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Syntheses, crystal structures and thermal properties of catena-poly[cadmium(II)-di-μ-bromido-μ-pyridazine-κ2N1:N2] and catena-poly[cadmium(II)-di-μ-iodido-μ-pyridazine-κ2N1:N2]

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aInstitut für Anorganische Chemie, Universität Kiel, Max-Eyth.-Str. 2, 24118 Kiel, Germany
*Correspondence e-mail: cnaether@ac.uni-kiel.de

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 27 February 2023; accepted 2 March 2023; online 10 March 2023)

The reactions of cadmium bromide and cadmium iodide with pyridazine (C4H4N2) in ethanol under solvothermal conditions led to the formation of crystals of [CdBr2(pyridazine)]n (1) and [CdI2(pyridazine)]n (2), which were characterized by single-crystal X-ray diffraction. The asymmetric units of both compounds consist of a cadmium cation located on the inter­section point of a twofold screw axis and a mirror plane (2/m), a halide anion that is located on a mirror plane and a pyridazine ligand, with all atoms occupying Wyckoff position 4e (mm2). These compounds are isotypic and consist of cadmium cations that are octa­hedrally coordinated by four halide anions and two pyridazine ligands and are linked into [100] chains by pairs of μ-1,1-bridging halide anions and bridging pyridazine ligands. In the crystals, the pyridazine ligands of neighboring chains are stacked onto each other, indicating ππ inter­actions. Larger amounts of pure samples can also be obtained by stirring at room-temperature, as proven by powder X-ray diffraction. Measurements using thermogravimetry and differential thermoanalysis (TG-DTA) reveal that upon heating all the pyridiazine ligands are removed in one step, which leads to the formation of CdBr2 or CdI2.

1. Chemical context

Coordination polymers based on transition-metal halides show a versatile structural behavior and can form networks of different dimensionalities (Peng et al., 2010[Peng, R., Li, M. & Li, D. (2010). Coord. Chem. Rev. 254, 1-18.]). This is especially valid for compounds based on CuI, which show different CuX substructures (X = Cl, Br, I) such as, for example, dimeric units, chains or layers that can be additionally connected by bridging neutral coligands (Peng et al., 2010[Peng, R., Li, M. & Li, D. (2010). Coord. Chem. Rev. 254, 1-18.]). These compounds are of additional inter­est because of their lumin­escence behavior (Gibbons et al., 2017[Gibbons, S. K., Hughes, R. P., Glueck, D. S., Royappa, A. T., Rheingold, A. L., Arthur, R. B., Nicholas, A. D. & Patterson, H. H. (2017). Inorg. Chem. 56, 12809-12820.]; Mensah et al., 2022[Mensah, A., Shao, J. J., Ni, J. L., Li, G. J., Wang, F. M. & Chen, L. Z. (2022). Front. Chem. 9, 816363. https://doi.org/10.3389/fchem.2021.816363]). For one particular metal halide and coligand, compounds of different stoichiometry are frequently observed. In most cases they were synthesized in the liquid state, but in some cases the coligand-deficient phases cannot be obtained from solution or are obtained only as mixtures with coligand-rich phases.

We have been inter­ested in the structural properties of such compounds for several years and have found that upon heating most of the coligand-rich compounds lose their co­ligands stepwise and transform into new coligand-deficient compounds that show condensed copper-halide networks (Näther & Jess, 2004[Näther, C. & Jess, I. (2004). Eur. J. Inorg. Chem. pp. 2868-2876.]; Näther et al., 2001[Näther, C., Jess, I. & Greve, J. (2001). Polyhedron, 20, 1017-1022.], 2007[Näther, C., Bhosekar, G. & Jess, I. (2007). Inorg. Chem. 46, 8079-8087.]). The advantage of this method is the fact that this reaction is irreversible, and that the new compounds are obtained in qu­anti­tative yields. Moreover, in some cases, metastable polymorphs or isomers can also be obtained (Näther et al., 2007[Näther, C., Bhosekar, G. & Jess, I. (2007). Inorg. Chem. 46, 8079-8087.]) and this method can also be used for the synthesis of new coordination polymers with other bridging anionic ligands such as, for example, thio- or seleno­cyanates (Werner et al., 2015[Werner, J., Runčevski, T., Dinnebier, R. E., Ebbinghaus, S. G., Suckert, S. & Näther, C. (2015). Eur. J. Inorg. Chem. 2015, 3236-3245.]; Wriedt & Näther, 2010[Wriedt, M. & Näther, C. (2010). Chem. Commun. 46, 4707-4709.]).

