A new one-dimensional Cd^II coordination polymer with a two-dimensional layered structure incorporating 2-[(1H-imidazol-1-yl)meth­yl]-1H-benzimidazole and benzene-1,2-di­carboxyl­ate ligands

The N-heterocyclic ligand 2-[(1H-imidazol-1-yl)meth­yl]-1H-benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and inter­esting properties. In the coordination polymer catena-poly[[cadmium(II)-bis­[[mu]-benzene-1,2-di­carboxyl­ato-[kappa]⁴O¹,O^1':O²,O^2']-cadmium(II)-bis­{[mu]-2-[(1H-imidazol-1-yl)meth­yl]-1H-benzimidazole}-[kappa]²N²:N³;[kappa]²N³:N²] di­methyl­formamide disolvate], {[Cd(C₈H₄O₄)(C₁₁H₁₀N₄)]·C₃H₇NO}_n, (I), each Cd^II ion exhibits an irregular octa­hedral CdO₄N₂ coordination geometry and is coordinated by four O atoms from two symmetry-related ben­zene-1,2-di­­carboxyl­ate (1,2-bdic^2-) ligands and two N atoms from two symmetry-related imb ligands. Two Cd^II ions are connected by two benzene-1,2-di­carboxyl­ate ligands to generate a binuclear [Cd₂(1,2-bdic)₂] unit. The binuclear units are further connected into a one-dimensional chain by pairs of bridging imb ligands. These one-dimensional chains are further connected through N-H...O hydrogen bonds and [pi]-[pi] inter­actions, leading to a two-dimensional layered structure. The di­methyl­formamide solvent mol­ecules are organized in dimeric pairs via weak inter­actions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.

S1. Introduction

Recently, we have been inter­ested in the design and synthesis of coordination polymers based on N-heterocyclic ligand 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb), since it has rich coordination modes and can lead to polymers with intriguing structures and inter­esting properties (Wang et al., 2010; Li et al., 2012). Up to now, more than 40 coordination polymers constructed from the imb ligand have been reported, ranging from zero- to three-dimensional structures. Among the reported imb-based polymers, several are constructed using a mixture of imb and benzene­dicarboxyl­ate isomers, such as {[Co(1,4-bdic)(imb)₂(H₂O)₂].2H₂O}_n, (II), {[Ni(1,4-bdic)(imb)₂(H₂O)₂].2H₂O}_n, (III) (Wang et al., 2013), {[Cu(1,3-bdic)(imb)].1.5H₂O.DMF}_n, (IV), {[Cu(1,3-bdic)(imb)].2H₂O}_n, (V) (Yan et al., 2012), {[Cd(1,3-bdic)(imb) (H₂O)].CH₃OH}_n, (VI) (Huang et al., 2014), and [Zn₂(1,2-bdic)₂(imb)₂]_n, (VII) (Huang, Liu, Yang & Meng, 2015). Further studies showed that in polymers (II)–(VI), the 1,4-bdic^2- (or 1,3-bdic^2-) dianionic ligands coordinate to the metal ions by a bridging mode, forming one-dimensional ···M–bdic–M–bdic··· chains. In contrast, in polymer (VII), the 1,2-bdic^2- dianionic ligands coordinate to the Zn^II ions in a cis conformation, forming a binuclear [Zn₂(1,2-bdic)₂] unit. In this paper, we continue the use of imb and 1,2-bdic^2- as mixed ligands to self-assemble with Cd(NO₃)₂ and obtained a new one-dimensional coordination polymer, namely {[Cd(1,2-bdic)(imb)].DMF}_n, (I). In addition, to the single-crystal structure, the IR spectrum and the thermostability and fluorescence properties were investigated.

S2. Experimental

Elemental analyses (C, H and N) were carried out on a FLASH EA 1112 elemental analyzer. IR data were recorded on a Bruker TENSOR 27 spectrophotometer with KBr pellets from 400 to 4000 cm^-1. TG measurement was performed by heating the sample from 303 to 973 K at a rate of 10 K min^-1 in air on a NETZSCH STA 409 PC/PG differential thermal analyzer. Steady-state fluorescence measurements were performed using an F-7000 fluorescence spectrophotometer at room temperature in the solid state.

S2.1. Synthesis and crystallization

2-(1H-Imidazolyl-1-methyl)-1H-benzimidazole (imb) was synthesized according to the literature method of Meng et al. (2010), with some modification, i.e. 1H-tetra­zole-1-acetic acid was replaced with 2-(imidazol-1-yl)acetic acid, but the other experimental conditions were left unchanged. An aqueous solution (2 ml) of imb (0.1 mmol) was added dropwise to an aqueous solution (2 ml) of Cd(NO₃)₂ (0.1 mmol) and then a DMF solution (2 ml) of 1,2-H₂bdic (0.1 mmol) was added dropwise to the above mixture to give a clear solution at room temperature. Colorless crystals (57% yield based on Cd) suitable for X-ray analysis were obtained by slow crystallization in a closed container over a period of five weeks. Elemental analysis calculated for C₂₂H₂₁CdN₅O₅: C 48.23, H 3.86, N 12.78%; found: C 47.72, H 3.90, N 13.11%. IR (KBr disc, ν, cm^-1): 3444 (m), 3125 (w), 3102 (w), 3008 (w), 1602 (s), 1574 (s), 1524 (w), 1495 (w), 1454 (w), 1384 (s), 1242 (m), 1225 (m), 1089 (m), 1026 (m), 745 (s).

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. Crystal data, data collection and structure refinement details are summarized in Table 1. The DMF solvent molecule could be identified from the residual electron-density peaks. 10 restraints were used to fasten the DMF molecule since it incurred deformation in the process of refinement. H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (aromatic), 0.96 (methyl), 0.97 (methyl­ene) and N—H = 0.86 Å. The formyl H atom was positioned by using the `Calculate Hydrogens' instruction (SHELXL2014; Sheldrick, 2015) and refined as riding, with C—H = 0.93 Å. H atoms were assigned U_iso(H) = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C,N) otherwise.

