Graphene-like nets of hydrogen-bonded water mol­ecules in the dihydrate of 2-[(2-ammonio­eth­yl)amino]­acetate and the structure of its anhydrous hydro­iodide salt

2-[(2-Ammonio­eth­yl)amino]­acetate dihydrate, better known as N-(2-amino­eth­yl)glycine dihydrate, C₄H₁₀N₂O₂·2H₂O, (I), crystallizes as a three-dimensional hydrogen-bonded network. Amino acid mol­ecules form layers in the ac plane separated by layers of water mol­ecules, which form a hydrogen-bonded two-dimensional net composed of fused six-membered rings having boat conformations. The crystal structure of the corresponding hydro­iodide salt, namely 2-[(2-ammonio­eth­yl)ammonio]­acetate iodide, C₄H₁₁N₂O₂⁺·I^-, (II), has also been determined. The structure of (II) does not accommodate any solvent water mol­ecules, and displays stacks of amino acid mol­ecules parallel to the a axis, with iodide ions located in channels, resulting in an overall three-dimensional hydrogen-bonded network structure. N-(2-Amino­eth­yl)glycine is a mol­ecule of considerable bio­logical inter­est, since its polyamide derivative forms the backbone in the DNA mimic peptide nucleic acid (PNA).

S1. Comment

Slow addition of chloroacetic acid to a large excess of 1,2-diaminoethane at 273 K gives rise to an oily reaction product, from which 2-[(2-ammonioethyl)amino]acetate dihydrate, (I), can be isolated after trituration with dimethylsulfoxide and recrystallization from 96% ethanol. The amino acid of compound (I) is better known as N-(2-aminoethyl)glycine or N-(β-aminoethyl)glycine and has gained considerable interest over the last 20 years. A polypeptide built from N-(2-aminoethyl)glycine molecules forms the backbone in peptide nucleic acid (PNA), a synthetic nucleic acid analogue (Nielsen et al.1991). PNA forms DNA-like double helices and is able to hybridize with DNA (Egholm et al., 1993; Wittung et al., 1994). PNA is resistant to nucleases and proteases, the absence of the phosphate groups found in DNA and RNA renders PNA uncharged, and the absence of saccharide residues makes PNA achiral. It has even been argued that simple molecules such as PNA may have been the first genetic molecules, preceding RNA and DNA in the evolution of life (Nelson et al., 2000). In this paper we describe the crystal structures of (I) and its hydroiodide salt, 2-[(2-ammonioethyl)ammonio]acetate iodide, (II).

Crystallized under similar conditions, from water and ethanol in the case of (I) or water and propan-2-ol in the case of (II), (I) forms a dihydrate while (II) forms an anhydrous product. In the crystalline state, the conformations of the amino acid backbone in (I) and (II) are different. In (I), all non-H atoms lie approximately in one plane, except the terminal amino group which is bent out of this plane (Fig. 1); the N1—C3—C4—N2 torsion angle is -73.96 (11)°. In (II), atoms C2, N1, C3, C4 and N2 lie approximately in one plane (Fig. 2), and in this structure, it is the carboxylate group that is bent out of the plane; the C3—N1—C2—C1 torsion angle is 76.09 (21)°.

In the crystal structure of (I), the amino acid molecules form stacks parallel to the crystallographic a axis, and the molecules in these stacks are directly connected through H3N···N1(1 + x,y, z) interactions. Adjacent stacks intercalate, with both atoms H1N and H4N forming hydrogen bonds to O1(- x, 1 - y, 1 - z). These interactions connect two stacks into a double stack, since atoms H1N(-x, 1 - y, 1 - z) and H4N(-x, 1 - y, 1 - z) form hydrogen bonds to atom O1. These double stacks interact with adjacent double stacks through two sets of interactions, one set of classical N—H···O interactions and one set of C—H···O interactions; atom H2N forms a hydrogen bond with atom O2(1 + x, y, -1 + z) and atom H4A forms a hydrogen bond with atom O2(x, y, -1 + z). The H2N···O2(1 + x, y, -1 + z) interactions give rise to chains extending parallel to the [101] direction, while the H4A··· O2(x, y, -1 + z) interactions give rise to chains extending parallel to the c axis. As a result, the amino acid molecules form hydrogen-bonded layers in the ac plane (Fig. 3).