We subsequently found that transition-metal halide compounds with twofold positively charged cations such as CdII that also show a pronounced structural variability can be obtained by this route (Näther et al., 2017[Näther, C., Jess, I., Germann, L. S., Dinnebier, R. E., Braun, M. & Terraschke, H. (2017). Eur. J. Inorg. Chem. pp. 1245-1255.]; Jess et al., 2020[Jess, I., Neumann, T., Terraschke, H., Gallo, G., Dinnebier, R. E. & Näther, C. (2020). Z. Anorg. Allg. Chem. 646, 1046-1054.]). In most cases, discrete CdX2 complexes are observed (Ghanbari et al., 2017[Ghanbari Niyaky, S., Montazerozohori, M., Masoudiasl, A. & White, J. M. (2017). J. Mol. Struct. 1131, 201-211.]; Liu, 2011[Liu, D. (2011). Acta Cryst. E67, m1407.]), but these units can also condense into dinuclear (Santra et al., 2016[Santra, A., Mondal, G., Acharjya, M., Bera, P., Panja, A., Mandal, T. K., Mitra, P. & Bera, P. (2016). Polyhedron, 113, 5-15.]; Xie et al., 2003[Xie, Y. S., Liu, X. T., Yang, J. X., Jiang, H., Liu, Q. L., Du, C. X. & Zhu, Y. (2003). Collect. Czech. Chem. Commun. 68, 2139-2149.]) and tetra­nuclear units (Zhu, 2011[Zhu, R.-Q. (2011). Acta Cryst. E67, m1416.]) or polymers (Nezhadali Baghan et al., 2021[Nezhadali Baghan, Z., Salimi, A., Eshtiagh-Hosseini, H. & Oliver, A. G. (2021). CrystEngComm, 23, 6276-6290.]; Satoh et al., 2001[Satoh, K., Suzuki, T. & Sawada, K. (2001). Monatsh. Chem. 132, 1145-1155.]), where the latter can be further linked by the coligands into layers (Hu et al., 2009[Hu, J. J., Jin, C. M., Sun, T. Q. & Mei, T. F. Z. (2009). Z. Anorg. Allg. Chem. 635, 2579-2584.]; Marchetti et al., 2011[Marchetti, F., Masciocchi, N., Albisetti, A. F., Pettinari, C. & Pettinari, R. (2011). Inorg. Chim. Acta, 373, 32-39.]).

In this context, we have reported on CdX2 coordination polymers with 2-chloro and 2-methyl­pyrazine with the composition CdX2(L)2 with X = Cl, Br, I and L = 2-chloro or 2-methyl­pyrazine). These compounds consists of CdX2 chains in which the Cd cations are linked by two pairs of μ-1,1-bridging halide anions (Näther et al., 2017[Näther, C., Jess, I., Germann, L. S., Dinnebier, R. E., Braun, M. & Terraschke, H. (2017). Eur. J. Inorg. Chem. pp. 1245-1255.]). Surprisingly, upon heating, the compounds with 2-chloro­pyrazine lose all the coligands in one single step, whereas decomposition of the 2-methyl­pyrazine compounds leads to the formation of compounds with the composition CdX2(2-methyl­pyrazine), in which the CDX2 chains are linked into layers by the 2-meth­yl­pyrazine ligands. These compounds can also be obtained if the discrete complex CdI2(2-methyl­pyrazine)2(H2O) is thermally decomposed. In further work we investigated similar compounds with 2-cyano­pyrazine as coligand, where we observed a different thermal reactivity as a function of the nature of the halide anions (Jess et al., 2020[Jess, I., Neumann, T., Terraschke, H., Gallo, G., Dinnebier, R. E. & Näther, C. (2020). Z. Anorg. Allg. Chem. 646, 1046-1054.]).

