N,N,N′,N′,N′′-Penta­methyl-N′′-[3-(tri­methyl­aza­nium­yl)prop­yl]guanidinium bis­(tetra­phenyl­borate)

Ioannis Tiritiris

doi:10.1107/S1600536813001992

. 2013 Jan 26;69(Pt 2):o292. doi: 10.1107/S1600536813001992

N,N,N′,N′,N′′-Pentamethyl-N′′-[3-(trimethylazaniumyl)propyl]guanidinium bis(tetraphenylborate)

Ioannis Tiritiris ^a,^*

PMCID: PMC3569815 PMID: 23424561

Abstract

In the crystal structure of the title salt, C₁₂H₃₀N₄ ²⁺·2C₂₄H₂₀B⁻, the C—N bond lengths in the central CN₃ unit of the guanidinium ion are 1.3388 (17), 1.3390 (16) and 1.3540 (17) Å, indicating partial double-bond character in each. 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 bonds between the N atoms and the terminal C-methyl groups of the guanidinium moiety, all have values close to a typical single bond [1.4630 (16)–1.4697 (17) Å]. C—H⋯π interactions are present between the guanidinium H atoms and the phenyl C atoms of one tetraphenylborate ion. The phenyl rings form a kind of aromatic pocket, in which the guanidinium ion is embedded.

Related literature

For the synthesis of N′′-[3-(dimethylamino)propyl]- N,N,N′,N′-tetramethylguanidine, see: Tiritiris & Kantlehner (2012 ▶). For the crystal structures of alkali metal tetraphenylborates, see: Behrens et al. (2012 ▶). graphic file with name e-69-0o292-scheme1.jpg

Experimental

Crystal data

C₁₂H₃₀N₄ ⁺·2C₂₄H₂₀B⁻
M _r = 868.82
Monoclinic,
a = 17.7622 (4) Å
b = 16.1667 (3) Å
c = 17.3787 (4) Å
β = 98.045 (1)°
V = 4941.29 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 100 K
0.27 × 0.25 × 0.20 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
22713 measured reflections
12056 independent reflections
8821 reflections with I > 2σ(I)
R _int = 0.038

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.108
S = 1.02
12056 reflections
603 parameters
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.27 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.^{(53.6KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813001992/zl2530sup1.cif

e-69-0o292-sup1.cif^{(53.6KB, cif)}

Click here for additional data file.^{(589.5KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813001992/zl2530Isup2.hkl

e-69-0o292-Isup2.hkl^{(589.5KB, hkl)}

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

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

Cg1, Cg4, Cg5, Cg6, and Cg8 are the centroids of the C13–C18,C31–C36, C37–C42, C43–C48 and C55–C60 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3C⋯Cg7	0.98	2.62	3.3783 (16)	134
C7—H7B⋯Cg1	0.99	2.80	3.7805 (14)	169
C9—H9B⋯Cg6	0.99	2.52	3.4075 (14)	149
C11—H11C⋯Cg5ⁱ	0.98	2.62	3.4852 (15)	147
C12—H12A⋯Cg4	0.98	2.59	3.4044 (15)	141
C12—H12B⋯Cg8ⁱⁱ	0.98	2.69	3.5990 (15)	155

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

Acknowledgments

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

supplementary crystallographic information

Comment

Molecules in which alkylamino groups are connected with a guanidine function represent promising candidates for CO₂ capture, since in such type of compounds two nitrogen centers with different basicity are present, which can react with CO₂. Guanidines with additional basic nitrogen functions like tertiary amino groups are well known in the literature (Tiritiris & Kantlehner, 2012), except of their peralkylated guanidinium salts. By alkylation of the corresponding aminoguanidine with dimethyl sulfate and subsequent anion exchange, it was possible to obtain the here presented title compound. According to the structure analysis, the C1–N1 bond of the the CN₃ unit is 1.3390 (16) Å, C1–N2 = 1.3388 (17) Å and C1–N3 = 1.3540 (17) Å, showing partial double-bond character. The N–C1–N angles are: 121.12 (12)° (N1–C1–N2), 120.28 (12)° (N1–C1–N3) and 118.60 (11)° (N2–C1–N3), which indicates a nearly ideal trigonal-planar surrounding of the carbon centre by the nitrogen atoms. The positive charge is completely delocalized on the CN₃ plane (Fig. 1). The bonds between the N atoms and the terminal C-methyl groups of the guanidinium moiety all have values close to a typical single bond [1.4630 (16)–1.4697 (17) Å]. The C–N bond lengths in the terminal trimethylammonium group are slightly elongated [1.4983 (17)–1.5171 (16) Å]. The bond lengths and angles in the tetraphenylborate ions are in good agreement with the data from the crystal structure analysis of the alkali metal tetraphenylborates (Behrens et al., 2012). C–H···π interactions between the hydrogen atoms of –N(CH₃)₂, –CH₂ and –N⁺(CH₃)₃ groups of the guanidinium ion and the phenyl carbon atoms of only one tetraphenylborate ion are mainly present, ranging from 2.724 (2) to 2.895 (2) Å (Fig. 2).

Experimental

The title compound was obtained by reaction of N''-[3-(dimethylamino)propyl]-N,N,N',N'-tetramethylguanidine (Tiritiris & Kantlehner, 2012) with two equivalents dimethyl sulfate in acetonitrile at room temperature. After evaporation of the solvent the crude N,N,N',N',N''-pentamethyl-N''-[3-(trimethylazaniumyl)propyl]-guanidinium bis(methylsulfate) (I) was washed with diethylether and dried in vacuo. 1.0 g (2.2 mmol) of (I) was dissolved in 20 ml acetonitrile and 1.51 g (4.4 mmol) of sodium tetraphenylborate in 20 ml acetonitrile were added. After stirring for one hour at room temperature, the precipitated sodium methylsulfate was filtered off. The title compound crystallized from a saturated acetone solution after several days at 273 K, forming colorless single crystals. Yield: 1.34 g (68.2%). ¹H NMR (500 MHz, CD₃CN/TMS): δ = 2.10 (broad s, 1 H, –CH₂), 2.35 (broad s, 1 H, –CH₂), 2.95 (s, 3 H, –NCH₃), 2.98 [s, 12 H, –N(CH₃)₂], 3.13 [s, 9 H, –N⁺(CH₃)₃], 3.20–3.40 (m, 4 H, –CH₂), 6.86–6.91 (t, 8 H, –C₆H₅), 6.96–7.04 (t, 16 H,–C₆H₅), 7.25–7.30 (m, 16 H, –C₆H₅). ¹³C NMR (125 MHz, CD₃CN/TMS): δ = 22.5 (–CH₂), 37.9 (–NCH₃), 40.5 [–N(CH₃)₂], 49.8 (–CH₂), 53.6–53.9 [–N⁺(CH₃)₃], 64.3 (–CH₂), 122.3 (–C₆H₅), 126.1 – 126.7 (–C₆H₅), 137.0 (–C₆H₅), 162.9 – 164.0 (–C₆H₅), 165.5 (N₃C⁺).