Compound (I) crystallizes with two molecules of water in the asymmetric unit. One of these, corresponding to atom O3, forms a hydrogen bond to the carboxylate group through an H2W···O2 hydrogen bond. The other water molecule, corresponding to atom O4, does not form a hydrogen bond to the amino acid molecules, but only to other water molecules in the crystal structure. In addition to the hydrogen bond to O2, the O3 water molecule forms hydrogen bonds to three different water molecules O4: atom H1W forms a hydrogen bond to atom O4, and atom O3 forms two hydrogen bonds to atoms H3W(-1 + x, y, z) and H4W(-1/2 + x, 3/2 - y, 1/2 + z). The O4 water molecule forms hydrogen bonds to three other water molecules. Apart from accepting a hydrogen bond from atom H1W, it acts as a donor for two additional hydrogen bonds: atom H3W forms a hydrogen bond to atom O3(1 + x, y, z) and atom H4W forms a hydrogen bond to atom O3(1/2 + x, 3/2 - y, -1/2 + z). The water molecules give rise to layers in the ac plane, built from fused six-membered rings in a honeycomb-like fashion, with each ring bent into a boat conformation (Fig. 4). Using the graph-set notation introduced by Etter (Etter, 1990; Etter et al., 1990), these rings may be described as R₆⁶(12). Atoms O3 and O4 form the nodes and atom O3 forms hydrogen bonds to the adjacent layers of amino acid molecules situated on both sides of the layer. Extended hydrogen-bonded water motifs have attracted attention (Mascal et al., 2006; Infantes et al., 2003). There are similar motifs in DL-2-amino-2-thiazoline-4-carboxylic acid trihydrate (Xuan et al., 2003) and in 6-methyl-2-pyridone pentahydrate, in which two similar layers are separated by layers of pyridone molecules (Clegg & Nichol, 2004).

The amino acid molecules in (II) form stacks parallel to the crystallographic a axis (Fig. 5), the molecules in these stacks being directly connected through one set of hydrogen bonds viz. H1N···O1(1 + x, y, z). The molecules in the stacks are further linked through iodide ions. Atom H3N forms a hydrogen bond to atom I1, and I1 forms a hydrogen bond to atom H5N(-1 + x, y, z) in the next molecule in the stack. As a result, the iodide anions also form stacks parallel to the a axis and are aligned in channels (Fig. 6). The stacks in (II) form hydrogen bonds to three adjacent stacks through two sets of hydrogen bonds. Atom H4N forms a hydrogen bond to atom O1(1/2 + x. 1/2 - y, -1/2 + z), and atom O1 forms a hydrogen bond to atom H4N(-1/2 + x,1/2 - y, 1/2 + z), which generates connections to two different stacks. Atom H2N forms a hydrogen bond to atom O2(1 - x, -y, 2 - z), but since atom H2N(1 - x, -y, 2 - z) forms a hydrogen bond to atom O2, this set of interactions only connects two adjacent stacks.

The structures of (I) and (II) can be compared with the structure of N-(2-ammonioethyl)carbamate, which differs from (I) and (II) by only one methylene group. Three different polymorphs, (III)–(V), of anhydrous N-(2-ammonioethyl)carbamate have been described. Polymorph (III) crystallizes in space group Pna2₁ (Garbauskas et al., 1983) and its molecular conformation resembles that of (II). Polymorphs (IV) (Garbauskas et al., 1983) and (V) (Antsyshkina et al., 2007) were refined in space groups P2₁/a and P2₁/c, respectively, and have molecular conformations resembling the conformation of (I). Polymorph (III) forms a hydrogen-bonded network structure, quite dissimilar from either (I) or (II). In polymorph (IV), the molecules form layers, where all hydrogen bonds occur within the layers. The two surfaces of the layers are dominated by the hydrophobic methylene groups, and the layers appear to be largely held together by dispersion forces. Polymorph (V) forms another hydrogen-bonded network structure. It may expected that a more detailed study of (I) and (II) would reveal similar cases of polymorphism, or phases displaying different cocrystallized solvents.

Do you wish to discuss the graphene-like nets of the title?

Related literature

For related literature, see: Antsyshkina et al. (2007); Clegg & Nichol (2004); Egholm et al. (1993); Etter (1990); Etter, MacDonald & Bernstein (1990); Garbauskas et al. (1983); Heimer et al. (1984); Infantes et al. (2003); Mascal et al. (2006); Nelson et al. (2000); Nielsen et al. (1991); Wittung et al. (1994); Xuan et al. (2003).

