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Structural characterization and Hirshfeld surface analysis of a CoII complex with imidazo[1,2-a]pyridine

aDepartment of Physics, Jadavpur University, Kolkata 700 032, India
*Correspondence e-mail: skseth@phys.jdvu.ac.in

Edited by C. Massera, Università di Parma, Italy (Received 14 November 2017; accepted 5 March 2018; online 17 April 2018)

A new mononuclear tetra­hedral CoII complex, di­chlorido­bis­(imidazo[1,2-a]pyridine-κN1)cobalt(II), [CoCl2(C7H6N2)2], has been synthesized using a bioactive imidazo­pyridine ligand. X-ray crystallography reveals that the solid-state structure of the title complex exhibits both C—H⋯Cl and ππ stacking inter­actions in building supra­molecular assemblies. Indeed, the mol­ecules are linked by C—H⋯Cl inter­actions into a two-dimensional framework, with finite zero-dimensional dimeric units as building blocks, whereas ππ stacking plays a crucial role in building a supra­molecular layered network. An exhaustive investigation of the diverse inter­molecular inter­actions via Hirshfeld surface analysis enables contributions to the crystal packing of the title complex to be qu­anti­fied. The fingerprint plots associated with the Hirshfeld surface clearly display each significant inter­action involved in the structure, by qu­anti­fying them in an effective visual manner.

1. Chemical context

In the realm of the synthesis of heterocyclic compounds, imidazo­pyridines have proven to be a most important class of mol­ecules and have attracted significant inter­est because of their promising applications. They are biologically important and have shown a wide variety of pharmacological effects (Adib et al., 2011[Adib, M., Sheikhi, E. & Rezaei, N. (2011). Tetrahedron Lett. 52, 3191-3194.]): anti-inflammatory (Rupert et al., 2003[Rupert, K. C., Henry, J. R., Dodd, J. H., Wadsworth, S. A., Cavender, D. E., Olini, G. C., Fahmy, B. & Siekierka, J. J. (2003). Bioorg. Med. Chem. Lett. 13, 347-350.]), anti­viral (Puerstinger et al., 2007[Puerstinger, G., Paeshuyse, J., De Clercq, E. & Neyts, J. (2007). Bioorg. Med. Chem. Lett. 17, 390-393.]), anti­ulcer (Kaminski & Doweyko, 1997[Kaminski, J. J. & Doweyko, A. M. (1997). J. Med. Chem. 40, 427-436.]), anti­bacterial (Rival et al., 1992[Rival, Y., Grassy, G. & Michel, G. (1992). Chem. Pharm. Bull. 40, 1170-1176.]), anti­fungal (Rival et al., 1991[Rival, Y., Grassy, G., Taudou, A. & Ecalle, R. (1991). Eur. J. Med. Chem. 26, 13-18.]), anti­protozoal (Biftu et al., 2006[Biftu, T., Feng, D., Fisher, M., Liang, G. B., Qian, X., Scribner, A., Dennis, R., Lee, S., Liberator, P. A., Brown, C., Gurnett, A., Leavitt, P. S., Thompson, D., Mathew, J., Misura, A., Samaras, S., Tamas, T., Sina, J. F., McNulty, K. A., McKnight, C. G., Schmatz, D. M. & Wyvratt, M. (2006). Bioorg. Med. Chem. Lett. 16, 2479-2483.]; Ismail et al. 2008[Ismail, M. A., Arafa, R. K., Wenzler, T., Brun, R., Tanious, F. A., Wilson, W. D. & Boykin, D. W. (2008). Bioorg. Med. Chem. 16, 683-691.]), anti­herpes (Gudmundsson & Johns, 2007[Gudmundsson, K. S. & Johns, B. A. (2007). Bioorg. Med. Chem. Lett. 17, 2735-2739.]; Véron et al., 2007[Véron, J. B., Enguehard-Gueiffier, C., Snoeck, R., Andrei, G., De Clercq, E. & Gueiffier, A. (2007). Bioorg. Med. Chem. 15, 7209-7219.]), and for the treatment of hepatitis C (Bravi et al., 2007[Bravi, G., Cheasty, A. G., Corfield, J. A., Grimes, R. M., Harrison, D., Hartley, C. D., Howes, P. D., Medhurst, K. J., Meeson, M. L., Mordaunt, J. E., et al. (2007). World patent WO 2,007,039,146.]), and HIV (Gudmundsson & Boggs, 2007[Gudmundsson, K. S. & Boggs, S. D. (2007). World patent WO 2,007 027,999.]). These medically relevant compounds exhibit a wide range of activities including anti-herpes, anti­apoptotic, sedative, anxiolytic, anti­convulsant, muscle relaxant, analgesic, anti­tuberculosis and anti­cancer actions (Dymińska, 2015[Dymińska, L. (2015). Bioorg. Med. Chem. 23, 6087-6099.]; Bagdi et al., 2015[Bagdi, A. K., Santra, S., Monir, K. & Hajra, A. (2015). Chem. Commun. 51, 1555-1575.]). The core structure of imidazo[1,2-a]pyridine is present in several drugs, such as zolpidem, alpidem, zolimidine, olprinone, GSK812397, saripidem, and necopidem (Gunja, 2013[Gunja, N. (2013). J. Med. Toxicol. 9, 163-171.]; Harrison & Keating, 2005[Harrison, T. S. & Keating, G. M. (2005). CNS Drugs, 19, 709-716.]; Bagdi et al., 2015[Bagdi, A. K., Santra, S., Monir, K. & Hajra, A. (2015). Chem. Commun. 51, 1555-1575.]). Besides, this heterocyclic scaffold has attracted tremendous attention from the synthetic community due to its prevalence in dyes, ligands for metal catalysts, and electronic materials (Enguehard-Gueiffier & Gueiffier, 2007[Enguehard-Gueiffier, C. & Gueiffier, A. (2007). Mini Rev. Med. Chem. 7, 888-899.]; Prostota et al., 2013[Prostota, Y., Kachkovsky, O. D., Reis, L. V. & Santos, P. F. (2013). Dyes Pigments, 96, 554-562.]; Ke et al., 2013[Ke, C.-H., Kuo, B.-C., Nandi, D. & Lee, H. M. (2013). Organometallics, 32, 4775-4784.]).

