Crystal structure of bis-[2-(1H-benzimidazol-2-yl-κN 3)aniline-κN]bis-(nitrato-κO)cadmium(II).

In the title compound, [Cd(NO3)2(C13H11N3)2], the CdII atom lies on a twofold rotation axis and is coordinated by four N atoms and two O atoms, provided by two bidentate 2-(1H-benzimidazol-2-yl)aniline ligands, and two nitrato O atoms, forming a distorted octa-hedral geometry [range of bond angles around the Cd atom = 73.82 (2)-106.95 (8)°]. In the ligand, the dihedral angle between the aniline ring and the benzimidazole ring system is 30.43 (7)°. The discrete complex mol-ecule is stabilized by an intra-molecular N-H⋯O hydrogen bond. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules, forming a three-dimensional network. © Kim and Kang 2019.

Chemical context

Azole and benzazole derivatives are well-known nitro­gen-containing heterocyclic compounds, and are of great inter­est because of their broad spectrum of biological activity (Esparza-Ruiz et al., 2011 ▸; Hock et al., 2013 ▸). Imidazole is an aza­pyrrole in which the nitro­gen atoms are separated by one carbon atom. Benzimidazole, a fused heterocycle with benzene and imidazole, is associated with a wide array of pharmacological activities (Akhtar et al., 2017 ▸), and benzimidazole derivatives exhibit a wide range of various biological activities. These include bactericidal (Carcanague et al., 2002 ▸) and fungicidal (Lezcano et al., 2002 ▸; Aghatabay et al., 2007 ▸) properties. Their metal complexes have been shown to display anti­tumor activity and are important biological mol­ecules (Sánchez-Guadarrama et al., 2009 ▸; Ramla et al., 2007 ▸; Wang et al., 2007 ▸). Recently, we reported on the synthesis and structural features of Zn (Kim & Kang, 2015a ▸) and Ag (Kim & Kang, 2015b ▸) complexes with benzimidazole derivatives. In this work, we have synthesized the title compound and characterized it by single crystal X-ray crystallography.

Structural commentary

The mol­ecular structure of the title complex is shown in Fig. 1 ▸. The complex lies about a twofold rotation axis which passes through the CdII atom, the coordination geometry around which is distorted octa­hedral with two O atoms of two nitrato ligands and four N atoms of two bidentate 2-(1H-benzimidazol-2-yl)aniline ligands. The Cd—N and Cd—O bond lengths [Cd1—N2 = 2.317 (2), Cd1—N17 = 2.437 (2) and Cd1—O19 = 2.3175 (19) Å] are comparable with those of other Cd complexes (Barszcz et al., 2013 ▸; Jalilehvand et al., 2009 ▸). The bond angles around the Cd1 atom are in the range of 73.82 (8)–106.95 (8)°. The dihedral angle between the benzimidazole (N2/C3–C8/N9/C10) ring system and the aniline (C11–C16/N17) plane in the bidentate ligand is 30.43 (7)°. This twisting is a driving force in the formation of weak Cd1—N17 bonding, this bond being [2.437 (2) Å] a little longer than Cd1—N2 [2.317 (2) Å]. This elongation was also observed in our previous studies of imidazole­aniline–metal complexes (Zn: Kim & Kang, 2015a ▸; Ag: Kim & Kang, 2015b ▸). The N2—C10 bond length of 1.327 (3) Å in the imidazole ring shows double-bond character compared to the other N—C bond lengths [N2—C3 = 1.397 (3), C8—N9 = 1.384 (3) and N9—C10 = 1.355 (3) Å]. The discrete mol­ecule is stabilized by an intra­molecular N—H⋯O hydrogen bond (Table 1 ▸).

Figure 1

Mol­ecular structure of the title compound, showing the atom-numbering scheme and displacement ellipsoids drawn at the 30% probability level. The intramolecular N—H⋯O hydrogen bonds are indicated by dashed lines. [Symmetry code: (i) −x + 1, y, −z + .]

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N9—H9⋯O20i	0.75 (3)	2.39 (3)	3.012 (3)	140 (3)
N9—H9⋯O21i	0.75 (3)	2.51 (3)	3.238 (3)	163 (3)
N17—H17A⋯O21	0.86 (3)	2.34 (3)	2.973 (3)	131 (2)
N17—H17B⋯O20ii	0.79 (3)	2.24 (3)	3.024 (3)	170 (3)

Symmetry codes: (i) ; (ii) .

