1,1'-Di(hydrazinocarbonylmethyl)-2,2'-biimidazole monohydrate and 1,1'-di[2-(hydrazinocarbonyl)ethyl]-2,2'-bi­imidazole

The crystal structures of the title compounds, alternatively called 2,2'-(2,2'-bi­imid­azole-1,1'-diyl)­diaceto­hydra­zide monohydrate, C₁₀H₁₄N₈O₂·H₂O, (I), and 3,3'-(2,2'-bi­imid­azole-1,1'-diyl)­dipropion­o­hydra­zide, C₁₂H₁₈N₈O₂, (II), respectively, have been determined. The mol­ecules consist of half-mol­ecule asymmetric units related by a twofold rotation in (I) and by a center of inversion in (II). The imidazole rings of both mol­ecules crystallize in a nearly coplanar fashion [dihedral angles of 5.91 (3) and 0.0 (1)° for (I) and (II), respectively]. Both planar hy­dra­zinocarbonylalkyl substituents are essentially planar and assume the E orientation.

S1. Comment

Compounds containing the 2,2'-biimidazole moiety have been the focus of several investigations due to their biological activity as cardiotonics (Matthews et al., 1990), antiprotozoals (Melloni et al., 1975), and enzyme active-site models (Overberger & Vorchheimer, 1963; Kirchner & Krebs, 1987). In addition to its physiological activity, the aromatic biheterocyclic structure has also been incorporated into a variety of polymer systems (Chi & Collier, 1988; Lui, et al., 1988; Elmer & Collier, 1993; Lister & Collier, 1993; Barnett, 1997) in a series of attempts to imbue polymers with thermal stability, conductivity and metal-ion binding selectivity. Recently, a new class of 2,2'-biimidazole compounds, the 1,1'-diester derivatives (Barnett, 1997; Barnett et al., 1996, 1997, 1999; Secondo et al., 1996), has been developed. Ready acylation of primary amines or hydrazine with these diesters proceeds with excellent yields. The hydrazide macromolecules 1,1'-di(hydrazinecarbonylmethyl)-2,2'-biimidazole, (I), and 1,1'-di(hydrazinecarbonylethyl)-2,2'-biimidazole, (II), illustrated in the Scheme below, were prepared as monomers for subsequent polymer syntheses.

As with similar unconjugated disubstituted biimidazole derivatives, the imidazole rings of both structures (I) and (II) are coplanar, with r.m.s. deviations of 0.003 and 0.001 Å, respectively. The N1/C1/N2/C3/C2 planes and their associated symmetry partners, as shown in Figs. 1 and 2, are essentially coplanar as they exhibit dihedral angles of 5.91 (3) and 0.0 (1)° for (I) and (II), respectively. Previously reported derivatives (Barnett, 1997; Barnett et al., 1999; Secondo et al., 1996) have torsion angles along the ring-bridging C atoms of less than 1°, while the dihedral angle for the ring planes of the unsubstituted 2,2'-biimidazole has been reported to be 4.6° (Cromer et al., 1987). So biimidazoles (I) and (II) represent the greatest disparity between imidazole plane torsion angles for similar derivatives.

The N1/C4/C5 least-squares plane of (I) possesses a dihedral angle of 76.7 (2)° with respect to the adjacent imidazole ring, while the same plane in (II) is 84.9 (1)° (cf. Figs. 1 and 2). Both dihedral angles are comparable to those observed in analogous compounds. Each hydrazinoalkanoyl (R) group is in the zigzag conformation and is essentially planar, as the r.m.s. deviations for the non-H atoms (including N1) are 0.092 and 0.550 Å for (I) and (II), respectively. Fig. 1 shows hydrogen bonding to the water molecules entrained in the crystal lattice of (I). The remaining bond angles and lengths do not differ significantly from 1,1'-disubstituted biimidazole structures reported previously. Selected distances and angles, together with hydrogen-bonding parameters, for (I) and (II) are given in Tables 1–4.