S3. Results and discussion

Single-crystal X-ray analysis has revealed that the title complex, (I), crystallizes as a one-dimensional polymeric structure in the triclinic space group P1. The asymmetric unit contains one Cd^II ion, one 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) ligand, one benzene-1,2-di­carboxyl­ate (1,2-bdic^2-) dianionic ligand and one uncoordinated di­methyl­formamide (DMF) molecule. As illustrated in Fig. 1, each Cd1 ion is six-coordinated and located in an irregular o­cta­hedral CdO₄N₂ coordination environment with four O atoms [O1, O2, O3ⁱ and O4ⁱ; symmetry code: (i) -x+2, -y+1, -z+2] from two chelating carboxyl­ate groups of two symmetry-related 1,2-bdic^2- ligands and two N atoms [N1 and N4ⁱⁱ; symmetry code: (ii) -x+1, -y+2, -z+2] from two symmetry-related imb ligands. The significant deviations from an o­cta­hedral CdO₄N₂ coordination geometry involve the O atoms of the chelating carboxyl­ate groups. The Cd1—N and Cd1—O bond lengths (Table 2) are close to those reported in other Cd^II coordination polymers, i.e. {[Cd(1,3-bdic)(imb) (H₂O)].CH₃OH}_n [Cd—N = 2.320 (2)–2.321 (2) Å and Cd—O = 2.332 (2)–2.5831 (18) Å; Huang et al., 2014] and {[Cd(imb)(Hbtc)(CH₃OH)].2H₂O.CH₃OH}_n [H₃btc = benzene-1,3,5-tri­carb­oxy­lic acid; Cd—N = 2.241 (4)–2.265 (3) Å and Cd—O = 2.334 (3)–2.570 (3) Å; Huang et al., 2014].

As shown in Fig. 1, the benzene-1,2-di­carb­oxy­lic acid molecule is fully deprotonated and the dihedral angles between the mean plane defined by the benzene ring and the planes of the carboxyl­ate ligands are ca 86.8 and 7.3°, respectively. The 1,2-bdic^2- ligands serve as bis-connectors through two chelating carboxyl­ate groups bridging two Cd^II ions to afford a [Cd₂(1,2-bdic)₂] binuclear unit with a Cd1···Cd1ⁱ separation of 5.506 (2) Å. The binuclear units are further connected by pairs of bridging imb ligands through two N atoms from the benzimidazole and imidazole rings, with a Cd1···Cd1ⁱⁱ separation of 6.414 (3) Å, forming an infinite one-dimensional chain (Fig. 2). For each imb ligand, the dihedral angle between the mean plane defined by the benzimidazole and imidazole rings is ca 77.2°. The imidazole rings from adjacent chains are parallel to each other, with a centroid–centroid distance of ca 3.8058 (12) Å, which is in the range for common π–π inter­actions (Fig. 3). The one-dimensional chains are further connected through N—H···O hydrogen bonds between the benzimidazole groups and carboxyl­ate groups and π–π inter­actions, leading to a two-dimensional layered structure parallel to the ab plane. The DMF solvent molecules are organized in dimeric pairs via weak inter­actions.

Thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses of polymer (I) were performed in air. As shown in Fig. 4, the TG curve of the polymer shows that the first mass loss of 13.36% occurs between 378 and 498 K, corresponding to the release of DMF solvent molecules (calculated 13.33%). Continuous mass loss from 547 to 873 K corresponds to the gradual decomposition of the 1,2-bdic^2- and imb ligands. Finally, a plateau occurs from 873 to 973 K. The residue equals 23.67%, which is attributed to CdO (calculated 23.44%). In addition, the corresponding endothermic peaks (423 K) and exothermic peaks (619 and 808 K) in the DSC curve also record the process of weight loss.

The photoluminescence properties of polymer (I) were investigated in the solid state at room temperature. As shown in Fig. 5, (I) exhibits a photoluminescence peak at a maximum at 374 nm upon excitation at 340 nm. To understand the nature of the emission spectra, the luminescence properties of the free ligands under the same experimental conditions were recorded for comparison. Free imb displays a photoluminescence with an emission maximum at 310 nm upon excitation at 268 nm, 1,2-H₂bdc gives an emission band at 340 nm upon excitation at 277 nm. In contrast to the free ligands, polymer (I) shows a slightly red-shifted emission band caused by the metal–ligand coordination inter­actions which influence the rigidity and asymmetry of the ligands (Huang, Wang, Li & Meng, 2015). The emission observed in (I) is neither MLCT(metal-to-ligand charge transfer) nor LMCT (ligand-to-metal charge transfer) since the Cd^II ions are difficult to oxidize or reduce due to the d¹⁰ configuration (Chen et al., 2009). As a result, the emission observed in (I) likely originates from the intra­ligand transitions of imb and 1,2-bdic^2- ligands. The N-donors and O-donors [N-/O-donor atoms or N-/O-donor ligands] contribute to the fluorescence emission of polymer (I) simultaneously.

