3,3′-(2,2′-Bi-1H-imidazole-1,1′-diyl)di­propanol

In the title compound, C₁₂H₁₈N₄O₂, unlike other unconjugated disubstituted biimidazole derivatives reported so far, the two imidazole rings in a trans conformation exhibit a large planar rotation angle of 51.27 (4)°, and consist of half-mol­ecule asymmetric units related by a twofold rotation. The mol­ecules are linked into a three-dimensional framework with a parallel laminated construction via O—H⋯N and C—H⋯O inter­actions.

Related literature

For background to 2,2′-biimidazole derivatives, see: Forster et al. (2004); Fortin & Beauchamp (2000); Fu et al. (2007); Ion et al. (2007); Mao et al. (2003); Pereira et al. (2006); Xiao & Shreeve (2005); Xiao et al. (2004). For other unconjugated 1,1′-disubstituted compounds, see: Barnett et al. (1997, 2002); Secondo et al. (1996, 1997). For the synthesis, see: Barnett et al. (1999)

Experimental

Crystal data

• C₁₂H₁₈N₄O₂

• M_r = 250.30

• Monoclinic, C 2/c

• a = 15.812 (3) Å

• b = 9.5961 (19) Å

• c = 9.3194 (19) Å

• β = 119.44 (3)°

• V = 1231.5 (6) ų

• Z = 4

• Mo Kα radiation

• μ = 0.10 mm⁻¹

• T = 295 (2) K

• 0.56 × 0.48 × 0.37 mm

Data collection

• Rigaku R-AXIS RAPID diffractometer

• Absorption correction: multi-scan (ABSCOR; Higashi, 1995) T_min = 0.948, T_max = 0.970

• 4715 measured reflections

• 1400 independent reflections

• 1183 reflections with I > 2σ(I)

• R_int = 0.015

Refinement

• R[F² > 2σ(F²)] = 0.036

• wR(F²) = 0.104

• S = 1.07

• 1400 reflections

• 86 parameters

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

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.23 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H9⋯N2^i	0.89 (2)	1.92 (2)	2.8047 (17)	175
C2—H2⋯O1^ii	0.93	2.59	3.5019 (17)	166
Symmetry codes: (i) ; (ii) .

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

2,2'-Biimidazole (H₂biim) derivatives as versatile ligands are widely used in the construction of metal complexes (Ion et al., 2007; Pereira et al., 2006; Fortin et al., 2000). In addition to the study of metal complexes, attention has also been devoted to the polymeric systems (Fu et al., 2007; Forster et al., 2004; Mao et al., 2003) and the ionic liquids (Xiao et al., 2005, 2004). The title compound (I), as a hydroxy-terminated derivative can be easily synthesized by Michael addition of dianion biim^2- to alkyl acrylate (Barnett et al., 1999) and subsequent mild reduction by NaBH₄ in an excellent yield.

The crystal structure of (I), shown in Fig. 1, adopts a trans conformation, and consists of half-molecule asymmetric units related by a twofold rotation. Exceptionally, unlike the other unconjugated 1,1'-disubstituted compounds reported before (Barnett et al., 1997, 2002; Secondo et al., 1996, 1996), the imidazole rings of the investigated compound (I) exhibit a rather large torsion angle of 51.27 (4)°, as shown in Fig. 1. The terminal hydroxyl groups are responsible for this noncoplanarity. The imdazole rings are forced to rotate by intermolecular interactions via strong O–H···N hydrogen bonds. The N1–C4–C5–C6 moiety is essentially planar with an r.m.s. deviation of 0.054 Å. This plane is at angle of 71.90 (7)° with respect to the adjacent imidazole ring, which is consistent with the reported analogous compounds referenced before. While the atom O1 does not lie in the N1–C4–C5–C6 plane, rather it lies 1.116 Å from this plane. The bond length and bond angle in (I) are within normal ranges.

The molecules of (I) are linked into a three-dimensional framework with parallel laminated construction by a combination of one strong O–H···N hydrogen bond and the other weak C–H···O hydrogen bond (Table 1). It can be analyzed in terms of thousands of one-dimensional substructures, linked by C–H···O hydrogen bonds, which generate series of two-dimensional sheets through C–H···O hydrogen bonds (Fig.2).