Extensive hydrogen-bonding networks exist in (I) and (II), as both compounds take advantage of the presence of various amine and amide H atoms and a carbonyl O atom. These are supplemented in (I) with the presence of a water of hydration. In this crystal, an intra-asymmetric unit hydrogen bond exists between atoms H4d and O2 (dashed lines in Fig. 1), while inter-asymmetric unit hydrogen bonds are present between H2a and N4, and H3a and O1, as well as between H4c and N2 (cf. Table 2). Thus, the presence of water in the crystal is an important contributor to the overall packing of this biimidazole derivative. In contrast, no strong intramolecular hydrogen bond is present in (II), although a number of intermolecular bonds, similar to those in (I), do exist (cf. Table 4). While both compounds were crystallized from water, only (I) draws on the hydrogen-bonding potential of the water in crystal formation.

S2. Experimental

The title compounds were prepared by separately reacting 1,1'-di(methylacetato)-2,2'-biimidazole (0.25 g, 0.898 mmol) or 1,1'-di(ethylpropionato)-2,2'-biimidazole (0.25 g, 0.748 mmol) with 64% hydrazine (10 ml, 200 mmol) in a 25 ml round-bottomed flask with stirring. The mixtures were stirred for a minimum of 3 d, after which, the white powdery products were washed with water, filtered and crystallized by slow cooling from hot aqueous solutions. Yields were \sim60 and 78% for (I) and (II), respectively. The crystal of (I) was sealed with mother liquor in a capillary to minimize possible gain or loss of water.

S3. Refinement

The C—H bond lengths were constrained at 0.96 Å, N—H at 0.90 Å and O—H at 0.85 Å.

Computing details

For both compounds, data collection: P3/P4-PC Diffractometer Program (Siemens, 1991); cell refinement: P3/P4-PC Diffractometer Program; data reduction: XDISK (Siemens, 1991); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990a); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: SHELXTL/PC (Sheldrick, 1990b); software used to prepare material for publication: SHELXTL/PC and SHELXL93.

Figures

	Fig. 1. View of (I), showing the labeling of the non-H atoms. Displacement ellipsoids are shown at 50% probability levels and H atoms are drawn as small spheres of arbitrary radii.
	Fig. 2. View of (II), showing the labeling of the non-H atoms. Displacement ellipsoids are shown at 50% probability levels.

(I) 1,1'-di(hydrazinoethanoyl)2,2'-biimidazole monohydrate

Crystal data

C10H14N8O2·H2O	Dx = 1.462 Mg m^−3
Mr = 296.29	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I41	Cell parameters from 100 reflections
Hall symbol: I 4bw	θ = 6.4–19.7°
a = 9.7451 (3) Å	µ = 0.11 mm^−1
c = 14.1764 (6) Å	T = 293 K
V = 1346.30 (8) Å^3	Block cut from larger crystal, colorless
Z = 4	0.59 × 0.50 × 0.45 mm
F(000) = 624

Data collection

Siemens–Bruker P4 diffractometer	Rint = 0.015
Radiation source: normal-focus sealed tube	θmax = 25.0°, θmin = 2.5°
Graphite monochromator	h = −11→1
θ/2θ scans	k = −1→11
939 measured reflections	l = −16→1
620 independent reflections	3 standard reflections every 100 reflections
562 reflections with I > 2σ(I)	intensity decay: ave. in σ(I)'s of 1.7%