S2. Experimental

2-[(2-Ammonioethyl)amino]acetate dihydrate, (I), was prepared by published procedures (Heimer et al., 1984) with modifications. Chloroacetic acid (28 g, 0.3 mol) was added to stirred 1,2-diamioethane (200 ml, 3 mol) in small portions at 273 K. The mixture was stirred at ambient temperature overnight, and the excess 1,2-diaminoethane was removed on a rotary evaporator at 333 K. The oily residue was dissolved in a small amount of dimethylsulfoxide and triturated with acetonitrile. This procedure was repeated until the thick residue was insoluble in dimethylsulfoxide. Trituration was continued with small portions of dimethylsulfoxide until the residue solidified. The crystals were washed with dimethylsulfoxide and diethyl ether (yield 29 g, 63%). The raw product was recrystallized from hot ethanol, washed with ethanol and allowed to dry in air (yield 15.2 g, 33%). Large crystals of (I) suitable for X-ray diffraction grew slowly overnight from a nearly saturated solution in hot ca 70% aqueous ethanol.

2-[(2-Ammonioethyl)ammonio]acetate iodide, (II), was obtained in an attempt to methylate (I). 2-[(2-Ammonioethyl)amino]acetate dihydrate (0.15 g, 1 mmol) was dissolved in boiling ethanol (10 ml). Iodomethane (0.2 ml, 3 mmol) was added, and the reaction mixture was allowed to stand at ambient temperature overnight. The ethanol was evaporated, and the product was dissolved in water (0.5 ml) and layered with propan-2-ol (1.5 ml). Crystals of (II) were isolated after approximately one week.

S3. Refinement

All atoms were refined without restraints.

Computing details

For both compounds, data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLUTON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Dashed lines indicate hydrogen bonds.
	Fig. 2. The molecular structure of (II), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. The dashed line indicates the hydrogen bond.
	Fig. 3. Compound (I) forms a layered structure. Three layers of amino acid molecules separated by two layers of H2O molecules are shown running vertically. Dashed lines indicate hydrogen bonds. H atoms not involved in intermolecular interactions have been omitted for clarity.
	Fig. 4. The water molecules in the crystal structure of (I) give rise to a hydrogen-bonded two-dimensional graphene-like net. (Symmetry codes as in Table 1?)
	Fig. 5. The hydrogen-bonded chain in the structure of (II), running parallel to the crystallographic a axis. Dashed lines indicate hydrogen bonds. H atoms not involved in intermolecular interactions have been omitted for clarity.
	Fig. 6. The crystal structure of (II), viewed along the a axis. Both amino acid molecules and iodide anions are stacked along the a axis. Dashed lines indicate hydrogen bonds. H atoms not involved in intermolecular interactions have been omitted for clarity.

(I) 2-[(2-ammonioethyl)amino]acetate dihydrate

Crystal data

C4H10N2O2·2H2O	F(000) = 336
Mr = 154.17	Dx = 1.319 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 4911 reflections
a = 4.7106 (4) Å	θ = 3.0–28.3°
b = 22.8634 (19) Å	µ = 0.12 mm^−1
c = 7.2804 (6) Å	T = 120 K
β = 98.154 (3)°	Needle, colourless
V = 776.17 (11) Å^3	0.22 × 0.22 × 0.18 mm
Z = 4

Data collection

Bruker X8 APEXII CCD area-detector diffractometer	1521 independent reflections
Radiation source: fine-focus sealed tube	1246 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
thin–slice ω and ϕ scans	θmax = 26.0°, θmin = 3.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −5→5
Tmin = 0.877, Tmax = 0.982	k = −28→27
13219 measured reflections	l = −8→8

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0648P)^2 + 0.0169P] where P = (Fo^2 + 2Fc^2)/3
1521 reflections	(Δ/σ)max < 0.001
123 parameters	Δρmax = 0.23 e Å^−3
0 restraints	Δρmin = −0.22 e Å^−3

Special details

Experimental. SADABS v.2.10 (Sheldrick, 2003) Ratio of minimum to maximum apparent transmission: 0.897049

