Morpholine-4-carboxamidinium ethyl carbonate

Ioannis Tiritiris

doi:10.1107/S1600536812046922

. 2012 Nov 24;68(Pt 12):o3431. doi: 10.1107/S1600536812046922

Morpholine-4-carboxamidinium ethyl carbonate

Ioannis Tiritiris ^a,^*

PMCID: PMC3589013 PMID: 23476249

Abstract

The asymmetric unit of the title salt, C₅H₁₂N₃O⁺·C₃H₅O₃ ⁻, contains two carboxamidinium and two ethyl carbonate ions. In the crystal, the C—N bond lengths in the central CN₃ units of the cations range between 1.324 (2) and 1.352 (2) Å, indicating partial double-bond character. The central C atoms are bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charges are delocalized in the CN₃ planes. The morpholine rings are in chair conformations. The C—O bond lengths in both ethyl carbonate ions are characteristic for delocalized double bonds [1.243 (2)–1.251 (2) Å] and typical single bonds [1.368 (2) and 1.375 (2) Å]. In the crystal, N—H⋯O hydrogen bonds between cations and anions generate a two-dimensional network in the ac plane.

Related literature

For the synthesis and crystal structures of guanidinium hydrogen carbonates, see: Tiritiris et al. (2011 ▶). For the crystal structure of 4-morpholinecarboxamidine, see: Tiritiris (2012a ▶). For the crystal structure of piperidine-1-carboxamidinium ethyl carbonate, see: Tiritiris (2012b ▶). graphic file with name e-68-o3431-scheme1.jpg

Experimental

Crystal data

C₅H₁₂N₃O⁺·C₃H₅O₃ ⁻
M _r = 219.25
Monoclinic,
a = 10.2163 (5) Å
b = 20.8874 (9) Å
c = 10.4616 (5) Å
β = 109.505 (2)°
V = 2104.31 (17) Å³
Z = 8
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 100 K
0.30 × 0.25 × 0.15 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
9902 measured reflections
5199 independent reflections
2981 reflections with I > 2σ(I)
R _int = 0.055

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.112
S = 1.00
5199 reflections
305 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: COLLECT (Hooft, 2004 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Click here for additional data file.^{(22.6KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812046922/kp2441sup1.cif

e-68-o3431-sup1.cif^{(22.6KB, cif)}

Click here for additional data file.^{(254.6KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812046922/kp2441Isup2.hkl

e-68-o3431-Isup2.hkl^{(254.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H11⋯O4ⁱ	0.84 (2)	2.12 (2)	2.944 (1)	168 (1)
N1—H12⋯O3ⁱⁱ	0.89 (2)	1.91 (2)	2.795 (1)	174 (1)
N2—H21⋯O6	0.85 (2)	1.97 (2)	2.807 (1)	168 (1)
N2—H22⋯O4ⁱⁱ	0.92 (2)	1.95 (2)	2.851 (1)	164 (1)
N4—H41⋯O6ⁱⁱ	0.86 (2)	1.97 (2)	2.817 (1)	167 (1)
N4—H42⋯O7ⁱ	0.93 (2)	2.00 (2)	2.889 (1)	159 (1)
N5—H51⋯O7ⁱⁱ	0.90 (2)	1.99 (2)	2.879 (1)	172 (1)
N5—H52⋯O3ⁱⁱⁱ	0.90 (2)	1.94 (2)	2.776 (1)	154 (1)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The author thanks Dr F. Lissner (Institut für Anorganische Chemie, Universität Stuttgart) for the data collection.

supplementary crystallographic information

Comment

The reaction of several guanidines with CO₂ in undried aprotic solvents are well described in the literature (Tiritiris et al., 2011). Here, the corresponding guanidinium hydrogen carbonate salts were obtained and their crystal structures could be determined. By reacting carboxamidines with CO₂ we first used aprotic solvents and due to their water content, sparingly soluble and non crystalline hydrogen carbonate salts were also formed. By using alcohols as solvents for the reaction, we obtained a few crystalline alkyl carbonate salts. One of them is the here presented title compound. According to the structure analysis, the asymmetric unit contains two carboxamidinium and two ethyl carbonate ions. The C–N bonds of the CN₃ units are ranging from 1.324 (2) to 1.352 (2) Å, showing partial double-bond character. The N–C1–N and N–C6–N angles are indicating a nearly ideal trigonal-planar surrounding of the carbon centres by the nitrogen atoms. The positive charges are completely delocalized on the CN₃ planes (Fig. 1). The structural parameters of the morpholine rings in the here presented title compound agree very well with the data obtained from the X-ray analysis of the starting compound 4-morpholinecarboxamidine (Tiritiris, 2012a). The morpholine rings adopt a chair conformation. The C–O bond lengths in both ethyl carbonate ions indicate evenly distributed double bonds [1.243 (2)–1.251 (2) Å] and typical single bonds [1.368 (2) and 1.375 (2) Å]. The data fit with the C–O bond lengths and angles of the anion in piperidine-1-carboxamidinium ethyl carbonate (Tiritiris, 2012b). In the crystal structure, strong N—H···O hydrogen bonds between hydrogen atoms of carboxamidinium ions and oxygen atoms of neighboring ethyl carbonate ions are observed, generating an infinite two-dimensional network [d(H···O) = 1.91 (2)–2.12 (2) Å] (Tab. 1) with base vectors [0 0 1] and [1 0 0] (Fig. 2). In contrast to the crystal structure of 4-morpholinecarboxamidine (Tiritiris, 2012a), the oxygen atoms of the morpholine rings are not involved in the N—H···O hydrogen bonding system.

Experimental

The title compound was prepared by bubbling excess CO₂ gas into an ethanolic solution of 2.0 g (15.5 mmol) 4-morpholinecarboxamidine (Tiritiris, 2012a). The resulting colorless precipitate was recrystallized from a small amount of ethanol and single crystals suitable for X-ray analysis were obtained. Yield: 3.05 g (90%). ¹H NMR (500 MHz, D₂O/DSS): δ = 1.17–1.20 [t, 3 H, –CH₃], 3.49–3.52 [m, 4 H, –CH₂], 3.64–3.68 [q, 2 H, –CH₂], 3.80–3.83 [m, 4 H, –CH₂]. Because of the H/D exchange, the hydrogen atoms of the –NH₂ groups were not observed. ¹³C NMR (125 MHz, D₂O/DSS): δ = 16.8 (–CH₃), 45.2 (–CH₂), 57.4 (–CH₂), 65.4 (–CH₂), 156.6 (N₃C⁺), 160.3 (C═O).