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Crystal structures of ZnCl2·2.5H2O, ZnCl2·3H2O and ZnCl2·4.5H2O

aTU Bergakademie Freiberg, Institute of Inorganic Chemistry, Leipziger Strasse 29, D-09596 Freiberg, Germany
*Correspondence e-mail: horst.schmidt@chemie.tu-freiberg.de

Edited by M. Weil, Vienna University of Technology, Austria (Received 15 October 2014; accepted 11 November 2014; online 15 November 2014)

The formation of different complexes in aqueous solutions is an important step in understanding the behavior of zinc chloride in water. The structure of concentrated ZnCl2 solutions is governed by coordination competition of Cl and H2O around Zn2+. According to the solid–liquid phase diagram, the title compounds were crystallized below room temperature. The structure of ZnCl2·2.5H2O contains Zn2+ both in a tetra­hedral coordination with Cl and in an octa­hedral environment defined by five water mol­ecules and one Cl shared with the [ZnCl4]2− unit. Thus, these two different types of Zn2+ cations form isolated units with composition [Zn2Cl4(H2O)5] (penta­aqua-μ-chlorido-tri­chlorido­di­zinc). The trihydrate {hexa­aqua­zinc tetra­chlorido­zinc, [Zn(H2O)6][ZnCl4]}, consists of three different Zn2+ cations, one of which is tetra­hedrally coordinated by four Cl anions. The two other Zn2+ cations are each located on an inversion centre and are octa­hedrally surrounded by water mol­ecules. The [ZnCl4] tetra­hedra and [Zn(H2O)6] octa­hedra are arranged in alternating rows parallel to [001]. The structure of the 4.5-hydrate {hexa­aqua­zinc tetra­chlorido­zinc trihydrate, [Zn(H2O)6][ZnCl4]·3H2O}, consists of isolated octa­hedral [Zn(H2O)6] and tetra­hedral [ZnCl4] units, as well as additional lattice water mol­ecules. O—H⋯O hydrogen bonds between the water mol­ecules as donor and ZnCl4 tetra­hedra and water mol­ecules as acceptor groups leads to the formation of a three-dimensional network in each of the three structures.

1. Chemical context

Zinc chloride solutions, especially at lower temperatures, are helpful in the understanding of the formation of different complex ion species in solution. The solubility of zinc chloride in water has been investigated by several authors in different concentration areas and at different temperatures (Haghighi et al., 2008[Haghighi, H., Chapoy, A. & Tohidi, B. (2008). Ind. Eng. Chem. Res. 47, 3983-3989.]; Mylius & Dietz, 1905[Mylius, F. & Dietz, R. (1905). Z. Anorg. Chem. 44, 209-220.]; Jones & Getman, 1904[Jones, H. C. & Getman, F. H. (1904). Z. Phys. Chem. 49, 385-455.]; Chambers & Frazer, 1900[Chambers, V. J. & Frazer, F. C. J. (1900). Am. Chem. J. 23, 512-520.]; Biltz, 1902[Biltz, W. (1902). Z. Phys. Chem. 40, 185-221.]; Dietz, 1899[Dietz, R. (1899). Z. Anorg. Chem. 20, 240-263.]; Etard, 1894[Etard, A. (1894). Ann. Chim. Phys. 7, 503-574.]). In the literature (Mylius & Dietz, 1905[Mylius, F. & Dietz, R. (1905). Z. Anorg. Chem. 44, 209-220.]), the 4-, 3-, and 2.5-hydrates have been reported at lower temperatures. We have also found the 2.5-hydrate, the trihydrate and the 4.5-hydrate as stable phases along the equilibrium crystallization curves. The 4.5-hydrate crystallizes below 240 K. The crystal structure of the trihydrate reported herein has also been determined by Wilcox (2009[Wilcox, R. J. (2009). PhD thesis, North Carolina State University, Raleigh, USA.]) in his thesis, but was never published. While writing the formula of the trihydrate in a more detailed formula as [Zn(H2O)6][ZnCl4], the analogy to other structures like that of [Mg(H2O)6][SO4] (Zalkin et al., 1964[Zalkin, A., Ruben, H. & Templeton, D. H. (1964). Acta Cryst. 17, 235-240.]) and [Zn(H2O)6][SO4] (Spiess & Gruehn, 1979[Spiess, M. & Gruehn, R. (1979). Z. Anorg. Allg. Chem. 456, 222-240.]) becomes obvious. These structures are very similar in the arrangement of octa­hedral units and anions in the unit cell.

2. Structural commentary

Within the crystal structure of the 2.5-hydrate, there are two crystallographic different Zn2+ cations, as shown in Fig. 1[link]. The Zn1 cation is octa­hedrally coordinated by five water mol­ecules and one chloride anion. The Zn2 cation is coordinated by four chloride anions, one shared with the Zn1 cation, leading to the formation of isolated [Zn2Cl4(H2O)5] units. Since the bond lengths of the bridging Cl atom of the tetra­hedron are shorter than to that of the octa­hedron, the latter becomes more distorted. The crystal structure of zinc chloride trihydrate consists of three crystallographically different Zn2+ cations (Fig. 2[link]a). Two (Zn2 and Zn3) are located about an inversion centre and are coordinated octa­hedrally by six water mol­ecules, forming [Zn(H2O)6]2+ cations. The third one (Zn1) is tetra­hedrally coordinated by chlorine anions, [ZnCl4]2−. The polyhedra are not connected by sharing a single atom like in the 2.5-hydrate, but they are linked by hydrogen bonds (Fig. 2[link]b). The octa­hedra and tetra­hedra are arranged in a CsCl-like arrangement with eight tetra­hedra located around one octa­hedron (Fig. 3[link]a). As shown in Fig. 4[link]a, in the asymmetric unit of ZnCl2·4.5H2O, two different Zn2+ cations are present. The Zn1 cation is coordinated octa­hedrally by six water mol­ecules and the Zn2 cation tetra­hedrally by four chloride anions. The three remaining water mol­ecules are hydrogen-bonded to a [Zn1(H2O]2+ octa­hedron (Fig. 4[link]b).

[Figure 1]
Figure 1
The asymmetric unit of ZnCl2·2.5H2O. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2]
Figure 2
(a) The mol­ecular units and (b) the unit cell in the structure of ZnCl2·3H2O. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate hydrogen bonds. [Symmetry codes: (i) 1 − x, 1 − y, 2 − z; (ii) 1 − x, 1 − y, 1 − z.]
[Figure 3]
Figure 3
(a) Arrangement of [ZnCl4]2−-anions and [Zn(H2O)6]2+ cations in a CsCl-like structure and (b) formation of chains by alternation of different coordination polyhedra in ZnCl2·3H2O. Dashed lines indicate hydrogen bonds. Only hydrogen bonds in one chain are shown.
[Figure 4]
Figure 4
(a) The mol­ecular units in the structure of ZnCl2·4.5H2O and (b) formation of a second coordination shell. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate hydrogen bonds.

3. Supra­molecular features

In the structure of ZnCl2·2.5H2O, all terminal Cl anions are connected to the octa­hedral parts of neighbouring [Zn2Cl4(H2O)5] units by three O—H⋯Cl hydrogen bonds per anion (Table 1[link], Fig. 5[link]). The coordination polyhedra in the trihydrate are arranged in zigzag chains parallel to [001] in the crystal structure. The chains are highlighted in different shades of colors in Fig. 3[link]b. Hydrogen bonds (Table 2[link]) are established within one chain and between neighbouring chains (not shown in the Figure). As can be seen from Fig. 4[link]b, five water mol­ecules in the crystal structure of ZnCl2·4.5H2O are connected via hydrogen bonds to the [Zn1(H2O]2+ octa­hedron, three of them at the axial coordination sites and two of them at the equatorial coordination sites. Seven chloride anions from [Zn2Cl4]2− tetra­hedra contribute to the second coordination sphere of Zn1. Thus, every coordinating water mol­ecule forms two hydrogen bonds. The structural situation in this salt can be compared with the second coordination shells around magnesium in magnesium halide nonahydrates like MgBr2·9H2O or MgI2·9H2O (Hennings et al., 2013[Hennings, E., Schmidt, H. & Voigt, W. (2013). Acta Cryst. C69, 1292-1300.]). Each water mol­ecule of the [Mg(H2O)6]2+ octa­hedra forms two hydrogen bonds, thus six water mol­ecules and six halide atoms are involved in the second shell. However, in case of the magnesium halides each water mol­ecule donates a hydrogen bond towards a halide anion and towards another water mol­ecule. The hydrogen-bond geometry in ZnCl2·4.5H2O is given inTable 3[link].