In the course of our investigations we also became inter­ested in compounds with pyridazine as coligand. A search in the CCDC database revealed that several transition-metal halide coordination compounds with this ligand have already been reported in the literature (see Database survey). With cadmium, one compound with the composition CdCl2(pyridazine) is reported, in which the CdII cations are linked by μ-1,1-bridging chloride anions into chains, in which each two CdII cations are additionally connected by the pyridazine ligands (Pazderski et al., 2004a[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L., Sitkowski, J. & Kamieński, B. (2004a). J. Mol. Struct. 697, 143-149.]). As this compound is isotypic to many other MX2(pyridazine) coordination compounds, one can assume that this structure represents a very stable arrangement. On the other hand, compounds with this composition have also been reported with ZnX2. In contrast to the bromide and iodide compounds, the chloride analog crystallizes in three different modifications, which indicates that the structural behavior also depends on the nature of the halide anion (Bhosekar et al., 2006a[Bhosekar, G., Jess, I. & Näther, C. (2006a). Acta Cryst. E62, m2073-m2074.],b[Bhosekar, G., Jess, I. & Näther, C. (2006b). Acta Cryst. E62, m1859-m1860.]; Pazderski et al., 2004b[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L. & Sitkowski, J. (2004b). Acta Cryst. E60, m1270-m1272.]; Bhosekar et al., 2007[Bhosekar, G., Jess, I., Havlas, Z. & Näther, C. (2007). Cryst. Growth Des. 7, 2627-2634.]). Moreover, even if in the majority of compounds Nezhadali acts as a bridging ligands, some examples have been reported in which this ligand is coordinated to metal cations with only one of the two N atoms, thereby forming discrete complexes, which also include transition-metal halide complexes (Handy et al., 2017[Handy, J. V., Ayala, G. & Pike, R. D. (2017). Inorg. Chim. Acta, 456, 64-75.]; Boeckmann et al., 2011[Boeckmann, J., Jess, I., Reinert, T. & Näther, C. (2011). Eur. J. Inorg. Chem. pp. 5502-5511.]; Laramée & Hanan, 2014[Laramée, B. & Hanan, G. S. (2014). Acta Cryst. E70, m17.]; Yang, 2017[Yang, J. (2017). J. Coord. Chem. 70, 3749-3758.]; Harvey et al., 2004[Harvey, B. G., Arif, A. M. & Ernst, R. D. (2004). Polyhedron, 23, 2725-2731.]).

[Scheme 1]

Based on all these findings, we reacted CdBr2 and CdI2 in different molar ratios with pyridazine in several solvents to investigate whether compounds with a different ratio between CdX2 and pyridazine can be prepared, which also might include pyridazine-rich discrete complexes that upon heating might transform into new compounds with a more condensed network. However, independent of the reaction conditions and the stoichiometric ratio, we always obtained the same crystalline phases, as proven by powder X-ray diffraction (PXRD). Crystals of both compounds were obtained at elevated temperatures and structure analysis proves that compounds with the composition CdBr2(pyridazine) (1) and CdI2(pyridazine) (2) were obtained. Comparison of the experimental PXRD patterns with those calculated from the results of the structure determinations, prove that both compounds were obtained as pure phases (Figs. S1 and S2). Measurements using thermogravimetry and differential thermoanalysis reveal that both compounds decompose in one step, which is accompanied with an endothermic event in the DTA curve (Figs. S3 and S4). The experimental mass losses of 22.9% for 1 and 18.1% for 2 are in good agreement with those calculated for the removal of one pyridazine ligand (Δmcalc. = 22.7% for 1 and 17.9% for 2), indicating that CdBr2 and CdI2, respectively, have formed.

In this context, it is noted that the formation of a more pyridazine-deficient compound with a more condensed network is not expected, because for M2+ cations, the network should be negatively charged. This is impossible in this case, but it is noted that one compound with CdCl2 and a more condensed metal–halide network is reported in the literature (Jin et al., 2014[Jin, Y., Yu, C., Wang, W. X., Li, S. C. & Zhang, W. (2014). Inorg. Chim. Acta, 413, 97-101.]).

2. Structural commentary

The reaction of cadmium dibromide or cadmium diiodide with pyridazine leads to the formation of crystals of CdBr2(pyridazine) (1) and CdI2(pyridazine) (2). Both compounds are isotypic to their CdCl2 analog already reported in the literature (Pazderski et al., 2004a[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L., Sitkowski, J. & Kamieński, B. (2004a). J. Mol. Struct. 697, 143-149.]). In this context, it is noted that for compound 2 a pseudo-translation along the crystallographic b-axis is detected, leading to half of the unit cell and space group Cmmm but the refinement clearly shows that the present unit cell and space group is correct (see Refinement). Both compounds are also isotypic to a number of other metal–halide coordination polymers, indicating that this is a very stable arrangement (see Database survey).