Related literature

For background to 2,2'-biimidazole derivatives, see: Forster et al. (2004); Fortin & Beauchamp (2000); Fu et al. (2007); Ion et al. (2007); Mao et al. (2003); Pereira et al. (2006); Xiao & Shreeve (2005); Xiao et al. (2004). For other unconjugated 1,1'-disubstituted compounds, see: Barnett et al. (1997, 2002); Secondo et al. (1996, 1997). For the synthesis, see: Barnett et al. (1999)

S2. Experimental

1,1'-Di(ethylpropionato)-2,2'-biimidazole (0.80 g, 2.40 mmol) was dissolved in absolute ethyl alcohol (50 ml). To this mixture was added batchly NaBH₄ (0.906 g, 24.0 mmol). The mixture was heated to reflux for 3 h. Evaporating the solvent and added to 30 ml H₂O yield a transparent solution. Adjusting the PH of the solution to 8–9 with 1M HCl led to a white suspension. The mixture was filtered, then the filtrate extracted with chloroform (10 ml) three times. The combined organic layer was washed with H₂O (5 ml) two times, dried by MgSO₄. After evaporating the solvent, the residue was chromatographed on silica gel. Elution with CH₃CO₂C₂H₅/C₂H₅OH (10:1) afforded a white solid (0.52 g, 86.7%). Tetragonal crystals of the titled compound were formed by evaporating saturated petroleum ether/chloroform solution slowly.

Similarly, the title compound(I) can be synthesized by reduction of other 1,1'-di(alkylpropionato)-2,2??-biimidazole (alkyl = methyl, butyl) which was prepared according to the published procedure (Barnett et al., 1999) with NaBH₄ in anhydrous ethyl alcohol or with LiAlH₄ in anhydrous ethereal solution. The yields ranges from 44 to 85°.

S3. Refinement

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms (C—H = 0.93 and = 0.97 Å; O—H = 0.82 Å) and U_iso(H) values were taken to be equal to 1.2 U_eq(C) and 1.5U_eq(O).

Computing details

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL (Sheldrick, 2008); software used to prepare material for publication: SHELXL (Sheldrick, 2008).

Figures

Fig. 1. A perspective view of (I) with the atom-labelling scheme, showing that the two imidazole rings are distinctly non-coplanar. Displacement ellipsoids are drawn at the 40% probability level and H atoms are shown as small spheres of arbitrary radius.

Fig. 2. A perspective view of the three–dimensional framework with parallellaminated construction containing two sheets from [011] direction, showing the packing mode and the interactions of hydrogen bonds O–H···N (pink dashed lines in the electronic version of the paper) and C–H···O (green dashed lines in the electronic version). All H atoms not involved in the hydrogen-bond motifs have been omitted for clarity.

3,3'-(2,2'-Bi-1H-imidazole-1,1'-diyl)dipropanol

Crystal data

C12H18N4O2	F(000) = 536
Mr = 250.30	Dx = 1.350 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1400 reflections
a = 15.812 (3) Å	θ = 3.1–27.5°
b = 9.5961 (19) Å	µ = 0.10 mm^−1
c = 9.3194 (19) Å	T = 295 K
β = 119.44 (3)°	Block, colourless
V = 1231.5 (6) Å^3	0.56 × 0.48 × 0.37 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID diffractometer	1400 independent reflections
Radiation source: fine-focus sealed tube	1183 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
ω scans	θmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −20→20
Tmin = 0.948, Tmax = 0.970	k = −12→12
4715 measured reflections	l = −12→12