Table 1
Hydrogen-bond geometry (Å, °) for ZnCl2·2.5H2O

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1A⋯Cl2i 0.83 (1) 2.43 (1) 3.243 (2) 167 (3)
O1—H1B⋯O5ii 0.84 (1) 2.02 (1) 2.853 (3) 178 (4)
O2—H2A⋯Cl2iii 0.83 (1) 2.51 (2) 3.299 (2) 158 (3)
O2—H2B⋯Cl4ii 0.84 (1) 2.41 (1) 3.2212 (19) 162 (3)
O3—H3B⋯Cl1iv 0.83 (1) 2.42 (1) 3.225 (2) 164 (3)
O3—H3A⋯Cl4v 0.83 (1) 2.38 (1) 3.205 (2) 171 (3)
O4—H4B⋯Cl2v 0.83 (1) 2.35 (1) 3.181 (2) 177 (3)
O4—H4A⋯Cl1iii 0.83 (1) 2.45 (2) 3.2349 (19) 157 (3)
O5—H5A⋯Cl4i 0.83 (1) 2.55 (2) 3.233 (2) 141 (3)
O5—H5B⋯Cl1 0.83 (1) 2.56 (1) 3.359 (3) 163 (3)
Symmetry codes: (i) x+1, y, z; (ii) [-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iii) [-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iv) [x-{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]; (v) [x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}].

Table 2
Hydrogen-bond geometry (Å, °) for ZnCl2·3H2O

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1B⋯Cl3i 0.84 (1) 2.42 (1) 3.2520 (14) 168 (4)
O1—H1A⋯Cl4ii 0.84 (1) 2.43 (1) 3.2431 (14) 166 (3)
O2—H2A⋯Cl2iii 0.84 (1) 2.41 (2) 3.2260 (14) 163 (4)
O2—H2B⋯Cl3iv 0.84 (1) 2.54 (2) 3.3264 (15) 157 (3)
O3—H3B⋯Cl2ii 0.84 (1) 2.42 (2) 3.1715 (14) 149 (3)
O3—H3B⋯Cl2v 0.84 (1) 2.81 (3) 3.3159 (14) 120 (2)
O3—H3A⋯Cl4iv 0.83 (1) 2.45 (1) 3.2552 (15) 162 (3)
O4—H4A⋯Cl4 0.84 (1) 2.43 (2) 3.2307 (18) 159 (4)
O4—H4B⋯Cl1vi 0.84 (1) 2.39 (1) 3.2114 (17) 167 (4)
O5—H5B⋯Cl3vii 0.84 (1) 2.91 (5) 3.4565 (17) 125 (5)
O5—H5B⋯Cl4vii 0.84 (1) 2.59 (3) 3.3527 (18) 151 (6)
O5—H5A⋯Cl1ii 0.84 (1) 2.48 (1) 3.3159 (18) 170 (5)
O6—H6A⋯Cl1 0.84 (1) 2.52 (2) 3.3142 (18) 158 (4)
O6—H6B⋯Cl3i 0.84 (1) 2.41 (1) 3.2405 (17) 169 (3)
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) -x, -y+1, -z+1; (iii) -x, -y+2, -z+1; (iv) x, y, z+1; (v) x, y-1, z+1; (vi) x, y-1, z; (vii) -x+1, -y+1, -z+1.

Table 3
Hydrogen-bond geometry (Å, °) for ZnCl2·4.5H2O

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1B⋯Cl3i 0.84 (1) 2.50 (2) 3.300 (3) 161 (6)
O1—H1A⋯O3ii 0.84 (1) 2.00 (2) 2.823 (4) 167 (5)
O2—H2B⋯O7iii 0.84 (1) 2.02 (2) 2.853 (3) 176 (6)
O2—H2A⋯Cl2iv 0.83 (1) 2.75 (5) 3.347 (2) 130 (5)
O2—H2A⋯Cl1 0.83 (1) 2.68 (4) 3.386 (2) 143 (6)
O2—H2A⋯Cl2iv 0.83 (1) 2.75 (5) 3.347 (2) 130 (5)
O2—H2B⋯O7iii 0.84 (1) 2.02 (2) 2.853 (3) 176 (6)
O3—H3A⋯Cl2 0.84 (1) 2.41 (2) 3.237 (3) 171 (5)
O3—H3B⋯Cl3v 0.84 (1) 2.71 (5) 3.312 (3) 130 (5)
O3—H3B⋯Cl4v 0.84 (1) 2.79 (4) 3.512 (3) 146 (6)
O4—H4B⋯O1vi 0.84 (1) 2.01 (2) 2.831 (4) 167 (5)
O4—H4A⋯O3vii 0.84 (1) 1.99 (2) 2.821 (4) 175 (6)
O5—H5A⋯Cl1viii 0.84 (1) 2.32 (1) 3.157 (2) 180 (6)
O5—H5B⋯Cl4vii 0.84 (1) 2.33 (2) 3.165 (3) 175 (5)
O6—H6A⋯Cl4viii 0.84 (1) 2.32 (1) 3.159 (2) 177 (4)
O6—H6B⋯O1ix 0.84 (1) 1.92 (2) 2.754 (3) 175 (6)
O7—H7A⋯O2x 0.84 (1) 1.90 (1) 2.739 (3) 176 (5)
O7—H7B⋯Cl2ix 0.84 (1) 2.38 (3) 3.181 (2) 160 (6)
O8—H8A⋯Cl3x 0.84 (1) 2.34 (2) 3.155 (3) 164 (5)
O8—H8B⋯O2iii 0.84 (1) 1.91 (2) 2.738 (3) 170 (5)
O9—H9A⋯Cl1x 0.84 (1) 2.39 (1) 3.230 (2) 176 (4)
O9—H9B⋯Cl3xi 0.84 (1) 2.42 (2) 3.236 (2) 167 (5)
Symmetry codes: (i) x, y+1, z; (ii) [-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (iv) x+1, y, z; (v) [-x, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (vi) x, y-1, z-1; (vii) [-x+{\script{1\over 2}}, -y, z-{\script{1\over 2}}]; (viii) [-x+{\script{3\over 2}}, -y, z-{\script{1\over 2}}]; (ix) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (x) x, y, z-1; (xi) x+1, y, z-1.
[Figure 5]
Figure 5
The connection of individual [Zn2Cl4(H2O)5] units through hydrogen bonds (dashed lines) in the structure of ZnCl2·2.5H2O.

4. Database survey

For crystal structures of other zinc chloride hydrates (ZnCl2·RH2O), see: Follner & Brehler (1970[Follner, H. & Brehler, B. (1970). Acta Cryst. B26, 1679-1682.]; R = 1.33); Wilcox (2009[Wilcox, R. J. (2009). PhD thesis, North Carolina State University, Raleigh, USA.]; R = 3). For crystal structures of anhydrous zinc chloride, see: Brehler (1961[Brehler, B. (1961). Z. Kristallogr. 115, 373-402.]); Yakel & Brynestad (1978[Yakel, H. L. & Brynestad, J. (1978). Inorg. Chem. 17, 3294-3296.]). For similar structural set-ups in comparison with the 3-hydrate, [Zn(H2O)6][ZnCl4], see: Zalkin et al. (1964[Zalkin, A., Ruben, H. & Templeton, D. H. (1964). Acta Cryst. 17, 235-240.]; [Mg(H2O)6][SO4]); Spiess & Gruehn (1979[Spiess, M. & Gruehn, R. (1979). Z. Anorg. Allg. Chem. 456, 222-240.]; [Zn(H2O)6][SO4]); Agron & Busing (1985[Agron, P. A. & Busing, W. R. (1985). Acta Cryst. C41, 8-10.]; [Mg(H2O)6][Cl2]); Ferrari et al. (1967[Ferrari, A., Braibanti, A., Lanfredi, A. M. M. & Tiripicchio, A. (1967). Acta Cryst. 22, 240-246.]; [Zn(H2O)6][NO3]2).