Although the overall structure of the title polymer, (I), is similar to that of polymeric [Zn₂(1,2-bdic)₂(imb)₂]_n, (VII), reported in our previous work (Huang, Liu, Yang & Meng, 2015), their detailed structures are significantly different. First, in (VII), there are two crystallographically distinct Zn^II ions, two crystallographically distinct 1,2-bdic^2- dianionic ligands, and two crystallographically distinct imb ligands in each asymmetric unit. But the Cd^II ions, imb ligands, 1,2-bdic^2- dianionic ligands and DMF molecules in polymer (I) are equivalent, respectively. Second, as the radius of the Cd^II ion is larger than that of Zn^II ion, the Zn^II ion in (VII) is four-(or five-)coordinated, while the Cd^II ion in (I) is six-coordinated. Third, in (VII), the carboxyl­ate groups of the 1,2-bdic^2- ligand coordinate to the Zn^II ions in monodentate or chelating mode, while the carboxyl­ate groups of the 1,2-bdic^2- ligand in (I) coordinate to the Cd^II ions in chelating fashion. Fourth, compared with the emission spectrum of (VII), that of (I) exhibits a red shift of 29 nm. These results indicate that changing of the central metal ion can influence the coordination environment of the central metal ion and the coordination mode of the 1,2-bdic^2- ligands, and thus influence the detailed architectures of the polymer formed, and ultimately lead to the different photophysical properties.

Structure description

Recently, we have been inter­ested in the design and synthesis of coordination polymers based on N-heterocyclic ligand 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb), since it has rich coordination modes and can lead to polymers with intriguing structures and inter­esting properties (Wang et al., 2010; Li et al., 2012). Up to now, more than 40 coordination polymers constructed from the imb ligand have been reported, ranging from zero- to three-dimensional structures. Among the reported imb-based polymers, several are constructed using a mixture of imb and benzene­dicarboxyl­ate isomers, such as {[Co(1,4-bdic)(imb)₂(H₂O)₂].2H₂O}_n, (II), {[Ni(1,4-bdic)(imb)₂(H₂O)₂].2H₂O}_n, (III) (Wang et al., 2013), {[Cu(1,3-bdic)(imb)].1.5H₂O.DMF}_n, (IV), {[Cu(1,3-bdic)(imb)].2H₂O}_n, (V) (Yan et al., 2012), {[Cd(1,3-bdic)(imb) (H₂O)].CH₃OH}_n, (VI) (Huang et al., 2014), and [Zn₂(1,2-bdic)₂(imb)₂]_n, (VII) (Huang, Liu, Yang & Meng, 2015). Further studies showed that in polymers (II)–(VI), the 1,4-bdic^2- (or 1,3-bdic^2-) dianionic ligands coordinate to the metal ions by a bridging mode, forming one-dimensional ···M–bdic–M–bdic··· chains. In contrast, in polymer (VII), the 1,2-bdic^2- dianionic ligands coordinate to the Zn^II ions in a cis conformation, forming a binuclear [Zn₂(1,2-bdic)₂] unit. In this paper, we continue the use of imb and 1,2-bdic^2- as mixed ligands to self-assemble with Cd(NO₃)₂ and obtained a new one-dimensional coordination polymer, namely {[Cd(1,2-bdic)(imb)].DMF}_n, (I). In addition, to the single-crystal structure, the IR spectrum and the thermostability and fluorescence properties were investigated.

Elemental analyses (C, H and N) were carried out on a FLASH EA 1112 elemental analyzer. IR data were recorded on a Bruker TENSOR 27 spectrophotometer with KBr pellets from 400 to 4000 cm^-1. TG measurement was performed by heating the sample from 303 to 973 K at a rate of 10 K min^-1 in air on a NETZSCH STA 409 PC/PG differential thermal analyzer. Steady-state fluorescence measurements were performed using an F-7000 fluorescence spectrophotometer at room temperature in the solid state.

Single-crystal X-ray analysis has revealed that the title complex, (I), crystallizes as a one-dimensional polymeric structure in the triclinic space group P1. The asymmetric unit contains one Cd^II ion, one 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) ligand, one benzene-1,2-di­carboxyl­ate (1,2-bdic^2-) dianionic ligand and one uncoordinated di­methyl­formamide (DMF) molecule. As illustrated in Fig. 1, each Cd1 ion is six-coordinated and located in an irregular o­cta­hedral CdO₄N₂ coordination environment with four O atoms [O1, O2, O3ⁱ and O4ⁱ; symmetry code: (i) -x+2, -y+1, -z+2] from two chelating carboxyl­ate groups of two symmetry-related 1,2-bdic^2- ligands and two N atoms [N1 and N4ⁱⁱ; symmetry code: (ii) -x+1, -y+2, -z+2] from two symmetry-related imb ligands. The significant deviations from an o­cta­hedral CdO₄N₂ coordination geometry involve the O atoms of the chelating carboxyl­ate groups. The Cd1—N and Cd1—O bond lengths (Table 2) are close to those reported in other Cd^II coordination polymers, i.e. {[Cd(1,3-bdic)(imb) (H₂O)].CH₃OH}_n [Cd—N = 2.320 (2)–2.321 (2) Å and Cd—O = 2.332 (2)–2.5831 (18) Å; Huang et al., 2014] and {[Cd(imb)(Hbtc)(CH₃OH)].2H₂O.CH₃OH}_n [H₃btc = benzene-1,3,5-tri­carb­oxy­lic acid; Cd—N = 2.241 (4)–2.265 (3) Å and Cd—O = 2.334 (3)–2.570 (3) Å; Huang et al., 2014].

As shown in Fig. 1, the benzene-1,2-di­carb­oxy­lic acid molecule is fully deprotonated and the dihedral angles between the mean plane defined by the benzene ring and the planes of the carboxyl­ate ligands are ca 86.8 and 7.3°, respectively. The 1,2-bdic^2- ligands serve as bis-connectors through two chelating carboxyl­ate groups bridging two Cd^II ions to afford a [Cd₂(1,2-bdic)₂] binuclear unit with a Cd1···Cd1ⁱ separation of 5.506 (2) Å. The binuclear units are further connected by pairs of bridging imb ligands through two N atoms from the benzimidazole and imidazole rings, with a Cd1···Cd1ⁱⁱ separation of 6.414 (3) Å, forming an infinite one-dimensional chain (Fig. 2). For each imb ligand, the dihedral angle between the mean plane defined by the benzimidazole and imidazole rings is ca 77.2°. The imidazole rings from adjacent chains are parallel to each other, with a centroid–centroid distance of ca 3.8058 (12) Å, which is in the range for common π–π inter­actions (Fig. 3). The one-dimensional chains are further connected through N—H···O hydrogen bonds between the benzimidazole groups and carboxyl­ate groups and π–π inter­actions, leading to a two-dimensional layered structure parallel to the ab plane. The DMF solvent molecules are organized in dimeric pairs via weak inter­actions.

Thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses of polymer (I) were performed in air. As shown in Fig. 4, the TG curve of the polymer shows that the first mass loss of 13.36% occurs between 378 and 498 K, corresponding to the release of DMF solvent molecules (calculated 13.33%). Continuous mass loss from 547 to 873 K corresponds to the gradual decomposition of the 1,2-bdic^2- and imb ligands. Finally, a plateau occurs from 873 to 973 K. The residue equals 23.67%, which is attributed to CdO (calculated 23.44%). In addition, the corresponding endothermic peaks (423 K) and exothermic peaks (619 and 808 K) in the DSC curve also record the process of weight loss.

The photoluminescence properties of polymer (I) were investigated in the solid state at room temperature. As shown in Fig. 5, (I) exhibits a photoluminescence peak at a maximum at 374 nm upon excitation at 340 nm. To understand the nature of the emission spectra, the luminescence properties of the free ligands under the same experimental conditions were recorded for comparison. Free imb displays a photoluminescence with an emission maximum at 310 nm upon excitation at 268 nm, 1,2-H₂bdc gives an emission band at 340 nm upon excitation at 277 nm. In contrast to the free ligands, polymer (I) shows a slightly red-shifted emission band caused by the metal–ligand coordination inter­actions which influence the rigidity and asymmetry of the ligands (Huang, Wang, Li & Meng, 2015). The emission observed in (I) is neither MLCT(metal-to-ligand charge transfer) nor LMCT (ligand-to-metal charge transfer) since the Cd^II ions are difficult to oxidize or reduce due to the d¹⁰ configuration (Chen et al., 2009). As a result, the emission observed in (I) likely originates from the intra­ligand transitions of imb and 1,2-bdic^2- ligands. The N-donors and O-donors [N-/O-donor atoms or N-/O-donor ligands] contribute to the fluorescence emission of polymer (I) simultaneously.

Although the overall structure of the title polymer, (I), is similar to that of polymeric [Zn₂(1,2-bdic)₂(imb)₂]_n, (VII), reported in our previous work (Huang, Liu, Yang & Meng, 2015), their detailed structures are significantly different. First, in (VII), there are two crystallographically distinct Zn^II ions, two crystallographically distinct 1,2-bdic^2- dianionic ligands, and two crystallographically distinct imb ligands in each asymmetric unit. But the Cd^II ions, imb ligands, 1,2-bdic^2- dianionic ligands and DMF molecules in polymer (I) are equivalent, respectively. Second, as the radius of the Cd^II ion is larger than that of Zn^II ion, the Zn^II ion in (VII) is four-(or five-)coordinated, while the Cd^II ion in (I) is six-coordinated. Third, in (VII), the carboxyl­ate groups of the 1,2-bdic^2- ligand coordinate to the Zn^II ions in monodentate or chelating mode, while the carboxyl­ate groups of the 1,2-bdic^2- ligand in (I) coordinate to the Cd^II ions in chelating fashion. Fourth, compared with the emission spectrum of (VII), that of (I) exhibits a red shift of 29 nm. These results indicate that changing of the central metal ion can influence the coordination environment of the central metal ion and the coordination mode of the 1,2-bdic^2- ligands, and thus influence the detailed architectures of the polymer formed, and ultimately lead to the different photophysical properties.

Synthesis and crystallization

2-(1H-Imidazolyl-1-methyl)-1H-benzimidazole (imb) was synthesized according to the literature method of Meng et al. (2010), with some modification, i.e. 1H-tetra­zole-1-acetic acid was replaced with 2-(imidazol-1-yl)acetic acid, but the other experimental conditions were left unchanged. An aqueous solution (2 ml) of imb (0.1 mmol) was added dropwise to an aqueous solution (2 ml) of Cd(NO₃)₂ (0.1 mmol) and then a DMF solution (2 ml) of 1,2-H₂bdic (0.1 mmol) was added dropwise to the above mixture to give a clear solution at room temperature. Colorless crystals (57% yield based on Cd) suitable for X-ray analysis were obtained by slow crystallization in a closed container over a period of five weeks. Elemental analysis calculated for C₂₂H₂₁CdN₅O₅: C 48.23, H 3.86, N 12.78%; found: C 47.72, H 3.90, N 13.11%. IR (KBr disc, ν, cm^-1): 3444 (m), 3125 (w), 3102 (w), 3008 (w), 1602 (s), 1574 (s), 1524 (w), 1495 (w), 1454 (w), 1384 (s), 1242 (m), 1225 (m), 1089 (m), 1026 (m), 745 (s).

Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 1. Crystal data, data collection and structure refinement details are summarized in Table 1. The DMF solvent molecule could be identified from the residual electron-density peaks. 10 restraints were used to fasten the DMF molecule since it incurred deformation in the process of refinement. H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (aromatic), 0.96 (methyl), 0.97 (methyl­ene) and N—H = 0.86 Å. The formyl H atom was positioned by using the `Calculate Hydrogens' instruction (SHELXL2014; Sheldrick, 2015) and refined as riding, with C—H = 0.93 Å. H atoms were assigned U_iso(H) = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C,N) otherwise.

