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

Hennings, E.; Schmidt, H.; Voigt, W.

doi:10.1107/S1600536814024738

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Volume 70| Part 12| December 2014| Pages 515-518

doi:10.1107/S1600536814024738

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

Erik Hennings,^a Horst Schmidt ^a ^* and Wolfgang Voigt ^a

^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.

Keywords: crystal structure; low-temperature salt hydrates; chloride hydrates; zinc salts.

CCDC references: 1033587; 1033586; 1033585

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 ; 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.

2. Structural commentary

Within the crystal structure of the 2.5-hydrate, there are two crystallographic different Zn²⁺ cations, as shown in Fig. 1. 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 (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. 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).

Figure 1
The asymmetric unit of ZnCl₂·2.5H₂O. Displacement ellipsoids are drawn at the 50% probability level.

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
(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
(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, 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 nonahydrates 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. The hydrogen-bond geometry in ZnCl₂·4.5H₂O is given inTable 3.

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

D—H⋯A	D—H	H⋯A	D⋯A	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⋯Cl1^iv	0.83 (1)	2.42 (1)	3.225 (2)	164 (3)
O3—H3A⋯Cl4^v	0.83 (1)	2.38 (1)	3.205 (2)	171 (3)
O4—H4B⋯Cl2^v	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	D⋯A	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⋯Cl3^iv	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⋯Cl2^v	0.84 (1)	2.81 (3)	3.3159 (14)	120 (2)
O3—H3A⋯Cl4^iv	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⋯Cl1^vi	0.84 (1)	2.39 (1)	3.2114 (17)	167 (4)
O5—H5B⋯Cl3^vii	0.84 (1)	2.91 (5)	3.4565 (17)	125 (5)
O5—H5B⋯Cl4^vii	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	D⋯A	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⋯Cl2^iv	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⋯Cl2^iv	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⋯Cl3^v	0.84 (1)	2.71 (5)	3.312 (3)	130 (5)
O3—H3B⋯Cl4^v	0.84 (1)	2.79 (4)	3.512 (3)	146 (6)
O4—H4B⋯O1^vi	0.84 (1)	2.01 (2)	2.831 (4)	167 (5)
O4—H4A⋯O3^vii	0.84 (1)	1.99 (2)	2.821 (4)	175 (6)
O5—H5A⋯Cl1^viii	0.84 (1)	2.32 (1)	3.157 (2)	180 (6)
O5—H5B⋯Cl4^vii	0.84 (1)	2.33 (2)	3.165 (3)	175 (5)
O6—H6A⋯Cl4^viii	0.84 (1)	2.32 (1)	3.159 (2)	177 (4)
O6—H6B⋯O1^ix	0.84 (1)	1.92 (2)	2.754 (3)	175 (6)
O7—H7A⋯O2^x	0.84 (1)	1.90 (1)	2.739 (3)	176 (5)
O7—H7B⋯Cl2^ix	0.84 (1)	2.38 (3)	3.181 (2)	160 (6)
O8—H8A⋯Cl3^x	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⋯Cl1^x	0.84 (1)	2.39 (1)	3.230 (2)	176 (4)
O9—H9B⋯Cl3^xi	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
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 ; 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]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. 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 U_iso values were set at 1.2U_eq(O) using a riding-model approximation.

Table 4
Experimental details

	ZnCl₂·2.5H₂O	ZnCl₂·3H₂O	ZnCl₂·4.5H₂O
Crystal data
M_r	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
V (Å³)	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 )	Integration (Coppens, 1970)	Integration (Coppens, 1970)
T_min, T_max	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
R_int	0.043	0.091	0.140
(sin θ/λ)_max (Å⁻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
Δρ_max, Δρ_min (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 )
Absolute structure parameter	–	–	0.089 (8)
Computer programs: X-AREA and X-RED (Stoe & Cie, 2009 ), SHELXS97 and SHELXL2012 (Sheldrick, 2008 ), DIAMOND (Brandenburg, 2006 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 1033587; 1033586; 1033585

Crystal structure: contains datablocks ZnCl2_2halbH2O_150K, zncl2_3H2O_150K, ZnCl2_4halbH2O_120K. DOI: 10.1107/S1600536814024738/wm5081sup1.cif

Structure factors: contains datablock ZnCl2_2halbH2O_150K. DOI: 10.1107/S1600536814024738/wm5081ZnCl2_2halbH2O_150Ksup2.hkl

Structure factors: contains datablock zncl2_3H2O_150K. DOI: 10.1107/S1600536814024738/wm5081zncl2_3H2O_150Ksup3.hkl