5. Synthesis and crystallization

Zinc chloride 2.5 hydrate was crystallized from an aqueous solution of 73.41 wt% ZnCl2 at 280 K after 2 d, zinc chloride trihydrate from an aqueous solution of 69.14 wt% ZnCl2 at 263 K after 2 d and zinc chloride 4.5 hydrate from an aqueous solution of 53.98 wt% ZnCl2 at 223K after 2 d. For preparing these solutions, zinc chloride (Merck, 99%) was used. The content of Zn2+ was analysed by complexometric titration with EDTA. The crystals are stable in their saturated solutions over a period of at least four weeks. The samples were stored in a freezer or a cryostat at low temperatures. The crystals were separated and embedded in perfluorinated ether for X-ray diffraction analysis.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 4[link]. The H atoms of each structure were placed in the positions indicated by difference Fourier maps. For all three structures, distance restraints were applied for all water mol­ecules, with O—H and H—H distance restraints of 0.84 (1) and 1.4 (1) Å, respectively. For ZnCl2·2.5H2O Uiso values were set at 1.2Ueq(O) using a riding-model approximation.

Table 4
Experimental details

  ZnCl2·2.5H2O ZnCl2·3H2O ZnCl2·4.5H2O
Crystal data
Mr 362.66 380.68 434.72
Crystal system, space group Monoclinic, P21/n Triclinic, P[\overline{1}] Orthorhombic, P212121
Temperature (K) 150 150 120
a, b, c (Å) 7.2909 (5), 9.7971 (5), 15.0912 (10) 6.4339 (5), 6.5202 (5), 14.2769 (11) 6.9795 (3), 12.5421 (6), 18.1849 (11)
α, β, γ (°) 90, 103.375 (5), 90 90.910 (6), 99.146 (6), 95.574 (6) 90, 90, 90
V3) 1048.72 (12) 588.21 (8) 1591.86 (14)
Z 4 2 4
Radiation type Mo Kα Mo Kα Mo Kα
μ (mm−1) 5.57 4.98 3.70
Crystal size (mm) 0.27 × 0.19 × 0.11 0.60 × 0.42 × 0.16 1.00 × 0.75 × 0.09
 
Data collection
Diffractometer Stoe IPDS 2 Stoe IPDS 2T Stoe IPDS 2T
Absorption correction Integration (Coppens, 1970[Coppens, P. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 255-270. Copenhagen: Munksgaard.]) Integration (Coppens, 1970[Coppens, P. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 255-270. Copenhagen: Munksgaard.]) Integration (Coppens, 1970[Coppens, P. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 255-270. Copenhagen: Munksgaard.])
Tmin, Tmax 0.287, 0.534 0.093, 0.441 0.050, 0.708
No. of measured, independent and observed [I > 2σ(I)] reflections 9997, 2923, 2222 13092, 3239, 3120 40776, 4414, 3955
Rint 0.043 0.091 0.140
(sin θ/λ)max−1) 0.628 0.693 0.694
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.035, 1.01 0.029, 0.089, 1.02 0.021, 0.053, 0.99
No. of reflections 2171 3239 4414
No. of parameters 130 161 208
No. of restraints 15 18 27
H-atom treatment Only H-atom coordinates refined All H-atom parameters refined All H-atom parameters refined
Δρmax, Δρmin (e Å−3) 0.44, −0.36 0.95, −0.95 0.77, −0.64
Absolute structure Flack x determined using 1730 quotients [(I+)−(I)]/[(I+)+(I)] (Parsons & Flack, 2004[Parsons, S. & Flack, H. (2004). Acta Cryst. A60, s61.])
Absolute structure parameter 0.089 (8)
Computer programs: X-AREA and X-RED (Stoe & Cie, 2009[Stoe & Cie (2009). X-AREA and X-RED. Stoe & Cie, Darmstadt, Germany.]), SHELXS97 and SHELXL2012 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), DIAMOND (Brandenburg, 2006[Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Chemical context top

Zinc chloride solutions, especially at lower temperatures, are helpful in the understanding of the formation of different complex ion species in solution. The solubility of zinc chloride in water has been investigated by several authors in different concentration areas and at different temperatures (Haghighi et al., 2008; Mylius & Dietz, 1905; Jones & Getman, 1904; Chambers & Frazer, 1900; Biltz, 1902; Dietz, 1899; Etard, 1894). In the literature (Mylius & Dietz, 1905), the 4-, 3-, and 2.5-hydrates have been reported at lower temperatures. We have also found the 2.5-hydrate, the trihydrate and the 4.5-hydrate as stable phases along the equilibrium crystallization curves. The 4.5-hydrate crystallizes below 240 K. The crystal structure of the trihydrate reported herein has also been determined by Wilcox (2009) in his thesis, but was never published. While writing the formula of the trihydrate in a more detailed formula as [Zn(H2O)6][ZnCl4], the analogy to other structures like that of [Mg(H2O)6][SO4] (Zalkin et al., 1964) and [Zn(H2O)6][SO4] (Spiess & Gruehn, 1979) becomes obvious. These structures are very similar in the arrangement of o­cta­hedral units and anions in the unit cell.

Structural commentary top

Within the crystal structure of the 2.5-hydrate, there are two crystallographic different Zn2+ cations, as shown in Fig. 1a. The Zn1 cation is o­cta­hedrally coordinated by five water molecules and one chloride anion. The Zn2 cation is coordinated by four chloride anions, one shared with the Zn1 cation, leading to the formation of isolated [Zn2Cl4(H2O)5] units. Since the bond lengths of the bridging Cl atom of the tetra­hedron are shorter than to that of the o­cta­hedron, the latter becomes more distorted. The crystal structure of zinc chloride trihydrate consists of three crystallographically different Zn2+ cations (Fig. 2a). Two (Zn2 and Zn3) are located about an inversion centre and are coordinated o­cta­hedrally by six water molecules, forming [Zn(H2O)6]2+ cations. The third one is tetra­hedrally coordinated by chlorine anions, [ZnCl4]2-. The polyhedra are not connected by sharing a single atom like in the 2.5-hydrate, but they are linked by hydrogen bonds (Fig. 2b). The o­cta­hedra and tetra­hedra are arranged in a CsCl-like arrangement with eight tetra­hedra located around one o­cta­hedron (Fig. 3a). As shown in Fig. 4a, in the asymmetric unit of ZnCl2·4.5H2O, two different Zn2+ cations are present. The Zn1 cation is coordinated o­cta­hedrally by six water molecules and the Zn2 cation tetra­hedrally by four chloride anions. The three remaining water molecules are hydrogen-bonded to a [Zn1(H2O]2+ o­cta­hedron (Fig. 4b). .

Supra­molecular features top

In the structure of ZnCl2·2.5H2O, all terminal Cl- anions are connected to the o­cta­hedral parts of neighbouring [Zn2Cl4(H2O)5] units by three O—H···Cl hydrogen bonds per anion (Table 1, Fig. 5). The coordination polyhedra in the trihydrate are arranged in zigzag chains parallel to [001] in the crystal structure. The chains are highlighted in different shades of colors in Fig. 3b. Hydrogen bonds (Table 2) are established within one chain and between neighbouring chains (not shown in the Figure). As can be seen from Fig. 4b, five water molecules in the crystal structure of ZnCl2·4.5H2O are connected via hydrogen bonds to the [Zn1(H2O]2+ o­cta­hedron, three of them at the axial coordination sites and two of them at the equatorial coordination sites. Seven chloride anions from [Zn2Cl4]2- tetra­hedra contribute to the second coordination sphere of Zn1. Thus, every coordinating water molecule forms two hydrogen bonds. The structural situation in this salt can be compared with the second coordination shells around magnesium in magnesium halide hydrates like MgBr2·9H2O or MgI2·9H2O (Hennings et al., 2013). Each water molecule of the [Mg(H2O)6]2+ o­cta­hedra forms two hydrogen bonds, thus six water molecules and six halide atoms are involved in the second shell. However, in case of the magnesium halides each water molecule donates a hydrogen bond towards a halide anion and towards another water molecule.