The asymmetric units of compound 1 and 2 consist of a cadmium cation located on the inter­section point of a twofold screw axis and a mirror plane (Wyckoff site 4c, symmetry 2/m), as well as a bromide or iodide anion lying on a mirror plane (Wyckoff site 8h) and a pyridazine ligand, with all atoms located on Wyckoff position 4e (mm2) (Fig. 1[link]). In both compounds, the CdII cations are octa­hedrally in a trans-CdX4N2 arrangement, coordinated by four halide anions and two pyridazine ligands, and are linked by pairs of μ-1,1-bridg­ing halide anions into chains that propagate in the crystallographic a-axis direction (Fig. 2[link]). The pyridazine ligands also act as bridging ligands, connecting two neighboring CdII cations (Fig. 2[link]). Within the chains, all of the pyridazine ligands are coplanar. (Fig. 2[link]).

[Figure 1]
Figure 1
The metal atom polyhedra in 1 (left) and 2 (right) with labeling and displacement ellipsoids drawn at the 50% probability level. Symmetry codes for the generation of equivalent atoms: (i) −x + [{1\over 2}], −y + [{1\over 2}], −z + [{1\over 2}]; (ii) −x + 1, −y + [{1\over 2}], z; (iii) x − [{1\over 2}], y, −z + [{1\over 2}].
[Figure 2]
Figure 2
Fragment of a [100] polymeric chain in the crystal structure of 1.

The Cd—N bond lengths to the pyridazine ligand are slightly longer in the iodide compound 2 compared to compound 1, which might be traced back to some crowding of the bulky iodide anion. In agreement, this distance is the shortest in the corresponding chloride compound (Pazderski et al., 2004a[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L., Sitkowski, J. & Kamieński, B. (2004a). J. Mol. Struct. 697, 143-149.]) reported in the literature (Tables 1[link] and 2[link]). The N—Cd—Br and N—Cd—I bond angles are comparable, which is also valid for that in the chloride compound (Pazderski et al., 2004a[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L., Sitkowski, J. & Kamieński, B. (2004a). J. Mol. Struct. 697, 143-149.]). As expected, the intra­chain Cd⋯Cd distance increases from Cl [Cd⋯Cd = 3.5280 (5) Å], to Br [Cd⋯Cd = 3.6270 (3) Å] to I [Cd⋯Cd = 3.7870 (3) Å].

Table 1
Selected geometric parameters (Å, °) for 1[link]

Cd1—Br1 2.7581 (2) Cd1—N1 2.385 (2)
       
Br1i—Cd1—Br1ii 95.243 (9) N1i—Cd1—Br1ii 91.08 (4)
Br1i—Cd1—Br1iii 84.757 (9) N1—Cd1—Br1 88.92 (4)
Symmetry codes: (i) [-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (ii) [-x+1, -y+{\script{1\over 2}}, z]; (iii) [x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}].

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

Cd1—I1 2.9555 (1) Cd1—N1 2.4216 (19)
       
I1i—Cd1—I1ii 93.237 (5) N1i—Cd1—I1ii 91.56 (4)
I1i—Cd1—I1iii 86.763 (5) N1—Cd1—I1 88.44 (4)
Symmetry codes: (i) [-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (ii) [-x+1, -y+{\script{1\over 2}}, z]; (iii) [x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}].

3. Supra­molecular features

In the crystal structures of 1 and 2, the chains extend in the crystallographic a-axis direction (Fig. 2[link]). Neighboring chains are arranged in such a way that the pyridazine ligands are perfectly stacked onto each other into columns that propagate along the crystallographic b-axis direction (Fig. 3[link]). The angle between two neighboring pyridazine ligands is 180° in both compounds, which is also valid for the chloride analog (Pazderski et al., 2004a[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L., Sitkowski, J. & Kamieński, B. (2004a). J. Mol. Struct. 697, 143-149.]). The distance between the centroids of adjacent pyridazine rings is 3.724 Å for the chloride, 3.8623 (1) Å (slippage = 0.095 Å) for the bromide and 4.1551 (1) Å (0.226 Å) for the iodide, consistent with ππ inter­actions (Fig. 4[link]), although they must be weak for the iodide. There are no directional inter­molecular inter­actions such as inter­molecular C—H⋯X hydrogen bonding. As mentioned above, this structure type is common for the majority of transition-metal pyridazine coordination compounds with such a metal-to-pyridazine ratio, indicating that ππ inter­actions might also be responsible for this obviously very stable arrangement.

[Figure 3]
Figure 3
Arrangement of the chains in the crystal structure of 1 in a view along the crystallographic b-axis direction.
[Figure 4]
Figure 4
Arrangement of neighboring pyridazine rings in 1 showing ππ stacking inter­actions.

