1,1′-(Ethane-1,2-di­yl)bis­(1,4,7-triazonane)

Abstract

In the centrosymmetric title compound (dtne), C₁₄H₃₂N₆, two 1,4,7-triaza­cyclo­nonane (tacn, or 1,4,7-triazonane) moieties are linked together each at an amino position by a single ethyl­ene spacer. The mol­ecular packing is supported by pairs of inter­molecular N—H⋯N hydrogen bonds, which form R ₂ ²(22) ring motifs and link the mol­ecules into infinite chains running parallel to the a axis.

Related literature

For an investigation into the coordination chemistry of dtne derivatives and similarly bridged polyaza macrocyclic frameworks, see: Schröder et al. (2000 ▶). For dinuclear metal complexes of related ligands, see: Sinnecker et al. (2004 ▶); Marlin et al. (2005 ▶). For the crystal structure of the related compound 1,4,7-triaza­cyclo­nonane (tacn), see: Battle et al. (2005 ▶). For the structures of other metal complexes of dtne, see: Li et al. (2009 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For the preparation of a similar compound, see: Burdinski et al. (2000 ▶).

Experimental

Crystal data

• C₁₄H₃₂N₆

• M _r = 284.46

• Triclinic,

• a = 6.2732 (3) Å

• b = 6.4988 (3) Å

• c = 10.7152 (6) Å

• α = 99.751 (2)°

• β = 93.115 (2)°

• γ = 110.410 (3)°

• V = 400.45 (3) ų

• Z = 1

• Mo Kα radiation

• μ = 0.08 mm⁻¹

• T = 150 K

• 0.4 × 0.28 × 0.28 mm

Data collection

• Bruker–Nonius KappaCCD diffractometer

• Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T _min = 0.649, T _max = 0.985

• 4952 measured reflections

• 1806 independent reflections

• 1599 reflections with I > 2σ(I)

• R _int = 0.099

Refinement

• R[F ² > 2σ(F ²)] = 0.068

• wR(F ²) = 0.208

• S = 1.23

• 1806 reflections

• 99 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.30 e Å⁻³

• Δρ_min = −0.33 e Å⁻³

Data collection: COLLECT (Nonius, 2000 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

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
N2—H2⋯N1i	0.80 (3)	2.37 (3)	3.129 (3)	159 (2)

Symmetry code: (i) .

supplementary crystallographic information

Comment

The coordination chemistry of ligand frameworks which contain two tacn moieties linked by two to six carbon atoms has been extensively studied (Schröder et al., 2000). The ability of these so-called "earmuff" ligands to form dinuclear metal complexes, in which two metal centres lie in close proximity, has provided a useful means of investigating the active sites of various biological systems. For example, the dinuclear manganese complexes of ligands dtne (Sinnecker et al., 2004) and 1,2-bis(4,7-dimethyl-1,4,7-triaza-1-cyclononyl)ethane (Me₄dtne) (Marlin et al., 2005) have received particular attention as a means of investigating Photosystem II. Whilst crystal structures of several dtne transition metal complexes have been reported (Li et al., 2009), the structure of the free ligand in the solid state has, until now, remained elusive.

We can report that dtne crystallizes in the triclinic space group P -1 with one molecule in the unit cell. The asymmetric unit contains one-half molecule with the other half generated by a centre of inversion which lies at the midpoint of the C7—C7ⁱ bond [Symmetry code: (i) = -x, -y, -z] (Figure 1). The bond lengths and angles within each tacn moiety are comparable to those found in the crystal structure of 1,4,7-triazacyclononane hemihydrate (Battle et al., 2005). The N3—C7—C7ⁱ bond angle is 112.12 (15) ° which indicates no significant stretching or compression of the ethylene bridge. The molecular packing (Figure 2) is supported by pairs of N—H···N hydrogen bonds between N1 and N2ⁱⁱ [Symmetry code: (ii) = x-1, y, z] (Figure 3). These H-bond interactions generate R₂²(22) ring motifs (Bernstein et al., 1995) and link the molecules into supramolecular one-dimensional chains which run parallel to the a-axis.

Experimental

1,2-Bis(1,4,7-triaza-1-cyclononyl)ethane, commonly referred to by the abbreviation dtne, was prepared by a modification of the procedure for that of 1,2-bis(4-methyl-1,4,7-triazacyclononyl)ethane (Me4dtne) reported by Burdinski et al., 2000. To a stirred solution of 1,4,7-triazatricyclo[5.2.1.0^4,10]decane (6.96 g, 5 mmol) in dry acetonitrile (25 ml) was added 1,2-dibromoethane (4.51 g, 2.4 mmol). After 5 days an off-white hygroscopic precipitate was collected by filtration and subsequently dissolved in 6 M hydrochloric acid (100 ml). The resulting solution was heated at reflux for 3 days after which the solvent was removed by evaporation under reduced pressure. The title compound was isolated by the addition of 10 M NaOH (20 ml) and subsequent removal of water by azeotropic distillation with toluene and a water collector. Solvent removal under reduced pressure afforded the title compound as a low melting slightly yellow solid. Crystals appropriate for data collection were obtained by slow diffusion of diethyl ether into a chloroform solution under an inert atmosphere.