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.077	H atoms treated by a mixture of independent and constrained refinement
S = 1.12	w = 1/[σ^2(Fo^2) + (0.038P)^2 + 0.5103P] where P = (Fo^2 + 2Fc^2)/3
620 reflections	(Δ/σ)max < 0.001
99 parameters	Δρmax = 0.14 e Å^−3
3 restraints	Δρmin = −0.16 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 on F² for ALL reflections except for 4 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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
O1	0.5130 (2)	0.2547 (2)	0.5599 (2)	0.0384 (5)
O2	0.5000	0.0000	0.41219 (13)	0.0676 (13)
H2A	0.503 (6)	0.0691 (2)	0.3757 (3)	0.080*
N1	0.4009 (2)	0.3361 (2)	0.7275 (2)	0.0314 (5)
N2	0.3170 (3)	0.5473 (3)	0.7237 (3)	0.0395 (7)
N3	0.6668 (2)	0.1164 (3)	0.6313 (3)	0.0338 (6)
H3A	0.6945 (2)	0.0809 (3)	0.6870 (3)	0.080*
N4	0.7422 (3)	0.0819 (3)	0.5499 (2)	0.0402 (6)
H4D	0.6858 (3)	0.0402 (3)	0.5084 (2)	0.080*
H4C	0.7767 (3)	0.1584 (3)	0.5234 (2)	0.080*
C1	0.4306 (3)	0.4728 (3)	0.7275 (3)	0.0302 (6)
C2	0.2607 (3)	0.3242 (3)	0.7222 (3)	0.0397 (7)
H2	0.2071 (3)	0.2414 (3)	0.7198 (3)	0.080*
C3	0.2128 (3)	0.4538 (4)	0.7201 (3)	0.0448 (8)
H3	0.1173 (3)	0.4782 (4)	0.7174 (3)	0.080*
C4	0.4940 (3)	0.2194 (3)	0.7275 (3)	0.0320 (7)
H4A	0.4453 (3)	0.1374 (3)	0.7450 (3)	0.080*
H4B	0.5650 (3)	0.2348 (3)	0.7735 (3)	0.080*
C5	0.5589 (3)	0.2002 (3)	0.6308 (3)	0.0276 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0381 (11)	0.0450 (13)	0.0321 (11)	0.0104 (9)	0.0037 (10)	0.0089 (10)
O2	0.099 (3)	0.058 (2)	0.046 (2)	−0.025 (2)	0.000	0.000
N1	0.0289 (12)	0.0284 (12)	0.0367 (13)	−0.0004 (10)	0.0056 (11)	−0.0003 (12)
N2	0.0298 (13)	0.0344 (14)	0.054 (2)	0.0040 (10)	0.0030 (13)	−0.0013 (14)
N3	0.0335 (13)	0.0349 (14)	0.0331 (12)	0.0082 (11)	0.0011 (11)	0.0030 (11)
N4	0.0372 (14)	0.0402 (15)	0.0430 (15)	0.0095 (10)	0.0067 (13)	−0.0004 (13)
C1	0.0301 (14)	0.0284 (14)	0.032 (2)	0.0004 (12)	0.0007 (14)	−0.0002 (13)
C2	0.0294 (15)	0.041 (2)	0.049 (2)	−0.0050 (14)	0.0074 (15)	−0.005 (2)
C3	0.0250 (14)	0.046 (2)	0.063 (2)	−0.0011 (14)	0.006 (2)	−0.005 (2)
C4	0.036 (2)	0.0238 (14)	0.036 (2)	0.0007 (11)	0.0063 (15)	0.0053 (13)
C5	0.0276 (14)	0.0228 (15)	0.0324 (15)	−0.0033 (11)	0.0004 (13)	0.0030 (12)

Geometric parameters (Å, º)

O1—C5	1.222 (4)	N4—H4D	0.90
O2—H2A	0.850 (5)	N4—H4C	0.90
N1—C1	1.364 (4)	C1—C1^i	1.453 (5)
N1—C2	1.374 (4)	C2—C3	1.346 (5)
N1—C4	1.455 (3)	C2—H2	0.96
N2—C1	1.325 (4)	C3—H3	0.96
N2—C3	1.366 (4)	C4—C5	1.521 (4)
N3—C5	1.331 (4)	C4—H4A	0.96
N3—N4	1.410 (4)	C4—H4B	0.96
N3—H3A	0.90
C1—N1—C2	107.1 (2)	N1—C2—H2	127.8
C1—N1—C4	129.2 (2)	C2—C3—N2	111.6 (3)
C2—N1—C4	123.7 (3)	C2—C3—H3	124.7
C1—N2—C3	104.9 (3)	N2—C3—H3	123.8
C5—N3—N4	123.6 (3)	N1—C4—C5	110.8 (2)
C5—N3—H3A	118.4	N1—C4—H4A	109.98
N4—N3—H3A	117.96	C5—C4—H4A	109.65
N3—N4—H4D	108.9	N1—C4—H4B	109.1
N3—N4—H4C	109.8	C5—C4—H4B	109.33
H4D—N4—H4C	109.2	H4A—C4—H4B	108.0
N2—C1—N1	111.0 (2)	O1—C5—N3	124.0 (3)
N2—C1—C1^i	125.3 (3)	O1—C5—C4	122.4 (2)
N1—C1—C1^i	123.6 (3)	N3—C5—C4	113.5 (3)
C3—C2—N1	105.5 (3)	H4D—O2—H2A	102
C3—C2—H2	126.7	H4D—O2—H2A^ii	122

