodopyridinium bromide hemihydrate

Crystal data

C5H6IN2^+·Br^−·0.5H2O	F(000) = 1144
Mr = 309.94	Dx = 2.350 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 8192 reflections
a = 10.531 (3) Å	θ = 2.3–27.4°
b = 14.714 (5) Å	µ = 8.15 mm^−1
c = 11.675 (4) Å	T = 163 K
β = 104.457 (4)°	Block, colourless
V = 1751.8 (10) Å^3	0.37 × 0.21 × 0.19 mm
Z = 8

Data collection

Bruker SMART CCD area-detector diffractometer	3756 independent reflections
Radiation source: fine-focus sealed tube	3396 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
φ and ω scans	θmax = 27.0°, θmin = 2.3°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −13→13
Tmin = 0.752, Tmax = 1.000	k = −15→18
21720 measured reflections	l = −14→14

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.050	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0199P)^2 + 2.9908P] where P = (Fo^2 + 2Fc^2)/3
3756 reflections	(Δ/σ)max = 0.002
212 parameters	Δρmax = 0.51 e Å^−3
4 restraints	Δρmin = −0.93 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
N11	0.4447 (3)	0.82150 (19)	0.3848 (2)	0.0287 (6)
H11	0.408 (4)	0.847 (3)	0.434 (3)	0.034*
C12	0.4501 (3)	0.7300 (2)	0.3887 (3)	0.0274 (6)
N12	0.3926 (3)	0.6870 (2)	0.4630 (3)	0.0384 (7)
H12A	0.363 (4)	0.716 (3)	0.512 (4)	0.046*
H12B	0.390 (4)	0.630 (3)	0.468 (4)	0.046*
C13	0.5176 (3)	0.6859 (2)	0.3141 (3)	0.0302 (7)
H13	0.5243	0.6215	0.3150	0.036*
C14	0.5734 (3)	0.7358 (2)	0.2405 (3)	0.0286 (6)
H14	0.6190	0.7060	0.1906	0.034*
C15	0.5633 (3)	0.8315 (2)	0.2385 (3)	0.0272 (6)
C16	0.4997 (3)	0.8726 (2)	0.3118 (3)	0.0289 (6)
H16	0.4931	0.9370	0.3126	0.035*
I1	0.64342 (2)	0.910707 (15)	0.124040 (18)	0.03134 (6)
N21	0.1479 (3)	0.2682 (2)	0.5283 (3)	0.0394 (7)
H21	0.157 (4)	0.333 (3)	0.519 (3)	0.047*
C22	0.2071 (3)	0.2104 (2)	0.4674 (3)	0.0306 (7)
N22	0.2753 (3)	0.2428 (2)	0.3944 (3)	0.0369 (7)
H22A	0.291 (4)	0.298 (3)	0.393 (4)	0.044*
H22B	0.305 (4)	0.209 (3)	0.362 (4)	0.044*
C23	0.1931 (3)	0.1185 (2)	0.4845 (3)	0.0274 (6)
H23	0.2348	0.0766	0.4438	0.033*
C24	0.1215 (3)	0.0859 (2)	0.5581 (3)	0.0289 (6)
H24	0.1146	0.0222	0.5686	0.035*
C25	0.0586 (3)	0.1462 (2)	0.6177 (3)	0.0291 (6)