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
C1	−0.1610 (2)	0.57171 (5)	0.74596 (14)	0.0125 (3)
C2	0.0526 (2)	0.60999 (5)	0.66356 (15)	0.0139 (3)
H2A	−0.0202	0.6507	0.6549	0.017*
H2B	0.2365	0.6100	0.7484	0.017*
C3	0.3015 (2)	0.63178 (5)	0.40600 (15)	0.0134 (3)
H3A	0.4794	0.6351	0.4959	0.016*
H3B	0.2111	0.6709	0.3932	0.016*
C4	0.3791 (2)	0.61330 (5)	0.22016 (15)	0.0152 (3)
H4A	0.2018	0.6023	0.1375	0.018*
H4B	0.4658	0.6470	0.1631	0.018*
N1	0.10538 (19)	0.59101 (4)	0.48008 (12)	0.0119 (2)
N2	0.5835 (2)	0.56308 (4)	0.23365 (14)	0.0136 (2)
O1	−0.25969 (18)	0.52766 (4)	0.65803 (11)	0.0212 (2)
O2	−0.22566 (16)	0.58825 (3)	0.90082 (10)	0.0170 (2)
O3	−0.19371 (18)	0.70606 (4)	0.97998 (12)	0.0195 (2)
O4	0.2679 (2)	0.75396 (4)	0.84425 (14)	0.0235 (2)
H1N	0.496 (3)	0.5284 (7)	0.264 (2)	0.032 (4)*
H1W	−0.054 (4)	0.7204 (7)	0.931 (2)	0.036 (4)*
H2N	0.646 (3)	0.5595 (6)	0.120 (2)	0.025 (4)*
H2W	−0.191 (3)	0.6686 (9)	0.955 (2)	0.044 (5)*
H3N	0.752 (3)	0.5712 (7)	0.320 (2)	0.030 (4)*
H3W	0.437 (4)	0.7387 (7)	0.883 (2)	0.043 (5)*
H4N	0.177 (3)	0.5557 (6)	0.4911 (17)	0.017 (3)*
H4W	0.279 (4)	0.7653 (8)	0.727 (3)	0.055 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0120 (5)	0.0133 (6)	0.0122 (6)	0.0024 (4)	0.0017 (4)	0.0016 (4)
C2	0.0133 (5)	0.0172 (6)	0.0119 (5)	−0.0015 (5)	0.0038 (4)	−0.0022 (4)
C3	0.0125 (5)	0.0124 (6)	0.0161 (6)	−0.0013 (4)	0.0050 (4)	0.0013 (4)
C4	0.0141 (5)	0.0176 (6)	0.0146 (6)	−0.0001 (4)	0.0041 (4)	0.0036 (5)
N1	0.0135 (5)	0.0114 (5)	0.0118 (5)	−0.0003 (4)	0.0053 (4)	0.0003 (4)
N2	0.0149 (5)	0.0156 (5)	0.0113 (5)	−0.0022 (4)	0.0053 (4)	−0.0005 (4)
O1	0.0287 (5)	0.0170 (5)	0.0207 (4)	−0.0085 (4)	0.0125 (4)	−0.0049 (3)
O2	0.0195 (4)	0.0206 (5)	0.0123 (4)	−0.0022 (3)	0.0070 (3)	−0.0009 (3)
O3	0.0199 (5)	0.0181 (5)	0.0221 (5)	−0.0015 (4)	0.0089 (4)	−0.0013 (4)
O4	0.0187 (5)	0.0261 (5)	0.0267 (5)	−0.0004 (4)	0.0066 (4)	0.0055 (4)

Geometric parameters (Å, º)