Computing details

Data collection: CrystalClear (Rigaku/MSC, 2004); cell refinement: CrystalClear (Rigaku/MSC, 2004); data reduction: CrystalClear (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. The coordination environment of the Cd^II ion in the title polymer, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry codes: (i) -x + 2, -y + 1, -z + 2; (ii) -x + 1, -y + 2, -z + 2.]
	Fig. 2. A view of the one-dimensional structure of the title polymer. [Symmetry codes: (i) -x + 2, -y + 1, -z + 2; (ii) -x + 1, -y + 2, -z + 2.].
	Fig. 3. The two-dimensional structure of the title polymer linked by hydrogen bonds and π–π interactions. Adjacent chains are shown in different colours. Yellow dashed lines represent hydrogen bonds and black dashed lines represent π–π interactions.
	Fig. 4. Thermogravimetric (TG) and differential scanning calorimetry (DSC) curves for the title polymer.
	Fig. 5. Solid-state emission spectra of free imb, 1,2-H2bdic and the title polymer.

catena-Poly[[cadmium(II)-bis[µ-benzene-1,2-dicarboxylato-κ⁴O¹,O^1':O²,O^2']-cadmium(II)-bis{µ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole}-κ²N²:N³;κ²N³:N²] dimethylformamide disolvate]

Crystal data

[Cd(C8H4O4)(C11H10N4)]·C3H7NO	Z = 2
Mr = 547.84	F(000) = 552
Triclinic, P1	Dx = 1.545 Mg m^−3
a = 8.5502 (17) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.2713 (19) Å	Cell parameters from 3457 reflections
c = 15.363 (3) Å	θ = 2.5–27.8°
α = 88.48 (3)°	µ = 0.97 mm^−1
β = 83.73 (3)°	T = 293 K
γ = 76.65 (3)°	Prism, colourless
V = 1177.9 (4) Å^3	0.19 × 0.13 × 0.12 mm

Data collection

Rigaku Saturn diffractometer	5550 independent reflections
Radiation source: fine-focus sealed tube	4610 reflections with I > 2σ(I)
Detector resolution: 28.5714 pixels mm^-1	Rint = 0.046
ω scans	θmax = 27.9°, θmin = 2.5°
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2004)	h = −10→11
Tmin = 0.820, Tmax = 1.000	k = −12→12
14703 measured reflections	l = −20→20

Refinement

Refinement on F^2	10 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.058	H-atom parameters constrained
wR(F^2) = 0.140	w = 1/[σ^2(Fo^2) + (0.0654P)^2 + 0.3963P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
5550 reflections	Δρmax = 1.01 e Å^−3
298 parameters	Δρmin = −0.64 e Å^−3