4. Database survey

A search in the CCDC database (version 5.43, last update November 2022; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) revealed that some compounds with the general composition MX2(pyridazine) (M = transition metal and X = halide anion) have already been reported in the literature. The compounds with NiCl2 (CSD refcode POPCIG) and NiBr2 (POPCOM) were structurally characterized by Rietveld refinements using laboratory X-ray powder diffraction data and are isotypic to the title compounds (Masciocchi et al., 1994[Masciocchi, N., Cairati, O., Carlucci, L., Ciani, G., Mezza, G. & Sironi, A. (1994). J. Chem. Soc. Dalton Trans. pp. 3009-3015.]). In this contribution, the compounds with Mn, Fe, Co, Cu and Zn with chloride and bromide as anions were also synthesized, and their lattice parameters determined from their powder patterns, indicating that the compounds with Mn, Fe and Co are isotypic to the Ni compound, which is not the case for the compounds with Cu and Zn (Masciocchi et al., 1994[Masciocchi, N., Cairati, O., Carlucci, L., Ciani, G., Mezza, G. & Sironi, A. (1994). J. Chem. Soc. Dalton Trans. pp. 3009-3015.]). The compounds MCl2(pyridazine) with Mn (LANJEQ) and Fe (LANJAM) were later determined by single-crystal X-ray diffraction, which definitely proves that they crystallize in space group Immm (Yi et al., 2002[Yi, T., Chang, H. C. & Kitagawa, S. (2002). Mol. Cryst. Liq. Cryst. 376, 283-288.]).

In this context it is noted that three compounds containing diamagnetic ZnII cations have been reported, which consist of discrete complexes with a tetra­hedral coordination, viz. ZnI2(pyridazine)2 (MENSUU; Bhosekar et al., 2006a[Bhosekar, G., Jess, I. & Näther, C. (2006a). Acta Cryst. E62, m2073-m2074.]), ZnBr2(pyridazine)2 (VEMBEV; Bhosekar et al., 2006b[Bhosekar, G., Jess, I. & Näther, C. (2006b). Acta Cryst. E62, m1859-m1860.]) and three modifications of CuCl2(pyridazine)2 (YAFYOU, YAFYOU01, YAFYOU02 and YAFYOU03; Pazderski et al., 2004b[Pazderski, L., Szłyk, E., Wojtczak, A., Kozerski, L. & Sitkowski, J. (2004b). Acta Cryst. E60, m1270-m1272.] and Bhosekar et al., 2007[Bhosekar, G., Jess, I., Havlas, Z. & Näther, C. (2007). Cryst. Growth Des. 7, 2627-2634.]). Surprisingly, none of the different forms are isotypic to the chloride and bromide compounds reported by Masciocchi et al. (1994[Masciocchi, N., Cairati, O., Carlucci, L., Ciani, G., Mezza, G. & Sironi, A. (1994). J. Chem. Soc. Dalton Trans. pp. 3009-3015.]) based on XRPD patterns.

With CuII cations, CuCl2(pyridazine) (JEFFOS) and CuBr2(pyridazine) (JEFFUY) (Thomas & Ramanan, 2016[Thomas, J. & Ramanan, A. (2016). J. Chem. Sci. 128, 1687-1694.]) have been, reported, but most compounds are found with CuI cations, including CuI(pyridazine) [CAQXAT (Kromp & Sheldrick, 1999[Kromp, T. & Sheldrick, W. S. (1999). Z. Naturforsch. 54, 1175-1180.]) and CAQXAT01 (Thomas & Ramanan, 2016[Thomas, J. & Ramanan, A. (2016). J. Chem. Sci. 128, 1687-1694.])], CuBr(pyridazine) [CAQXEX (Kromp & Sheldrick, 1999[Kromp, T. & Sheldrick, W. S. (1999). Z. Naturforsch. 54, 1175-1180.]), CAQXEX01 and 02 (Thomas & Ramanan, 2016[Thomas, J. & Ramanan, A. (2016). J. Chem. Sci. 128, 1687-1694.])], Cu2I2(pyridazine) (CAQXIB; Kromp & Sheldrick, 1999[Kromp, T. & Sheldrick, W. S. (1999). Z. Naturforsch. 54, 1175-1180.]), Cu2Cl2(pyridazine) [CAQXOH (Kromp & Sheldrick, 1999[Kromp, T. & Sheldrick, W. S. (1999). Z. Naturforsch. 54, 1175-1180.]) and CAQXOH01 and 02 (Thomas & Ramanan, 2016[Thomas, J. & Ramanan, A. (2016). J. Chem. Sci. 128, 1687-1694.])], two modifications of CuCl(pyridazine) [EKINOB and EKINUH (Näther and Jess, 2003[Näther, C. & Jess, I. (2003). Inorg. Chem. 42, 2968-2976.]) and EKINUH01 (Thomas & Ramanan, 2016[Thomas, J. & Ramanan, A. (2016). J. Chem. Sci. 128, 1687-1694.])], Cu2Br2(pyridazine) [EKIPAP (Näther & Jess, 2003[Näther, C. & Jess, I. (2003). Inorg. Chem. 42, 2968-2976.]) and EKIPAP01 (Thomas & Ramanan, 2016[Thomas, J. & Ramanan, A. (2016). J. Chem. Sci. 128, 1687-1694.])].