C26	0.0727 (3)	0.2381 (2)	0.6024 (3)	0.0329 (7)
H26	0.0310	0.2805	0.6424	0.039*
I2	−0.05218 (2)	0.097875 (17)	0.731181 (19)	0.03694 (7)
Br1	0.28103 (3)	0.46720 (2)	0.43704 (3)	0.03961 (9)
O1	0.3808 (6)	0.1127 (6)	0.2599 (7)	0.077 (2)	0.62
H1A	0.473 (10)	0.104 (7)	0.281 (8)	0.093*	0.62
H1B	0.360 (10)	0.062 (3)	0.227 (8)	0.093*	0.62
O2	0.3478 (8)	0.0824 (6)	0.3212 (8)	0.049 (2)	0.38
H2A	0.355 (13)	0.093 (12)	0.247 (4)	0.059*	0.38
H2B	0.435 (3)	0.093 (9)	0.340 (11)	0.059*	0.38
Br2	0.32126 (4)	0.88204 (3)	0.60294 (3)	0.04179 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N11	0.0294 (14)	0.0338 (15)	0.0250 (13)	0.0021 (11)	0.0104 (11)	0.0004 (11)
C12	0.0261 (15)	0.0317 (16)	0.0222 (14)	−0.0047 (12)	0.0020 (12)	0.0000 (12)
N12	0.0478 (18)	0.0371 (16)	0.0340 (16)	−0.0109 (14)	0.0173 (13)	−0.0012 (13)
C13	0.0329 (16)	0.0277 (16)	0.0271 (15)	−0.0004 (13)	0.0019 (13)	−0.0008 (12)
C14	0.0238 (14)	0.0369 (17)	0.0240 (15)	0.0041 (13)	0.0040 (12)	−0.0007 (12)
C15	0.0213 (14)	0.0355 (17)	0.0239 (14)	−0.0006 (12)	0.0036 (11)	0.0043 (12)
C16	0.0291 (16)	0.0280 (15)	0.0293 (16)	0.0008 (13)	0.0066 (13)	0.0031 (12)
I1	0.02850 (11)	0.03829 (12)	0.02803 (11)	−0.00257 (8)	0.00855 (8)	0.00581 (8)
N21	0.0458 (17)	0.0324 (15)	0.0343 (15)	−0.0059 (13)	−0.0009 (13)	0.0066 (12)
C22	0.0236 (15)	0.0375 (18)	0.0256 (15)	−0.0042 (13)	−0.0035 (12)	0.0026 (13)
N22	0.0344 (16)	0.0349 (16)	0.0426 (17)	−0.0059 (13)	0.0117 (13)	0.0022 (13)
C23	0.0236 (15)	0.0318 (16)	0.0262 (15)	−0.0037 (12)	0.0051 (12)	−0.0025 (12)
C24	0.0281 (15)	0.0255 (15)	0.0311 (16)	−0.0012 (12)	0.0037 (13)	−0.0016 (12)
C25	0.0274 (15)	0.0355 (17)	0.0232 (15)	0.0020 (13)	0.0041 (12)	0.0014 (12)
C26	0.0375 (18)	0.0309 (17)	0.0270 (16)	0.0058 (14)	0.0019 (13)	−0.0011 (13)
I2	0.03043 (11)	0.05304 (14)	0.02828 (11)	−0.00007 (9)	0.00907 (9)	0.00127 (9)
Br1	0.03893 (19)	0.03716 (18)	0.04325 (19)	0.00645 (14)	0.01122 (15)	−0.01071 (15)
O1	0.042 (3)	0.094 (6)	0.088 (5)	0.010 (3)	0.000 (3)	−0.058 (4)
O2	0.041 (4)	0.048 (5)	0.057 (5)	0.001 (3)	0.009 (4)	−0.017 (4)
Br2	0.0485 (2)	0.0437 (2)	0.03836 (19)	0.00101 (16)	0.02075 (16)	−0.00498 (15)

