Dichloridobis[5-nitro-1-trimethyl­silyl­methyl-1H-benzimidazole-κN 3]cobalt(II) N,N-dimethyl­formamide solvate

Mehmet Akkurt; Şerife Pınar Yalçın; Nihat Şireci; Hasan Küçükbay; M Nawaz Tahir

doi:10.1107/S1600536810003922

. 2010 Feb 6;66(Pt 3):m253–m254. doi: 10.1107/S1600536810003922

Dichloridobis[5-nitro-1-trimethylsilylmethyl-1H-benzimidazole-κN ³]cobalt(II) N,N-dimethylformamide solvate

Mehmet Akkurt ^a,^*, Şerife Pınar Yalçın ^b, Nihat Şireci ^c, Hasan Küçükbay ^c, M Nawaz Tahir ^d

PMCID: PMC2983604 PMID: 21580208

Abstract

The title compound, [CoCl₂(C₁₁H₁₅N₃O₂Si)₂]·C₃H₇NO, was synthesized from 5-nitro-1-trimethylsilylmethyl-1H-benzimidazole and cobalt(II) chloride in dimethylformamide. The Co^II atom is coordinated in a distorted tetrahedral environment by two Cl atoms and two N atoms. In the crystal structure, there are a number of C—H⋯Cl and C—H⋯O hydrogen-bonding interactions between symmetry-related molecules.

Related literature

For the structures and properties of benzimidazole compounds and their metal complexes, see: Akkurt et al. (2005 ▶); Castro et al. (2002 ▶); Küçükbay et al. (1996 ▶, 2004 ▶, 2009 ▶); Liu et al. (2004 ▶); Lukevics et al. (2001 ▶); Pınar et al. (2006 ▶); Pan & Xu (2004 ▶); Türktekin et al. (2004 ▶); Tavman et al. (2005 ▶); Özdemir et al. (2005 ▶); Çetinkaya et al. (1996 ▶).

Experimental

Crystal data

[CoCl₂(C₁₁H₁₅N₃O₂Si)₂]·C₃H₇NO
M _r = 701.63
Triclinic,
a = 9.8982 (4) Å
b = 11.6936 (5) Å
c = 15.9293 (6) Å
α = 106.041 (2)°
β = 107.408 (2)°
γ = 99.040 (3)°
V = 1631.97 (12) Å³
Z = 2
Mo Kα radiation
μ = 0.81 mm⁻¹
T = 100 K
0.20 × 0.12 × 0.08 mm

Data collection

Bruker APEXII QUAZAR diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.890, T _max = 0.937
30895 measured reflections
8851 independent reflections
5342 reflections with I > 2σ(I)
R _int = 0.059

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.123
S = 1.02
8851 reflections
387 parameters
H-atom parameters constrained
Δρ_max = 0.90 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810003922/bt5186sup1.cif

e-66-0m253-sup1.cif^{(34.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810003922/bt5186Isup2.hkl

e-66-0m253-Isup2.hkl^{(424.2KB, 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
C5—H5⋯Cl1ⁱ	0.95	2.79	3.564 (3)	140
C7—H7⋯O5ⁱⁱ	0.95	2.32	3.132 (4)	143
C8—H8B⋯O5ⁱⁱ	0.99	2.54	3.406 (4)	145
C19—H19A⋯Cl2ⁱⁱⁱ	0.99	2.67	3.659 (3)	175
C19—H19B⋯O4ⁱ	0.99	2.38	3.182 (4)	137
C22—H22C⋯Cl1^iv	0.98	2.82	3.695 (3)	149
C24—H24A⋯O5	0.98	2.42	2.793 (5)	102

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

Acknowledgments

We thank Dr Holger Ott (Bruker AXS GmbH, Karlsruhe, Germany) for the data collection. HK & NŞ also thank İnönü University Research Fund (BAPB-2008–60) for financial support of this study.