Inspired by the manifold potential applications of imidazo[1,2-a]pyridine, we focused our attention on its coord­ination behavior towards metal ions and to the structural features of the resulting complexes. Herein, the crystal and mol­ecular structure of a new CoII complex with imidazo[1,2-a]pyridine is described, along with an investigation of the inter­molecular inter­actions via Hirshfeld surface analysis.

[Scheme 1]

2. Structural commentary

The mol­ecular structure of the title complex is shown in Fig. 1[link]. The CoII ion is located on a twofold axis, so that half of the complex is generated by symmetry. The metal center is coord­inated to the nitro­gen atoms of two imidazo­pyridine ligands and to two chlorine ions, and shows a tetra­hedral geometry with angles ranging from 107.70 (5) to 112.44 (5)°. Selected geometric parameters around CoII are reported in Table 1[link]. The imidazo­pyridine moiety is planar, with a dihedral angle between the rings of 2.47 (3)°. In the imidazo­pyridine moiety, atoms C6 and C4 show the largest deviations in opposite directions [C6: +0.034 (1) and N1: −0.037 (1)] from the least-squares mean plane through the atoms N1/C6/C7/N2/C1–C5.

Table 1
Selected geometric parameters (Å, °)

Co1—N1 2.0168 (4) Co1—Cl1 2.2556 (5)
       
N1—Co1—N1i 107.70 (5) N1i—Co1—Cl1 112.44 (5)
N1—Co1—Cl1 106.83 (1) Cl1—Co1—Cl1i 110.64 (4)
Symmetry code: (i) [-x+{\script{1\over 2}}, y, -z+{\script{3\over 2}}].
[Figure 1]
Figure 1
ORTEP view with atom-numbering scheme of the title complex with displacement ellipsoids drawn at the 30% probability level. The unlabeled counterpart is generated by the symmetry operationx + [{1\over 2}], y, −z + [{3\over 2}].

3. Supra­molecular features

The title structure exhibits inter­molecular C—H⋯Cl and ππ stacking inter­actions; the details are included in Tables 2[link] and 3[link], respectively. It is convenient to consider the `substructures' generated by each inter­action individually, and then combine these substructures to build up the supra­molecular assembly. The first substructure is formed considering the pyridine ring carbon atom C5 in a general position, which acts as donor to the Cl1 atom at (−x, −y, 1 − z). This C5—H5⋯Cl1 inter­action and its centrosymmetric analogue generate an R22(18) dimeric ring (M) centered at (0, 0, 1/2) (Fig. 2[link]). A second substructure is formed via pairs of symmetry-related C7—H7⋯Cl1(x, −1 + y, z) inter­actions, which generate a dimeric R22(10) ring (N) (Fig. 2[link]). The propagation of these dimers produces two infinite chains, the first running parallel to the ([\overline{1}]01) plane and the second running parallel to the [010] direction. The inter­connection of the two chains leads to the generation of another tetra­meric R42(14) ring motif (P). Thus, the two types of R22(18) and R42(14) rings are alternately linked into infinite MPMP… chains along the [010] direction whereas the R22(10) and R42(14) rings are linked alternately into an infinite NPNP… chain parallel to the ([\overline{1}]01) plane (Fig. 2[link]).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C5—H5⋯Cl1ii 0.93 2.89 3.663 (1) 141
C7—H7⋯Cl1iii 0.93 2.88 3.734 (1) 153
Symmetry codes: (ii) -x, -y, -z+1; (iii) x, y-1, z.

Table 3
Geometrical parameters (Å, °) for π–π stacking

(a) Cg1 and Cg2 are the centroids of the (N1/C1/N2/C6/C7) and (N2/C1–C5) rings, respectively; (b) centroid–centroid distance between ring i and ring j; (c) vertical distance from ring centroid i to ring j; (d) vertical distance from ring centroid j to ring i; (e) dihedral angle between the first ring mean plane and the second ring mean plane of the partner mol­ecule; (f) angle between the centroid of the first ring and the second ring; (g) angle between the centroid of the first ring and the normal to the mean plane of the second ring of the partner mol­ecule.

Rings ija Rcb R1vc R2vd αe βf γg Slippage
Cg1⋯Cg1ii 3.6414 (16) −3.4980 (8) −3.4980 (8) 0.0 16.13 16.13 1.012
Cg1⋯Cg2ii 3.9583 (16) −3.5303 (9) −3.5035 (9) 2.47 27.73 26.89
Cg1⋯Cg2iv 3.8371 (16) 3.4625 (9) 3.4846 (9) 2.47 24.75 25.53
Cg2⋯Cg2iv 3.5293 (16) 3.4671 (9) 3.4671 (9) 0.0 10.77 10.77 0.659
Symmetry codes: (ii) −x, −y, −z + 1; (iv) −x + 1, −y, −z + 1.
[Figure 2]
Figure 2
Formation of a two-dimensional supra­molecular network generated through self-complementary C—H⋯Cl inter­actions.

