Piperidine-1-carboxamidinium ethyl carbonate

Ioannis Tiritiris

doi:10.1107/S1600536812045497

. 2012 Nov 10;68(Pt 12):o3310. doi: 10.1107/S1600536812045497

Piperidine-1-carboxamidinium ethyl carbonate

Ioannis Tiritiris ^a,^*

PMCID: PMC3588849 PMID: 23468814

Abstract

In the title salt, C₆H₁₄N₃ ⁺·C₃H₅O₃ ⁻, the C—N bond lengths in the central CN₃ unit of the carboxamidinium cation are 1.3262 (18), 1.3359 (18) and 1.3498 (18) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN₃ plane. The piperidine ring is in a chair conformation. The C—O bond lengths in the ethyl carbonate anion are characteristic for a delocalized double bond and a typical single bond. In the crystal, N—H⋯O hydrogen bonds between cations and anions generate a two-dimensional network in the direction of the ab plane, whereas adjacent ion pairs form chains running along the b axis.

Related literature

For the synthesis and crystal structures of guanidinium hydrogencarbonates, see: Tiritiris et al. (2011 ▶). For the crystal structure of piperidine-1-carboximidamide, see: Tiritiris (2012 ▶), and for the crystal structure of sodium methyl carbonate, see: Kunert et al. (1998 ▶). graphic file with name e-68-o3310-scheme1.jpg

Experimental

Crystal data

C₆H₁₄N₃ ⁺·C₃H₅O₃ ⁻
M _r = 217.27
Monoclinic,
a = 11.8320 (6) Å
b = 7.2407 (4) Å
c = 13.3755 (9) Å
β = 105.292 (3)°
V = 1105.33 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.25 × 0.20 × 0.05 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
4452 measured reflections
2638 independent reflections
1982 reflections with I > 2σ(I)
R _int = 0.047

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.106
S = 1.02
2638 reflections
153 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.23 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.^{(16.4KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812045497/kp2439sup1.cif

e-68-o3310-sup1.cif^{(16.4KB, cif)}

Click here for additional data file.^{(129.6KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812045497/kp2439Isup2.hkl

e-68-o3310-Isup2.hkl^{(129.6KB, 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⋯O2ⁱ	0.88 (2)	1.99 (2)	2.812 (1)	155 (1)
N1—H12⋯O2ⁱⁱ	0.88 (2)	1.88 (2)	2.747 (1)	173 (1)
N2—H21⋯O1ⁱⁱ	0.84 (2)	2.19 (2)	3.033 (1)	175 (1)
N2—H22⋯O1ⁱⁱⁱ	0.87 (2)	2.06 (2)	2.923 (1)	170 (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 measuring the crystal data.

supplementary crystallographic information

Comment

By reacting guanidines with CO₂ in undried aprotic solvents, the corresponding guanidinium hydrogen carbonate salts are formed exclusively (Tiritiris et al., 2011). To investigate the reaction of carboxamidines with CO₂, we used both aprotic and protic solvents. Due to the water content in the common aprotic solvents, the hydrogen carbonate salts were formed too. Most of them are sparingly soluble and could therefore not be obtained in crystalline form. By using ethanol as a solvent for the reaction, the crystalline title compound emerged. According to the structure analysis, the C1–N1 bond in the title compound is 1.3262 (18) Å, C1–N2 = 1.3359 (18) Å and C1–N3 = 1.3498 (18) Å, showing partial double-bond character (Fig. 1). The N–C1–N angles are: 117.59 (13)° (N1–C1–N2), 121.04 (12)° (N1–C1–N3) and 121.36 (12)° (N2–C1–N3), which indicate a nearly ideal trigonal-planar surrounding of the carbon centre by the nitrogen atoms. The positive charge is completely delocalized on the CN₃ plane. The structural parameters of the piperidine ring in the here presented title compound agree very well with the data obtained from the X-ray analysis of the starting compound piperidine-1-carboximidamide (Tiritiris, 2012). The piperidine ring adopt a chair conformation. In the ethyl carbonate ion the C7–O1 and C7–O2 bond lengths indicate an evenly distributed double bond character (C7–O1, 1.2485 (16) Å; C7–O2, 1.2509 (17) Å) and a typical single bond (C7–O3, 1.3706 (18) Å). The data fit with the C–O bond lengths of the anion in sodium methyl carbonate (Kunert et al., 1998). 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) = 1.88 (2)–2.19 (2) Å] (Tab. 1) with base vectors [1 0 - 1] and [0 1 0] (Fig. 2). Furthermore, the hydrogen bonds are arranged in a way, that adjacent ion pairs are forming chains running along the b axis (Fig. 3).

Experimental

The title compound was prepared by bubbling excess CO₂ gas into an ethanolic solution of 2.04 g (16 mmol) piperidine-1-carboximidamide (Tiritiris, 2012). The resulting colourless precipitate was recrystallized from a small amount of ethanol and single crystals suitable for X-ray analysis were obtained. Yield: 3.25 g (93.3%). ¹H NMR (500 MHz, D₂O/DSS): δ = 1.17–1.20 [t, 3 H, –CH₃], 1.61–1.70 [m, 6 H, –CH₂], 3.40–3.43 [m, 4 H, –CH₂], 3.64–3.68 [q, 2 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), 23.1 (–CH₂), 24.7 (–CH₂), 46.7 (–CH₂), 57.4 (–CH₂), 155.5 (N₃C⁺), 160.3 (C═O).