C1—O1	1.2474 (14)	C4—H4A	0.9900
C1—O2	1.2667 (13)	C4—H4B	0.9900
C1—C2	1.5195 (16)	N1—H4N	0.875 (14)
C2—N1	1.4590 (14)	N2—H1N	0.934 (17)
C2—H2A	0.9900	N2—H2N	0.924 (16)
C2—H2B	0.9900	N2—H3N	0.958 (15)
C3—N1	1.4679 (14)	O3—H1W	0.856 (19)
C3—C4	1.5109 (15)	O3—H2W	0.87 (2)
C3—H3A	0.9900	O4—H3W	0.878 (19)
C3—H3B	0.9900	O4—H4W	0.90 (2)
C4—N2	1.4927 (15)
O1—C1—O2	125.35 (10)	N2—C4—H4A	109.0
O1—C1—C2	118.81 (9)	C3—C4—H4A	109.0
O2—C1—C2	115.84 (9)	N2—C4—H4B	109.0
N1—C2—C1	113.49 (9)	C3—C4—H4B	109.0
N1—C2—H2A	108.9	H4A—C4—H4B	107.8
C1—C2—H2A	108.9	C2—N1—C3	110.22 (9)
N1—C2—H2B	108.9	C2—N1—H4N	107.8 (8)
C1—C2—H2B	108.9	C3—N1—H4N	111.3 (9)
H2A—C2—H2B	107.7	C4—N2—H1N	111.5 (9)
N1—C3—C4	113.34 (9)	C4—N2—H2N	107.2 (9)
N1—C3—H3A	108.9	H1N—N2—H2N	110.1 (13)
C4—C3—H3A	108.9	C4—N2—H3N	111.2 (9)
N1—C3—H3B	108.9	H1N—N2—H3N	111.3 (12)
C4—C3—H3B	108.9	H2N—N2—H3N	105.2 (12)
H3A—C3—H3B	107.7	H1W—O3—H2W	104.7 (15)
N2—C4—C3	113.07 (9)	H3W—O4—H4W	104.1 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1N···O1^i	0.929 (17)	1.843 (17)	2.7557 (13)	166.7 (13)
O3—H1W···O4	0.852 (19)	1.893 (19)	2.7413 (13)	174.2 (15)
N2—H2N···O2^ii	0.932 (15)	1.891 (16)	2.7614 (13)	154.5 (13)
O3—H2W···O2	0.88 (2)	1.88 (2)	2.7541 (13)	173.9 (15)
N2—H3N···N1^iii	0.958 (15)	1.946 (15)	2.9018 (13)	176.0 (12)
O4—H3W···O3^iii	0.884 (19)	1.927 (19)	2.8102 (13)	177.3 (15)
N1—H4N···O1^i	0.875 (14)	2.256 (14)	3.0179 (13)	145.4 (11)
O4—H4W···O3^iv	0.91 (2)	1.93 (2)	2.8345 (14)	177.1 (17)

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x+1, y, z−1; (iii) x+1, y, z; (iv) x+1/2, −y+3/2, z−1/2.

(II) 2-[(2-ammonioethyl)ammonio]acetate iodide

Crystal data

C4H11N2O2^+·I^−	F(000) = 472
Mr = 246.05	Dx = 1.997 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 5038 reflections
a = 5.7129 (3) Å	θ = 3.6–30.1°
b = 12.4269 (7) Å	µ = 3.86 mm^−1
c = 11.6560 (7) Å	T = 120 K
β = 98.542 (2)°	Block, colourless
V = 818.32 (8) Å^3	0.22 × 0.12 × 0.12 mm
Z = 4

Data collection

Bruker X8 APEXII CCD area-detector diffractometer	1591 independent reflections
Radiation source: fine-focus sealed tube	1493 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
thin–slice ω and ϕ scans	θmax = 26.0°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −7→6
Tmin = 0.350, Tmax = 0.655	k = −15→15
14193 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)] = 0.014	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.032	H atoms treated by a mixture of independent and constrained refinement
S = 0.90	w = 1/[σ^2(Fo^2) + (0.0128P)^2 + 1.5266P] where P = (Fo^2 + 2Fc^2)/3
1591 reflections	(Δ/σ)max = 0.002
102 parameters	Δρmax = 0.68 e Å^−3
0 restraints	Δρmin = −0.64 e Å^−3

Special details

Experimental. SADABS v.2.10 (Sheldrick, 2003) Ratio of minimum to maximum apparent transmission: 0.723380