Database survey top

For crystal structures of other zinc chloride hydrates (ZnCl2·RH2O), see: Follner & Brehler (1970; R = 1.33); Wilcox (2009; R = 3). For crystal structures of anhydrous zinc chloride, see: Brehler (1961); Yakel & Brynestad (1978). For similar structural set-ups in comparison with the 3-hydrate, [Zn(H2O)6][ZnCl4], see: Zalkin et al. (1964; [Mg(H2O)6][SO4]); Spiess & Gruehn (1979; [Zn(H2O)6][SO4]); Agron & Busing (1985; [Mg(H2O)6][Cl2]); Ferrari et al. (1967; [Zn(H2O)6][NO3]).

Synthesis and crystallization top

Zinc chloride 2.5 hydrate was crystallized from an aqueous solution of 73.41 wt% ZnCl2 at 280 K after 2 d, zinc chloride trihydrate from an aqueous solution of 69.14 wt% ZnCl2 at 263 K after 2 d and zinc chloride 4.5 hydrate from an aqueous solution of 53.98 wt% ZnCl2 at 223K after 2 d. For preparing these solutions, zinc chloride (Merck, 99%) was used. The content of Zn2+ was analysed by complexometric titration with EDTA. The crystals are stable in their saturated solutions over a period of at least four weeks. The samples were stored in a freezer or a cryostat at low temperatures. The crystals were separated and embedded in perfluorinated ether for X-ray diffraction analysis.

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 4. The H atoms of each structure were placed in the positions indicated by difference Fourier maps. For all three structures, distance restraints were applied for all water molecules, with O—H and H—H distance restraints of 0.84 (1) and 1.4 (1) Å , respectively. For ZnCl2·2.5H2O Uiso values were set at 1.2Ueq(O) using a riding-model approximation.

Related literature top

For related literature, see: Agron & Busing (1985); Biltz (1902); Brehler (1961); Chambers & Frazer (1900); Dietz (1899); Etard (1894); Ferrari et al. (1967); Follner & Brehler (1970); Haghighi et al. (2008); Hennings et al. (2013); Jones & Getman (1904); Mylius & Dietz (1905); Spiess & Gruehn (1979); Wilcox (2009); Yakel & Brynestad (1978); Zalkin et al. (1964).

Computing details top

For all compounds, data collection: X-AREA (Stoe & Cie, 2009); cell refinement: X-AREA (Stoe & Cie, 2009); data reduction: X-RED (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
The asymmetric unit of ZnCl2·2.5H2O. Displacement ellipsoids are drawn at the 50% probability level.

(a) The molecular units and (b) the unit cell in the structure of ZnCl2·3H2O. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate hydrogen bonds. [Symmetry codes: (i) 1 - x, 1 - y, 2 - z; (ii) 1 - x, 1 - y, 1 - z.]

(a) Arrangement of [ZnCl4]2--anions and [Zn(H2O)6]2+ cations in a CsCl-like structure and (b) formation of chains by alternation of different coordination polyhedra in ZnCl2·3H2O. Dashed lines indicate hydrogen bonds. Only hydrogen bonds in one chain are shown.

(a) The molecular units in the structure of ZnCl2·4.5H2O and (b) formation of a second coordination shell. Displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate hydrogen bonds.