Geometric parameters (Å, º)

N11—C12	1.348 (4)	C22—C23	1.380 (5)
N11—C16	1.369 (4)	N22—H22A	0.83 (4)
N11—H11	0.86 (4)	N22—H22B	0.74 (4)
C12—N12	1.334 (4)	C23—C24	1.364 (4)
C12—C13	1.412 (4)	C23—H23	0.9500
N12—H12A	0.83 (4)	C24—C25	1.394 (4)
N12—H12B	0.84 (4)	C24—H24	0.9500
C13—C14	1.370 (4)	C25—C26	1.378 (5)
C13—H13	0.9500	C25—I2	2.096 (3)
C14—C15	1.412 (5)	C26—H26	0.9500
C14—H14	0.9500	O1—H1A	0.95 (10)
C15—C16	1.355 (4)	O1—H1B	0.85 (2)
C15—I1	2.102 (3)	O1—H2A	0.40 (15)
C16—H16	0.9500	O1—H2B	1.01 (11)
N21—C22	1.356 (5)	O2—H1B	1.18 (8)
N21—C26	1.384 (5)	O2—H2A	0.90 (2)
N21—H21	0.97 (4)	O2—H2B	0.90 (2)
C22—N22	1.333 (4)
C12—N11—C16	123.3 (3)	N21—C22—C23	117.4 (3)
C12—N11—H11	116 (2)	C22—N22—H22A	121 (3)
C16—N11—H11	121 (2)	C22—N22—H22B	117 (3)
N12—C12—N11	118.2 (3)	H22A—N22—H22B	122 (4)
N12—C12—C13	124.3 (3)	C24—C23—C22	122.1 (3)
N11—C12—C13	117.5 (3)	C24—C23—H23	119.0
C12—N12—H12A	121 (3)	C22—C23—H23	119.0
C12—N12—H12B	123 (3)	C23—C24—C25	119.8 (3)
H12A—N12—H12B	116 (4)	C23—C24—H24	120.1
C14—C13—C12	120.1 (3)	C25—C24—H24	120.1
C14—C13—H13	120.0	C26—C25—C24	118.7 (3)
C12—C13—H13	120.0	C26—C25—I2	120.7 (2)
C13—C14—C15	120.2 (3)	C24—C25—I2	120.6 (2)
C13—C14—H14	119.9	C25—C26—N21	119.5 (3)
C15—C14—H14	119.9	C25—C26—H26	120.2
C16—C15—C14	118.8 (3)	N21—C26—H26	120.2
C16—C15—I1	119.7 (2)	H1A—O1—H1B	97 (8)
C14—C15—I1	121.6 (2)	H1A—O1—H2A	123 (10)
C15—C16—N11	120.1 (3)	H1B—O1—H2A	27 (10)
C15—C16—H16	119.9	H1A—O1—H2B	54 (7)
N11—C16—H16	119.9	H1B—O1—H2B	101 (10)
C22—N21—C26	122.5 (3)	H2A—O1—H2B	108 (10)
C22—N21—H21	119 (2)	H1B—O2—H2A	25 (10)
C26—N21—H21	118 (2)	H1B—O2—H2B	86 (10)
N22—C22—N21	120.2 (3)	H2A—O2—H2B	83 (2)
N22—C22—C23	122.5 (3)
C16—N11—C12—N12	−179.8 (3)	C26—N21—C22—N22	178.0 (3)
C16—N11—C12—C13	0.8 (4)	C26—N21—C22—C23	−2.0 (5)
N12—C12—C13—C14	179.9 (3)	N22—C22—C23—C24	−179.0 (3)
N11—C12—C13—C14	−0.7 (4)	N21—C22—C23—C24	0.9 (5)
C12—C13—C14—C15	−0.2 (5)	C22—C23—C24—C25	0.7 (5)
C13—C14—C15—C16	1.1 (5)	C23—C24—C25—C26	−1.3 (5)
C13—C14—C15—I1	−178.5 (2)	C23—C24—C25—I2	180.0 (2)
C14—C15—C16—N11	−1.0 (5)	C24—C25—C26—N21	0.3 (5)
I1—C15—C16—N11	178.6 (2)	I2—C25—C26—N21	179.0 (2)
C12—N11—C16—C15	0.0 (5)	C22—N21—C26—C25	1.4 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N11—H11···Br2	0.86 (4)	2.42 (4)	3.259 (3)	165 (3)
N12—H12A···Br2	0.83 (4)	2.75 (4)	3.476 (4)	148 (4)
N12—H12B···Br1	0.84 (4)	2.64 (5)	3.429 (3)	157 (4)
N21—H21···Br1	0.97 (4)	2.67 (4)	3.524 (3)	147 (3)
N22—H22A···Br1	0.83 (4)	2.55 (4)	3.337 (4)	159 (4)
N22—H22B···O2	0.74 (4)	2.00 (4)	2.685 (9)	154 (4)
N22—H22B···O1	0.74 (4)	2.13 (4)	2.870 (8)	177 (5)
O1—H1A···Br2^i	0.95 (10)	2.26 (10)	3.147 (6)	156 (8)
O1—H1B···Br1^ii	0.85 (2)	2.53 (5)	3.289 (6)	150 (9)
O2—H2A···Br1^ii	0.90 (2)	2.92 (13)	3.430 (9)	117 (11)
O2—H2B···Br2^i	0.90 (2)	2.51 (2)	3.415 (9)	178 (11)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1/2, y−1/2, −z+1/2.