Supra­molecular features

In the crystal, mol­ecules are linked by a series of N—H⋯O inter­actions. The nitrate group containing oxygen atom O21 forms both intra- and inter­molecular hydrogen bonds. Mol­ecules are arranged into a zigzag chain along the c-axis direction via an N—H⋯O hydrogen bond (N17—H17B⋯O20ii; symmetry code as in Table 1 ▸; Fig. 2 ▸). The other N—H⋯O hydrogen bonds (N9—H9⋯O20i and N9—H9⋯O21i; Table 1 ▸) link the mol­ecules into a three-dimensional network (Fig. 3 ▸).

Figure 2

Partial packing diagram of the title compound, showing mol­ecules linked by inter­molecular N—H⋯O hydrogen bonds (dashed lines), viewed along the a-axis direction.

Figure 3

A view along the b axis of the crystal packing of the title compound, showing the three-dimensional network linked of molecules linked by N—H⋯O hydrogen bonds (dashed lines, Table 1 ▸).

Database survey

A search of the Cambridge Structural Database (CSD, Version 5.40, Feb. 2019; Groom et al., 2016 ▸) gave 4678 entries for crystal structures related to benzimidazoles. However, there are only 14 entries involving the ligands 2-(1H-benzimidazol-2-yl)aniline or 2-(2-amino­phen­yl)-1H-benzimidazole with a transition metal. These include Ni (refcode EWUZOM; Esparza-Ruiz et al., 2011 ▸), Zn [AWOLEE (Eltayeb et al., 2011 ▸) and JUFCOE (Kim & Kang, 2015a ▸)], Ru (NUNLID; Małecki, 2012 ▸) and Re (UYELEQ; Machura et al., 2011 ▸).

Synthesis and crystallization

Chemicals were obtained commercially in reagent grade and used as received. Solvents were dried using standard procedures described in the literature. To a stirred solution of Cd(NO3)·4H2O (0.154 g, 0.5 mmol) in ethanol (20 ml) was added a solution of 2-(1H-benzimidazol-2-yl)aniline (0.209 g, 1.0 mmol) in ethanol (10 ml) at 333 K. After 24 h of stirring, the title complex was obtained as a white powder. The powder was filtered off and washed with ethanol. Colourless crystals of the title complex were obtained by slow evaporation of the methanol solvent at room temperature within two weeks.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. H atoms of the NH and NH2 groups were located in a difference-Fourier map and refined freely [refined distances: N—H = 0.75 (3)–0.86 (3) Å]. Other H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å, and with U iso(H) = 1.2U eq(C).

Table 2

Experimental details

Crystal data
Chemical formula	[Cd(NO3)2(C13H11N3)2]
M r	654.91
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	296
a, b, c (Å)	14.6899 (4), 15.0250 (3), 12.2269 (3)
β (°)	106.8431 (15)
V (Å3)	2582.90 (11)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.91
Crystal size (mm)	0.15 × 0.13 × 0.12
Data collection
Diffractometer	Bruker SMART CCD area-detector
Absorption correction	Multi-scan (SADABS; Bruker, 2012 ▸)
T min, T max	0.546, 0.726
No. of measured, independent and observed [I > 2σ(I)] reflections	11727, 3087, 2729
R int	0.031
(sin θ/λ)max (Å−1)	0.667
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.035, 0.078, 1.06
No. of reflections	3087
No. of parameters	198
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.82, −0.35

Computer programs: SMART and SAINT (Bruker, 2012 ▸), SHELXS2013 (Sheldrick, 2008 ▸), SHELXL2013 (Sheldrick, 2015 ▸) and ORTEP-3 for Windows and WinGX (Farrugia, 2012 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989019012416/is5523sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989019012416/is5523Isup2.hkl

CCDC reference: 1951821

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Cd(NO3)2(C13H11N3)2]	F(000) = 1320
Mr = 654.91	Dx = 1.684 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 14.6899 (4) Å	Cell parameters from 5554 reflections
b = 15.0250 (3) Å	θ = 2.4–28.0°
c = 12.2269 (3) Å	µ = 0.91 mm−1
β = 106.8431 (15)°	T = 296 K
V = 2582.90 (11) Å3	Block, colourless
Z = 4	0.15 × 0.13 × 0.12 mm

Bruker SMART CCD area-detector diffractometer	2729 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.031
φ and ω scans	θmax = 28.3°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2012)	h = −19→17
Tmin = 0.546, Tmax = 0.726	k = −19→20
11727 measured reflections	l = −16→16
3087 independent reflections