5. Synthesis and crystallization

Synthesis

CdBr2, CdI2 and pyridazine were purchased from Sigma-Aldrich. All chemicals were used without further purification.

Colorless single crystals of compound 1 and 2 were obtained by the reaction of 0.500 mmol of CdBr2 or 0.500 mmol of CdI2 with 0.500 mmol of pyridazine in 1 ml of ethanol. The reaction mixtures were sealed in glass tubes and heated at 388 K for 1 d and finally cooled down to room temperature.

Larger amounts of a microcrystalline powder of 1 and 2 were obtained stirring the same amount of reactants in ethanol or water at room temperature for 1 d. For the IR spectra of 1 and 2 see Figs. S5 and S6.

Experimental details

The IR spectra were measured using an ATI Mattson Genesis Series FTIR Spectrometer, control software: WINFIRST, from ATI Mattson. The PXRD measurements were performed with Cu Kα1 radiation (λ = 1.540598 Å) using a Stoe Transmission Powder Diffraction System (STADI P) equipped with a MYTHEN 1K detector and a Johansson-type Ge(111) monochromator. Thermogravimetry and differential thermoanalysis (TG-DTA) measurements were performed in a dynamic nitro­gen atmosphere in Al2O3 crucibles using a STA-PT 1000 thermobalance from Linseis. The instrument was calibrated using standard reference materials.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3[link]. The C-bound hydrogen atoms were positioned with idealized geometry and refined with Uiso(H) = 1.2Ueq(C). For compound 2, PLATON (Spek, 2020[Spek, A. L. (2020). Acta Cryst. E76, 1-11.]) suggested a pseudo-translation along the b-axis with a fit of 80%. If the structure is determined in a unit cell with half of the b-axis, space group Cmmm is suggested. The structure can easily be solved in this space group but the refinement leads to only very poor reliability factors (R1 = 11.5%). Moreover, in this case, disorder of the nitro­gen atoms of the pyridazine ring is observed, because the N atoms of the pyridazine rings of neighboring chains are superimposed.

Table 3
Experimental details

  1 2
Crystal data
Chemical formula [CdBr2(C4H4N2)] [CdI2(C4H4N2)]
Mr 352.31 446.29
Crystal system, space group Orthorhombic, Imma Orthorhombic, Imma
Temperature (K) 293 293
a, b, c (Å) 7.2540 (2), 7.7223 (2), 13.2910 (4) 7.5740 (2), 8.2979 (2), 13.5363 (4)
V3) 744.53 (4) 850.73 (4)
Z 4 4
Radiation type Mo Kα Mo Kα
μ (mm−1) 13.58 9.75
Crystal size (mm) 0.08 × 0.06 × 0.04 0.12 × 0.03 × 0.02
 
Data collection
Diffractometer XtaLAB Synergy, Dualflex, HyPix XtaLAB Synergy, Dualflex, HyPix
Absorption correction Multi-scan (CrysAlis PRO; Rigaku OD, 2022[Rigaku OD (2022). CrysAlis PRO. Rigaku Oxford Diffraction.]) Multi-scan (CrysAlis PRO; Rigaku OD, 2022[Rigaku OD (2022). CrysAlis PRO. Rigaku Oxford Diffraction.])
Tmin, Tmax 0.582, 1.000 0.382, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections 6952, 769, 684 7478, 889, 857
Rint 0.039 0.037
(sin θ/λ)max−1) 0.772 0.774
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.057, 1.16 0.016, 0.046, 1.18
No. of reflections 769 889
No. of parameters 29 30
H-atom treatment H-atom parameters constrained H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 1.07, −0.52 0.78, −0.56
Computer programs: CrysAlis PRO (Rigaku OD, 2022[Rigaku OD (2022). CrysAlis PRO. Rigaku Oxford Diffraction.]), SHELXT2014/4 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2016/6 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), DIAMOND (Brandenburg, 1999[Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Computing details top

