[Journal logo]

Volume 68 
Part 6 
Pages m152-m155  
June 2012  

Received 7 March 2012
Accepted 29 April 2012
Online 10 May 2012

3,5-Bis{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine and its one-dimensional polymeric complex with HgCl2

aCollege of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, People's Republic of China
Correspondence e-mail: yubindong@sdnu.edu.cn

The molecule of 3,5-bis{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine (L), C30H24N8, has an antiperiplanar conformation of the two terminal benzimidazole groups and forms two-dimensional networks along the crystallographic b axis via two types of intermolecular hydrogen bonds. However, in catena-poly[[[dichloridomercury(II)]-[mu]-3,5-bis{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine] dichloromethane hemisolvate], {[HgCl2(C30H24N8)]·0.5CH2Cl2}n, synthesized by the combination of L with HgCl2, the L ligand adopts a synperiplanar conformation. The HgII cation lies in a distorted tetrahedral environment, which is defined by two N atoms and two Cl atoms to form a one-dimensional zigzag chain. These zigzag chains stack via hydrogen bonds which expand the dimensionality of the structure from one to two.

Comment

Organometallic complexes have attracted considerable attention because of their fascinating topological structures (Eddaoudi et al., 2002[Eddaoudi, M., Kim, J., Rosi, N., Vodak, D., Wachter, J., O'Keeffe, M. & Yaghi, O. M. (2002). Science, 295, 469-472.]) and potential applications as functional materials in gas storage (Ma & Zhou, 2010[Ma, S. & Zhou, H.-C. (2010). Chem. Commun. 46, 44-53.]), host-guest chemistry (Yoshizawa et al., 2006[Yoshizawa, M., Tamura, M. & Fujita, M. (2006). Science, 312, 251-254.]), catalysis (Kim et al., 2010[Kim, H. Y., Kim, S. & Oh, K. (2010). Angew. Chem. Int. Ed. 49, 4476-4478.]) and luminescence (Cui et al., 2012[Cui, Y., Yue, Y., Qian, G. & Chen, B. (2012). Chem. Rev. 112, 1126-1162.]). Over the past decade, the design and construction of rigid organic ligands bridged by 1,2,4-triazol-4-amine has been pursued, due to their diversity in coordination chemistry and model applications in functional materials (Wang et al., 2007[Wang, P., Ma, J.-P., Dong, Y.-B. & Huang, R.-Q. (2007). J. Am. Chem. Soc. 129, 10620-10621.], 2009[Wang, P., Ma, J.-P. & Dong, Y.-B. (2009). Chem. Eur. J. 15, 10432-10445.]; Liu et al., 2009[Liu, Q.-K., Ma, J.-P. & Dong, Y.-B. (2009). Chem. Eur. J. 15, 10364-10368.], 2010[Liu, Q.-K., Ma, J.-P. & Dong, Y.-B. (2010). J. Am. Chem. Soc. 132, 7005-7017.]).

To date, various organic ligands have been used as molecular building blocks, but the use of 1,2,4-triazol-4-amine-based bent organic ligands as semi-rigid components has remained rare until recently. In order to investigate how the semi-rigid organic ligands bridged by 1,2,4-triazol-4-amine affect the arrangement of molecular complexes in self-assembled aggregates, we synthesized a new 1,2,4-triazol-4-amine bridging ligand, namely 3,5-bis{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine, denoted L or (I)[link]. This compound introduces two large aromatic benzimidazole groups to the ligand. The combination of (I)[link] with HgCl2 afforded {[HgCl2L]·CH2Cl2}n, (II)[link], which features hydrogen-bonded stacking-driven two-dimensional networks.

[Scheme 1]

Within the free ligand, (I)[link] (Fig. 1[link]), the terminal benzimidazole groups adopt an antiperiplanar conformation across the central bridging 1,2,4-triazol-4-amine group. The dihedral angles between the planes of the benzimidazole and triazole rings are 58.1 (2) and 88.06 (18)° for the benzimidazole rings containing atoms N5 and N7, respectively, and the dihedral angles between the benzimidazole and adjacent benzene rings are 78.64 (18) and 80.37 (18)°, respectively. The two benzene rings of (I)[link] are almost coplanar, with a dihedral angle of 7.3 (2)°.

In the crystal structure, molecules of (I)[link] are arranged in chains via N4-H4A...N8i hydrogen bonds along the [101] direction (details and symmetry codes are given in Table 1[link]). The chains stack via a second hydrogen-bond interaction (N4-H4B...N1ii) to form a two-dimensional network which lies parallel to the (010) plane (Fig. 2[link]). This is in contrast with 3,5-bis(2-chlorophenyl)-1H-1,2,4-triazol-4-amine (Zachara et al., 2004[Zachara, J., Madura, I. & Wlostowski, M. (2004). Acta Cryst. C60, o57-o59.]), the molecules of which are linked by hydrogen bonds to form a one-dimensional chain.