Another substructure can be described considering that the mol­ecules, because of their self-complementarity nature, are juxtaposed through ππ stacking inter­actions (Seth et al., 2011a[Seth, S. K., Sarkar, D. & Kar, T. (2011a). CrystEngComm, 13, 4528-4535.], 2013[Seth, S. K., Manna, P., Singh, N. J., Mitra, M., Jana, A. D., Das, A., Choudhury, S. R., Kar, T., Mukhopadhyay, S. & Kim, K. S. (2013). CrystEngComm, 15, 1285-1288.]; Manna et al., 2013[Manna, P., Seth, S. K., Mitra, M., Das, A., Singh, N. J., Choudhury, S. R., Kar, T. & Mukhopadhyay, S. (2013). CrystEngComm, 15, 7879-7886.], 2014a[Manna, P., Seth, S. K., Mitra, M., Choudhury, S. R., Bauzá, A., Frontera, A. & Mukhopadhyay, S. (2014a). Cryst. Growth Des. 14, 5812-5821.]). The mol­ecular packing of the complex is such that the ππ stacking inter­actions between the pyridine rings, as well as between the imidazo rings, are optimized. The pyridine rings of the mol­ecules at (x, y, z) and (−x + 1, −y, −z + 1) are strictly parallel, with an inter­planar spacing of 3.4671 (9) Å and a ring-centroid separation of 3.5293 (16) Å, corresponding to a ring offset of 0.659 Å. In addition, the imidazo rings at (x, y, z) and (−x, −y, −z + 1) are juxtaposed through face-to-face π-stacking with an inter-centroid separation of 3.6414 (16) Å. Moreover, the imidazo and pyridine rings of the parent mol­ecules are also involved into multi π-stacking inter­actions with each other. In particular, the inter­planar spacing between the imidazo ring in a general position and the pyridine rings at (−x, −y, −z + 1) and (−x + 1, −y, −z + 1) are of 3.5303 (9) and 3.4625 (9) Å, respectively, while the relative ring-centroid separations are 3.9583 (16) and 3.8371 (16) Å. These ππ stacking inter­actions result in a two-dimensional supra­molecular layered assembly parallel to the (010) plane (Fig. 3[link]).

[Figure 3]
Figure 3
Monomeric units linked through multi ππ stacking inter­actions leading to the formation of a supra­molecular layered assembly. Color codes: the green and yellow dotted lines denote ππ stacking inter­actions between two pyridine rings and two imidazo rings, respectively, whereas ππ stacking inter­actions between pyridine and imidazo rings are represented by pink dotted lines.

4. Hirshfeld surface analysis

Mol­ecular Hirshfeld surfaces (Spackman & McKinnon, 2002[Spackman, M. A. & McKinnon, J. J. (2002). CrystEngComm, 4, 378-392.]) in the crystal structure are constructed considering the electron distribution calculated as the sum of spherical atom electron densities (Spackman & Byrom, 1997[Spackman, M. A. & Byrom, P. G. (1997). Chem. Phys. Lett. 267, 215-220.]; McKinnon et al., 1998[McKinnon, J. J., Mitchell, A. S. & Spackman, M. A. (1998). Chem. Eur. J. 4, 2136-2141.]). The normalized contact distance (dnorm) based on both de and di, and the van der Waals (vdw) radii of the atom, given by the equation

[ d_{\rm norm} = {d_{\rm i} - r_{\rm i}^{\rm vdw} \over r_{\rm i}^{\rm vdw}} + {d_{\rm e} - r_{\rm i}^{\rm vdw} \over r_{\rm e}^{\rm vdw}}]

enable the identification of the regions of particular importance to inter­molecular inter­actions (McKinnon et al., 2007[McKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2007). Chem. Commun. pp. 3814-3816.]). The combination of de and di in the form of a two-dimensional fingerprint plot (Rohl et al., 2008[Rohl, A. L., Moret, M., Kaminsky, W., Claborn, K., McKinnon, J. J. & Kahr, B. (2008). Cryst. Growth Des. 8, 4517-4525.]) provides a summary of the inter­molecular contacts in the crystal (Spackman & McKinnon, 2002[Spackman, M. A. & McKinnon, J. J. (2002). CrystEngComm, 4, 378-392.]). The Hirshfeld surfaces are mapped with dnorm, and the two-dimensional fingerprint plots presented in this work were generated using CrystalExplorer 3.1 (Wolff et al., 2012[Wolff, S. K., Grimwood, D. J., McKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2012). CrystalExplorer 3.1. The University of Western Australia.]).

The pattern of the inter­molecular inter­actions of the solid-state structure of the title complex prompted us to explore and qu­antify the contribution of the non-covalent inter­actions in the crystal packing, as well as the importance of the C—H⋯Cl bonding in directing the organization of the extended supra­molecular network (Seth et al., 2011a[Seth, S. K., Sarkar, D. & Kar, T. (2011a). CrystEngComm, 13, 4528-4535.],b[Seth, S. K., Saha, I., Estarellas, C., Frontera, A., Kar, T. & Mukhopadhyay, S. (2011b). Cryst. Growth Des. 11, 3250-3265.], Manna et al., 2012[Manna, P., Seth, S. K., Das, A., Hemming, J., Prendergast, R., Helliwell, M., Choudhury, S. R., Frontera, A. & Mukhopadhyay, S. (2012). Inorg. Chem. 51, 3557-3571.]; Seth, 2013[Seth, S. K. (2013). CrystEngComm, 15, 1772-1781.]; Mitra et al., 2014[Mitra, M., Manna, P., Bauzá, A., Ballester, P., Seth, S. K., Ray Choudhury, S., Frontera, A. & Mukhopadhyay, S. (2014). J. Phys. Chem. B, 118, 14713-14726.]). In this present investigation, the contacts responsible for building the supra­molecular assembly were evaluated with respect to their contribution to the overall stability of the crystal structure. In this context, the Hirshfeld surface analysis (Spackman & McKinnon, 2002[Spackman, M. A. & McKinnon, J. J. (2002). CrystEngComm, 4, 378-392.]; Seth et al., 2011a[Seth, S. K., Sarkar, D. & Kar, T. (2011a). CrystEngComm, 13, 4528-4535.],b[Seth, S. K., Saha, I., Estarellas, C., Frontera, A., Kar, T. & Mukhopadhyay, S. (2011b). Cryst. Growth Des. 11, 3250-3265.],c[Seth, S. K., Sarkar, D., Roy, A. & Kar, T. (2011c). CrystEngComm, 13, 6728-6741.],d[Seth, S. K., Sarkar, D., Jana, A. D. & Kar, T. (2011d). Cryst. Growth Des. 11, 4837-4849.]; Mitra et al., 2013[Mitra, M., Seth, S. K., Choudhury, S. R., Manna, P., Das, A., Helliwell, M., Bauzá, A., Frontera, A. & Mukhopadhyay, S. (2013). Eur. J. Inorg. Chem. pp. 4679-4685.]) of the title complex was performed and the results are illustrated in Fig. 4[link]. The surfaces represented were mapped over dnorm, de, shape-index and curvedness in the ranges −0.0620 to 0.9660 Å, 1.0626 to 2.4714 Å, −1.0000 to 1.0000 Å and −4.0000 to 0.4000 Å, respectively. The information regarding the inter­molecular inter­actions summarized in Tables 2[link] and 3[link] are visible as spots on the Hirshfeld surfaces (Fig. 4[link]). For instance, the distinct circular depressions (red spots) on the dnorm surface (Fig. 4[link]a) are due to the C—H⋯Cl contacts, whereas other visible spots are due to H⋯H contacts. From the Hirshfeld surfaces, it is also evident that the mol­ecules are related to one another by ππ stacking inter­actions, as can be inferred from inspection of the adjacent red and blue triangles (highlighted by yellow circles) on the shape-index surface (Fig. 4[link]c). Indeed, the pattern of red and blue triangles in the same region of the shape-index surface is characteristic of ππ stacking inter­actions; the blue triangles represent convex regions resulting from the presence of ring carbon atoms of the mol­ecule inside the surface, while the red triangles represent concave regions caused by carbon atoms of the π-stacked mol­ecule above it. The presence of ππ stacking is also evident in the flat region toward the bottom of both sides of the mol­ecules and is clearly visible on the curvedness surface (Fig. 4[link]d): the shape of the blue outline on the curvedness surface unambiguously delineates the contacting patches of the mol­ecules. On the de surface, this feature appears as a relatively flat green region where the contact distances are similar (Fig. 4[link]b).