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2a···N4^iii	0.85 (1)	2.27 (2)	3.080 (3)	161 (4)
N3—H3a···O1^iv	0.90	1.93	2.830 (3)	176
N4—H4c···N2^v	0.90	2.41	3.260 (4)	157
N4—H4d···O2	0.90	2.30	3.165 (4)	161

Symmetry codes: (iii) y+1/2, −x+1, z−1/4; (iv) −y+1, x−1/2, z+1/4; (v) −y+3/2, x, z−1/4.

(II) 1,1'-di(hydrazinopropanoyl)-2,2'-biimidazole

Crystal data

C12H18N8O2	F(000) = 324
Mr = 306.33	Dx = 1.387 Mg m^−3 Dm = not determined Mg m^−3 Dm measured by ?
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 100 reflections
a = 10.0505 (5) Å	θ = 7.7–19.7°
b = 4.9326 (2) Å	µ = 0.10 mm^−1
c = 15.4663 (7) Å	T = 293 K
β = 106.904 (3)°	Rectangular block, colorless
V = 733.61 (6) Å^3	0.50 × 0.36 × 0.30 mm
Z = 2

Data collection

Siemens–Bruker P4 diffractometer	Rint = 0.026
Radiation source: normal-focus sealed tube	θmax = 25.0°, θmin = 2.1°
Graphite monochromator	h = −11→1
θ/2θ scans	k = −5→1
1899 measured reflections	l = −17→18
1287 independent reflections	3 standard reflections every 100 reflections
1078 reflections with I > 2 σ(I)	intensity decay: ave. of 1.7 % in σ(I)s

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.101	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0496P)^2 + 0.2482P] where P = (Fo^2 + 2Fc^2)/3
1283 reflections	(Δ/σ)max < 0.001
100 parameters	Δρmax = 0.18 e Å^−3
0 restraints	Δρmin = −0.19 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 on F² for ALL reflections except for 4 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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
O1	0.84779 (13)	1.0937 (2)	0.87916 (9)	0.0451 (4)
N1	0.56996 (15)	0.7806 (3)	0.94387 (9)	0.0388 (4)
N2	0.3743 (2)	0.5492 (3)	0.88759 (10)	0.0447 (4)
N3	0.8717 (2)	0.6660 (3)	0.83692 (11)	0.0442 (4)
H3A	0.8687 (2)	0.4891 (3)	0.85044 (11)	0.080*
N4	0.9002 (2)	0.7358 (3)	0.75521 (12)	0.0526 (4)
H4C	0.8281 (2)	0.8303 (3)	0.72000 (12)	0.080*
H4D	0.9776 (2)	0.8382 (3)	0.76777 (12)	0.080*
C1	0.4855 (2)	0.5785 (3)	0.95835 (11)	0.0356 (4)
C2	0.5070 (2)	0.8814 (4)	0.85903 (12)	0.0471 (5)
H2	0.5411 (2)	1.0261 (4)	0.82984 (12)	0.080*
C3	0.3888 (2)	0.7385 (4)	0.82599 (13)	0.0498 (5)
H3	0.3239 (2)	0.7658 (4)	0.76737 (13)	0.080*
C4	0.7041 (2)	0.8773 (4)	1.00172 (12)	0.0457 (5)
H4A	0.7096 (2)	0.8431 (4)	1.06378 (12)	0.080*
H4B	0.7105 (2)	1.0695 (4)	0.99418 (12)	0.080*
C5	0.8255 (2)	0.7397 (4)	0.97986 (12)	0.0440 (5)
H5A	0.8075 (2)	0.5485 (4)	0.97329 (12)	0.080*
H5B	0.9086 (2)	0.7653 (4)	1.02893 (12)	0.080*
C6	0.8484 (2)	0.8480 (3)	0.89408 (11)	0.0348 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0572 (8)	0.0255 (7)	0.0574 (8)	−0.0039 (5)	0.0240 (6)	0.0030 (5)
N1	0.0434 (8)	0.0360 (8)	0.0413 (8)	−0.0038 (6)	0.0193 (6)	−0.0002 (6)
N2	0.0431 (8)	0.0426 (9)	0.0472 (8)	0.0008 (7)	0.0111 (7)	0.0019 (7)
N3	0.0506 (9)	0.0278 (8)	0.0577 (9)	−0.0011 (7)	0.0211 (7)	0.0014 (7)
N4	0.0595 (10)	0.0459 (10)	0.0607 (10)	0.0020 (8)	0.0302 (8)	−0.0024 (8)
C1	0.0390 (9)	0.0311 (9)	0.0400 (8)	0.0003 (7)	0.0168 (7)	−0.0024 (7)
C2	0.0574 (11)	0.0443 (11)	0.0453 (10)	0.0019 (9)	0.0239 (9)	0.0080 (8)
C3	0.0541 (11)	0.0514 (12)	0.0432 (10)	0.0065 (9)	0.0130 (8)	0.0052 (9)
C4	0.0551 (11)	0.0424 (10)	0.0433 (9)	−0.0160 (9)	0.0203 (8)	−0.0069 (8)
C5	0.0428 (10)	0.0393 (10)	0.0464 (10)	−0.0074 (8)	0.0073 (8)	0.0069 (8)
C6	0.0276 (8)	0.0275 (9)	0.0480 (9)	−0.0048 (6)	0.0090 (7)	0.0013 (7)