The connection of individual [Zn2Cl4(H2O)5] units through hydrogen bonds (dashed lines) in the structure of ZnCl2·2.5H2O.
(ZnCl2_2halbH2O_150K) Pentaaqua-µ-chlorido-trichloridodizinc top
Crystal data top
[Zn2Cl4(H2O)5]F(000) = 712
Mr = 362.66Dx = 2.297 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 7.2909 (5) ÅCell parameters from 245 reflections
b = 9.7971 (5) Åθ = 3.6–29.1°
c = 15.0912 (10) ŵ = 5.57 mm1
β = 103.375 (5)°T = 150 K
V = 1048.72 (12) Å3Prism, colourless
Z = 40.27 × 0.19 × 0.11 mm
Data collection top
Stoe IPDS 2
diffractometer
2923 independent reflections
Radiation source: fine-focus sealed tube2222 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1Rint = 0.043
rotation method scansθmax = 26.5°, θmin = 2.5°
Absorption correction: integration
(Coppens, 1970)
h = 1010
Tmin = 0.287, Tmax = 0.534k = 1313
9997 measured reflectionsl = 1920
Refinement top
Refinement on F215 restraints
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.018Only H-atom coordinates refined
wR(F2) = 0.035 w = 1/[σ2(Fo2) + (0.0151P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max = 0.001
2171 reflectionsΔρmax = 0.44 e Å3
130 parametersΔρmin = 0.36 e Å3
Crystal data top
[Zn2Cl4(H2O)5]V = 1048.72 (12) Å3
Mr = 362.66Z = 4
Monoclinic, P21/nMo Kα radiation
a = 7.2909 (5) ŵ = 5.57 mm1
b = 9.7971 (5) ÅT = 150 K
c = 15.0912 (10) Å0.27 × 0.19 × 0.11 mm
β = 103.375 (5)°
Data collection top
Stoe IPDS 2
diffractometer
2923 independent reflections
Absorption correction: integration
(Coppens, 1970)
2222 reflections with I > 2σ(I)
Tmin = 0.287, Tmax = 0.534Rint = 0.043
9997 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01815 restraints
wR(F2) = 0.035Only H-atom coordinates refined
S = 1.01Δρmax = 0.44 e Å3
2171 reflectionsΔρmin = 0.36 e Å3
130 parameters
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
Zn10.78704 (3)0.77180 (3)0.15458 (2)0.01517 (6)
Zn20.47584 (3)0.76881 (3)0.35389 (2)0.01443 (6)
Cl30.48529 (7)0.77940 (6)0.20228 (3)0.01632 (11)
Cl40.31569 (9)0.95388 (6)0.38493 (4)0.02143 (13)
Cl10.77848 (8)0.75449 (6)0.43488 (4)0.02454 (13)
Cl20.30975 (10)0.57892 (6)0.37038 (4)0.02560 (14)
O30.6623 (3)0.62440 (18)0.06100 (13)0.0239 (4)
H3A0.715 (4)0.602 (3)0.0197 (16)0.029*
H3B0.553 (2)0.644 (3)0.0340 (19)0.029*
O21.0303 (2)0.76289 (19)0.10641 (13)0.0269 (4)
H2A1.101 (4)0.831 (2)0.114 (2)0.032*
H2B1.094 (4)0.691 (2)0.108 (2)0.032*
O40.6948 (3)0.92487 (18)0.06129 (14)0.0276 (4)
H4A0.690 (5)1.0064 (14)0.076 (2)0.033*
H4B0.724 (5)0.921 (3)0.0111 (13)0.033*
O10.8850 (3)0.6172 (2)0.24737 (16)0.0332 (5)
H1A0.997 (2)0.600 (3)0.272 (2)0.040*
H1B0.801 (4)0.558 (3)0.245 (2)0.040*
O50.8963 (3)0.9128 (2)0.25850 (17)0.0381 (5)
H5A1.002 (3)0.948 (3)0.268 (3)0.046*
H5B0.874 (5)0.891 (4)0.3079 (14)0.046*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.01214 (12)0.01726 (12)0.01619 (12)0.00135 (11)0.00343 (9)0.00051 (10)
Zn20.01283 (11)0.01446 (12)0.01622 (12)0.00030 (10)0.00379 (9)0.00026 (10)
Cl30.0111 (2)0.0235 (3)0.0147 (2)0.0010 (2)0.00364 (18)0.0011 (2)
Cl40.0257 (3)0.0181 (3)0.0218 (3)0.0061 (2)0.0080 (2)0.0005 (2)
Cl10.0151 (2)0.0355 (3)0.0205 (3)0.0024 (2)0.0011 (2)0.0020 (2)
Cl20.0296 (4)0.0200 (3)0.0255 (3)0.0110 (2)0.0030 (3)0.0015 (2)
O30.0209 (10)0.0246 (9)0.0287 (10)0.0020 (8)0.0110 (8)0.0088 (7)
O20.0163 (8)0.0275 (10)0.0393 (10)0.0031 (8)0.0111 (7)0.0025 (9)
O40.0307 (11)0.0200 (9)0.0369 (11)0.0082 (8)0.0173 (9)0.0101 (8)
O10.0187 (11)0.0389 (11)0.0425 (12)0.0123 (9)0.0084 (9)0.0253 (10)
O50.0176 (11)0.0506 (13)0.0470 (14)0.0106 (9)0.0095 (10)0.0309 (11)
Geometric parameters (Å, º) top
Zn1—O42.0604 (18)Zn1—Cl32.4691 (6)
Zn1—O22.0681 (17)Zn2—Cl42.2635 (6)
Zn1—O12.0742 (19)Zn2—Cl22.2647 (6)
Zn1—O32.0767 (18)Zn2—Cl12.2659 (6)
Zn1—O52.103 (2)Zn2—Cl32.3073 (6)
O4—Zn1—O287.79 (8)O2—Zn1—Cl3176.40 (6)
O4—Zn1—O1178.76 (8)O1—Zn1—Cl390.93 (6)
O2—Zn1—O190.97 (8)O3—Zn1—Cl386.54 (5)
O4—Zn1—O391.09 (8)O5—Zn1—Cl388.40 (6)
O2—Zn1—O390.45 (8)Cl4—Zn2—Cl2108.71 (2)
O1—Zn1—O388.83 (9)Cl4—Zn2—Cl1115.00 (3)
O4—Zn1—O592.24 (10)Cl2—Zn2—Cl1111.63 (3)
O2—Zn1—O594.72 (8)Cl4—Zn2—Cl3107.72 (2)
O1—Zn1—O587.95 (9)Cl2—Zn2—Cl3106.58 (2)
O3—Zn1—O5173.95 (8)Cl1—Zn2—Cl3106.80 (2)
O4—Zn1—Cl390.30 (6)Zn2—Cl3—Zn1121.38 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···Cl2i0.83 (1)2.43 (1)3.243 (2)167 (3)
O1—H1B···O5ii0.84 (1)2.02 (1)2.853 (3)178 (4)
O2—H2A···Cl2iii0.83 (1)2.51 (2)3.299 (2)158 (3)
O2—H2B···Cl4ii0.84 (1)2.41 (1)3.2212 (19)162 (3)
O3—H3B···Cl1iv0.83 (1)2.42 (1)3.225 (2)164 (3)
O3—H3A···Cl4v0.83 (1)2.38 (1)3.205 (2)171 (3)
O4—H4B···Cl2v0.83 (1)2.35 (1)3.181 (2)177 (3)
O4—H4A···Cl1iii0.83 (1)2.45 (2)3.2349 (19)157 (3)
O5—H5A···Cl4i0.83 (1)2.55 (2)3.233 (2)141 (3)
O5—H5B···Cl10.83 (1)2.56 (1)3.359 (3)163 (3)
Symmetry codes: (i) x+1, y, z; (ii) x+3/2, y1/2, z+1/2; (iii) x+3/2, y+1/2, z+1/2; (iv) x1/2, y+3/2, z1/2; (v) x+1/2, y+3/2, z1/2.
(zncl2_3H2O_150K) Dexaaquazinc tetrachloridozinc top
Crystal data top
[Zn(H2O)6][ZnCl4]Z = 2
Mr = 380.68F(000) = 376
Triclinic, P1Dx = 2.149 Mg m3
a = 6.4339 (5) ÅMo Kα radiation, λ = 0.71073 Å
b = 6.5202 (5) ÅCell parameters from 16445 reflections
c = 14.2769 (11) Åθ = 2.9–29.7°
α = 90.910 (6)°µ = 4.98 mm1
β = 99.146 (6)°T = 150 K
γ = 95.574 (6)°Prism, colourless
V = 588.21 (8) Å30.60 × 0.42 × 0.16 mm
Data collection top
Stoe IPDS 2T
diffractometer
3239 independent reflections
Radiation source: fine-focus sealed tube3120 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1Rint = 0.091
rotation method scansθmax = 29.5°, θmin = 2.9°
Absorption correction: integration
(Coppens, 1970)
h = 88
Tmin = 0.093, Tmax = 0.441k = 88
13092 measured reflectionsl = 019
Refinement top
Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullAll H-atom parameters refined
R[F2 > 2σ(F2)] = 0.029 w = 1/[σ2(Fo2) + (0.0816P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.089(Δ/σ)max = 0.001
S = 1.02Δρmax = 0.95 e Å3
3239 reflectionsΔρmin = 0.95 e Å3
161 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
18 restraintsExtinction coefficient: 0.027 (3)
Crystal data top
[Zn(H2O)6][ZnCl4]γ = 95.574 (6)°
Mr = 380.68V = 588.21 (8) Å3
Triclinic, P1Z = 2
a = 6.4339 (5) ÅMo Kα radiation
b = 6.5202 (5) ŵ = 4.98 mm1
c = 14.2769 (11) ÅT = 150 K
α = 90.910 (6)°0.60 × 0.42 × 0.16 mm
β = 99.146 (6)°
Data collection top
Stoe IPDS 2T
diffractometer
3239 independent reflections
Absorption correction: integration
(Coppens, 1970)
3120 reflections with I > 2σ(I)
Tmin = 0.093, Tmax = 0.441Rint = 0.091
13092 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02918 restraints
wR(F2) = 0.089All H-atom parameters refined
S = 1.02Δρmax = 0.95 e Å3
3239 reflectionsΔρmin = 0.95 e Å3
161 parameters
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
Zn10.11523 (3)0.89978 (3)0.24118 (2)0.01505 (10)
Zn20.50000.50001.00000.01412 (10)
Zn30.50000.50000.50000.01952 (10)