Refinement

The carbon bound H atoms were placed in calculated positions and subsequently treated as riding with C—H distances of 0.99 Å and U_iso(H) = 1.2Ueq(C). The hydrogen atoms located on N1 and N2 were located on a difference map and freely refined with individual isotropic temperature factors. The deepest hole in electron density (-0.33 e A^-3) is located at a distance of 0.94 Å from C5.

Figures

Fig. 1.

Perspective view of the asymmetric unit, showing the atom numbering. Displacement ellipsoids are at the 50% probablility level. H atoms are represented by circles of arbitrary size. Unlabelled atoms are related to labelled atoms by the symmetry operation -x, -y, -z.

Fig. 2.

The crystal packing, viewed along the a axis.

Fig. 3.

A fragment of the molecular packing, clearly showing H-bond interactions between adjacent molecules. [Symmetry code: (ii) x-1, y, z.].

Crystal data

C14H32N6	Z = 1
Mr = 284.46	F(000) = 158
Triclinic, P1	Dx = 1.18 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.2732 (3) Å	Cell parameters from 6758 reflections
b = 6.4988 (3) Å	θ = 1.0–27.5°
c = 10.7152 (6) Å	µ = 0.08 mm−1
α = 99.751 (2)°	T = 150 K
β = 93.115 (2)°	Block, colourless
γ = 110.410 (3)°	0.4 × 0.28 × 0.28 mm
V = 400.45 (3) Å3

Data collection

Bruker–Nonius KappaCCD diffractometer	1806 independent reflections
Radiation source: fine-focus sealed tube	1599 reflections with I > 2σ(I)
graphite	Rint = 0.099
φ and ω scans	θmax = 27.5°, θmin = 1.9°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −7→8
Tmin = 0.649, Tmax = 0.985	k = −8→8
4952 measured reflections	l = −13→13

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.208	H atoms treated by a mixture of independent and constrained refinement
S = 1.23	w = 1/[σ2(Fo2) + (0.0859P)2 + 0.2591P] where P = (Fo2 + 2Fc2)/3
1806 reflections	(Δ/σ)max < 0.001
99 parameters	Δρmax = 0.30 e Å−3
0 restraints	Δρmin = −0.33 e Å−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
N1	0.1344 (3)	0.5390 (3)	0.32247 (17)	0.0229 (4)
H1	0.145 (5)	0.533 (5)	0.233 (3)	0.033 (7)*
N2	0.6399 (3)	0.5507 (3)	0.29452 (16)	0.0202 (4)
H2	0.775 (5)	0.583 (4)	0.312 (2)	0.019 (6)*
N3	0.1962 (3)	0.1707 (3)	0.15019 (15)	0.0200 (4)
C1	0.3489 (3)	0.6779 (3)	0.4061 (2)	0.0231 (5)
H1A	0.3671	0.5978	0.4744	0.028*
H1B	0.3328	0.819	0.4475	0.028*
C2	0.5687 (3)	0.7378 (3)	0.3420 (2)	0.0234 (5)
H2A	0.5468	0.808	0.2696	0.028*
H2B	0.6945	0.8513	0.404	0.028*
C3	0.5883 (3)	0.4564 (3)	0.15762 (18)	0.0234 (5)
H3A	0.7345	0.473	0.1221	0.028*
H3B	0.5167	0.5461	0.1168	0.028*
C4	0.4308 (3)	0.2106 (3)	0.12080 (18)	0.0225 (5)
H4A	0.4267	0.1575	0.0282	0.027*
H4B	0.4954	0.1211	0.1664	0.027*
C5	0.1748 (3)	0.1640 (3)	0.28616 (18)	0.0211 (5)
H5A	0.329	0.2224	0.3355	0.025*
H5B	0.0966	0.0072	0.2955	0.025*
C6	0.0377 (3)	0.3056 (3)	0.33779 (19)	0.0230 (5)
H6A	−0.1207	0.2366	0.2934	0.028*
H6B	0.0293	0.3037	0.4296	0.028*
C7	0.0265 (4)	−0.0249 (3)	0.06487 (18)	0.0241 (5)
H7A	−0.1166	−0.0741	0.1049	0.029*
H7B	0.0849	−0.1493	0.0528	0.029*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.0170 (8)	0.0243 (9)	0.0240 (9)	0.0054 (7)	0.0015 (6)	0.0006 (7)
N2	0.0140 (8)	0.0237 (9)	0.0189 (8)	0.0049 (6)	0.0007 (6)	−0.0013 (6)
N3	0.0168 (8)	0.0211 (8)	0.0152 (8)	0.0016 (6)	0.0000 (6)	−0.0021 (6)
C1	0.0182 (9)	0.0242 (10)	0.0229 (10)	0.0068 (8)	0.0025 (7)	−0.0037 (8)
C2	0.0190 (9)	0.0193 (9)	0.0276 (10)	0.0033 (7)	0.0038 (7)	0.0009 (8)
C3	0.0199 (9)	0.0266 (10)	0.0183 (9)	0.0033 (8)	0.0038 (7)	0.0010 (8)
C4	0.0205 (10)	0.0246 (10)	0.0181 (9)	0.0061 (8)	0.0024 (7)	−0.0028 (7)
C5	0.0209 (9)	0.0214 (9)	0.0166 (9)	0.0034 (7)	0.0007 (7)	0.0018 (7)
C6	0.0174 (9)	0.0243 (10)	0.0226 (10)	0.0028 (7)	0.0043 (7)	0.0016 (8)
C7	0.0231 (10)	0.0193 (9)	0.0205 (10)	−0.0007 (7)	−0.0025 (7)	−0.0014 (8)