Compound (II)[link] crystallizes with one unique four-coordinated HgII centre in a distorted tetrahedral {HgCl2N2} environment involving two Cl atoms (Cl1 and Cl2) and two N atoms [N2 and N6i; symmetry code: (i) x, -y + [{3\over 2}], z - [{1\over 2}]] from two different ligands (Fig. 3[link] and Table 2[link]). Neighbouring HgII cations are bound together by triazole atom N2 and the terminal benzimidazole N6 atom of the L ligand to form an {HgCl2L}n one-dimensional zigzag chain. The coordination behaviour of the HgII cation is similar to that observed in Hg[1-(pyridin-2-ylmethyl)-1H-benzotriazole]Cl2 (Liu et al., 2008[Liu, C.-S., Zhou, L.-M., Guo, L.-Q., Ma, S.-T. & Fang, S.-M. (2008). Acta Cryst. C64, m394-m397.]), where the 1-(pyridin-2-ylmethyl)-1H-benzotriazole ligand (L2) is also coordinated to two HgII centres to form a single chain. Similarly, in [Hg(L2)Cl2], there are no bonding interactions observed between adjacent chains.

The ligand L adopts different conformations under different conditions. In the solid state, the benzimidazole moieties adopt a synperiplanar orientation about the triazole core in the free ligand, whereas after coordination to HgII the benzimidazole groups adopt a cis conformation. Compared with those given above for (I)[link], the dihedral angles in (II)[link] between the planes of the benzimidazole groups and the adjacent benzene rings change to 87.9 (3) and 75.8 (3)° for the benzimidazole rings containing atoms N5 and N7, respectively. These are nearly perpendicular, clearly as a result of coordination to HgII. Additionally, the dihedral angle formed by the two benzene rings changes from 7.3 (2)° in the free ligand to 18.9 (3)° in (II)[link].

In the solid state, the zigzag chains in (II)[link] are arranged along the c axis, where they interact via N4-H4A...Cl2iii hydrogen-bond interactions, as shown in Fig. 4[link] (details in Table 3[link]; symmetry code given in Table 3[link]). The result is that a two-dimensional sheet is generated in the bc plane. The dichloromethane solvent molecules are located within the cavities formed by the layered stacking of (II)[link] (Fig. 5[link]), although it appears that only about half of the solvent molecule sites are occupied.

In summary, a new compound with a common zigzag chain motif has been successfully obtained based on a new 1,2,4-triazol-4-amine bridging bent organic ligand, (I)[link], and HgCl2. The chains assemble through hydrogen bonds to form a two-dimensional network. The hydrogen-bond interactions play an important role in constructing high-dimensional supramolecular compounds.

[Figure 1]
Figure 1
The molecular structure of (I)[link], showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2]
Figure 2
The two-dimensional structure of (I)[link], constructed by hydrogen bonds (dashed lines). Uninvolved H atoms have been omitted for clarity. [Symmetry codes: (i) x - [{1\over 2}], -y + [{1\over 2}], z - [{1\over 2}]; (ii) x - 1, y, z.]
[Figure 3]
Figure 3
The molecular structure of (II)[link], showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry code: (i) x, -y + [{3\over 2}], z - [{1\over 2}].]
[Figure 4]
Figure 4
The two-dimensional structure of (II)[link], constructed by hydrogen bonds (dashed lines). Uninvolved H atoms have been omitted for clarity. [Symmetry codes: (ii) x, -y + [{3\over 2}], z + [{1\over 2}]; (iii) x, y - 1, z.]
[Figure 5]
Figure 5
The crystal packing of (II)[link], viewed along the b axis. The dichloromethane solvent molecules are located in channels.

Experimental

For the preparation of (I)[link], 80% hydrazine hydrate (2.8 g, 45 mmol) was added with stirring to a solution of 3,5-bis{4-[(benzimidazol-1-yl)methyl]phenyl}-1,3,4-oxadiazole (1.49 g, 3.0 mmol) in N,N-dimethylformamide (DMF; 20 ml). The mixture was stirred for 4 h at 423 K, then cooled to room temperature and poured into water (100 ml). The product was obtained as a white solid and purified on a silica-gel column using tetrahydrofuran as the eluent to afford (I)[link] as a white crystalline solid (yield 1.00 g, 67%). A solution of (I)[link] (5.00 mg, 0.010 mmol) in CH2Cl2 (10 ml) was left for about 2 d at room temperature, after which time colourless crystals were obtained (yield 3.24 mg, 65%). IR (KBr pellet, [nu], cm-1): 3442 (s), 1633 (s), 1496 (s), 1385 (s), 1295 (m), 1200 (w), 1123 (w), 974 (w), 765 (s), 619 (m); 1H NMR (300 MHz, DMSO, 298 K, TMS): [delta] 8.44 (s, 2H, -C3H2N2-), 7.96-7.94, 7.47-7.44 (aabb, 8H, -C6H4-), 7.67-7.64 (d, 2H, -C3H2N2-, 7.56-7.53 (d, 2H, -C6H3-), 7.23-7.18 (m, 4H, -C6H3-), 6.17 (s, 2H, -NH2), 5.57 (s, 4H, -CH2-). Elemental analysis calculated for C30H24N8: C 72.32, H 4.91, N 22.77%; found: C 72.56, H 4.87, N 22.57%.