Cl40.11763 (7)0.54937 (6)0.21964 (3)0.01909 (11)
Cl10.00446 (7)0.93575 (7)0.38328 (3)0.02259 (12)
Cl20.08727 (7)1.02596 (6)0.11685 (3)0.01956 (11)
Cl30.45614 (6)1.04172 (7)0.25090 (3)0.02155 (12)
O10.3849 (2)0.5508 (2)0.85688 (10)0.0202 (3)
O30.2012 (2)0.3787 (2)1.01476 (10)0.0220 (3)
O20.4233 (2)0.7893 (2)1.04390 (10)0.0218 (3)
O40.1902 (3)0.4054 (2)0.43689 (13)0.0338 (4)
O50.4216 (3)0.4000 (3)0.63059 (11)0.0316 (3)
O60.4103 (3)0.7891 (2)0.53108 (12)0.0330 (4)
H3A0.153 (4)0.406 (4)1.0635 (14)0.027 (7)*
H1A0.2554 (19)0.549 (5)0.837 (2)0.031 (7)*
H5A0.324 (6)0.304 (6)0.631 (5)0.099 (19)*
H5B0.523 (6)0.365 (9)0.670 (3)0.11 (2)*
H3B0.158 (4)0.255 (2)1.001 (2)0.028 (7)*
H4B0.150 (6)0.2781 (19)0.433 (3)0.046 (9)*
H1B0.444 (5)0.656 (4)0.835 (3)0.052 (10)*
H6B0.430 (6)0.842 (5)0.5863 (12)0.043 (9)*
H2B0.469 (5)0.846 (5)1.0973 (12)0.033 (8)*
H4A0.138 (7)0.443 (7)0.3831 (16)0.068 (13)*
H2A0.326 (5)0.848 (6)1.012 (3)0.067 (12)*
H6A0.312 (5)0.856 (6)0.505 (3)0.068 (13)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.01631 (13)0.01664 (13)0.01182 (13)0.00047 (8)0.00172 (8)0.00148 (8)
Zn20.01421 (15)0.01364 (15)0.01422 (15)0.00026 (10)0.00197 (10)0.00211 (10)
Zn30.02499 (17)0.01508 (16)0.01623 (16)0.00053 (11)0.00294 (12)0.00295 (11)
Cl40.0226 (2)0.01568 (19)0.0180 (2)0.00149 (13)0.00074 (14)0.00044 (14)
Cl10.0276 (2)0.0269 (2)0.0138 (2)0.00023 (16)0.00716 (15)0.00085 (15)
Cl20.0214 (2)0.01837 (19)0.0172 (2)0.00167 (14)0.00233 (15)0.00332 (14)
Cl30.01682 (19)0.0240 (2)0.0227 (2)0.00282 (15)0.00277 (15)0.00254 (15)
O10.0181 (5)0.0231 (6)0.0185 (6)0.0001 (4)0.0003 (5)0.0057 (5)
O30.0204 (6)0.0212 (6)0.0243 (7)0.0047 (5)0.0081 (5)0.0033 (5)
O20.0246 (6)0.0193 (6)0.0205 (6)0.0071 (5)0.0021 (5)0.0003 (5)
O40.0339 (8)0.0262 (7)0.0336 (8)0.0064 (6)0.0133 (7)0.0092 (6)
O50.0396 (8)0.0325 (8)0.0208 (7)0.0004 (6)0.0011 (6)0.0091 (6)
O60.0504 (10)0.0230 (7)0.0246 (8)0.0105 (6)0.0011 (7)0.0001 (6)
Geometric parameters (Å, º) top
Zn1—Cl22.2460 (5)Zn2—O22.1066 (13)
Zn1—Cl12.2706 (5)Zn2—O2i2.1066 (13)
Zn1—Cl32.2785 (5)Zn3—O42.0829 (16)
Zn1—Cl42.3024 (5)Zn3—O4ii2.0829 (16)
Zn2—O32.0506 (13)Zn3—O62.0852 (16)
Zn2—O3i2.0506 (13)Zn3—O6ii2.0852 (16)
Zn2—O12.1027 (13)Zn3—O5ii2.1045 (16)
Zn2—O1i2.1027 (13)Zn3—O52.1045 (16)
Cl2—Zn1—Cl1115.478 (19)O1—Zn2—O2i87.84 (5)
Cl2—Zn1—Cl3109.745 (18)O1i—Zn2—O2i92.16 (5)
Cl1—Zn1—Cl3110.036 (19)O2—Zn2—O2i180.0
Cl2—Zn1—Cl4109.947 (18)O4—Zn3—O4ii180.0
Cl1—Zn1—Cl4104.334 (18)O4—Zn3—O689.91 (7)
Cl3—Zn1—Cl4106.860 (18)O4ii—Zn3—O690.09 (7)
O3—Zn2—O3i180.0O4—Zn3—O6ii90.09 (7)
O3—Zn2—O188.54 (5)O4ii—Zn3—O6ii89.91 (7)
O3i—Zn2—O191.46 (5)O6—Zn3—O6ii180.0
O3—Zn2—O1i91.46 (5)O4—Zn3—O5ii91.29 (7)
O3i—Zn2—O1i88.54 (5)O4ii—Zn3—O5ii88.71 (7)
O1—Zn2—O1i180.00 (3)O6—Zn3—O5ii91.31 (7)
O3—Zn2—O288.50 (6)O6ii—Zn3—O5ii88.69 (7)
O3i—Zn2—O291.50 (6)O4—Zn3—O588.71 (7)
O1—Zn2—O292.17 (5)O4ii—Zn3—O591.29 (7)
O1i—Zn2—O287.83 (5)O6—Zn3—O588.69 (7)
O3—Zn2—O2i91.50 (6)O6ii—Zn3—O591.31 (7)
O3i—Zn2—O2i88.50 (6)O5ii—Zn3—O5180.00 (9)
Symmetry codes: (i) x+1, y+1, z+2; (ii) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1B···Cl3iii0.84 (1)2.42 (1)3.2520 (14)168 (4)
O1—H1A···Cl4iv0.84 (1)2.43 (1)3.2431 (14)166 (3)
O2—H2A···Cl2v0.84 (1)2.41 (2)3.2260 (14)163 (4)
O2—H2B···Cl3vi0.84 (1)2.54 (2)3.3264 (15)157 (3)
O3—H3B···Cl2iv0.84 (1)2.42 (2)3.1715 (14)149 (3)
O3—H3B···Cl2vii0.84 (1)2.81 (3)3.3159 (14)120 (2)
O3—H3A···Cl4vi0.83 (1)2.45 (1)3.2552 (15)162 (3)
O4—H4A···Cl40.84 (1)2.43 (2)3.2307 (18)159 (4)
O4—H4B···Cl1viii0.84 (1)2.38 (1)3.2114 (17)167 (4)
O5—H5B···Cl3ii0.84 (1)2.91 (5)3.4565 (17)125 (5)
O5—H5B···Cl4ii0.84 (1)2.59 (3)3.3527 (18)151 (6)
O5—H5A···Cl1iv0.84 (1)2.48 (1)3.3159 (18)170 (5)
O6—H6A···Cl10.84 (1)2.52 (2)3.3142 (18)158 (4)
O6—H6B···Cl3iii0.84 (1)2.41 (1)3.2405 (17)169 (3)
Symmetry codes: (ii) x+1, y+1, z+1; (iii) x+1, y+2, z+1; (iv) x, y+1, z+1; (v) x, y+2, z+1; (vi) x, y, z+1; (vii) x, y1, z+1; (viii) x, y1, z.
(ZnCl2_4halbH2O_120K) Hexaaquazinc tetrachloridozinc trihydrate top
Crystal data top
[Zn(H2O)6][ZnCl4]·3H2ODx = 1.814 Mg m3
Mr = 434.72Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121Cell parameters from 33650 reflections
a = 6.9795 (3) Åθ = 1.8–29.6°
b = 12.5421 (6) ŵ = 3.70 mm1
c = 18.1849 (11) ÅT = 120 K
V = 1591.86 (14) Å3Prism, colourless
Z = 41 × 0.75 × 0.09 mm
F(000) = 872
Data collection top
Stoe IPDS 2T
diffractometer
4414 independent reflections
Radiation source: fine-focus sealed tube3955 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1Rint = 0.140
rotation method scansθmax = 29.6°, θmin = 2.8°
Absorption correction: integration
(Coppens, 1970)
h = 99
Tmin = 0.050, Tmax = 0.708k = 1717
40776 measured reflectionsl = 2525
Refinement top
Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullAll H-atom parameters refined
R[F2 > 2σ(F2)] = 0.021 w = 1/[σ2(Fo2) + (0.0379P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.053(Δ/σ)max = 0.001
S = 0.99Δρmax = 0.77 e Å3
4414 reflectionsΔρmin = 0.64 e Å3
208 parametersAbsolute structure: Flack x determined using 1730 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons & Flack, 2004)
27 restraintsAbsolute structure parameter: 0.089 (8)
Crystal data top
[Zn(H2O)6][ZnCl4]·3H2OV = 1591.86 (14) Å3
Mr = 434.72Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.9795 (3) ŵ = 3.70 mm1
b = 12.5421 (6) ÅT = 120 K
c = 18.1849 (11) Å1 × 0.75 × 0.09 mm
Data collection top
Stoe IPDS 2T
diffractometer
4414 independent reflections
Absorption correction: integration
(Coppens, 1970)
3955 reflections with I > 2σ(I)
Tmin = 0.050, Tmax = 0.708Rint = 0.140
40776 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.021All H-atom parameters refined
wR(F2) = 0.053Δρmax = 0.77 e Å3
S = 0.99Δρmin = 0.64 e Å3
4414 reflectionsAbsolute structure: Flack x determined using 1730 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons & Flack, 2004)
208 parametersAbsolute structure parameter: 0.089 (8)
27 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
Zn10.77065 (5)0.00714 (2)0.06201 (2)0.01250 (7)
Zn20.31706 (5)0.03464 (3)0.81771 (2)0.01309 (7)
Cl30.27768 (11)0.08062 (5)0.91458 (4)0.01637 (13)
Cl40.22957 (11)0.06620 (6)0.71906 (4)0.01873 (14)
Cl10.62302 (10)0.09178 (6)0.80989 (4)0.01949 (14)
Cl20.11859 (11)0.17633 (6)0.83407 (4)0.01869 (14)
O50.7005 (4)0.0248 (2)0.17173 (12)0.0221 (4)
O61.0486 (3)0.03761 (19)0.08567 (14)0.0194 (4)
O40.6863 (4)0.15048 (17)0.05792 (14)0.0230 (5)
O70.8639 (3)0.17112 (16)0.06267 (13)0.0155 (4)
O20.7609 (3)0.27476 (16)0.93613 (13)0.0180 (4)
O30.0251 (4)0.25556 (19)0.66850 (15)0.0233 (5)
O10.6408 (4)0.75102 (19)0.91896 (15)0.0216 (5)
O80.5001 (3)0.05893 (19)0.03098 (15)0.0216 (5)
O90.8442 (3)0.00564 (19)0.04927 (12)0.0193 (4)
H6A1.106 (7)0.008 (3)0.1205 (18)0.027 (12)*
H1A0.732 (5)0.761 (4)0.890 (2)0.030 (12)*
H4B0.681 (8)0.188 (3)0.0199 (16)0.031 (12)*