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.104	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0631P)^2 + 0.3657P] where P = (Fo^2 + 2Fc^2)/3
1400 reflections	(Δ/σ)max < 0.001
86 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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
C1	0.03257 (9)	0.22372 (12)	0.47224 (14)	0.0366 (3)
H1	0.0646	0.2434	0.4134	0.044*
C2	−0.05565 (9)	0.16313 (12)	0.41318 (14)	0.0375 (3)
H2	−0.0946	0.1336	0.3050	0.045*
C3	−0.00459 (7)	0.20468 (10)	0.66867 (13)	0.0280 (3)
C4	0.15367 (7)	0.32897 (11)	0.74530 (14)	0.0328 (3)
H3	0.1970	0.3292	0.6993	0.039*
H4	0.1869	0.2829	0.8516	0.039*
C5	0.13141 (8)	0.47728 (12)	0.76898 (17)	0.0418 (3)
H5	0.0930	0.4771	0.8241	0.050*
H6	0.0930	0.5207	0.6620	0.050*
C6	0.22260 (8)	0.56240 (12)	0.86937 (16)	0.0390 (3)
H7	0.2635	0.5562	0.8189	0.047*
H8	0.2048	0.6594	0.8674	0.047*
N1	0.06543 (6)	0.25027 (9)	0.63558 (11)	0.0300 (2)
N2	−0.07917 (6)	0.15167 (10)	0.53523 (11)	0.0340 (3)
O1	0.27596 (7)	0.51756 (11)	1.03437 (12)	0.0475 (3)
H9	0.3207 (14)	0.460 (2)	1.037 (2)	0.073 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0423 (6)	0.0386 (6)	0.0319 (6)	0.0015 (5)	0.0206 (5)	0.0000 (4)
C2	0.0425 (6)	0.0373 (6)	0.0258 (6)	−0.0003 (4)	0.0114 (4)	−0.0030 (4)
C3	0.0253 (5)	0.0265 (5)	0.0287 (6)	0.0014 (4)	0.0107 (4)	0.0005 (4)
C4	0.0246 (5)	0.0324 (5)	0.0387 (6)	−0.0004 (4)	0.0134 (4)	−0.0013 (4)
C5	0.0285 (6)	0.0333 (6)	0.0525 (8)	0.0020 (4)	0.0114 (5)	−0.0050 (5)
C6	0.0330 (6)	0.0316 (5)	0.0477 (7)	−0.0014 (4)	0.0163 (5)	−0.0033 (5)
N1	0.0284 (5)	0.0313 (5)	0.0295 (5)	0.0000 (3)	0.0136 (4)	−0.0014 (3)
N2	0.0318 (5)	0.0351 (5)	0.0281 (5)	−0.0035 (4)	0.0093 (4)	−0.0020 (3)
O1	0.0407 (5)	0.0592 (6)	0.0391 (6)	0.0028 (4)	0.0168 (4)	−0.0102 (4)

Geometric parameters (Å, º)

C1—C2	1.3536 (18)	C4—H3	0.9700
C1—N1	1.3692 (16)	C4—H4	0.9700
C1—H1	0.9300	C5—C6	1.5151 (16)
C2—N2	1.3638 (16)	C5—H5	0.9700
C2—H2	0.9300	C5—H6	0.9700
C3—N2	1.3245 (14)	C6—O1	1.4093 (17)
C3—N1	1.3595 (14)	C6—H7	0.9700
C3—C3^i	1.450 (2)	C6—H8	0.9700
C4—N1	1.4697 (14)	O1—H9	0.89 (2)
C4—C5	1.5081 (16)
C2—C1—N1	106.51 (11)	C4—C5—H5	109.1
C2—C1—H1	126.7	C6—C5—H5	109.1
N1—C1—H1	126.7	C4—C5—H6	109.1
C1—C2—N2	110.15 (10)	C6—C5—H6	109.1
C1—C2—H2	124.9	H5—C5—H6	107.9
N2—C2—H2	124.9	O1—C6—C5	112.75 (11)
N2—C3—N1	111.05 (10)	O1—C6—H7	109.0
N2—C3—C3^i	124.54 (11)	C5—C6—H7	109.0
N1—C3—C3^i	124.26 (11)	O1—C6—H8	109.0
N1—C4—C5	112.13 (9)	C5—C6—H8	109.0
N1—C4—H3	109.2	H7—C6—H8	107.8
C5—C4—H3	109.2	C3—N1—C1	106.62 (10)
N1—C4—H4	109.2	C3—N1—C4	127.45 (10)
C5—C4—H4	109.2	C1—N1—C4	125.51 (10)
H3—C4—H4	107.9	C3—N2—C2	105.68 (10)
C4—C5—C6	112.29 (9)	C6—O1—H9	105.3 (12)

Symmetry code: (i) −x, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H9···N2^ii	0.89 (2)	1.92 (2)	2.8047 (17)	175
C2—H2···O1^iii	0.93	2.59	3.5019 (17)	166

Symmetry codes: (ii) x+1/2, −y+1/2, z+1/2; (iii) x−1/2, y−1/2, z−1.