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
C1	0.3355 (3)	0.16147 (15)	1.03772 (16)	0.0112 (4)
C2	0.5843 (3)	0.20867 (15)	1.04726 (17)	0.0123 (4)
H2A	0.5743	0.2831	1.0166	0.015*
H2B	0.6554	0.2119	1.1300	0.015*
C3	0.6911 (4)	0.15985 (17)	0.85388 (16)	0.0154 (4)
H3A	0.7215	0.2358	0.8349	0.018*
H3B	0.5230	0.1435	0.8251	0.018*
C4	0.8498 (4)	0.08618 (17)	0.79562 (17)	0.0177 (4)
H4A	1.0153	0.1121	0.8118	0.021*
H4B	0.8443	0.0125	0.8274	0.021*
N1	0.7396 (3)	0.14378 (14)	0.98227 (14)	0.0112 (3)
N2	0.7709 (3)	0.08411 (16)	0.66867 (15)	0.0149 (4)
O1	0.1901 (2)	0.21319 (11)	1.08802 (12)	0.0155 (3)
O2	0.2912 (2)	0.07665 (11)	0.98216 (12)	0.0150 (3)
I1	0.27331 (2)	−0.079540 (11)	0.649287 (11)	0.01745 (6)
H1N	0.885 (4)	0.1609 (19)	1.010 (2)	0.016 (6)*
H2N	0.718 (4)	0.077 (2)	1.002 (2)	0.016 (6)*
H3N	0.634 (5)	0.049 (2)	0.652 (2)	0.023 (6)*
H4N	0.745 (4)	0.149 (2)	0.637 (2)	0.027 (7)*
H5N	0.872 (5)	0.049 (2)	0.633 (2)	0.026 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0116 (10)	0.0120 (10)	0.0096 (9)	0.0007 (7)	0.0001 (8)	0.0043 (7)
C2	0.0116 (9)	0.0122 (9)	0.0130 (10)	0.0006 (7)	0.0015 (8)	−0.0014 (7)
C3	0.0169 (11)	0.0178 (10)	0.0117 (10)	0.0034 (8)	0.0029 (8)	0.0041 (8)
C4	0.0176 (11)	0.0230 (11)	0.0125 (10)	0.0053 (9)	0.0022 (8)	0.0017 (8)
N1	0.0091 (9)	0.0118 (9)	0.0128 (8)	0.0003 (7)	0.0020 (7)	0.0009 (7)
N2	0.0151 (9)	0.0170 (10)	0.0130 (9)	−0.0007 (8)	0.0037 (7)	0.0019 (7)
O1	0.0123 (7)	0.0173 (7)	0.0179 (7)	−0.0002 (6)	0.0052 (6)	−0.0027 (6)
O2	0.0133 (7)	0.0129 (7)	0.0183 (7)	0.0008 (5)	0.0006 (6)	−0.0008 (6)
I1	0.01626 (8)	0.02046 (8)	0.01548 (8)	−0.00298 (5)	0.00184 (5)	−0.00184 (5)

Geometric parameters (Å, º)

C1—O2	1.243 (2)	C3—H3B	0.9900
C1—O1	1.261 (2)	C4—N2	1.482 (3)
C1—C2	1.527 (3)	C4—H4A	0.9900
C2—N1	1.487 (3)	C4—H4B	0.9900
C2—H2A	0.9900	N1—H1N	0.87 (3)
C2—H2B	0.9900	N1—H2N	0.87 (3)
C3—N1	1.494 (2)	N2—H3N	0.89 (3)
C3—C4	1.518 (3)	N2—H4N	0.89 (3)
C3—H3A	0.9900	N2—H5N	0.87 (3)
O2—C1—O1	125.25 (18)	C3—C4—H4A	109.6
O2—C1—C2	118.60 (17)	N2—C4—H4B	109.6
O1—C1—C2	116.15 (17)	C3—C4—H4B	109.6
N1—C2—C1	111.97 (16)	H4A—C4—H4B	108.2
N1—C2—H2A	109.2	C2—N1—C3	113.69 (15)
C1—C2—H2A	109.2	C2—N1—H1N	106.7 (15)
N1—C2—H2B	109.2	C3—N1—H1N	111.2 (15)
C1—C2—H2B	109.2	C2—N1—H2N	105.5 (16)
H2A—C2—H2B	107.9	C3—N1—H2N	111.9 (16)
N1—C3—C4	109.46 (16)	H1N—N1—H2N	107 (2)
N1—C3—H3A	109.8	C4—N2—H3N	110.4 (16)
C4—C3—H3A	109.8	C4—N2—H4N	113.9 (17)
N1—C3—H3B	109.8	H3N—N2—H4N	105 (2)
C4—C3—H3B	109.8	C4—N2—H5N	110.9 (17)
H3A—C3—H3B	108.2	H3N—N2—H5N	106 (2)
N2—C4—C3	110.12 (17)	H4N—N2—H5N	110 (2)
N2—C4—H4A	109.6

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O1^i	0.87 (3)	1.95 (3)	2.819 (2)	171 (2)
N1—H1N···O2^i	0.87 (3)	2.61 (2)	3.260 (2)	132.3 (19)
N1—H2N···O2^ii	0.87 (3)	1.93 (3)	2.780 (2)	168 (2)
N2—H3N···I1	0.89 (3)	2.60 (3)	3.4753 (19)	166 (2)
N2—H4N···O1^iii	0.89 (3)	1.82 (3)	2.704 (2)	174 (2)
N2—H5N···I1^i	0.87 (3)	2.78 (3)	3.552 (2)	148 (2)

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