2-{(E)-N-[2-(1H-Inden-3-yl)eth­yl]imino­meth­yl}-1H-imidazole

Zhao Li; Chong Tian; Wanli Nie; Maxim V Borzov

doi:10.1107/S1600536811013286

. 2011 Apr 16;67(Pt 5):o1165–o1166. doi: 10.1107/S1600536811013286

2-{(E)-N-[2-(1H-Inden-3-yl)ethyl]iminomethyl}-1H-imidazole

Zhao Li ^a,^‡, Chong Tian ^a, Wanli Nie ^a,^*, Maxim V Borzov ^a

PMCID: PMC3089109 PMID: 21754472

Abstract

The asymmetric unit of the title compound, C₁₅H₁₅N₃, contains two crystallographically independent molecules with very similar geometries. The imidazole and indenyl planes are approximately orthogonal, making dihedral angles of 88.21 (9) and 83.08 (9)%deg; in the two independent molecules. In the crystal, the imidazole units are linked by N—H⋯N hydrogen bonds into chains parallel to the 101) plane stretched in the diagonal direction [translation vector ( Inline graphic ,1,0); C(4) motif]. Within a chain, there are two types of symmetrically non-equivalent alternating H-bonds which slightly differ in their parameters.

Related literature

For the structural parameters of 3-organyl substituted 1H-indenes (organic structures only), see: Sun et al. (2010 ▶) and references cited therein. For the structural parameters of 2-organyl-1H-imidazoles (organic structures only, not bi- or oligocyclic, non-ionic, recent publications only), see: Lassalle-Kaiser et al. (2006 ▶). For the structural parameters of Li, Ti, and Zr complexes derived from 1H-imidazol(in)-2-yl side-chain-functionalized cyclopentadienes see: Krut’ko et al. (2006 ▶); Nie et al. (2008 ▶); Wang et al. (2009 ▶); Ge et al. (2010 ▶). For the structural parameters of 1H-imidazol(in)-2-yl side-chain-functionalized 3-substituted 1H-indene and Li-indenide, see: Sun et al. (2009 ▶, 2010 ▶). For graph-set notation, see: Etter et al. (1990 ▶); Bernstein et al. (1995 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶). For preparation of 2-(1H-inden-3-yl)ethanamine, see: Winter et al. (1967 ▶).

Experimental

Crystal data

C₁₅H₁₅N₃
M _r = 237.30
Orthorhombic,
a = 5.8827 (5) Å
b = 8.3326 (7) Å
c = 51.909 (4) Å
V = 2544.5 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.36 × 0.22 × 0.14 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.973, T _max = 0.990
13315 measured reflections
2939 independent reflections
2328 reflections with I > 2σ(I)
R _int = 0.041

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.113
S = 1.03
2939 reflections
333 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶) and OLEX2 (Dolomanov et al., 2009 ▶); software used to prepare material for publication: SHELXTL and OLEX2.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811013286/im2276sup1.cif

e-67-o1165-sup1.cif^{(27KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013286/im2276Isup2.hkl

e-67-o1165-Isup2.hkl^{(144.3KB, 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
N1A—H1A⋯N2B	0.80 (4)	2.16 (4)	2.935 (4)	162 (4)
N1B—H1B⋯N2Aⁱ	0.92 (4)	2.10 (4)	3.006 (4)	170 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

Financial support from the National Natural Science Foundation of China (project Nos. 20702041 and 21072157) and the Shaanxi Province Administration of Foreign Experts Bureau Foundation (grant No. 20106100079) is gratefully acknowledged. The authors are thankful to Mr Wang Minchang and Mr Su Pengfei (Xi’an Modern Chemistry Research Institute) for their help in carrying out the NMR spectroscopic and X-ray diffraction experiments.

supplementary crystallographic information

Comment

1H-Imidazol(in)-2-yl side-chain functionalized cyclopentadiene-type (Cp) ligands were introduced into the organometallic chemistry, and, particularly into that of the Group 4 transition metals, not long ago (Krut'ko et al., 2006; Nie et al., 2008; Wang et al., 2009; Sun et al., 2009; Sun et al., 2010; Ge et al., 2010). All these compounds are usually considered to be prospective precursors for catalytic systems capable to effectively polymerize ethylene and α-olefins. However, in all of these previously reported ligands, the Cp- and imidazol-2-yl groups are linked by a C₁– or C₂-hydrocarbon bridge. Incorporating into the bridge another heteroatom groups capable of coordination towards a metal centre presents, this way, a logical step forward in the ligand design development. This contribution reports the first structural characterization of a potent tridentate ligand of the type where Cp- (1H-inden-3-yl) and 1H-imidazol-2-yl groups are connected with a bridge with a C═N imino-function.

The achiral title compound, C₁₅H₁₅N₃, I, was prepared by a condensation reaction of 2-(1H-inden-3-yl)ethanamine and 1H-imidazol-2-carbaldehyde. It crystallizes in a chiral space group P2₁2₁2₁, with the c-axis of the lattice being very long comparatively to the others [51.909 (4) Å]. The asymmetric unit of I is presented by two crystallographically independent molecules with very close geometries (see Fig. 1). Imidazole moieties of the asymmetric unit are linked by NH···N hydrogen bonds and the units assemble in chains parallel to a0b plane stretched in the diagonal direction [translation vector (–1,1,0); C(4) motif; see Fig. 2]. Within a chain, these hydrogen bonds slightly alternate (see Table).

Both indenyl groups are planar within 0.03 Å and nearly parallel one to each other [interplane angle 1.44 (6)°]. Within the independent molecules, the imidazole and indenyl r. m. s. planes are approximately orthogonal [interplane angles 88.21 (9) and 96.92 (9)°]. However, the imidazole rings in the units form a noticible interplane angle [7.43 (11)°] what could be a result of their mutual hydrogen binding. The same binding could also be a reason of noticible twisting of the C═N fragments in respect to the imidazole ring planes [torsion angles 7.5 (4) and 7.3 (4)°].

Analysis of the Cambridge Structural database [CSD; Version 5.27, release May 2009; Allen, 2002; 317 entries, 483 fragments] reveals that the observed C═ N distances in I [1.251 (4) and 1.253 (4) Å] are close to the median value for C═N bond in Schiff bases derived from primary aliphatic amines and aromatic (and/or heteroaromatic) aldehydes (1.27 Å). As for the 1H-inden-3-yl and 1H-imidazol-2-yl groups, all the bond lengths and angles are within normal ranges (for references, see Related literature section).

Experimental

Methanol was refluxed with Mg powder until the metal dissolved and then distilled from over Mg(OMe)₂. 1H-Imidazol-2-carbaldehyde was purchased from Fluka. 2-(1H-inden-3-yl)ethanamine was prepared as described by Winter et al., 1967.

Compound I: Solutions of 2-(1H-inden-3-yl)ethanamine (1.56 g, 10 mmol) and 1H-imidazol-2-carbaldehyde (0.96 g, 10 mmol) in anhydrous methanol (total amount 20 ml) were mixed under stirring at 253 K, the reaction mixture was kept at this temperature for 6 h and then cooled down to 233 K. The solution was removed from the wthite thin-crystalline precipitate with a canula. The precipitate was washed with small portions of cold diethyl ether and dried on the high-vacuum line what gave 1.85 g (78%) of I. Single crystal of I suitable for the X-ray diffraction analysis was prepared by re-crystallization from anhydrous methanol (slow evaporation, ambient temperature).