Structure factors: contains datablock ZnCl2_4halbH2O_120K. DOI: 10.1107/S1600536814024738/wm5081ZnCl2_4halbH2O_120Ksup4.hkl

checkCIF report

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

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 U_iso values were set at 1.2U_eq(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
M_r = 362.66	D_x = 2.297 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.2909 (5) Å	Cell parameters from 245 reflections
b = 9.7971 (5) Å	θ = 3.6–29.1°
c = 15.0912 (10) Å	µ = 5.57 mm⁻¹
β = 103.375 (5)°	T = 150 K
V = 1048.72 (12) Å³	Prism, colourless
Z = 4	0.27 × 0.19 × 0.11 mm

Data collection top

Stoe IPDS 2 diffractometer	2923 independent reflections
Radiation source: fine-focus sealed tube	2222 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm^-1	R_int = 0.043
rotation method scans	θ_max = 26.5°, θ_min = 2.5°
Absorption correction: integration (Coppens, 1970)	h = −10→10
T_min = 0.287, T_max = 0.534	k = −13→13
9997 measured reflections	l = −19→20

Refinement top

Refinement on F²	15 restraints
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.018	Only H-atom coordinates refined
wR(F²) = 0.035	w = 1/[σ²(F_o²) + (0.0151P)²] where P = (F_o² + 2F_c²)/3
S = 1.01	(Δ/σ)_max = 0.001
2171 reflections	Δρ_max = 0.44 e Å⁻³
130 parameters	Δρ_min = −0.36 e Å⁻³

Crystal data top

[Zn₂Cl₄(H₂O)₅]	V = 1048.72 (12) Å³
M_r = 362.66	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 7.2909 (5) Å	µ = 5.57 mm⁻¹
b = 9.7971 (5) Å	T = 150 K
c = 15.0912 (10) Å	0.27 × 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)
T_min = 0.287, T_max = 0.534	R_int = 0.043
9997 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.018	15 restraints
wR(F²) = 0.035	Only H-atom coordinates refined
S = 1.01	Δρ_max = 0.44 e Å⁻³
2171 reflections	Δρ_min = −0.36 e Å⁻³
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

	x	y	z	U_iso*/U_eq
Zn1	0.78704 (3)	0.77180 (3)	0.15458 (2)	0.01517 (6)
Zn2	0.47584 (3)	0.76881 (3)	0.35389 (2)	0.01443 (6)
Cl3	0.48529 (7)	0.77940 (6)	0.20228 (3)	0.01632 (11)
Cl4	0.31569 (9)	0.95388 (6)	0.38493 (4)	0.02143 (13)
Cl1	0.77848 (8)	0.75449 (6)	0.43488 (4)	0.02454 (13)
Cl2	0.30975 (10)	0.57892 (6)	0.37038 (4)	0.02560 (14)
O3	0.6623 (3)	0.62440 (18)	0.06100 (13)	0.0239 (4)
H3A	0.715 (4)	0.602 (3)	0.0197 (16)	0.029*
H3B	0.553 (2)	0.644 (3)	0.0340 (19)	0.029*
O2	1.0303 (2)	0.76289 (19)	0.10641 (13)	0.0269 (4)
H2A	1.101 (4)	0.831 (2)	0.114 (2)	0.032*
H2B	1.094 (4)	0.691 (2)	0.108 (2)	0.032*
O4	0.6948 (3)	0.92487 (18)	0.06129 (14)	0.0276 (4)
H4A	0.690 (5)	1.0064 (14)	0.076 (2)	0.033*
H4B	0.724 (5)	0.921 (3)	0.0111 (13)	0.033*
O1	0.8850 (3)	0.6172 (2)	0.24737 (16)	0.0332 (5)
H1A	0.997 (2)	0.600 (3)	0.272 (2)	0.040*
H1B	0.801 (4)	0.558 (3)	0.245 (2)	0.040*
O5	0.8963 (3)	0.9128 (2)	0.25850 (17)	0.0381 (5)
H5A	1.002 (3)	0.948 (3)	0.268 (3)	0.046*
H5B	0.874 (5)	0.891 (4)	0.3079 (14)	0.046*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn1	0.01214 (12)	0.01726 (12)	0.01619 (12)	0.00135 (11)	0.00343 (9)	−0.00051 (10)
Zn2	0.01283 (11)	0.01446 (12)	0.01622 (12)	−0.00030 (10)	0.00379 (9)	−0.00026 (10)
Cl3	0.0111 (2)	0.0235 (3)	0.0147 (2)	0.0010 (2)	0.00364 (18)	−0.0011 (2)
Cl4	0.0257 (3)	0.0181 (3)	0.0218 (3)	0.0061 (2)	0.0080 (2)	−0.0005 (2)
Cl1	0.0151 (2)	0.0355 (3)	0.0205 (3)	0.0024 (2)	−0.0011 (2)	0.0020 (2)
Cl2	0.0296 (4)	0.0200 (3)	0.0255 (3)	−0.0110 (2)	0.0030 (3)	0.0015 (2)
O3	0.0209 (10)	0.0246 (9)	0.0287 (10)	−0.0020 (8)	0.0110 (8)	−0.0088 (7)
O2	0.0163 (8)	0.0275 (10)	0.0393 (10)	0.0031 (8)	0.0111 (7)	0.0025 (9)
O4	0.0307 (11)	0.0200 (9)	0.0369 (11)	0.0082 (8)	0.0173 (9)	0.0101 (8)
O1	0.0187 (11)	0.0389 (11)	0.0425 (12)	0.0123 (9)	0.0084 (9)	0.0253 (10)
O5	0.0176 (11)	0.0506 (13)	0.0470 (14)	−0.0106 (9)	0.0095 (10)	−0.0309 (11)