H7A0.829 (8)0.201 (4)0.0235 (16)0.033 (13)*
H9A0.784 (6)0.017 (4)0.0860 (17)0.029 (12)*
H5A0.747 (7)0.006 (4)0.2084 (19)0.043 (15)*
H5B0.586 (3)0.032 (4)0.184 (3)0.041 (14)*
H8A0.433 (6)0.015 (3)0.008 (2)0.031 (13)*
H7B0.816 (9)0.204 (4)0.099 (2)0.054 (18)*
H8B0.423 (6)0.106 (3)0.045 (3)0.028 (12)*
H6B1.069 (8)0.1034 (13)0.084 (3)0.038 (15)*
H9B0.959 (3)0.014 (5)0.061 (3)0.050 (16)*
H4A0.629 (7)0.181 (4)0.092 (2)0.035 (14)*
H2A0.780 (9)0.239 (4)0.8979 (19)0.049 (17)*
H3A0.046 (8)0.228 (4)0.7098 (15)0.040 (15)*
H1B0.550 (6)0.791 (4)0.906 (3)0.047 (17)*
H2B0.645 (3)0.292 (4)0.939 (4)0.050 (17)*
H3B0.041 (7)0.310 (3)0.676 (4)0.047 (16)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.01058 (15)0.01326 (13)0.01365 (14)0.00118 (11)0.00037 (11)0.00004 (10)
Zn20.00971 (15)0.01571 (13)0.01386 (14)0.00083 (11)0.00053 (11)0.00135 (11)
Cl30.0161 (3)0.0176 (3)0.0154 (3)0.0007 (2)0.0006 (2)0.0012 (2)
Cl40.0175 (3)0.0241 (3)0.0146 (3)0.0049 (3)0.0008 (3)0.0039 (2)
Cl10.0108 (3)0.0288 (3)0.0189 (3)0.0047 (2)0.0008 (3)0.0050 (3)
Cl20.0137 (3)0.0185 (3)0.0239 (4)0.0027 (2)0.0013 (3)0.0032 (2)
O50.0198 (11)0.0340 (11)0.0126 (9)0.0063 (10)0.0007 (8)0.0015 (8)
O60.0161 (10)0.0193 (10)0.0227 (11)0.0046 (9)0.0063 (8)0.0035 (9)
O40.0319 (13)0.0176 (10)0.0195 (11)0.0053 (9)0.0026 (11)0.0007 (8)
O70.0147 (10)0.0154 (9)0.0164 (10)0.0004 (7)0.0007 (8)0.0009 (8)
O20.0170 (11)0.0175 (9)0.0194 (10)0.0004 (8)0.0005 (9)0.0012 (8)
O30.0220 (12)0.0236 (11)0.0245 (13)0.0060 (9)0.0043 (10)0.0005 (9)
O10.0189 (12)0.0199 (10)0.0260 (12)0.0012 (9)0.0012 (9)0.0014 (9)
O80.0122 (10)0.0244 (11)0.0281 (13)0.0056 (8)0.0062 (9)0.0088 (9)
O90.0157 (10)0.0294 (11)0.0127 (9)0.0038 (9)0.0025 (8)0.0012 (8)
Geometric parameters (Å, º) top
Zn1—O42.064 (2)Zn1—O72.157 (2)
Zn1—O62.065 (2)Zn2—Cl12.2570 (8)
Zn1—O52.066 (2)Zn2—Cl22.2728 (8)
Zn1—O82.075 (2)Zn2—Cl42.2783 (8)
Zn1—O92.094 (2)Zn2—Cl32.2953 (8)
O4—Zn1—O690.86 (10)O6—Zn1—O788.54 (9)
O4—Zn1—O594.02 (10)O5—Zn1—O787.92 (10)
O6—Zn1—O592.91 (10)O8—Zn1—O788.72 (9)
O4—Zn1—O891.75 (10)O9—Zn1—O790.25 (9)
O6—Zn1—O8175.34 (10)Cl1—Zn2—Cl2109.67 (3)
O5—Zn1—O890.76 (10)Cl1—Zn2—Cl4112.35 (3)
O4—Zn1—O987.81 (10)Cl2—Zn2—Cl4111.95 (3)
O6—Zn1—O987.15 (9)Cl1—Zn2—Cl3111.20 (3)
O5—Zn1—O9178.17 (10)Cl2—Zn2—Cl3108.60 (3)
O8—Zn1—O989.09 (10)Cl4—Zn2—Cl3102.86 (3)
O4—Zn1—O7178.00 (10)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1B···Cl3i0.84 (1)2.50 (2)3.300 (3)161 (6)
O1—H1A···O3ii0.84 (1)2.00 (2)2.823 (4)167 (5)
O2—H2B···O7iii0.84 (1)2.02 (2)2.853 (3)176 (6)
O2—H2A···Cl2iv0.83 (1)2.75 (5)3.347 (2)130 (5)
O2—H2A···Cl10.83 (1)2.68 (4)3.386 (2)143 (6)
O2—H2A···Cl2iv0.83 (1)2.75 (5)3.347 (2)130 (5)
O2—H2B···O7iii0.84 (1)2.02 (2)2.853 (3)176 (6)
O3—H3A···Cl20.84 (1)2.41 (2)3.237 (3)171 (5)
O3—H3B···Cl3v0.84 (1)2.71 (5)3.312 (3)130 (5)
O3—H3B···Cl4v0.84 (1)2.79 (4)3.512 (3)146 (6)
O4—H4B···O1vi0.84 (1)2.01 (2)2.831 (4)167 (5)
O4—H4A···O3vii0.84 (1)1.99 (2)2.821 (4)175 (6)
O5—H5A···Cl1viii0.84 (1)2.32 (1)3.157 (2)180 (6)
O5—H5B···Cl4vii0.84 (1)2.33 (2)3.165 (3)175 (5)
O6—H6A···Cl4viii0.84 (1)2.32 (1)3.159 (2)177 (4)
O6—H6B···O1ix0.84 (1)1.92 (2)2.754 (3)175 (6)
O7—H7A···O2x0.84 (1)1.90 (1)2.739 (3)176 (5)
O7—H7B···Cl2ix0.84 (1)2.38 (3)3.181 (2)160 (6)
O8—H8A···Cl3x0.84 (1)2.34 (2)3.155 (3)164 (5)
O8—H8B···O2iii0.84 (1)1.91 (2)2.738 (3)170 (5)
O9—H9A···Cl1x0.84 (1)2.39 (1)3.230 (2)176 (4)
O9—H9B···Cl3xi0.84 (1)2.42 (2)3.236 (2)167 (5)
Symmetry codes: (i) x, y+1, z; (ii) x+1, y+1/2, z+3/2; (iii) x1/2, y+1/2, z+1; (iv) x+1, y, z; (v) x, y+1/2, z+3/2; (vi) x, y1, z1; (vii) x+1/2, y, z1/2; (viii) x+3/2, y, z1/2; (ix) x+1/2, y+1/2, z+1; (x) x, y, z1; (xi) x+1, y, z1.
Hydrogen-bond geometry (Å, º) for (ZnCl2_2halbH2O_150K) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···Cl2i0.832 (10)2.426 (13)3.243 (2)167 (3)
O1—H1B···O5ii0.835 (10)2.018 (11)2.853 (3)178 (4)
O2—H2A···Cl2iii0.834 (10)2.511 (15)3.299 (2)158 (3)
O2—H2B···Cl4ii0.840 (10)2.414 (14)3.2212 (19)162 (3)
O3—H3B···Cl1iv0.830 (10)2.418 (13)3.225 (2)164 (3)
O3—H3A···Cl4v0.832 (10)2.381 (11)3.205 (2)171 (3)
O4—H4B···Cl2v0.833 (10)2.349 (10)3.181 (2)177 (3)
O4—H4A···Cl1iii0.833 (10)2.450 (16)3.2349 (19)157 (3)
O5—H5A···Cl4i0.829 (10)2.55 (2)3.233 (2)141 (3)
O5—H5B···Cl10.827 (10)2.560 (14)3.359 (3)163 (3)
Symmetry codes: (i) x+1, y, z; (ii) x+3/2, y1/2, z+1/2; (iii) x+3/2, y+1/2, z+1/2; (iv) x1/2, y+3/2, z1/2; (v) x+1/2, y+3/2, z1/2.
Hydrogen-bond geometry (Å, º) for (zncl2_3H2O_150K) top
D—H···AD—HH···AD···AD—H···A
O1—H1B···Cl3i0.843 (10)2.423 (13)3.2520 (14)168 (4)
O1—H1A···Cl4ii0.836 (10)2.427 (12)3.2431 (14)166 (3)
O2—H2A···Cl2iii0.840 (10)2.412 (16)3.2260 (14)163 (4)
O2—H2B···Cl3iv0.837 (10)2.538 (15)3.3264 (15)157 (3)
O3—H3B···Cl2ii0.840 (10)2.422 (18)3.1715 (14)149 (3)
O3—H3B···Cl2v0.840 (10)2.81 (3)3.3159 (14)120 (2)
O3—H3A···Cl4iv0.831 (10)2.454 (13)3.2552 (15)162 (3)
O4—H4A···Cl40.838 (10)2.432 (19)3.2307 (18)159 (4)
O4—H4B···Cl1vi0.843 (10)2.385 (13)3.2114 (17)167 (4)
O5—H5B···Cl3vii0.838 (10)2.91 (5)3.4565 (17)125 (5)
O5—H5B···Cl4vii0.838 (10)2.59 (3)3.3527 (18)151 (6)
O5—H5A···Cl1ii0.842 (10)2.483 (14)3.3159 (18)170 (5)
O6—H6A···Cl10.843 (10)2.52 (2)3.3142 (18)158 (4)
O6—H6B···Cl3i0.841 (10)2.410 (12)3.2405 (17)169 (3)
Symmetry codes: (i) x+1, y+2, z+1; (ii) x, y+1, z+1; (iii) x, y+2, z+1; (iv) x, y, z+1; (v) x, y1, z+1; (vi) x, y1, z; (vii) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) for (ZnCl2_4halbH2O_120K) top
D—H···AD—HH···AD···AD—H···A
O1—H1B···Cl3i0.838 (14)2.50 (2)3.300 (3)161 (6)
O1—H1A···O3ii0.839 (14)2.000 (17)2.823 (4)167 (5)
O2—H2B···O7iii0.838 (14)2.017 (15)2.853 (3)176 (6)
O2—H2A···Cl2iv0.834 (13)2.75 (5)3.347 (2)130 (5)
O2—H2A···Cl10.834 (13)2.68 (4)3.386 (2)143 (6)
O2—H2A···Cl2iv0.834 (13)2.75 (5)3.347 (2)130 (5)
O2—H2B···O7iii0.838 (14)2.017 (15)2.853 (3)176 (6)
O3—H3A···Cl20.839 (13)2.406 (16)3.237 (3)171 (5)
O3—H3B···Cl3v0.835 (13)2.71 (5)3.312 (3)130 (5)
O3—H3B···Cl4v0.835 (13)2.79 (4)3.512 (3)146 (6)
O4—H4B···O1vi0.837 (13)2.008 (18)2.831 (4)167 (5)
O4—H4A···O3vii0.838 (13)1.985 (15)2.821 (4)175 (6)
O5—H5A···Cl1viii0.838 (13)2.319 (14)3.157 (2)180 (6)
O5—H5B···Cl4vii0.838 (13)2.330 (15)3.165 (3)175 (5)
O6—H6A···Cl4viii0.841 (13)2.319 (14)3.159 (2)177 (4)
O6—H6B···O1ix0.837 (13)1.920 (15)2.754 (3)175 (6)
O7—H7A···O2x0.839 (13)1.901 (14)2.739 (3)176 (5)
O7—H7B···Cl2ix0.840 (13)2.38 (3)3.181 (2)160 (6)
O8—H8A···Cl3x0.841 (13)2.339 (19)3.155 (3)164 (5)
O8—H8B···O2iii0.839 (13)1.907 (16)2.738 (3)170 (5)
O9—H9A···Cl1x0.840 (13)2.392 (14)3.230 (2)176 (4)
O9—H9B···Cl3xi0.838 (13)2.415 (19)3.236 (2)167 (5)
Symmetry codes: (i) x, y+1, z; (ii) x+1, y+1/2, z+3/2; (iii) x1/2, y+1/2, z+1; (iv) x+1, y, z; (v) x, y+1/2, z+3/2; (vi) x, y1, z1; (vii) x+1/2, y, z1/2; (viii) x+3/2, y, z1/2; (ix) x+1/2, y+1/2, z+1; (x) x, y, z1; (xi) x+1, y, z1.