For both structures, data collection: CrysAlis PRO 1.171.42.67a (Rigaku OD, 2022); cell refinement: CrysAlis PRO 1.171.42.67a (Rigaku OD, 2022); data reduction: CrysAlis PRO 1.171.42.67a (Rigaku OD, 2022); program(s) used to solve structure: SHELXT2014/4 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016/6 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).

catena-Poly[cadmium(II)-di-µ-bromido-µ-pyridazine-κ2N1:N2] (1) top
Crystal data top
[CdBr2(C4H4N2)]Dx = 3.143 Mg m3
Mr = 352.31Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, ImmaCell parameters from 4638 reflections
a = 7.2540 (2) Åθ = 3.0–33.2°
b = 7.7223 (2) ŵ = 13.58 mm1
c = 13.2910 (4) ÅT = 293 K
V = 744.53 (4) Å3Block, colourless
Z = 40.08 × 0.06 × 0.04 mm
F(000) = 640
Data collection top
XtaLAB Synergy, Dualflex, HyPix
diffractometer
769 independent reflections
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Mo) X-ray Source684 reflections with I > 2σ(I)
Mirror monochromatorRint = 0.039
Detector resolution: 10.0000 pixels mm-1θmax = 33.3°, θmin = 3.1°
ω scansh = 1010
Absorption correction: multi-scan
(CrysAlisPro; Rigaku OD, 2022)
k = 1111
Tmin = 0.582, Tmax = 1.000l = 1920
6952 measured reflections
Refinement top
Refinement on F2Primary atom site location: dual
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.020H-atom parameters constrained
wR(F2) = 0.057 w = 1/[σ2(Fo2) + (0.0315P)2 + 0.191P]
where P = (Fo2 + 2Fc2)/3
S = 1.16(Δ/σ)max < 0.001
769 reflectionsΔρmax = 1.07 e Å3
29 parametersΔρmin = 0.52 e Å3
0 restraints
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cd10.2500000.2500000.2500000.02829 (10)
Br10.5000000.49073 (3)0.18013 (2)0.03175 (10)
N10.4072 (3)0.2500000.40756 (16)0.0294 (4)
C10.3181 (4)0.2500000.4947 (2)0.0365 (6)
H10.1899440.2500000.4937180.044*
C20.4065 (4)0.2500000.5870 (2)0.0369 (6)
H20.3400420.2500000.6468800.044*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.01738 (14)0.04001 (17)0.02748 (15)0.0000.00137 (9)0.000
Br10.02359 (15)0.03169 (16)0.03996 (18)0.0000.0000.00394 (10)
N10.0203 (10)0.0403 (11)0.0276 (11)0.0000.0005 (9)0.000
C10.0216 (13)0.0565 (18)0.0313 (13)0.0000.0041 (12)0.000
C20.0317 (14)0.0527 (16)0.0262 (12)0.0000.0042 (12)0.000
Geometric parameters (Å, º) top
Cd1—Br12.7581 (2)N1—N1ii1.346 (4)
Cd1—Br1i2.7581 (2)N1—C11.326 (4)
Cd1—Br1ii2.7581 (2)C1—H10.9300
Cd1—Br1iii2.7581 (2)C1—C21.385 (4)
Cd1—N12.385 (2)C2—C2ii1.357 (6)
Cd1—N1iii2.385 (2)C2—H20.9300
Br1—Cd1—Br1iii180.0N1iii—Cd1—Br1i88.92 (4)
Br1iii—Cd1—Br1ii95.243 (9)N1—Cd1—N1iii180.0
Br1ii—Cd1—Br1i180.0Cd1—Br1—Cd1ii82.223 (7)
Br1iii—Cd1—Br1i84.757 (9)N1ii—N1—Cd1118.58 (5)
Br1—Cd1—Br1i95.244 (9)C1—N1—Cd1122.26 (19)
Br1—Cd1—Br1ii84.756 (9)C1—N1—N1ii119.16 (16)
N1iii—Cd1—Br1ii91.08 (4)N1—C1—H1118.4
N1—Cd1—Br188.92 (4)N1—C1—C2123.3 (3)
N1—Cd1—Br1iii91.08 (4)C2—C1—H1118.4
N1iii—Cd1—Br1iii88.92 (4)C1—C2—H2121.2
N1—Cd1—Br1i91.08 (4)C2ii—C2—C1117.57 (17)
N1—Cd1—Br1ii88.92 (4)C2ii—C2—H2121.2