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.035	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.078	w = 1/[σ2(Fo2) + (0.0422P)2 + 0.8298P] where P = (Fo2 + 2Fc2)/3
S = 1.06	(Δ/σ)max = 0.001
3087 reflections	Δρmax = 0.82 e Å−3
198 parameters	Δρmin = −0.35 e Å−3

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.

	x	y	z	Uiso*/Ueq
Cd1	0.5000	0.62214 (2)	0.7500	0.03198 (10)
N2	0.59443 (14)	0.72062 (13)	0.68561 (17)	0.0345 (4)
C3	0.60535 (16)	0.72958 (16)	0.5763 (2)	0.0357 (5)
C4	0.57954 (19)	0.6718 (2)	0.4835 (2)	0.0470 (7)
H4	0.5507	0.6173	0.4877	0.056*
C5	0.5990 (2)	0.6994 (2)	0.3847 (3)	0.0562 (8)
H5	0.5826	0.6628	0.3206	0.067*
C6	0.6425 (2)	0.7807 (2)	0.3793 (3)	0.0594 (8)
H6	0.6538	0.7970	0.3110	0.071*
C7	0.6695 (2)	0.8379 (2)	0.4705 (3)	0.0495 (7)
H7	0.6997	0.8917	0.4663	0.059*
C8	0.64909 (17)	0.81075 (17)	0.5695 (2)	0.0373 (5)
N9	0.66350 (16)	0.85021 (15)	0.67542 (19)	0.0380 (5)
H9	0.696 (2)	0.889 (2)	0.697 (3)	0.054 (10)*
C10	0.62989 (16)	0.79434 (15)	0.7417 (2)	0.0323 (5)
C11	0.62624 (16)	0.81778 (15)	0.8566 (2)	0.0334 (5)
C12	0.6159 (2)	0.90724 (18)	0.8829 (2)	0.0443 (6)
H12	0.6155	0.9506	0.8285	0.053*
C13	0.6065 (2)	0.93253 (19)	0.9865 (3)	0.0540 (7)
H13	0.5984	0.9922	1.0017	0.065*
C14	0.6090 (2)	0.86845 (19)	1.0683 (3)	0.0520 (7)
H14	0.6028	0.8852	1.1390	0.062*
C15	0.62043 (18)	0.78054 (18)	1.0463 (2)	0.0428 (6)
H15	0.6230	0.7383	1.1027	0.051*
C16	0.62832 (16)	0.75354 (16)	0.9400 (2)	0.0331 (5)
N17	0.63122 (16)	0.66172 (14)	0.9164 (2)	0.0367 (5)
H17A	0.674 (2)	0.6453 (18)	0.885 (3)	0.040 (8)*
H17B	0.640 (2)	0.6314 (18)	0.972 (3)	0.037 (8)*
N18	0.63805 (17)	0.48486 (14)	0.6968 (2)	0.0457 (5)
O19	0.55302 (15)	0.50697 (13)	0.6581 (2)	0.0584 (6)
O20	0.67211 (17)	0.43131 (17)	0.6449 (2)	0.0793 (8)
O21	0.6875 (2)	0.51407 (17)	0.7877 (2)	0.0861 (8)