[Figure 4]
Figure 4
Hirshfeld surfaces of the title complex mapped with (a) dnorm, (b) de, (c) shape-index and (d) curvedness.

The inter­molecular inter­actions present in the structure are also visible on the two-dimensional fingerprint plot (Rohl et al., 2008[Rohl, A. L., Moret, M., Kaminsky, W., Claborn, K., McKinnon, J. J. & Kahr, B. (2008). Cryst. Growth Des. 8, 4517-4525.]; Samanta et al., 2014[Samanta, T., Dey, L., Dinda, J., Chattopadhyay, S. K. & Seth, S. K. (2014). J. Mol. Struct. 1068, 58-70.]; Seth, 2014a[Seth, S. K. (2014a). J. Mol. Struct. 1064, 70-75.],b[Seth, S. K. (2014b). J. Mol. Struct. 1070, 65-74.],c[Seth, S. K. (2014c). Inorg. Chem. Commun. 43, 60-63.]), which can be decomposed to qu­antify the individual contributions of each inter­molecular inter­action involved in the structure (Manna et al., 2014b[Manna, P., Ray Choudhury, S., Mitra, M., Kumar Seth, S., Helliwell, M., Bauzá, A., Frontera, A. & Mukhopadhyay, S. (2014b). J. Solid State Chem. 220, 149-156.]). These complementary regions are visible in the fingerprint, where one mol­ecule acts as donor (de > di) and the other as an acceptor (di > de). Table 4[link] contains the percentages of contributions for a variety of contacts in the crystal structure of the title compound.

Table 4
Percentage contributions of inter­atomic contacts to the Hirshfeld surface

Contact % contribution Contact % contribution
Cl⋯H/H⋯Cl 30.0 Cl⋯Cl 0.4
N⋯H/H⋯N 4.1 N⋯N 0.9
C⋯H/H⋯C 12.1 C⋯C 7.9
Cl⋯C/C⋯Cl 0.5 H⋯H 38.4
N⋯C/C⋯N 5.7    

The C—H⋯Cl inter­actions appear as two distinct spikes in the fingerprint plot (Fig. 5[link]) of the title complex, where Cl⋯H inter­actions have a larger contribution (18.4%) than their H⋯Cl counterparts (11.6%). Thus, the sum of Cl⋯H/H⋯Cl inter­actions comprises 30.0% of the total Hirshfeld surface area of the mol­ecule (Table 4[link]). The Cl⋯H/H⋯Cl inter­actions represented by the spikes in the bottom right and left region (de + di ≃ 2.77 Å) indicate that the hydrogen atoms from the ligand moiety are in contact with the metal-coord­inated Cl atoms to build the two-dimensional supra­molecular framework. The spoon-like tips in the region (de + di ≃ 3.37 Å) of the fingerprint plot (Fig. 5[link]) represent a significant N⋯H/H⋯N contribution, covering 4.1% of the total Hirshfeld surface of the mol­ecules. The forceps-like tips in the region (de + di ≃ 3.12 Å) of the fingerprint plot (Fig. 5[link]) represent the C⋯H/H⋯C contacts where the C⋯H counterpart shows a larger contribution (7.6%) than the H⋯C counterpart (4.5%). Overall, the C⋯H/H⋯C inter­actions account for 12.1% of the total Hirshfeld surface of the mol­ecules (Table 4[link]), and the carbon atoms of the imidazo­pyridine moiety mainly act as donors in building the mol­ecular assembly. The scattered points in the breakdown of the fingerprint plot show that the ππ stacking inter­actions comprise 7.9% of the total Hirshfeld surface of the mol­ecule (Table 5[link]) displayed as a region of blue/green color on the diagonal at around dedi ≃ 1.743 Å. Another contribution comes from H⋯H contacts (38.4%) represented by the scattered points in the fingerprint plots, and spread up only to di = de = 1.092 Å (Fig. 5[link]).

Table 5
Summary of the short inter­atomic contacts (Å)

Contact Distance Contact Distance
Cl1⋯H7v 2.883 C2⋯H6v 2.992
Cl1⋯C2i 3.613 (2) C2⋯C5iv 3.535 (3)
Cl1⋯H2i 2.932 C2⋯H3vii 3.021
Cl1⋯H5ii 2.893 C4⋯C4viii 3.525 (3)
Cl1⋯H3vi 3.055 C4⋯H4viii 2.834
N1⋯N1i 3.257 (2) C6⋯H2iii 3.050
C1⋯C4iv 3.482 (3) H2⋯H3vii 2.416
C1⋯C5iv 3.516 (3) H4⋯H4viii 2.309
C1⋯C6ii 3.518 (3) H6⋯H2iii 2.535
Symmetry codes: (i) −x + [{1\over 2}], y, −z + [{3\over 2}]; (ii) −x, −y, −z + 1; (iii) x, y − 1, z; (iv) −x + 1, −y, −z + 1; (v) x, y + 1, z; (vi) x − [{1\over 2}], −y + 1, z + [{1\over 2}]; (vii) −x + 1, −y + 1, −z + 1; (viii) −x + [{1\over 2}], y, −z + [{1\over 2}];
[Figure 5]
Figure 5
Fingerprint plots: full (middle) and decomposed plots corresponding to all contacts involved in the structure [clockwise: from bottom left to bottom right]. The relative contributions of various inter­molecular contacts to the Hirshfeld surface area of the title structure are displayed by the schematic illustration.