Geometric parameters (Å, º) top

Zn1—O4	2.0604 (18)	Zn1—Cl3	2.4691 (6)
Zn1—O2	2.0681 (17)	Zn2—Cl4	2.2635 (6)
Zn1—O1	2.0742 (19)	Zn2—Cl2	2.2647 (6)
Zn1—O3	2.0767 (18)	Zn2—Cl1	2.2659 (6)
Zn1—O5	2.103 (2)	Zn2—Cl3	2.3073 (6)

O4—Zn1—O2	87.79 (8)	O2—Zn1—Cl3	176.40 (6)
O4—Zn1—O1	178.76 (8)	O1—Zn1—Cl3	90.93 (6)
O2—Zn1—O1	90.97 (8)	O3—Zn1—Cl3	86.54 (5)
O4—Zn1—O3	91.09 (8)	O5—Zn1—Cl3	88.40 (6)
O2—Zn1—O3	90.45 (8)	Cl4—Zn2—Cl2	108.71 (2)
O1—Zn1—O3	88.83 (9)	Cl4—Zn2—Cl1	115.00 (3)
O4—Zn1—O5	92.24 (10)	Cl2—Zn2—Cl1	111.63 (3)
O2—Zn1—O5	94.72 (8)	Cl4—Zn2—Cl3	107.72 (2)
O1—Zn1—O5	87.95 (9)	Cl2—Zn2—Cl3	106.58 (2)
O3—Zn1—O5	173.95 (8)	Cl1—Zn2—Cl3	106.80 (2)
O4—Zn1—Cl3	90.30 (6)	Zn2—Cl3—Zn1	121.38 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	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···Cl1^iv	0.83 (1)	2.42 (1)	3.225 (2)	164 (3)
O3—H3A···Cl4^v	0.83 (1)	2.38 (1)	3.205 (2)	171 (3)
O4—H4B···Cl2^v	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+3/2, y−1/2, −z+1/2; (iii) −x+3/2, y+1/2, −z+1/2; (iv) x−1/2, −y+3/2, z−1/2; (v) x+1/2, −y+3/2, z−1/2.

(zncl2_3H2O_150K) Dexaaquazinc tetrachloridozinc top

Crystal data top

[Zn(H₂O)₆][ZnCl₄]	Z = 2
M_r = 380.68	F(000) = 376
Triclinic, P1	D_x = 2.149 Mg m⁻³
a = 6.4339 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.5202 (5) Å	Cell parameters from 16445 reflections
c = 14.2769 (11) Å	θ = 2.9–29.7°
α = 90.910 (6)°	µ = 4.98 mm⁻¹
β = 99.146 (6)°	T = 150 K
γ = 95.574 (6)°	Prism, colourless
V = 588.21 (8) Å³	0.60 × 0.42 × 0.16 mm

Data collection top

Stoe IPDS 2T diffractometer	3239 independent reflections
Radiation source: fine-focus sealed tube	3120 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm^-1	R_int = 0.091
rotation method scans	θ_max = 29.5°, θ_min = 2.9°
Absorption correction: integration (Coppens, 1970)	h = −8→8
T_min = 0.093, T_max = 0.441	k = −8→8
13092 measured reflections	l = 0→19

Refinement top

Refinement on F²	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F² > 2σ(F²)] = 0.029	w = 1/[σ²(F_o²) + (0.0816P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.089	(Δ/σ)_max = 0.001
S = 1.02	Δρ_max = 0.95 e Å⁻³
3239 reflections	Δρ_min = −0.95 e Å⁻³
161 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
18 restraints	Extinction coefficient: 0.027 (3)

Crystal data top

[Zn(H₂O)₆][ZnCl₄]	γ = 95.574 (6)°
M_r = 380.68	V = 588.21 (8) Å³
Triclinic, P1	Z = 2
a = 6.4339 (5) Å	Mo Kα radiation
b = 6.5202 (5) Å	µ = 4.98 mm⁻¹
c = 14.2769 (11) Å	T = 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)
T_min = 0.093, T_max = 0.441	R_int = 0.091
13092 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	18 restraints
wR(F²) = 0.089	All H-atom parameters refined
S = 1.02	Δρ_max = 0.95 e Å⁻³
3239 reflections	Δρ_min = −0.95 e Å⁻³
161 parameters