	U11	U22	U33	U12	U13	U23
Cd1	0.02785 (14)	0.02431 (13)	0.04112 (16)	0.000	0.00582 (10)	0.000
N2	0.0292 (11)	0.0388 (11)	0.0348 (11)	−0.0043 (8)	0.0083 (8)	−0.0076 (9)
C3	0.0269 (12)	0.0433 (14)	0.0362 (14)	0.0012 (9)	0.0078 (10)	−0.0038 (11)
C4	0.0370 (15)	0.0591 (18)	0.0432 (16)	−0.0004 (12)	0.0090 (11)	−0.0138 (13)
C5	0.0521 (18)	0.076 (2)	0.0366 (16)	0.0124 (15)	0.0060 (13)	−0.0119 (15)
C6	0.066 (2)	0.079 (2)	0.0350 (16)	0.0263 (17)	0.0172 (14)	0.0110 (16)
C7	0.0522 (18)	0.0522 (17)	0.0479 (17)	0.0117 (13)	0.0205 (13)	0.0133 (14)
C8	0.0321 (13)	0.0434 (14)	0.0361 (14)	0.0049 (10)	0.0092 (10)	0.0016 (11)
N9	0.0379 (12)	0.0354 (11)	0.0402 (12)	−0.0066 (9)	0.0107 (9)	−0.0014 (10)
C10	0.0267 (12)	0.0323 (12)	0.0351 (13)	−0.0033 (9)	0.0046 (9)	−0.0005 (10)
C11	0.0320 (13)	0.0318 (12)	0.0355 (13)	−0.0066 (9)	0.0084 (10)	−0.0045 (10)
C12	0.0547 (17)	0.0322 (12)	0.0476 (16)	−0.0077 (11)	0.0175 (13)	−0.0027 (12)
C13	0.070 (2)	0.0368 (15)	0.0595 (19)	−0.0068 (13)	0.0257 (16)	−0.0164 (14)
C14	0.066 (2)	0.0513 (17)	0.0434 (16)	−0.0139 (14)	0.0238 (14)	−0.0129 (13)
C15	0.0465 (16)	0.0441 (15)	0.0365 (15)	−0.0082 (11)	0.0097 (11)	−0.0019 (11)
C16	0.0265 (12)	0.0341 (12)	0.0357 (13)	−0.0047 (9)	0.0042 (9)	−0.0031 (10)
N17	0.0372 (13)	0.0329 (11)	0.0374 (13)	0.0007 (9)	0.0068 (10)	0.0019 (10)
N18	0.0556 (15)	0.0329 (11)	0.0444 (14)	0.0093 (10)	0.0079 (11)	−0.0038 (10)
O19	0.0457 (12)	0.0411 (11)	0.0832 (16)	0.0077 (8)	0.0105 (11)	−0.0139 (10)
O20	0.0740 (16)	0.0897 (19)	0.0650 (15)	0.0407 (14)	0.0059 (12)	−0.0261 (14)
O21	0.099 (2)	0.0681 (16)	0.0665 (17)	0.0171 (14)	−0.0153 (14)	−0.0294 (13)

