Bis(2-aminomethyl-1H-benzimidazole-κ2 N 2,N 3)bis­(nitrato-κO)copper(II)

Jing Zhao; Heng Zhang; Xueliang Zhai; Guoyi Zhu

doi:10.1107/S1600536812020910

. 2012 May 16;68(Pt 6):m767. doi: 10.1107/S1600536812020910

Bis(2-aminomethyl-1H-benzimidazole-κ² N ²,N ³)bis(nitrato-κO)copper(II)

Jing Zhao ^a,^b, Heng Zhang ^c, Xueliang Zhai ^c, Guoyi Zhu ^a,^*

PMCID: PMC3379102 PMID: 22719323

Abstract

In the title compound, [Cu(NO₃)₂(C₈H₉N₃)₂], the Cu^II atom, lying on an inversion center, has a distorted octahedral coordination environment defined by four N atoms from two chelating 2-aminomethyl-1H-benzimidazole ligands and two O atoms from two monodentate nitrate anions. In the crystal, N—H⋯O hydrogen bonds link the complex molecules into a three-dimensional network. An intramolecular N—H⋯O hydrogen bond is also observed.

Related literature

For the synthesis of the 2-(2-aminomethyl)benzimidazole ligand, see: Pascaly et al. (2001 ▶). For the structures and properties of transition metal complexes with 2-(2-aminomethyl)benzimidazole ligands, see: Gable et al. (1996 ▶); Gómez-Segura et al. (2006 ▶); He et al. (2003 ▶); Jiang et al. (2004 ▶). graphic file with name e-68-0m767-scheme1.jpg

Experimental

Crystal data

[Cu(NO₃)₂(C₈H₉N₃)₂]
M _r = 481.93
Trigonal,
a = 24.6913 (8) Å
c = 7.9620 (5) Å
V = 4203.8 (4) Å³
Z = 9
Mo Kα radiation
μ = 1.23 mm⁻¹
T = 184 K
0.34 × 0.21 × 0.11 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.681, T _max = 0.877
7196 measured reflections
1833 independent reflections
1764 reflections with I > 2σ(I)
R _int = 0.015

Refinement

R[F ² > 2σ(F ²)] = 0.023
wR(F ²) = 0.063
S = 1.04
1833 reflections
142 parameters
H-atom parameters constrained
Δρ_max = 0.52 e Å⁻³
Δρ_min = −0.23 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 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812020910/hy2548sup1.cif

e-68-0m767-sup1.cif^{(15.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812020910/hy2548Isup2.hkl

e-68-0m767-Isup2.hkl^{(90.6KB, 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
N3—H3A⋯O1ⁱ	0.92	2.42	3.266 (2)	153
N3—H3A⋯O3ⁱ	0.92	2.37	3.0521 (17)	131
N3—H3B⋯O1ⁱⁱ	0.92	2.33	3.1036 (19)	142
N2—H2⋯O3ⁱⁱⁱ	0.88	2.50	3.0276 (18)	119
N2—H2⋯O3^iv	0.88	2.40	3.0823 (18)	134
N2—H2⋯O2ⁱⁱⁱ	0.88	2.20	2.8901 (17)	135

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

This work was supported by the Youth Foundation of Hebei Normal University (No. L2006Q20).

supplementary crystallographic information

Comment

Benzimidazole is of considerable interest as a ligand for transition metal ions. Some of their polyfunctional derivatives have been proved to possess extensive biological activities (Gómez-Segura et al., 2006). Therefore, substituted benzimidazoles have attracted interest of various research groups, especially the substitution at 1, 2 and 5 positions of the benzimidazole ring is very important for their coordination behavior. The 2-(2-aminomethyl)-1H-benzimidazole (AMBI) ligand is a suitable model system for compounds of this sort, which is a bidentate ligand and can chelate a 3d metal ion through two nitrogen atoms of the pendant aminomethyl group and the imidazole ring (Gable et al., 1996; He et al., 2003; Jiang et al., 2004). Moreover, AMBI possesses a larger conjugated π-system and a nitrogen electron-donor of the secondary amine group, which has an important effect on the structures and functions of the complexes. On the other hand, metalloproteins that contain Cu are widespread. Characterization of model Cu complexes that mimic Cu proteins has led to a better understanding of the chemistry of Cu in biological systems. A new copper(II) complex with AMBI, which is reported in this paper, may be of interest with respect to both of the above-mentioned areas.

In the title compound, as shown in Fig. 1, two bidentate AMBI ligands are coordinated to the Cu^II atom via two N atoms and two nitrate anions are coordinated to the Cu^II atom via one O atom. The coordination geometry around the Cu^II atom, which lies on an inversion center, is distorted octahedral, with a bite angle of 83.84 (5)° for two bidentate ligands. The other cis bond angles at the Cu^II atom fall in the range of 80.71 (5)–99.29 (5)° and the trans bond angles are 180°, suggesting a significant deviation from a perfect octahedral coordination. The Cu—N bond lengths are 1.9839 (12) and 2.0244 (12) Å, with an average of 2.0042 (12) Å. The Cu—O bond length is 2.5870 (12) Å. Extensive N—H···O hydrogen bonds in the crystal, as shown in Fig. 2 and Table 1, link the complex molecules into a three-dimensional network.

Experimental

The title compound was prepared by adding a methanol-water solution (4:1 v/v, 5 ml) of Cu(NO₃)₂.3H₂O (0.1 mmol) to a methanol solution (5 ml) of 2-(2-aminomethyl)benzimidazole (0.2 mmol) (Pascaly et al., 2001). The blue mixture was stirred at room temperature for 4 h and then filtered. Purple crystals suitable for X-ray diffraction were obtained by slow evaporation of the solvent after several days. Analysis, calculated for C₁₆H₁₈CuN₈O₆: C 39.88, H 3.76, N 23.25%; found: C 39.92, H 3.75, N 23.30%.