N1iii—Cd1—Br191.08 (4)
Symmetry codes: (i) x1/2, y, z+1/2; (ii) x+1, y+1/2, z; (iii) x+1/2, y+1/2, z+1/2.
catena-Poly[cadmium(II)-di-µ-iodido-µ-pyridazine-κ2N1:N2] (2) top
Crystal data top
[CdI2(C4H4N2)]Dx = 3.484 Mg m3
Mr = 446.29Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, ImmaCell parameters from 6483 reflections
a = 7.5740 (2) Åθ = 2.9–33.4°
b = 8.2979 (2) ŵ = 9.75 mm1
c = 13.5363 (4) ÅT = 293 K
V = 850.73 (4) Å3Needle, colourless
Z = 40.12 × 0.03 × 0.02 mm
F(000) = 784
Data collection top
XtaLAB Synergy, Dualflex, HyPix
diffractometer
889 independent reflections
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Mo) X-ray Source857 reflections with I > 2σ(I)
Mirror monochromatorRint = 0.037
Detector resolution: 10.0000 pixels mm-1θmax = 33.4°, θmin = 2.9°
ω scansh = 1111
Absorption correction: multi-scan
(CrysalisPro; Rigaku OD, 2022)
k = 1212
Tmin = 0.382, Tmax = 1.000l = 2019
7478 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.016 w = 1/[σ2(Fo2) + (0.0233P)2 + 0.8677P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.046(Δ/σ)max = 0.001
S = 1.18Δρmax = 0.78 e Å3
889 reflectionsΔρmin = 0.56 e Å3
30 parametersExtinction correction: SHELXL2016/6 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00206 (14)
Primary atom site location: dual
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cd10.2500000.2500000.2500000.02666 (8)
I10.5000000.49464 (2)0.17507 (2)0.02931 (8)
N10.4115 (3)0.2500000.40441 (14)0.0272 (4)
C10.3246 (4)0.2500000.48983 (19)0.0354 (6)
H10.2018200.2500000.4886610.042*
C20.4099 (4)0.2500000.5807 (2)0.0377 (6)
H20.3463280.2500000.6395340.045*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.01738 (12)0.03918 (15)0.02342 (12)0.0000.00147 (7)0.000
I10.02338 (10)0.02851 (11)0.03603 (12)0.0000.0000.00422 (5)
N10.0194 (9)0.0420 (11)0.0203 (8)0.0000.0006 (7)0.000
C10.0224 (11)0.0607 (19)0.0230 (10)0.0000.0017 (9)0.000
C20.0303 (13)0.0615 (18)0.0212 (10)0.0000.0031 (10)0.000
Geometric parameters (Å, º) top
Cd1—I12.9555 (1)N1—N1ii1.341 (4)
Cd1—I1i2.9555 (1)N1—C11.330 (3)
Cd1—I1ii2.9555 (1)C1—H10.9300
Cd1—I1iii2.9555 (1)C1—C21.390 (4)
Cd1—N12.4216 (19)C2—C2ii1.366 (6)
Cd1—N1iii2.4216 (19)C2—H20.9300
I1iii—Cd1—I1180.0N1iii—Cd1—I191.56 (4)
I1iii—Cd1—I1ii93.237 (5)N1—Cd1—N1iii180.0
I1iii—Cd1—I1i86.763 (5)Cd1—I1—Cd1ii79.683 (4)
I1i—Cd1—I1ii180.0N1ii—N1—Cd1120.33 (5)
I1ii—Cd1—I186.763 (5)C1—N1—Cd1120.03 (18)
I1i—Cd1—I193.237 (5)C1—N1—N1ii119.64 (16)
N1iii—Cd1—I1ii91.56 (4)N1—C1—H1118.7
N1—Cd1—I1iii91.56 (4)N1—C1—C2122.7 (3)
N1—Cd1—I1i91.56 (4)C2—C1—H1118.7
N1iii—Cd1—I1i88.44 (4)C1—C2—H2121.2
N1—Cd1—I188.44 (4)C2ii—C2—C1117.69 (17)
N1—Cd1—I1ii88.44 (4)C2ii—C2—H2121.2
N1iii—Cd1—I1iii88.44 (4)
Symmetry codes: (i) x1/2, y, z+1/2; (ii) x+1, y+1/2, z; (iii) x+1/2, y+1/2, z+1/2.
 

Acknowledgements

Financial support by the State of Schleswig-Holstein is gratefully acknowledged.

References

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