Cd1—N2	2.317 (2)	N9—C10	1.355 (3)
Cd1—N2i	2.317 (2)	N9—H9	0.75 (3)
Cd1—O19	2.3175 (19)	C10—C11	1.464 (3)
Cd1—O19i	2.3175 (19)	C11—C16	1.398 (3)
Cd1—N17	2.437 (2)	C11—C12	1.401 (3)
Cd1—N17i	2.437 (2)	C12—C13	1.368 (4)
N2—C10	1.327 (3)	C12—H12	0.9300
N2—C3	1.397 (3)	C13—C14	1.381 (4)
C3—C4	1.392 (4)	C13—H13	0.9300
C3—C8	1.392 (3)	C14—C15	1.368 (4)
C4—C5	1.384 (4)	C14—H14	0.9300
C4—H4	0.9300	C15—C16	1.398 (4)
C5—C6	1.389 (5)	C15—H15	0.9300
C5—H5	0.9300	C16—N17	1.413 (3)
C6—C7	1.373 (4)	N17—H17A	0.86 (3)
C6—H6	0.9300	N17—H17B	0.79 (3)
C7—C8	1.390 (4)	N18—O20	1.218 (3)
C7—H7	0.9300	N18—O21	1.219 (3)
C8—N9	1.384 (3)	N18—O19	1.246 (3)
N2—Cd1—N2i	100.60 (10)	C7—C8—C3	122.0 (3)
N2—Cd1—O19	89.64 (8)	C10—N9—C8	108.1 (2)
N2i—Cd1—O19	163.78 (7)	C10—N9—H9	125 (3)
N2—Cd1—O19i	163.78 (7)	C8—N9—H9	125 (3)
N2i—Cd1—O19i	89.64 (8)	N2—C10—N9	111.4 (2)
O19—Cd1—O19i	83.39 (11)	N2—C10—C11	125.3 (2)
N2—Cd1—N17	73.82 (8)	N9—C10—C11	123.1 (2)
N2i—Cd1—N17	88.10 (7)	C16—C11—C12	118.4 (2)
O19—Cd1—N17	106.95 (8)	C16—C11—C10	122.3 (2)
O19i—Cd1—N17	94.19 (8)	C12—C11—C10	119.2 (2)
N2—Cd1—N17i	88.10 (7)	C13—C12—C11	121.8 (3)
N2i—Cd1—N17i	73.82 (8)	C13—C12—H12	119.1
O19—Cd1—N17i	94.18 (8)	C11—C12—H12	119.1
O19i—Cd1—N17i	106.95 (8)	C12—C13—C14	119.2 (3)
N17—Cd1—N17i	151.75 (10)	C12—C13—H13	120.4
C10—N2—C3	106.1 (2)	C14—C13—H13	120.4
C10—N2—Cd1	122.79 (16)	C15—C14—C13	120.6 (3)
C3—N2—Cd1	129.23 (15)	C15—C14—H14	119.7
C4—C3—C8	121.3 (2)	C13—C14—H14	119.7
C4—C3—N2	129.8 (2)	C14—C15—C16	120.7 (3)
C8—C3—N2	109.0 (2)	C14—C15—H15	119.6
C5—C4—C3	116.7 (3)	C16—C15—H15	119.6
C5—C4—H4	121.7	C15—C16—C11	119.2 (2)
C3—C4—H4	121.7	C15—C16—N17	119.2 (2)
C4—C5—C6	121.3 (3)	C11—C16—N17	121.4 (2)
C4—C5—H5	119.3	C16—N17—Cd1	110.21 (15)
C6—C5—H5	119.3	C16—N17—H17A	116.2 (19)
C7—C6—C5	122.7 (3)	Cd1—N17—H17A	93 (2)
C7—C6—H6	118.6	C16—N17—H17B	113 (2)
C5—C6—H6	118.6	Cd1—N17—H17B	118 (2)
C6—C7—C8	116.1 (3)	H17A—N17—H17B	105 (3)
C6—C7—H7	122.0	O20—N18—O21	119.1 (3)
C8—C7—H7	122.0	O20—N18—O19	119.7 (2)
N9—C8—C7	132.5 (3)	O21—N18—O19	121.1 (2)
N9—C8—C3	105.5 (2)	N18—O19—Cd1	117.12 (17)
C10—N2—C3—C4	−179.5 (3)	C8—N9—C10—N2	0.1 (3)
Cd1—N2—C3—C4	−15.2 (4)	C8—N9—C10—C11	−174.8 (2)
C10—N2—C3—C8	0.4 (3)	N2—C10—C11—C16	31.7 (4)
Cd1—N2—C3—C8	164.74 (16)	N9—C10—C11—C16	−154.1 (2)
C8—C3—C4—C5	−0.4 (4)	N2—C10—C11—C12	−145.3 (2)
N2—C3—C4—C5	179.5 (3)	N9—C10—C11—C12	28.9 (4)
C3—C4—C5—C6	0.3 (4)	C16—C11—C12—C13	−1.0 (4)
C4—C5—C6—C7	0.6 (5)	C10—C11—C12—C13	176.1 (3)
C5—C6—C7—C8	−1.2 (4)	C11—C12—C13—C14	1.3 (5)
C6—C7—C8—N9	−178.7 (3)	C12—C13—C14—C15	−0.2 (5)
C6—C7—C8—C3	1.1 (4)	C13—C14—C15—C16	−1.0 (5)
C4—C3—C8—N9	179.5 (2)	C14—C15—C16—C11	1.3 (4)
N2—C3—C8—N9	−0.4 (3)	C14—C15—C16—N17	−174.2 (3)
C4—C3—C8—C7	−0.3 (4)	C12—C11—C16—C15	−0.2 (3)
N2—C3—C8—C7	179.8 (2)	C10—C11—C16—C15	−177.2 (2)
C7—C8—N9—C10	180.0 (3)	C12—C11—C16—N17	175.1 (2)
C3—C8—N9—C10	0.2 (3)	C10—C11—C16—N17	−1.9 (3)
C3—N2—C10—N9	−0.3 (3)	C15—C16—N17—Cd1	120.8 (2)
Cd1—N2—C10—N9	−165.88 (16)	C11—C16—N17—Cd1	−54.5 (3)
C3—N2—C10—C11	174.4 (2)	O20—N18—O19—Cd1	−172.3 (2)
Cd1—N2—C10—C11	8.8 (3)	O21—N18—O19—Cd1	9.7 (3)

D—H···A	D—H	H···A	D···A	D—H···A
N9—H9···O20ii	0.75 (3)	2.39 (3)	3.012 (3)	140 (3)
N9—H9···O21ii	0.75 (3)	2.51 (3)	3.238 (3)	163 (3)
N17—H17A···O21	0.86 (3)	2.34 (3)	2.973 (3)	131 (2)
N17—H17B···O20iii	0.79 (3)	2.24 (3)	3.024 (3)	170 (3)