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cd1	0.76797 (4)	0.71354 (3)	0.92926 (2)	0.03756 (13)
N1	0.5440 (4)	0.7365 (4)	0.8603 (3)	0.0424 (9)
N2	0.3105 (5)	0.7191 (5)	0.8176 (3)	0.0502 (11)
H2A	0.2139	0.7056	0.8203	0.060*
N3	0.2489 (5)	0.8241 (4)	1.0201 (3)	0.0400 (9)
N4	0.1993 (5)	1.0546 (4)	1.0641 (3)	0.0433 (9)
O1	0.8730 (4)	0.4925 (4)	0.8485 (2)	0.0495 (8)
O2	1.0155 (4)	0.6618 (3)	0.8346 (2)	0.0445 (8)
O3	1.1641 (5)	0.3940 (4)	0.9441 (2)	0.0559 (10)
O4	1.3880 (5)	0.2229 (5)	0.9192 (3)	0.0654 (11)
C1	0.9984 (6)	0.5322 (5)	0.8206 (3)	0.0385 (10)
C2	1.1279 (6)	0.4283 (5)	0.7637 (3)	0.0410 (10)
C3	1.1207 (8)	0.4376 (7)	0.6742 (4)	0.0655 (16)
H3A	1.0438	0.5125	0.6512	0.079*
C4	1.2264 (9)	0.3369 (9)	0.6188 (4)	0.086 (2)
H4A	1.2199	0.3434	0.5587	0.103*
C5	1.3417 (9)	0.2265 (8)	0.6520 (5)	0.090 (2)
H5A	1.4108	0.1568	0.6147	0.108*
C6	1.3540 (8)	0.2200 (7)	0.7395 (4)	0.0685 (17)
H6A	1.4333	0.1461	0.7612	0.082*
C7	1.2506 (6)	0.3215 (5)	0.7976 (3)	0.0431 (11)
C8	1.2697 (6)	0.3124 (5)	0.8933 (3)	0.0434 (11)
C9	0.5473 (6)	0.7645 (5)	0.7709 (3)	0.0433 (11)
C10	0.6683 (7)	0.7972 (7)	0.7109 (4)	0.0596 (15)
H10A	0.7676	0.8032	0.7280	0.072*
C11	0.6358 (9)	0.8203 (8)	0.6251 (4)	0.0778 (19)
H11A	0.7138	0.8437	0.5837	0.093*
C12	0.4868 (9)	0.8089 (9)	0.5993 (5)	0.085 (2)
H12A	0.4689	0.8248	0.5408	0.101*
C13	0.3678 (8)	0.7756 (8)	0.6566 (4)	0.0727 (18)
H13A	0.2693	0.7685	0.6388	0.087*
C14	0.4004 (6)	0.7523 (6)	0.7441 (3)	0.0509 (13)
C15	0.4000 (6)	0.7112 (5)	0.8849 (3)	0.0409 (11)
C16	0.3356 (6)	0.6841 (5)	0.9765 (3)	0.0454 (11)
H16A	0.2626	0.6181	0.9759	0.054*
H16B	0.4242	0.6360	1.0092	0.054*
C17	0.2913 (5)	0.9537 (5)	1.0105 (3)	0.0437 (11)
H17A	0.3754	0.9707	0.9708	0.052*
C18	0.1207 (7)	0.8418 (6)	1.0821 (4)	0.0537 (14)
H18A	0.0648	0.7705	1.1022	0.064*
C19	0.0906 (7)	0.9845 (6)	1.1090 (4)	0.0570 (14)
H19A	0.0086	1.0283	1.1514	0.068*
N5	0.1884 (12)	0.7279 (11)	0.3925 (6)	0.138 (4)
O5	0.0549 (13)	0.7944 (12)	0.5270 (7)	0.209 (5)
C21	0.1220 (19)	0.8519 (15)	0.3408 (10)	0.305 (14)
H21A	0.1839	0.8461	0.2845	0.458*
H21B	0.0120	0.8517	0.3336	0.458*
H21C	0.1254	0.9417	0.3695	0.458*
C22	0.127 (2)	0.7047 (12)	0.4762 (7)	0.320 (16)
H22	0.1443	0.6066	0.4949	0.383*
C20	0.305 (2)	0.5929 (17)	0.3545 (13)	0.46 (3)
H20A	0.3457	0.6138	0.2959	0.685*
H20B	0.3940	0.5656	0.3897	0.685*
H20C	0.2519	0.5128	0.3537	0.685*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0354 (2)	0.0336 (2)	0.0430 (2)	−0.00685 (14)	−0.00268 (14)	−0.00228 (14)
N1	0.033 (2)	0.045 (2)	0.049 (2)	−0.0097 (17)	−0.0042 (17)	−0.0054 (18)
N2	0.034 (2)	0.057 (3)	0.061 (3)	−0.0119 (19)	−0.006 (2)	−0.013 (2)
N3	0.039 (2)	0.0299 (19)	0.051 (2)	−0.0097 (16)	−0.0016 (18)	−0.0020 (17)
N4	0.046 (2)	0.0275 (19)	0.055 (2)	−0.0074 (16)	0.0005 (19)	−0.0024 (17)
O1	0.0421 (19)	0.0418 (19)	0.064 (2)	−0.0132 (15)	0.0076 (16)	−0.0079 (16)
O2	0.0401 (18)	0.0357 (17)	0.056 (2)	−0.0076 (14)	0.0003 (15)	−0.0062 (15)
O3	0.070 (3)	0.049 (2)	0.0395 (19)	0.0061 (18)	−0.0098 (17)	−0.0001 (16)
O4	0.047 (2)	0.077 (3)	0.065 (3)	0.000 (2)	−0.0050 (19)	0.016 (2)
C1	0.042 (3)	0.038 (2)	0.033 (2)	−0.005 (2)	−0.0026 (19)	0.0004 (18)
C2	0.041 (3)	0.041 (3)	0.040 (2)	−0.008 (2)	0.001 (2)	−0.008 (2)
C3	0.074 (4)	0.069 (4)	0.046 (3)	−0.005 (3)	−0.002 (3)	−0.003 (3)
C4	0.109 (6)	0.097 (5)	0.038 (3)	−0.002 (5)	0.004 (3)	−0.013 (3)
C5	0.105 (6)	0.081 (5)	0.062 (4)	0.009 (4)	0.029 (4)	−0.023 (4)
C6	0.069 (4)	0.061 (4)	0.059 (4)	0.010 (3)	0.013 (3)	−0.008 (3)
C7	0.043 (3)	0.040 (3)	0.044 (3)	−0.008 (2)	0.003 (2)	−0.001 (2)
C8	0.041 (3)	0.039 (3)	0.051 (3)	−0.011 (2)	−0.003 (2)	−0.002 (2)
C9	0.038 (3)	0.044 (3)	0.045 (3)	−0.002 (2)	−0.005 (2)	−0.008 (2)
C10	0.047 (3)	0.072 (4)	0.060 (4)	−0.015 (3)	0.000 (3)	−0.005 (3)
C11	0.079 (5)	0.097 (5)	0.052 (4)	−0.017 (4)	0.008 (3)	0.002 (3)
C12	0.085 (5)	0.116 (6)	0.049 (4)	−0.014 (4)	−0.011 (4)	−0.009 (4)
C13	0.065 (4)	0.096 (5)	0.057 (4)	−0.012 (4)	−0.014 (3)	−0.014 (3)
C14	0.046 (3)	0.061 (3)	0.046 (3)	−0.010 (2)	−0.007 (2)	−0.014 (2)
C15	0.037 (3)	0.033 (2)	0.051 (3)	−0.0046 (19)	−0.002 (2)	−0.012 (2)
C16	0.049 (3)	0.032 (2)	0.056 (3)	−0.012 (2)	0.001 (2)	−0.005 (2)
C17	0.032 (2)	0.037 (3)	0.061 (3)	−0.0096 (19)	0.004 (2)	−0.008 (2)
C18	0.057 (3)	0.039 (3)	0.064 (3)	−0.017 (2)	0.015 (3)	0.000 (2)
C19	0.061 (3)	0.044 (3)	0.060 (3)	−0.012 (2)	0.021 (3)	−0.002 (2)
N5	0.179 (10)	0.160 (9)	0.117 (7)	−0.109 (8)	−0.047 (7)	0.019 (7)
O5	0.162 (8)	0.224 (12)	0.237 (12)	−0.007 (8)	−0.063 (8)	−0.095 (9)
C21	0.41 (3)	0.27 (2)	0.35 (3)	−0.23 (2)	−0.23 (2)	0.18 (2)
C22	0.35 (4)	0.35 (4)	0.35 (4)	−0.20 (3)	−0.17 (3)	−0.05 (3)
C20	0.22 (2)	0.18 (2)	0.97 (8)	−0.046 (16)	−0.03 (3)	−0.19 (3)