(2) 2-Amino-5-iodopyridinium chloride monohydrate hydrochloric acid 0.375-solvate

Crystal data

C5H6IN2^+·Cl^−·H2O·0.375HCl	F(000) = 558
Mr = 292.61	Dx = 2.045 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 8192 reflections
a = 4.177 (2) Å	θ = 2.3–26.4°
b = 12.972 (7) Å	µ = 3.67 mm^−1
c = 17.601 (10) Å	T = 163 K
β = 94.904 (11)°	Needle, colourless
V = 950.2 (9) Å^3	0.77 × 0.12 × 0.07 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1910 independent reflections
Radiation source: fine-focus sealed tube	1779 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
φ and ω scans	θmax = 26.4°, θmin = 2.3°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −2→5
Tmin = 0.795, Tmax = 1.000	k = −16→15
11816 measured reflections	l = −21→21

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.061	H atoms treated by a mixture of independent and constrained refinement
S = 1.15	w = 1/[σ^2(Fo^2) + (0.0305P)^2 + 1.5217P] where P = (Fo^2 + 2Fc^2)/3
1910 reflections	(Δ/σ)max = 0.002
127 parameters	Δρmax = 0.49 e Å^−3
7 restraints	Δρmin = −0.96 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
I1	−0.25640 (4)	0.356052 (15)	0.573263 (10)	0.02409 (9)
N11	−0.1165 (7)	0.37045 (19)	0.33345 (15)	0.0232 (5)
H11	−0.171 (9)	0.425 (3)	0.300 (2)	0.028*
N12	0.1423 (8)	0.2731 (2)	0.24582 (16)	0.0303 (6)
H12B	0.237 (10)	0.219 (3)	0.236 (2)	0.036*
H12A	0.089 (10)	0.319 (3)	0.208 (2)	0.036*
C12	0.0566 (7)	0.2863 (2)	0.31633 (17)	0.0223 (6)
C13	0.1402 (8)	0.2153 (2)	0.37638 (18)	0.0252 (6)
H13	0.2551	0.1560	0.3668	0.030*
C14	0.0525 (7)	0.2339 (2)	0.44790 (17)	0.0253 (6)
H14	0.1096	0.1873	0.4869	0.030*
C15	−0.1244 (7)	0.3232 (2)	0.46346 (16)	0.0212 (6)
C16	−0.2053 (7)	0.3899 (2)	0.40479 (18)	0.0237 (6)
H16	−0.3220	0.4491	0.4137	0.028*
O1	0.0530 (7)	0.4444 (2)	0.13376 (14)	0.0285 (5)	0.88
H1A	0.145 (9)	0.485 (3)	0.168 (2)	0.034*	0.88
H1B	−0.153 (5)	0.451 (3)	0.117 (2)	0.034*	0.88
H1C	0.231 (9)	0.448 (6)	0.112 (4)	0.034*	0.50
Cl2	−0.5000	0.5000	0.0000	0.0297 (5)	0.50
O2	−0.4787 (12)	0.4426 (4)	0.0556 (3)	0.0334 (10)	0.13
H2A	−0.44 (5)	0.507 (4)	0.055 (15)	0.040*	0.13
Cl3	−0.4787 (12)	0.4426 (4)	0.0556 (3)	0.0334 (10)	0.13
Cl1	−0.52590 (18)	0.55337 (6)	0.26034 (4)	0.02613 (17)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.02301 (13)	0.02732 (13)	0.02192 (13)	0.00207 (7)	0.00182 (8)	0.00093 (7)
N11	0.0288 (14)	0.0190 (12)	0.0210 (13)	0.0028 (10)	−0.0027 (10)	0.0048 (10)
N12	0.0464 (17)	0.0233 (14)	0.0209 (13)	0.0037 (12)	0.0021 (12)	−0.0020 (11)
C12	0.0230 (14)	0.0187 (14)	0.0245 (15)	−0.0019 (11)	−0.0027 (11)	−0.0021 (11)
C13	0.0308 (16)	0.0186 (14)	0.0260 (15)	0.0044 (12)	0.0009 (12)	0.0012 (11)
C14	0.0278 (15)	0.0227 (14)	0.0249 (15)	0.0023 (12)	−0.0013 (12)	0.0047 (12)
C15	0.0197 (14)	0.0228 (14)	0.0208 (14)	−0.0006 (11)	−0.0004 (11)	−0.0003 (11)
C16	0.0242 (15)	0.0195 (14)	0.0271 (15)	0.0016 (11)	0.0005 (12)	0.0002 (12)
O1	0.0367 (15)	0.0263 (13)	0.0208 (12)	−0.0001 (11)	−0.0074 (11)	−0.0004 (10)
Cl2	0.0290 (11)	0.0341 (11)	0.0254 (11)	−0.0087 (9)	−0.0016 (8)	−0.0036 (9)
O2	0.031 (2)	0.043 (3)	0.025 (2)	−0.002 (2)	−0.0077 (18)	0.003 (2)
Cl3	0.031 (2)	0.043 (3)	0.025 (2)	−0.002 (2)	−0.0077 (18)	0.003 (2)
Cl1	0.0288 (4)	0.0262 (4)	0.0228 (4)	0.0005 (3)	−0.0006 (3)	0.0037 (3)