Finally, the short inter-atomic contacts of the structure (Table 5[link]) of the type Cl⋯C/ C⋯Cl, N⋯C/ C⋯N, Cl⋯Cl and N⋯N are clearly visible as scattered points in the region de + di ≃ 4.07 Å, de + di ≃ 3.58 Å, de + di ≃ 4.11 Å and de + di ≃ 3.82 Å of the breakdown fingerprint plots (Fig. 5[link]). They contribute 0.5%, 5.7%, 0.4% and 0.9%, respectively, to the total Hirshfeld area of the title complex (Table 4[link], see Fig. 6[link]).

[Figure 6]
Figure 6
Perspective view of the decomposed dnorm surfaces of the title structure corresponding to (a) Cl⋯H/H⋯Cl; (b) N⋯H/H⋯N; (c) C⋯H/H⋯C; (d) Cl⋯C/C⋯Cl; (e) N⋯C/C⋯N; (f) Cl⋯Cl; (g) N⋯N; (h) C⋯C and (i) H⋯H contacts.

The individual inter­molecular inter­actions described above and the qu­anti­tative contributions included in Table 4[link] can be also visualized by the different dnorm surfaces shown in Fig. 6[link], confirming that the Hirshfeld surface analysis provides a full understanding of the inter­molecular inter­actions in a facile and immediate way.

5. Database survey

A search in the Cambridge Structural Database (Version 5.38, update May 2017; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) for structures of the general formula [ML2X2], where M is any transition metal, L is the ligand imidazo[1,2-a]pyridine, and X any halogen, yielded no results. However, two related complexes exist, with ruthenium and tin, respectively: (i) di­chloro-[2,2′-(pyridine-2,6-di­yl)bis­(imidazo[1,2-a]pyridine)]tri­phenyl­phosphine­ruthenium(II) (GULNEI; Li et al., 2015[Li, K., Niu, J.-L., Yang, M.-Z., Li, Z., Wu, L.-Y., Hao, X.-Q. & Song, M.-P. (2015). Organometallics, 34, 1170-1176.]); (ii) di­bromo-bis(imidazo[1,2-a]pyridine)­dimethyl­tin (NODREF; Agrawal et al., 2014[Agrawal, R., Goyal, V., Gupta, R., Pallepogu, R., Kotikalapudi, R., Jones, P. G. & Bansal, R. K. (2014). Polyhedron, 70, 138-143.]). In both cases, the presence of the halogen atoms is relevant to the stabilization of the crystal structure. In the case of the ruthenium compound, the complex mol­ecules are linked into discrete supra­molecular dimers through pairs of C—H(imidazo)⋯Cl inter­actions. On the other hand, the tin complex forms undulating sheets parallel to the (100) plane by means of C—H(pyridine)⋯Br inter­actions in which both the Br ions and the ligands of one complex act as acceptor and donor, respectively.

6. Synthesis and crystallization

The title complex was prepared by simple hydro­thermal reaction. CoCl2·6H2O (2.0 mmol, 0.476 g) was dissolved in water (20 ml) yielding a clear pink solution. A hot water–methanol (1:1) solution (20 ml) of imidazo[1,2-a]pyridine (1.0 mmol, 0.118 g) was added dropwise to the above solution under continuous stirring. The solution mixture thus obtained was further heated at 343 K for 2 h and then kept for crystallization at room temperature (303 K). The resulting solution was allowed to evaporate slowly at room temperature for several weeks, yielding testable dark-pink crystals, which were collected by filtration, washed with water and dried in air.

7. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 6[link]. The hydrogen atoms were located in the difference-Fourier map and refined as riding atoms, with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C).

Table 6
Experimental details

Crystal data
Chemical formula [CoCl2(C7H6N2)2]
Mr 366.11
Crystal system, space group Monoclinic, P2/n
Temperature (K) 293
a, b, c (Å) 7.712 (2), 6.7898 (18), 14.348 (4)
β (°) 98.533 (5)
V3) 743.0 (4)
Z 2
Radiation type Mo Kα
μ (mm−1) 1.51
Crystal size (mm) 0.17 × 0.11 × 0.06
 
Data collection
Diffractometer Bruker SMART APEXII CCD area-detector
Absorption correction Multi-scan (SADABS; Bruker, 2007[Bruker (2007). APEX2, SAINT, XPREP and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.82, 0.92
No. of measured, independent and observed [I > 2σ(I)] reflections 6663, 1307, 1241
Rint 0.023
(sin θ/λ)max−1) 0.595
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.064, 1.06
No. of reflections 1307
No. of parameters 96
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.18, −0.32
Computer programs: APEX2 , SAINT and XPREP (Bruker, 2007[Bruker (2007). APEX2, SAINT, XPREP and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2018 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), DIAMOND (Brandenburg, 2006[Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.]), Mercury (Macrae et al., 2006[Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453-457.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: APEX2 (Bruker, 2007) and SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007) and XPREP (Bruker, 2007); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), DIAMOND (Brandenburg, 2006) and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2009).