Geometric parameters (Å, °)

N1—C6	1.466 (3)	C3—C4	1.526 (3)
N1—C1	1.475 (2)	C3—H3A	0.99
N1—H1	0.96 (3)	C3—H3B	0.99
N2—C2	1.460 (3)	C4—H4A	0.99
N2—C3	1.462 (2)	C4—H4B	0.99
N2—H2	0.80 (3)	C5—C6	1.524 (3)
N3—C7	1.464 (2)	C5—H5A	0.99
N3—C4	1.464 (2)	C5—H5B	0.99
N3—C5	1.477 (2)	C6—H6A	0.99
C1—C2	1.531 (3)	C6—H6B	0.99
C1—H1A	0.99	C7—C7i	1.525 (4)
C1—H1B	0.99	C7—H7A	0.99
C2—H2A	0.99	C7—H7B	0.99
C2—H2B	0.99
C6—N1—C1	114.96 (17)	H3A—C3—H3B	107.5
C6—N1—H1	106.1 (17)	N3—C4—C3	113.41 (16)
C1—N1—H1	114.6 (17)	N3—C4—H4A	108.9
C2—N2—C3	117.19 (17)	C3—C4—H4A	108.9
C2—N2—H2	111.5 (17)	N3—C4—H4B	108.9
C3—N2—H2	106.5 (18)	C3—C4—H4B	108.9
C7—N3—C4	112.85 (15)	H4A—C4—H4B	107.7
C7—N3—C5	112.41 (15)	N3—C5—C6	109.75 (16)
C4—N3—C5	112.25 (15)	N3—C5—H5A	109.7
N1—C1—C2	116.37 (17)	C6—C5—H5A	109.7
N1—C1—H1A	108.2	N3—C5—H5B	109.7
C2—C1—H1A	108.2	C6—C5—H5B	109.7
N1—C1—H1B	108.2	H5A—C5—H5B	108.2
C2—C1—H1B	108.2	N1—C6—C5	113.78 (16)
H1A—C1—H1B	107.3	N1—C6—H6A	108.8
N2—C2—C1	115.49 (16)	C5—C6—H6A	108.8
N2—C2—H2A	108.4	N1—C6—H6B	108.8
C1—C2—H2A	108.4	C5—C6—H6B	108.8
N2—C2—H2B	108.4	H6A—C6—H6B	107.7
C1—C2—H2B	108.4	N3—C7—C7i	112.1 (2)
H2A—C2—H2B	107.5	N3—C7—H7A	109.2
N2—C3—C4	115.55 (17)	C7i—C7—H7A	109.2
N2—C3—H3A	108.4	N3—C7—H7B	109.2
C4—C3—H3A	108.4	C7i—C7—H7B	109.2
N2—C3—H3B	108.4	H7A—C7—H7B	107.9
C4—C3—H3B	108.4
C6—N1—C1—C2	106.9 (2)	C7—N3—C5—C6	−97.75 (19)
C3—N2—C2—C1	101.1 (2)	C4—N3—C5—C6	133.75 (17)
N1—C1—C2—N2	−67.9 (2)	C1—N1—C6—C5	−71.3 (2)
C2—N2—C3—C4	−118.6 (2)	N3—C5—C6—N1	−56.6 (2)
C7—N3—C4—C3	151.78 (17)	C4—N3—C7—C7i	−77.7 (3)
C5—N3—C4—C3	−79.9 (2)	C5—N3—C7—C7i	154.1 (2)
N2—C3—C4—N3	67.4 (2)

Symmetry codes: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···N1ii	0.80 (3)	2.37 (3)	3.129 (3)	159 (2)

Symmetry codes: (ii) x+1, y, z.