Geometric parameters (Å, º)

I1—C15	2.098 (3)	C14—C15	1.413 (4)
N11—C12	1.357 (4)	C14—H14	0.9300
N11—C16	1.363 (4)	C15—C16	1.367 (4)
N11—H11	0.94 (4)	C16—H16	0.9300
N12—C12	1.332 (4)	O1—H1A	0.859 (18)
N12—H12B	0.84 (4)	O1—H1B	0.890 (18)
N12—H12A	0.91 (4)	O1—H1C	0.865 (19)
C12—C13	1.422 (4)	Cl2—H2A	1.0 (2)
C13—C14	1.362 (4)	O2—H2A	0.85 (2)
C13—H13	0.9300
C12—N11—C16	123.0 (3)	C13—C14—C15	120.7 (3)
C12—N11—H11	125 (2)	C13—C14—H14	119.7
C16—N11—H11	112 (2)	C15—C14—H14	119.7
C12—N12—H12B	119 (3)	C16—C15—C14	118.1 (3)
C12—N12—H12A	122 (3)	C16—C15—I1	120.0 (2)
H12B—N12—H12A	119 (4)	C14—C15—I1	121.9 (2)
N12—C12—N11	120.1 (3)	N11—C16—C15	120.7 (3)
N12—C12—C13	122.7 (3)	N11—C16—H16	119.7
N11—C12—C13	117.2 (3)	C15—C16—H16	119.7
C14—C13—C12	120.3 (3)	H1A—O1—H1B	123 (4)
C14—C13—H13	119.9	H1A—O1—H1C	85 (6)
C12—C13—H13	119.9	H1B—O1—H1C	134 (5)
C16—N11—C12—N12	−178.4 (3)	C13—C14—C15—C16	0.2 (4)
C16—N11—C12—C13	1.4 (4)	C13—C14—C15—I1	−178.8 (2)
N12—C12—C13—C14	178.5 (3)	C12—N11—C16—C15	−0.7 (5)
N11—C12—C13—C14	−1.3 (4)	C14—C15—C16—N11	−0.1 (4)
C12—C13—C14—C15	0.5 (5)	I1—C15—C16—N11	178.9 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N11—H11···Cl1	0.94 (4)	2.30 (4)	3.136 (3)	149 (3)
N12—H12A···Cl1^i	0.91 (4)	3.52 (4)	3.891 (4)	108 (3)
N12—H12A···O1	0.91 (4)	2.08 (5)	2.973 (4)	167 (4)
O1—H1B···Cl1	0.89 (2)	3.35 (4)	3.705 (3)	107 (3)
O1—H1C···O2^i	0.87 (2)	1.64 (3)	2.486 (6)	167 (8)
O1—H1C···Cl2^i	0.87 (2)	2.45 (4)	3.209 (3)	147 (6)
O1—H1B···O2	0.89 (2)	1.67 (2)	2.511 (5)	157 (4)
O1—H1B···Cl2	0.89 (2)	2.50 (3)	3.236 (3)	141 (4)
O2—H2A···O2^ii	0.85 (2)	2.1 (2)	2.454 (10)	108 (17)

Symmetry codes: (i) x+1, y, z; (ii) −x−1, −y+1, −z.