Dichloridobis(imidazo[1,2-a]pyridine-κN1)cobalt(II) top
Crystal data top
[CoCl2(C7H6N2)2]F(000) = 370
Mr = 366.11Dx = 1.636 Mg m3
Monoclinic, P2/nMo Kα radiation, λ = 0.71073 Å
a = 7.712 (2) ÅCell parameters from 647 reflections
b = 6.7898 (18) Åθ = 1.5–25.0°
c = 14.348 (4) ŵ = 1.51 mm1
β = 98.533 (5)°T = 293 K
V = 743.0 (4) Å3Block, pink
Z = 20.17 × 0.11 × 0.06 mm
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
1307 independent reflections
Radiation source: fine-focus sealed tube1241 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
ω and φ scansθmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Bruker, 2007)
h = 89
Tmin = 0.82, Tmax = 0.92k = 88
6663 measured reflectionsl = 1717
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.024Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.064H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0355P)2 + 0.2499P]
where P = (Fo2 + 2Fc2)/3
1307 reflections(Δ/σ)max < 0.001
96 parametersΔρmax = 0.18 e Å3
0 restraintsΔρmin = 0.31 e Å3
Special details top

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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Co10.2500000.21247 (5)0.7500000.03788 (13)
Cl10.00699 (6)0.40150 (8)0.73557 (4)0.05261 (16)
N10.2270 (2)0.0373 (2)0.63532 (10)0.0410 (3)
N20.2373 (2)0.0539 (2)0.48712 (11)0.0452 (4)
C20.3250 (3)0.2781 (3)0.52292 (15)0.0513 (5)
H20.3410710.3833480.5647970.062*
C10.2664 (2)0.0958 (3)0.55145 (12)0.0386 (4)
C60.1741 (3)0.2106 (3)0.53192 (17)0.0554 (5)
H60.1412180.3326230.5056040.066*
C50.2770 (3)0.0324 (4)0.39615 (14)0.0635 (6)
H50.2613000.1368020.3537860.076*
C70.1689 (3)0.1537 (3)0.62194 (16)0.0503 (5)
H70.1312850.2323550.6680940.060*
C30.3582 (3)0.2988 (4)0.43289 (15)0.0629 (6)
H30.3949720.4199670.4127940.075*
C40.3379 (3)0.1406 (5)0.37060 (15)0.0677 (7)
H40.3670030.1555120.3103750.081*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Co10.0447 (2)0.0343 (2)0.0365 (2)0.0000.01225 (14)0.000
Cl10.0507 (3)0.0496 (3)0.0578 (3)0.0098 (2)0.0093 (2)0.0003 (2)
N10.0469 (8)0.0342 (8)0.0436 (8)0.0029 (6)0.0121 (7)0.0024 (6)
N20.0415 (8)0.0476 (9)0.0451 (9)0.0027 (7)0.0022 (7)0.0107 (7)
C20.0594 (12)0.0493 (11)0.0442 (11)0.0098 (9)0.0045 (9)0.0033 (9)
C10.0383 (9)0.0406 (10)0.0367 (9)0.0018 (7)0.0049 (7)0.0037 (7)
C60.0561 (12)0.0403 (11)0.0677 (14)0.0017 (9)0.0023 (10)0.0165 (9)
C50.0534 (12)0.0963 (18)0.0387 (11)0.0085 (13)0.0003 (9)0.0252 (12)
C70.0520 (11)0.0353 (9)0.0644 (12)0.0050 (9)0.0109 (9)0.0038 (9)
C30.0607 (13)0.0808 (16)0.0454 (11)0.0161 (12)0.0019 (10)0.0154 (11)
C40.0540 (13)0.111 (2)0.0381 (11)0.0105 (14)0.0054 (9)0.0056 (13)
Geometric parameters (Å, º) top
Co1—N12.0168 (4)C2—C11.400 (3)
Co1—N1i2.0169 (15)C2—H20.9300
Co1—Cl12.2556 (5)C6—C71.355 (3)
Co1—Cl1i2.2556 (7)C6—H60.9300
N1—C11.344 (2)C5—C41.337 (4)
N1—C71.376 (2)C5—H50.9300
N2—C11.369 (2)C7—H70.9300
N2—C61.370 (3)C3—C41.391 (4)
N2—C51.392 (3)C3—H30.9300
C2—C31.361 (3)C4—H40.9300
N1—Co1—N1i107.70 (5)N2—C1—C2119.15 (17)
N1—Co1—Cl1106.83 (1)C7—C6—N2106.79 (17)