Geometric parameters (Å, º)

Cd1—O3^i	2.234 (3)	C5—H5A	0.9300
Cd1—N4^ii	2.237 (4)	C6—C7	1.398 (7)
Cd1—N1	2.254 (4)	C6—H6A	0.9300
Cd1—O1	2.363 (3)	C7—C8	1.495 (7)
Cd1—O2	2.392 (3)	C8—Cd1^i	2.721 (5)
Cd1—O4^i	2.565 (4)	C9—C10	1.391 (7)
Cd1—C1	2.719 (5)	C9—C14	1.393 (7)
Cd1—C8^i	2.721 (5)	C10—C11	1.377 (8)
N1—C15	1.319 (6)	C10—H10A	0.9300
N1—C9	1.389 (6)	C11—C12	1.402 (10)
N2—C15	1.343 (6)	C11—H11A	0.9300
N2—C14	1.365 (7)	C12—C13	1.357 (10)
N2—H2A	0.8600	C12—H12A	0.9300
N3—C17	1.332 (6)	C13—C14	1.403 (8)
N3—C18	1.355 (6)	C13—H13A	0.9300
N3—C16	1.476 (6)	C15—C16	1.491 (7)
N4—C17	1.316 (6)	C16—H16A	0.9700
N4—C19	1.370 (6)	C16—H16B	0.9700
N4—Cd1^ii	2.237 (4)	C17—H17A	0.9300
O1—C1	1.242 (5)	C18—C19	1.355 (7)
O2—C1	1.270 (5)	C18—H18A	0.9300
O3—C8	1.249 (6)	C19—H19A	0.9300
O3—Cd1^i	2.234 (3)	N5—C22	1.365 (6)
O4—C8	1.246 (6)	N5—C21	1.423 (8)
O4—Cd1^i	2.565 (4)	N5—C20	1.498 (12)
C1—C2	1.503 (6)	O5—C22	1.173 (7)
C2—C3	1.383 (7)	C21—H21A	0.9600
C2—C7	1.402 (7)	C21—H21B	0.9600
C3—C4	1.378 (8)	C21—H21C	0.9600
C3—H3A	0.9300	C22—H22	0.9300
C4—C5	1.376 (10)	C20—H20A	0.9600
C4—H4A	0.9300	C20—H20B	0.9600
C5—C6	1.358 (9)	C20—H20C	0.9600
O3^i—Cd1—N4^ii	106.08 (15)	C7—C6—H6A	119.1
O3^i—Cd1—N1	131.73 (15)	C6—C7—C2	118.1 (5)
N4^ii—Cd1—N1	104.19 (15)	C6—C7—C8	120.2 (5)
O3^i—Cd1—O1	93.14 (13)	C2—C7—C8	121.7 (4)
N4^ii—Cd1—O1	140.35 (14)	O4—C8—O3	122.8 (5)
N1—Cd1—O1	86.63 (14)	O4—C8—C7	119.1 (5)
O3^i—Cd1—O2	104.11 (13)	O3—C8—C7	118.1 (4)
N4^ii—Cd1—O2	86.50 (13)	O4—C8—Cd1^i	69.5 (3)
N1—Cd1—O2	114.48 (13)	O3—C8—Cd1^i	54.3 (3)
O1—Cd1—O2	54.87 (11)	C7—C8—Cd1^i	166.5 (3)
O3^i—Cd1—O4^i	53.77 (13)	N1—C9—C10	130.8 (5)
N4^ii—Cd1—O4^i	83.00 (15)	N1—C9—C14	108.5 (4)
N1—Cd1—O4^i	94.48 (14)	C10—C9—C14	120.7 (5)
O1—Cd1—O4^i	134.87 (13)	C11—C10—C9	117.6 (6)
O2—Cd1—O4^i	150.85 (13)	C11—C10—H10A	121.2
O3^i—Cd1—C1	97.92 (14)	C9—C10—H10A	121.2
N4^ii—Cd1—C1	114.19 (15)	C10—C11—C12	121.0 (6)
N1—Cd1—C1	102.84 (14)	C10—C11—H11A	119.5
O1—Cd1—C1	27.13 (12)	C12—C11—H11A	119.5
O2—Cd1—C1	27.84 (12)	C13—C12—C11	122.3 (6)
O4^i—Cd1—C1	151.08 (13)	C13—C12—H12A	118.8
O3^i—Cd1—C8^i	26.97 (13)	C11—C12—H12A	118.8
N4^ii—Cd1—C8^i	92.52 (15)	C12—C13—C14	116.8 (6)
N1—Cd1—C8^i	116.59 (15)	C12—C13—H13A	121.6
O1—Cd1—C8^i	116.85 (14)	C14—C13—H13A	121.6
O2—Cd1—C8^i	127.44 (14)	N2—C14—C9	106.0 (5)
O4^i—Cd1—C8^i	27.06 (12)	N2—C14—C13	132.5 (5)
C1—Cd1—C8^i	124.89 (14)	C9—C14—C13	121.5 (5)
C15—N1—C9	105.6 (4)	N1—C15—N2	112.2 (5)
C15—N1—Cd1	132.8 (3)	N1—C15—C16	125.7 (5)
C9—N1—Cd1	121.0 (3)	N2—C15—C16	122.0 (4)
C15—N2—C14	107.7 (4)	N3—C16—C15	111.1 (4)
C15—N2—H2A	126.1	N3—C16—H16A	109.4
C14—N2—H2A	126.1	C15—C16—H16A	109.4
C17—N3—C18	107.6 (4)	N3—C16—H16B	109.4
C17—N3—C16	125.8 (4)	C15—C16—H16B	109.4
C18—N3—C16	126.4 (4)	H16A—C16—H16B	108.0