For the synthesis of (II)[link], a solution of HgCl2 (5.42 mg, 0.020 mmol) in CH3OH (5 ml) was layered onto a solution of (I)[link] (9.93 mg, 0.020 mmol) in CH2Cl2 (8 ml). The mixture was left for about a week at room temperature and colourless crystals of (II)[link] were obtained (yield 8.64 mg, 62%). IR (KBr pellet, [nu], cm-1): 3447 (w), 1636 (s), 1509 (w), 1459 (m), 1384 (w), 1266 (m), 1193 (m), 740 (s). Elemental analysis calculated for C61H50Cl6Hg2N16: C 45.34, H 3.23, N 13.66%; found: C 45.20, H 3.11, N 13.82%.

Compound (I)[link]

Crystal data
  • C30H24N8

  • Mr = 496.57

  • Monoclinic, C c

  • a = 6.141 (2) Å

  • b = 19.914 (6) Å

  • c = 19.910 (6) Å

  • [beta] = 96.537 (6)°

  • V = 2418.8 (13) Å3

  • Z = 4

  • Mo K[alpha] radiation

  • [mu] = 0.09 mm-1

  • T = 298 K

  • 0.17 × 0.11 × 0.09 mm

Data collection
  • Bruker SMART CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2003[Bruker (2003). SADABS, SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.986, Tmax = 0.992

  • 5790 measured reflections

  • 2748 independent reflections

  • 2008 reflections with I > 2[sigma](I)

  • Rint = 0.063

Refinement
  • R[F2 > 2[sigma](F2)] = 0.053

  • wR(F2) = 0.116

  • S = 1.00

  • 2748 reflections

  • 343 parameters

  • 2 restraints

  • H-atom parameters constrained

  • [Delta][rho]max = 0.14 e Å-3

  • [Delta][rho]min = -0.15 e Å-3

Table 1
Hydrogen-bond geometry (Å, °) for (I)[link]

D-H...A D-H H...A D...A D-H...A
N4-H4A...N8i 0.89 2.53 3.354 (5) 155
N4-H4B...N1ii 0.89 2.50 3.222 (6) 138
Symmetry codes: (i) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]; (ii) x-1, y, z.

Compound (II)[link]

Crystal data
  • [HgCl2(C30H24N8)]·0.5CH2Cl2

  • Mr = 810.53

  • Monoclinic, P 21 /c

  • a = 16.627 (3) Å

  • b = 10.6199 (18) Å

  • c = 20.082 (3) Å

  • [beta] = 113.586 (2)°

  • V = 3249.9 (10) Å3

  • Z = 4

  • Mo K[alpha] radiation

  • [mu] = 5.02 mm-1

  • T = 298 K

  • 0.40 × 0.38 × 0.34 mm

Data collection
  • Bruker SMART CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2003[Bruker (2003). SADABS, SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.239, Tmax = 0.280

  • 16724 measured reflections

  • 6097 independent reflections

  • 4599 reflections with I > 2[sigma](I)

  • Rint = 0.040

Refinement
  • R[F2 > 2[sigma](F2)] = 0.038

  • wR(F2) = 0.102

  • S = 1.04

  • 6097 reflections

  • 397 parameters

  • 6 restraints

  • H-atom parameters constrained

  • [Delta][rho]max = 1.22 e Å-3

  • [Delta][rho]min = -0.64 e Å-3

Table 2
Selected geometric parameters (Å, °) for (II)[link]

Cl1-Hg1 2.4331 (17)
Cl2-Hg1 2.3793 (17)
Hg1-N6i 2.265 (4)
Hg1-N2 2.353 (4)
N6i-Hg1-N2 95.32 (15)
N6i-Hg1-Cl2 112.97 (12)
N2-Hg1-Cl2 111.62 (13)
N6i-Hg1-Cl1 109.17 (12)
N2-Hg1-Cl1 103.99 (11)
Cl2-Hg1-Cl1 120.51 (7)
Symmetry code: (i) [x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}].

Table 3
Hydrogen-bond geometry (Å, °) for (II)[link]

D-H...A D-H H...A D...A D-H...A
N4-H4B...N8ii 0.89 2.09 2.940 (8) 160
N4-H4A...Cl2iii 0.89 2.98 3.473 (5) 117
Symmetry codes: (ii) [x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]; (iii) x, y-1, z.