Geometric parameters (Å, º)

O1—C6	1.233 (2)	C1—C1^i	1.458 (3)
N1—C1	1.369 (2)	C2—C3	1.348 (3)
N1—C2	1.374 (2)	C2—H2	0.96
N1—C4	1.464 (2)	C3—H3	0.96
N2—C1	1.325 (2)	C4—C5	1.518 (3)
N2—C3	1.372 (2)	C4—H4A	0.96
N3—C6	1.328 (2)	C4—H4B	0.96
N3—N4	1.417 (2)	C5—C6	1.509 (2)
N3—H3A	0.90	C5—H5A	0.96
N4—H4C	0.90	C5—H5B	0.96
N4—H4D	0.90
C1—N1—C2	106.51 (15)	C2—C3—H3	124.48
C1—N1—C4	129.90 (15)	N2—C3—H3	124.87
C2—N1—C4	123.6 (2)	N1—C4—C5	112.03 (14)
C1—N2—C3	105.4 (2)	N1—C4—H4A	109.25
C6—N3—N4	123.37 (15)	C5—C4—H4A	109.09
C6—N3—H3A	118.44	N1—C4—H4B	109.28
N4—N3—H3A	118.19	C5—C4—H4B	109.11
N3—N4—H4C	109.24	H4A—C4—H4B	108.0
N3—N4—H4D	109.25	C6—C5—C4	112.07 (15)
H4C—N4—H4D	109.5	C6—C5—H5A	109.11
N2—C1—N1	111.01 (15)	C4—C5—H5A	108.88
N2—C1—C1^i	125.1 (2)	C6—C5—H5B	109.15
N1—C1—C1^i	123.9 (2)	C4—C5—H5B	109.65
C3—C2—N1	106.5 (2)	H5A—C5—H5B	107.9
C3—C2—H2	127.38	O1—C6—N3	122.2 (2)
N1—C2—H2	126.14	O1—C6—C5	121.3 (2)
C2—C3—N2	110.6 (2)	N3—C6—C5	116.58 (15)

Symmetry code: (i) −x+1, −y+1, −z+2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4C···N2^ii	0.90	2.47	3.367 (2)	174
N4—H4D···N4^iii	0.90	2.40	3.213 (2)	151
N3—H3A···O1^iv	0.90	2.03	2.923 (2)	176
C3—H3···O1^v	0.96	2.56	3.441 (2)	152
C4—H4A···N2^i	0.96	2.32	2.960 (2)	123
C4—H4B···O1	0.96	2.55	2.900 (2)	102
C5—H5B···O1^vi	0.96	2.54	3.471 (2)	162

Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) −x+1, y+1/2, −z+3/2; (iii) −x+2, y+1/2, −z+3/2; (iv) x, y−1, z; (v) −x+1, y−1/2, −z+3/2; (vi) −x+2, −y+2, −z+2.