Experimental details

[Zn2Cl4(H2O)5][Zn(H2O)6][ZnCl4][Zn(H2O)6][ZnCl4]·3H2O
Crystal data
Mr362.66380.68434.72
Crystal system, space groupMonoclinic, P21/nTriclinic, P1Orthorhombic, P212121
Temperature (K)150150120
a, b, c (Å)7.2909 (5), 9.7971 (5), 15.0912 (10)6.4339 (5), 6.5202 (5), 14.2769 (11)6.9795 (3), 12.5421 (6), 18.1849 (11)
α, β, γ (°)90, 103.375 (5), 9090.910 (6), 99.146 (6), 95.574 (6)90, 90, 90
V3)1048.72 (12)588.21 (8)1591.86 (14)
Z424
Radiation typeMo KαMo KαMo Kα
µ (mm1)5.574.983.70
Crystal size (mm)0.27 × 0.19 × 0.110.60 × 0.42 × 0.161 × 0.75 × 0.09
Data collection
DiffractometerStoe IPDS 2
diffractometer
Stoe IPDS 2T
diffractometer
Stoe IPDS 2T
diffractometer
Absorption correctionIntegration
(Coppens, 1970)
Integration
(Coppens, 1970)
Integration
(Coppens, 1970)
Tmin, Tmax0.287, 0.5340.093, 0.4410.050, 0.708
No. of measured, independent and
observed [I > 2σ(I)] reflections
9997, 2923, 2222 13092, 3239, 3120 40776, 4414, 3955
Rint0.0430.0910.140
(sin θ/λ)max1)0.6280.6930.694
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.035, 1.01 0.029, 0.089, 1.02 0.021, 0.053, 0.99
No. of reflections217132394414
No. of parameters130161208
No. of restraints151827
H-atom treatmentOnly H-atom coordinates refinedAll H-atom parameters refinedAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.44, 0.360.95, 0.950.77, 0.64
Absolute structure??Flack x determined using 1730 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons & Flack, 2004)
Absolute structure parameter??0.089 (8)

Computer programs: X-AREA (Stoe & Cie, 2009), X-RED (Stoe & Cie, 2009), SHELXS97 (Sheldrick, 2008), SHELXL2012 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006), publCIF (Westrip, 2010).

 

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