The H atoms on N4 were located in a difference map and their positions were initially refined subject to an N-H distance restraint of 0.89 (2) Å. Subsequently, these H atoms were treated as riding atoms, with Uiso(H) = 1.2Ueq(N). The remaining H atoms were placed in geometrically idealized positions and included as riding atoms, with C-H = 0.93 Å and Uiso(H) = 1.2Ueq(C) for aromatic H atoms or C-H = 0.97 Å and Uiso(H) = 1.2Ueq(C) for methylene H atoms.

In noncentrosymmetric (I)[link], Friedel pairs were merged in the final refinement and the absolute structure was chosen arbitrarily. In (II)[link], the dichloromethane solvent molecule was refined with the C-Cl and Cl...Cl distances restrained to 1.78 (1) and 2.80 (2) Å, respectively, in order to retain reasonable geometry. The solvent sites also appeared to be only partially occupied and a fixed site-occupation factor of 0.5 was employed for chemical and crystallographic rationality. The main directions of movement of covalently bonded atoms C29, C30 and C31 were likewise restrained to be similar, with an s.u. value of 0.005 Å2 (Müller et al., 2006[Müller, P., Herbst-Irmer, R., Spek, A. L., Schneider, T. R. & Sawaya, M. R. (2006). Crystal Structure Refinement: A Crystallographer's Guide to SHELXL, edited by P. Müller. Oxford University Press.]).

For both compounds, data collection: SMART (Bruker, 2003[Bruker (2003). SADABS, SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SMART; data reduction: SAINT (Bruker, 2003[Bruker (2003). SADABS, SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.


Supplementary data for this paper are available from the IUCr electronic archives (Reference: OV3013 ). Services for accessing these data are described at the back of the journal.


Acknowledgements

The authors are grateful for financial support from the Natural Science Foundation of China (grant Nos. 91027003 and 21072118), the 973 Programme (grant No. 2012CB821705), PCSIRT, the Shangdong Natural Science Foundation (grant No. JQ200803) and the Taishan Scholars' Construction Project Special Fund.

References

Bruker (2003). SADABS, SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.
Cui, Y., Yue, Y., Qian, G. & Chen, B. (2012). Chem. Rev. 112, 1126-1162.  [ISI] [CrossRef] [ChemPort] [PubMed]
Eddaoudi, M., Kim, J., Rosi, N., Vodak, D., Wachter, J., O'Keeffe, M. & Yaghi, O. M. (2002). Science, 295, 469-472.  [ISI] [CSD] [CrossRef] [PubMed] [ChemPort]
Kim, H. Y., Kim, S. & Oh, K. (2010). Angew. Chem. Int. Ed. 49, 4476-4478.  [ISI] [CrossRef] [ChemPort]
Liu, Q.-K., Ma, J.-P. & Dong, Y.-B. (2009). Chem. Eur. J. 15, 10364-10368.  [CSD] [CrossRef] [PubMed] [ChemPort]
Liu, Q.-K., Ma, J.-P. & Dong, Y.-B. (2010). J. Am. Chem. Soc. 132, 7005-7017.  [ISI] [CSD] [CrossRef] [ChemPort] [PubMed]
Liu, C.-S., Zhou, L.-M., Guo, L.-Q., Ma, S.-T. & Fang, S.-M. (2008). Acta Cryst. C64, m394-m397.  [CSD] [CrossRef] [details]
Ma, S. & Zhou, H.-C. (2010). Chem. Commun. 46, 44-53.  [CrossRef] [ChemPort]
Müller, P., Herbst-Irmer, R., Spek, A. L., Schneider, T. R. & Sawaya, M. R. (2006). Crystal Structure Refinement: A Crystallographer's Guide to SHELXL, edited by P. Müller. Oxford University Press.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.  [CrossRef] [details]
Wang, P., Ma, J.-P. & Dong, Y.-B. (2009). Chem. Eur. J. 15, 10432-10445.  [CSD] [CrossRef] [PubMed] [ChemPort]
Wang, P., Ma, J.-P., Dong, Y.-B. & Huang, R.-Q. (2007). J. Am. Chem. Soc. 129, 10620-10621.  [ISI] [CSD] [CrossRef] [PubMed] [ChemPort]
Yoshizawa, M., Tamura, M. & Fujita, M. (2006). Science, 312, 251-254.  [ISI] [CrossRef] [PubMed] [ChemPort]
Zachara, J., Madura, I. & Wlostowski, M. (2004). Acta Cryst. C60, o57-o59.  [CSD] [CrossRef] [details]


Acta Cryst (2012). C68, m152-m155   [ doi:10.1107/S0108270112019233 ]