N1i—Co1—Cl1112.44 (5)C7—C6—H6126.6
N1—Co1—Cl1i112.44 (5)N2—C6—H6126.6
N1i—Co1—Cl1i106.83 (5)C4—C5—N2119.0 (2)
Cl1—Co1—Cl1i110.64 (4)C4—C5—H5120.5
C1—N1—C7105.44 (16)N2—C5—H5120.5
C1—N1—Co1123.48 (12)C6—C7—N1110.28 (19)
C7—N1—Co1131.06 (14)C6—C7—H7124.9
C1—N2—C6107.13 (16)N1—C7—H7124.9
C1—N2—C5121.17 (19)C2—C3—C4120.7 (2)
C6—N2—C5131.65 (19)C2—C3—H3119.6
C3—C2—C1118.9 (2)C4—C3—H3119.6
C3—C2—H2120.5C5—C4—C3120.9 (2)
C1—C2—H2120.5C5—C4—H4119.6
N1—C1—N2110.35 (16)C3—C4—H4119.6
N1—C1—C2130.48 (17)
N1i—Co1—N1—C1157.31 (17)C5—N2—C1—C24.7 (3)
Cl1i—Co1—N1—C139.88 (15)C3—C2—C1—N1179.1 (2)
Cl1—Co1—N1—C181.68 (14)C3—C2—C1—N22.6 (3)
N1i—Co1—N1—C724.35 (15)C1—N2—C6—C70.9 (2)
Cl1i—Co1—N1—C7141.78 (16)C5—N2—C6—C7176.8 (2)
Cl1—Co1—N1—C796.66 (17)C1—N2—C5—C42.7 (3)
C7—N1—C1—N21.1 (2)C6—N2—C5—C4180.0 (2)
Co1—N1—C1—N2179.77 (11)N2—C6—C7—N10.2 (2)
C7—N1—C1—C2177.4 (2)C1—N1—C7—C60.5 (2)
Co1—N1—C1—C21.3 (3)Co1—N1—C7—C6179.08 (14)
C6—N2—C1—N11.2 (2)C1—C2—C3—C41.3 (3)
C5—N2—C1—N1176.69 (16)N2—C5—C4—C31.3 (3)
C6—N2—C1—C2177.42 (18)C2—C3—C4—C53.4 (4)
Symmetry code: (i) x+1/2, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···Cl1ii0.932.893.663 (1)141
C7—H7···Cl1iii0.932.883.734 (1)153
Symmetry codes: (ii) x, y, z+1; (iii) x, y1, z.
Geometrical parameters (Å, °) for ππ stacking top
(a) Cg1 and Cg2 are the centroids of the (N1/C1/N2/C6/C7) and (N2/C1–C5) rings, respectively; (b) centroid–centroid distance between ring i and ring j; (c) vertical distance from ring centroid i to ring j; (d) vertical distance from ring centroid j to ring i; (e) dihedral angle between the first ring mean plane and the second ring mean plane of the partner molecule; (f) angle between the centroid of the first ring and the second ring; (g) angle between the centroid of the first ring and the normal to the mean plane of the second ring of the partner molecule.
Rings ijaRcbR1vcR2vdαeβfγgSlippage
Cg1···Cg1ii3.6414 (16)-3.4980 (8)-3.4980 (8)0.016.1316.131.012
Cg1···Cg2ii3.9583 (16)-3.5303 (9)-3.5035 (9)2.4727.7326.89
Cg1···Cg2iv3.8371 (16)3.4625 (9)3.4846 (9)2.4724.7525.53
Cg2···Cg2iv3.5293 (16)3.4671 (9)3.4671 (9)0.010.7710.770.659
Symmetry codes: (ii) -x, -y, -z + 1; (iv) -x + 1, -y, -z + 1.
Percentage contributions of interatomic contacts to the Hirshfeld surface top
Contact% contributionContact% contribution
Cl···H/H···Cl30.0Cl···Cl0.4
N···H/H···N4.1N···N0.9
C···H/H···C12.1C···C7.9
Cl···C/C···Cl0.5H···H38.4
N···C/C···N5.7
Summary of the short interatomic contacts (Å) top
ContactDistanceContactDistance
Cl1···H7v2.883C2···H6v2.992
Cl1···C2i3.613 (2)C2···C5iv3.535 (3)
Cl1···H2i2.932C2···H3vii3.021
Cl1···H5ii2.893C4···C4viii3.525 (3)
Cl1···H3vi3.055C4···H4viii2.834
N1···N1i3.257 (2)C6···H2iii3.050
C1···C4iv3.482 (3)H2···H3vii2.416
C1···C5iv3.516 (3)H4···H4viii2.309
C1···C6ii3.518 (3)H6···H2iii2.535
Symmetry codes: (i) -x + 1/2, y, -z + 3/2; (ii) -x, -y, -z + 1; (iii) x, y -1, z; (iv) -x + 1, -y, -z + 1; (v) x, y + 1, z; (vi) x - 1/2, -y + 1, z + 1/2; (vii) -x + 1, -y + 1, -z + 1; (viii) -x + 1/2, y, -z + 1/2;
 