C17—N4—C19	105.1 (4)	N4—C17—N3	111.6 (4)
C17—N4—Cd1^ii	123.2 (3)	N4—C17—H17A	124.2
C19—N4—Cd1^ii	131.7 (3)	N3—C17—H17A	124.2
C1—O1—Cd1	92.6 (3)	N3—C18—C19	106.0 (4)
C1—O2—Cd1	90.6 (3)	N3—C18—H18A	127.0
C8—O3—Cd1^i	98.8 (3)	C19—C18—H18A	127.0
C8—O4—Cd1^i	83.5 (3)	C18—C19—N4	109.7 (5)
O1—C1—O2	121.5 (4)	C18—C19—H19A	125.2
O1—C1—C2	119.2 (4)	N4—C19—H19A	125.2
O2—C1—C2	119.1 (4)	C22—N5—C21	123.5 (9)
O1—C1—Cd1	60.2 (2)	C22—N5—C20	112.1 (7)
O2—C1—Cd1	61.6 (2)	C21—N5—C20	122.9 (8)
C2—C1—Cd1	177.7 (3)	N5—C21—H21A	109.5
C3—C2—C7	119.5 (5)	N5—C21—H21B	109.5
C3—C2—C1	117.5 (5)	H21A—C21—H21B	109.5
C7—C2—C1	123.0 (4)	N5—C21—H21C	109.5
C4—C3—C2	120.5 (6)	H21A—C21—H21C	109.5
C4—C3—H3A	119.7	H21B—C21—H21C	109.5
C2—C3—H3A	119.7	O5—C22—N5	127.3 (8)
C3—C4—C5	120.3 (6)	O5—C22—H22	116.3
C3—C4—H4A	119.9	N5—C22—H22	116.3
C5—C4—H4A	119.9	N5—C20—H20A	109.5
C6—C5—C4	119.7 (6)	N5—C20—H20B	109.5
C6—C5—H5A	120.2	H20A—C20—H20B	109.5
C4—C5—H5A	120.2	N5—C20—H20C	109.5
C5—C6—C7	121.8 (6)	H20A—C20—H20C	109.5
C5—C6—H6A	119.1	H20B—C20—H20C	109.5
Cd1—O1—C1—O2	−6.9 (5)	C14—C9—C10—C11	1.5 (8)
Cd1—O1—C1—C2	177.4 (4)	C9—C10—C11—C12	−0.9 (10)
Cd1—O2—C1—O1	6.8 (5)	C10—C11—C12—C13	0.2 (12)
Cd1—O2—C1—C2	−177.5 (4)	C11—C12—C13—C14	−0.1 (11)
O1—C1—C2—C3	90.6 (6)	C15—N2—C14—C9	−0.3 (6)
O2—C1—C2—C3	−85.3 (6)	C15—N2—C14—C13	−179.0 (6)
O1—C1—C2—C7	−87.5 (6)	N1—C9—C14—N2	0.7 (6)
O2—C1—C2—C7	96.6 (6)	C10—C9—C14—N2	179.6 (5)
C7—C2—C3—C4	4.2 (9)	N1—C9—C14—C13	179.6 (5)
C1—C2—C3—C4	−174.0 (6)	C10—C9—C14—C13	−1.5 (8)
C2—C3—C4—C5	−0.7 (12)	C12—C13—C14—N2	179.3 (6)
C3—C4—C5—C6	−2.0 (13)	C12—C13—C14—C9	0.7 (10)
C4—C5—C6—C7	1.0 (12)	C9—N1—C15—N2	0.7 (5)
C5—C6—C7—C2	2.5 (10)	Cd1—N1—C15—N2	−170.6 (3)
C5—C6—C7—C8	−179.0 (6)	C9—N1—C15—C16	−176.3 (4)
C3—C2—C7—C6	−5.0 (8)	Cd1—N1—C15—C16	12.4 (7)
C1—C2—C7—C6	173.0 (5)	C14—N2—C15—N1	−0.3 (6)
C3—C2—C7—C8	176.4 (5)	C14—N2—C15—C16	176.9 (4)
C1—C2—C7—C8	−5.5 (7)	C17—N3—C16—C15	−37.6 (7)
Cd1^i—O4—C8—O3	10.5 (5)	C18—N3—C16—C15	148.3 (5)
Cd1^i—O4—C8—C7	−168.5 (4)	N1—C15—C16—N3	90.4 (6)
Cd1^i—O3—C8—O4	−12.2 (6)	N2—C15—C16—N3	−86.4 (5)
Cd1^i—O3—C8—C7	166.8 (4)	C19—N4—C17—N3	−1.1 (6)
C6—C7—C8—O4	7.0 (8)	Cd1^ii—N4—C17—N3	179.0 (3)
C2—C7—C8—O4	−174.6 (5)	C18—N3—C17—N4	1.1 (6)
C6—C7—C8—O3	−172.1 (5)	C16—N3—C17—N4	−173.9 (4)
C2—C7—C8—O3	6.4 (7)	C17—N3—C18—C19	−0.6 (6)
C6—C7—C8—Cd1^i	−119.7 (14)	C16—N3—C18—C19	174.4 (5)
C2—C7—C8—Cd1^i	58.7 (16)	N3—C18—C19—N4	−0.1 (7)
C15—N1—C9—C10	−179.7 (5)	C17—N4—C19—C18	0.8 (7)
Cd1—N1—C9—C10	−7.1 (7)	Cd1^ii—N4—C19—C18	−179.4 (4)
C15—N1—C9—C14	−0.9 (5)	C21—N5—C22—O5	−27 (3)
Cd1—N1—C9—C14	171.7 (3)	C20—N5—C22—O5	166.4 (19)
N1—C9—C10—C11	−179.8 (6)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O2^iii	0.86	1.82	2.679 (5)	174

Symmetry code: (iii) x−1, y, z.