supplementary crystallographic information

Comment

Benzimidazole compounds and their metal complexes have been extensively investigated for their versatile properties such as biological activities (Küçükbay et al., 2004; Çetinkaya et al., 1996; Küçükbay et al., 2009; Tavman et al., 2005) and catalytic activities of their metal complexes in many organic syntheses (Küçükbay et al.,1996, Özdemir et al., 2005). Contrary to an extensive chemistry about substituted alkyl derivatives of benzimidazole, there are a limited number of studies of alkylsilyl substituted benzimidazoles (Lukevics et al., 2001). Alkylsilyl substituted benzimidazole derivatives exhibit important in vitro cytotoxicactivity. The insertion of the silicon atom into the N-alkyl chain in benzimidazoles increases the cytotoxic activity. For example,1-(3-trimethylsilylpropyl)benzimidazole inhibits carcinoma S-180 tumour growth in dose 1 mg kg^-1 by 62 % (on ICR mice) (Lukevics et al., 2001). The objective of the present study was to synthesize a trimethylsilylmethyl and NO₂substituted benzimidazole Co^II complex for the first time and compare it to those of related benzimidazole derivatives (Türktekin et al., 2004; Pınar et al., 2006; Akkurt et al., 2005) reported previously.

In the title molecule (Fig. 1), the Co^II atom is coordinated in a distorted tetrahedral environment by two Cl atoms and two N atoms. The bond lengths involving the Co atoms are Co1—N1 = 2.013 (3), Co1—N4 = 2.013 (2), Co1—Cl1 = 2.2330 (10) and Co1—Cl2 = 2.2455 (9) Å, while the angles around the Co atom are Cl1— Co1— Cl2 = 112.94 (4), Cl1— Co1— N1 = 111.06 (8), Cl1— Co1— N4 = 110.18 (7), Cl2— Co1— N1 = 106.74 (7), Cl2— Co1— N4 = 111.81 (7) and N1— Co1— N4 = 103.67 (9)°. The average Co—N bond length of 2.013 (3)Å is almost equal to the value of 2.008 (2)Å in dichlorobis[1-(2-ethoxyethyl)-1H-benzimidazole-κN³]cobalt(II) (Türktekin et al., 2004) and 2.032 (2) Å inbis[1-(but-2-enyl)-5-nitro-1H-benzimidazole-κN³]\ dichlorocobalt(II) (Pınar et al., 2006).

The Co—Cl bond lengths [2.2330 (10) and 2.2455 (9) Å] are comparable to the values of 2.2525 (8)Å inquinolinium trichloro(quinoline-N)cobaltate(II) (Pan & Xu, 2004) and 2.236 (1) Å in dichlorobis(1-propylimidazolidine-2-thione-κS)cobalt(II) (Castro et al., 2002) and 2.2680 (8) in bis[1-(but-2-enyl)-5-nitro-1H-benzimidazole-κN³]\ dichlorocobalt(II)(Pınar et al., 2006), but shorter than the value of 2.391 (1)Å observed in aquachlorobis(1,10-phenanthroline)cobalt(II)chloride dimethyl formamide solvate (Liu et al., 2004).

The two benzimidazole ring systems N1/N2/C1–C7 and N4/N5/C12–C18 are almost planar, with maximum deviations of -0.037 (3) for C6 and -0.016 (2) for N4, respectively. The dihedral angle between them is 64.54 (10)°. The angles around the Si atoms with a distorted tetrahedral geometry rang from 106.02 (18)° to 113.60 (17)°.

The crystal structure of the title compound is stabilized by C—H···Cl and C—H···O hydrogen-bonding interactions (Fig. 2 and Table 1).

Experimental

1-(Trimethylsilylmethyl)-5-nitrobenzimidazole used in this work as a starting compounds were prepared from reaction of 5(6)-methylbenzimidazole, (chloromethyl)trimethylsilane and KOH under reflux in EtOH.

A solution of 1-(trimethylsilylmethyl)-5-nitrobenzimidazole (2.0 g, 8.02 mmol) and cobalt(II) chloride (0.52 g, 4.01 mmol) in DMF (4 ml) was heated under reflux for 2 h. The mixture was then cooled to room temperature, after which the solvent was then removed from the filtrate in vacuo. The precipitate was then crystallized from EtOH / DMF(2:1). Yield : 2.30 g, 91%; m.p.: 473-474 K. Analysis calculated for C₂₂H₃₀N₆O₄Si₂CoCl₂.HCON(CH₃)₂: C 42.80, H 5.32, N 13.97%. Found: C 42.79, H 5.31, N 13.92%. IR : ν_(C=N): 1523 cm^-1. ¹H-NMR (DMSO-d₆): δ = 7.97 ppm (s, 2H, N=CH—N), 6.39 (m, 6H, Ar—H), 4.25 (m, 4H, CH₂Si), -0.27 (s, 18H, Si (CH₃)₃).