Funding information

The author is grateful to the Science and Engineering Research Board (SERB) –Department of Science and Technology (DST), Govt. of India for a SERB Overseas Postdoctoral Fellowship (SB/OS/PDF-524/2015–16).

References

First citationAdib, M., Sheikhi, E. & Rezaei, N. (2011). Tetrahedron Lett. 52, 3191–3194.  CrossRef CAS Google Scholar
First citationAgrawal, R., Goyal, V., Gupta, R., Pallepogu, R., Kotikalapudi, R., Jones, P. G. & Bansal, R. K. (2014). Polyhedron, 70, 138–143.  CSD CrossRef CAS Google Scholar
First citationBagdi, A. K., Santra, S., Monir, K. & Hajra, A. (2015). Chem. Commun. 51, 1555–1575.  CrossRef CAS Google Scholar
First citationBiftu, T., Feng, D., Fisher, M., Liang, G. B., Qian, X., Scribner, A., Dennis, R., Lee, S., Liberator, P. A., Brown, C., Gurnett, A., Leavitt, P. S., Thompson, D., Mathew, J., Misura, A., Samaras, S., Tamas, T., Sina, J. F., McNulty, K. A., McKnight, C. G., Schmatz, D. M. & Wyvratt, M. (2006). Bioorg. Med. Chem. Lett. 16, 2479–2483.  CrossRef CAS Google Scholar
First citationBrandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBravi, G., Cheasty, A. G., Corfield, J. A., Grimes, R. M., Harrison, D., Hartley, C. D., Howes, P. D., Medhurst, K. J., Meeson, M. L., Mordaunt, J. E., et al. (2007). World patent WO 2,007,039,146.  Google Scholar
First citationBruker (2007). APEX2, SAINT, XPREP and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationDymińska, L. (2015). Bioorg. Med. Chem. 23, 6087–6099.  Google Scholar
First citationEnguehard-Gueiffier, C. & Gueiffier, A. (2007). Mini Rev. Med. Chem. 7, 888–899.  CAS Google Scholar
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationGroom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationGudmundsson, K. S. & Boggs, S. D. (2007). World patent WO 2,007 027,999.  Google Scholar
First citationGudmundsson, K. S. & Johns, B. A. (2007). Bioorg. Med. Chem. Lett. 17, 2735–2739.  Web of Science CrossRef PubMed CAS Google Scholar
First citationGunja, N. (2013). J. Med. Toxicol. 9, 163–171.  CrossRef CAS Google Scholar
First citationHarrison, T. S. & Keating, G. M. (2005). CNS Drugs, 19, 709–716.  CAS Google Scholar
First citationIsmail, M. A., Arafa, R. K., Wenzler, T., Brun, R., Tanious, F. A., Wilson, W. D. & Boykin, D. W. (2008). Bioorg. Med. Chem. 16, 683–691.  CrossRef CAS Google Scholar
First citationKaminski, J. J. & Doweyko, A. M. (1997). J. Med. Chem. 40, 427–436.  CrossRef CAS PubMed Web of Science Google Scholar
First citationKe, C.-H., Kuo, B.-C., Nandi, D. & Lee, H. M. (2013). Organometallics, 32, 4775–4784.  CSD CrossRef CAS Google Scholar
First citationLi, K., Niu, J.-L., Yang, M.-Z., Li, Z., Wu, L.-Y., Hao, X.-Q. & Song, M.-P. (2015). Organometallics, 34, 1170–1176.  CSD CrossRef CAS Google Scholar
First citationMacrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationManna, P., Ray Choudhury, S., Mitra, M., Kumar Seth, S., Helliwell, M., Bauzá, A., Frontera, A. & Mukhopadhyay, S. (2014b). J. Solid State Chem. 220, 149–156.  CSD CrossRef CAS Google Scholar
First citationManna, P., Seth, S. K., Das, A., Hemming, J., Prendergast, R., Helliwell, M., Choudhury, S. R., Frontera, A. & Mukhopadhyay, S. (2012). Inorg. Chem. 51, 3557–3571.  CSD CrossRef CAS Google Scholar
First citationManna, P., Seth, S. K., Mitra, M., Choudhury, S. R., Bauzá, A., Frontera, A. & Mukhopadhyay, S. (2014a). Cryst. Growth Des. 14, 5812–5821.  CSD CrossRef CAS Google Scholar
First citationManna, P., Seth, S. K., Mitra, M., Das, A., Singh, N. J., Choudhury, S. R., Kar, T. & Mukhopadhyay, S. (2013). CrystEngComm, 15, 7879–7886.  Web of Science CSD CrossRef CAS Google Scholar
First citationMcKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2007). Chem. Commun. pp. 3814–3816.  Web of Science CrossRef Google Scholar
First citationMcKinnon, J. J., Mitchell, A. S. & Spackman, M. A. (1998). Chem. Eur. J. 4, 2136–2141.  CrossRef CAS Google Scholar
First citationMitra, M., Manna, P., Bauzá, A., Ballester, P., Seth, S. K., Ray Choudhury, S., Frontera, A. & Mukhopadhyay, S. (2014). J. Phys. Chem. B, 118, 14713–14726.  CSD CrossRef CAS Google Scholar
First citationMitra, M., Seth, S. K., Choudhury, S. R., Manna, P., Das, A., Helliwell, M., Bauzá, A., Frontera, A. & Mukhopadhyay, S. (2013). Eur. J. Inorg. Chem. pp. 4679–4685.  CSD CrossRef Google Scholar
First citationProstota, Y., Kachkovsky, O. D., Reis, L. V. & Santos, P. F. (2013). Dyes Pigments, 96, 554–562.  CrossRef CAS Google Scholar
First citationPuerstinger, G., Paeshuyse, J., De Clercq, E. & Neyts, J. (2007). Bioorg. Med. Chem. Lett. 17, 390–393.  CrossRef CAS Google Scholar
First citationRival, Y., Grassy, G. & Michel, G. (1992). Chem. Pharm. Bull. 40, 1170–1176.  CrossRef PubMed CAS Google Scholar
First citationRival, Y., Grassy, G., Taudou, A. & Ecalle, R. (1991). Eur. J. Med. Chem. 26, 13–18.  CrossRef CAS Web of Science Google Scholar
First citationRohl, A. L., Moret, M., Kaminsky, W., Claborn, K., McKinnon, J. J. & Kahr, B. (2008). Cryst. Growth Des. 8, 4517–4525.  Web of Science CSD CrossRef CAS Google Scholar
First citationRupert, K. C., Henry, J. R., Dodd, J. H., Wadsworth, S. A., Cavender, D. E., Olini, G. C., Fahmy, B. & Siekierka, J. J. (2003). Bioorg. Med. Chem. Lett. 13, 347–350.  Web of Science CrossRef PubMed CAS Google Scholar
First citationSamanta, T., Dey, L., Dinda, J., Chattopadhyay, S. K. & Seth, S. K. (2014). J. Mol. Struct. 1068, 58–70.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K. (2013). CrystEngComm, 15, 1772–1781.  Web of Science CSD CrossRef CAS Google Scholar
First citationSeth, S. K. (2014a). J. Mol. Struct. 1064, 70–75.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K. (2014b). J. Mol. Struct. 1070, 65–74.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K. (2014c). Inorg. Chem. Commun. 43, 60–63.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K., Manna, P., Singh, N. J., Mitra, M., Jana, A. D., Das, A., Choudhury, S. R., Kar, T., Mukhopadhyay, S. & Kim, K. S. (2013). CrystEngComm, 15, 1285–1288.  Web of Science CSD CrossRef CAS Google Scholar
First citationSeth, S. K., Saha, I., Estarellas, C., Frontera, A., Kar, T. & Mukhopadhyay, S. (2011b). Cryst. Growth Des. 11, 3250–3265.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K., Sarkar, D., Jana, A. D. & Kar, T. (2011d). Cryst. Growth Des. 11, 4837–4849.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K., Sarkar, D. & Kar, T. (2011a). CrystEngComm, 13, 4528–4535.  CSD CrossRef CAS Google Scholar
First citationSeth, S. K., Sarkar, D., Roy, A. & Kar, T. (2011c). CrystEngComm, 13, 6728–6741.  CSD CrossRef CAS Google Scholar
First citationSheldrick, G. M. (2015a). Acta Cryst. A71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015b). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSpackman, M. A. & Byrom, P. G. (1997). Chem. Phys. Lett. 267, 215–220.  CrossRef CAS Web of Science Google Scholar
First citationSpackman, M. A. & McKinnon, J. J. (2002). CrystEngComm, 4, 378–392.  Web of Science CrossRef CAS Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationVéron, J. B., Enguehard-Gueiffier, C., Snoeck, R., Andrei, G., De Clercq, E. & Gueiffier, A. (2007). Bioorg. Med. Chem. 15, 7209–7219.  Google Scholar
First citationWolff, S. K., Grimwood, D. J., McKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2012). CrystalExplorer 3.1. The University of Western Australia.  Google Scholar

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