Tris{2-[(2,6-dimethyl­phen­yl)amino]­eth­yl}amine

Yurii S Moroz; Michael K Takase; Peter Müller; Elena V Rybak-Akimova

doi:10.1107/S1600536811049397

. 2011 Nov 25;67(Pt 12):o3421. doi: 10.1107/S1600536811049397

Tris{2-[(2,6-dimethylphenyl)amino]ethyl}amine

Yurii S Moroz ^a, Michael K Takase ^b, Peter Müller ^b, Elena V Rybak-Akimova ^a,^*

PMCID: PMC3239057 PMID: 22199905

Abstract

The title compound, C₃₀H₄₂N₄, is an arylated tris(aminoethyl)amine derivative which was obtained by reducing the corresponding tris-amide with AlH₃. The asymmetric unit consists of one third of a C _3v-symmetric molecule with the tertiary N atom lying on a crystallographic threefold axis.

Related literature

For the structural parameters of arylated derivatives of tris(aminoethyl)amine, see: Almesåker et al. (2009 ▶); Amoroso et al. (2009 ▶). For the synthesis and the structural parameters of metal complexes based on arylated derivatives of tris(aminoethyl)amine, see: Morton et al. (2000 ▶); Yandulov & Schrock (2005 ▶); Smythe et al. (2006 ▶); Reithofer et al. (2010 ▶); Almesåker et al. (2010 ▶).

Experimental

Crystal data

C₃₀H₄₂N₄
M _r = 458.68
Trigonal,
a = 14.2880 (7) Å
c = 22.3811 (11) Å
V = 3956.9 (5) Å³
Z = 6
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 100 K
0.1 × 0.1 × 0.1 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2009 ▶) T _min = 0.680, T _max = 0.746
20390 measured reflections
2695 independent reflections
2330 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.113
S = 1.06
2695 reflections
109 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.42 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811049397/zl2430sup1.cif

e-67-o3421-sup1.cif^{(19.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811049397/zl2430Isup2.hkl

e-67-o3421-Isup2.hkl^{(130KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811049397/zl2430Isup3.cml

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

Acknowledgments

This material is based upon work supported by the US Department of Energy, Office of Basic Energy Science, grant No. DE—FG02–06ER15799. X-ray diffraction instrumentation was purchased with the help of funding from the National Science Foundation (CHE-0946721).

supplementary crystallographic information

Comment

Tris(aminoethyl)amine derivatives have attracted attention of chemists due to their ability to adopt a trigonal pyramidal geometry which is favourable for coordination of different metal ions in a trigonal bipyramidal environment, with one open coordination site for a small exchangeable ligand (Morton et al., 2000; Yandulov et al., 2005; Smythe et al., 2006; Reithofer et al., 2010; Almesåker et al., 2010). In this report, we disscuss the molecular structure of an arylated tris(aminoethyl)amine derivative which appears to be a promising ligand for obtaining high valent iron compounds.

The title compound (1) crystallizes in the trigonal space group R3 and consists of neutral molecules (Figure 1); inter-molecular interactions include a number of van der Waals and C–H···π contacts. There are two types of the C—H···π contacts that originate from hydrogen atoms of the methyl groups pointing towards the opposite sides of the same aromatic ring; no aryl H atoms are involved. The first type of non-covalent interactions has a C10 atom acting as a donor (the C—H···π separation is 3.530 (1) A) and results in the formation of pseudo-dimer aggregates (Figure 2) which form a three-dimensional, well defined symmetric cavity via the second type of C—H···π contacts and van der Waals contacts. The second type of C–H···π contacts includes C9 as a donor (the C–H···π separation is 3.641 (1) Å).

The secondary amino group is located in a cis-position to the tertiary N atom (N1—C1—C2—N2 torsion angle is 54.0 (1)°). The C—C, C—N bond lengths are comparable to the previously reported structures of arylated derivatives of tris(aminoethyl)amine (Almesåker et al., 2009; Amoroso et al., 2009).

Experimental

The title compound, (1), was obtained in three steps. Nitrilotriacetoanilide, (ArNC(O)CH₂)₃N, where Ar = Me₂C₆H₃, was synthesized via the reaction of nitrilotriacetic acid chloride and 2,6-dimethylaniline. The acid chloride was prepared in situ: Oxalyl chloride (10.6 ml) was added dropwise to a cooled (278 K, 5 °C) mixture of nitrilotriacetic acid (5 g, 0.03 mol, in 100 ml of DCM) with one drop of DMF as a catalyst. The mixture was stirred for 48 h at room temperature, and then the DCM and extra oxalyl chloride were removed by vacuum distillation. The crude acid chloride was dissolved in 50 ml of DCM and added dropwise to a 100 ml of DCM solution of 2,6-dimethylaniline (9.8 ml, 0.08 mol) and N-ethyldiisopropylamine (18.5 ml, 0.11 mol) at 263 K (–10 °C). After the addition was complete, the reaction mixture was allowed to warm up and stirred for 24 h at ambient temperature. The reaction mixture was washed with 1 N HCl (25 ml), and then with saturated NaHCO₃ (25 ml). The organic layer was dried (Na₂SO₄) and concentrated under reduced pressure. The solid was washed with water/methanol, 1/1 (v/v), filtered, and dried in an oven at 373 K (100 °C) for 2 days. Yield: 3.07 g (23%). ¹H NMR (300 MHz, dmso-d₆): δ 2.16 (s, 18, Me), 3.70 (s, 6, CH₂), 7.08 (m, 9, H_p, 2H_m), 9.63 (s, 3, NH). ¹³C NMR (75 MHz, dmso-d₆): δ 18.21, 57.99, 126.6, 127.74, 134.86, 135.21, 168.82.

N¹,N²,N³-Tris((2,6-dimethylphenyl)amino)ethyl)amine: To 200 ml of dry THF, 7.20 g (0.2 mol) of LiAlH₄ was added slowly in portions. Then the reaction mixture was cooled in an ice bath and 26 ml (0.2 mol) of chlorotrimethylsilane was added dropwise, followed by an addition of 3.07 g (0.006 mol) of nitrilotriacetoanilide. The reaction mixture was refluxed for 14 h (the reaction was controlled by NMR) and then cooled down to room temperature. Then 21 ml of water in 40 ml of THF was carefully added to the reaction mixture, followed by the addition of NaOH (50%, 21 ml). The reaction mixture was filtered, the precipitate was washed with THF (100 ml) and the filtrate was evaporated under reduced pressure. The solid was extracted with DCM (100 ml); the DCM solution was dried (Na₂SO₄) and concentrated. The crude product was washed with cold diethyl ether (100 ml), filtered, and dried under reduced pressure. Yield: 1.5 g (54%). Colourless crystals, which were suitable for X-ray analysis, were grown in an NMR tube from the dmso-d₆ solution. ¹H NMR (300 MHz, dmso-d₆): δ 2.18 (s, 18, Me), 2.64 (t, J = 6.3 Hz, 6, CH₂), 2.99 (td, J = 6.3, 6 Hz, 6, CH₂), 3.83 (t, J = 6 Hz, 3, NH), 6.69 (t, J = 7.2 Hz, 3, H_p), 6.90 (d, J = 7.2 Hz, 6, H_m). ¹³C NMR (75 MHz, dmso-d₆): δ 18.47, 45.54, 54.51, 120.8, 128.51, 146.38.