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Zn1	0.11523 (3)	0.89978 (3)	0.24118 (2)	0.01505 (10)
Zn2	0.5000	0.5000	1.0000	0.01412 (10)
Zn3	0.5000	0.5000	0.5000	0.01952 (10)
Cl4	0.11763 (7)	0.54937 (6)	0.21964 (3)	0.01909 (11)
Cl1	0.00446 (7)	0.93575 (7)	0.38328 (3)	0.02259 (12)
Cl2	−0.08727 (7)	1.02596 (6)	0.11685 (3)	0.01956 (11)
Cl3	0.45614 (6)	1.04172 (7)	0.25090 (3)	0.02155 (12)
O1	0.3849 (2)	0.5508 (2)	0.85688 (10)	0.0202 (3)
O3	0.2012 (2)	0.3787 (2)	1.01476 (10)	0.0220 (3)
O2	0.4233 (2)	0.7893 (2)	1.04390 (10)	0.0218 (3)
O4	0.1902 (3)	0.4054 (2)	0.43689 (13)	0.0338 (4)
O5	0.4216 (3)	0.4000 (3)	0.63059 (11)	0.0316 (3)
O6	0.4103 (3)	0.7891 (2)	0.53108 (12)	0.0330 (4)
H3A	0.153 (4)	0.406 (4)	1.0635 (14)	0.027 (7)*
H1A	0.2554 (19)	0.549 (5)	0.837 (2)	0.031 (7)*
H5A	0.324 (6)	0.304 (6)	0.631 (5)	0.099 (19)*
H5B	0.523 (6)	0.365 (9)	0.670 (3)	0.11 (2)*
H3B	0.158 (4)	0.255 (2)	1.001 (2)	0.028 (7)*
H4B	0.150 (6)	0.2781 (19)	0.433 (3)	0.046 (9)*
H1B	0.444 (5)	0.656 (4)	0.835 (3)	0.052 (10)*
H6B	0.430 (6)	0.842 (5)	0.5863 (12)	0.043 (9)*
H2B	0.469 (5)	0.846 (5)	1.0973 (12)	0.033 (8)*
H4A	0.138 (7)	0.443 (7)	0.3831 (16)	0.068 (13)*
H2A	0.326 (5)	0.848 (6)	1.012 (3)	0.067 (12)*
H6A	0.312 (5)	0.856 (6)	0.505 (3)	0.068 (13)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn1	0.01631 (13)	0.01664 (13)	0.01182 (13)	0.00047 (8)	0.00172 (8)	0.00148 (8)
Zn2	0.01421 (15)	0.01364 (15)	0.01422 (15)	0.00026 (10)	0.00197 (10)	0.00211 (10)
Zn3	0.02499 (17)	0.01508 (16)	0.01623 (16)	0.00053 (11)	−0.00294 (12)	0.00295 (11)
Cl4	0.0226 (2)	0.01568 (19)	0.0180 (2)	0.00149 (13)	0.00074 (14)	0.00044 (14)
Cl1	0.0276 (2)	0.0269 (2)	0.0138 (2)	−0.00023 (16)	0.00716 (15)	−0.00085 (15)
Cl2	0.0214 (2)	0.01837 (19)	0.0172 (2)	0.00167 (14)	−0.00233 (15)	0.00332 (14)
Cl3	0.01682 (19)	0.0240 (2)	0.0227 (2)	−0.00282 (15)	0.00277 (15)	0.00254 (15)
O1	0.0181 (5)	0.0231 (6)	0.0185 (6)	0.0001 (4)	0.0003 (5)	0.0057 (5)
O3	0.0204 (6)	0.0212 (6)	0.0243 (7)	−0.0047 (5)	0.0081 (5)	−0.0033 (5)
O2	0.0246 (6)	0.0193 (6)	0.0205 (6)	0.0071 (5)	−0.0021 (5)	−0.0003 (5)
O4	0.0339 (8)	0.0262 (7)	0.0336 (8)	−0.0064 (6)	−0.0133 (7)	0.0092 (6)
O5	0.0396 (8)	0.0325 (8)	0.0208 (7)	−0.0004 (6)	0.0011 (6)	0.0091 (6)
O6	0.0504 (10)	0.0230 (7)	0.0246 (8)	0.0105 (6)	−0.0011 (7)	0.0001 (6)

Geometric parameters (Å, º) top

Zn1—Cl2	2.2460 (5)	Zn2—O2	2.1066 (13)
Zn1—Cl1	2.2706 (5)	Zn2—O2ⁱ	2.1066 (13)
Zn1—Cl3	2.2785 (5)	Zn3—O4	2.0829 (16)
Zn1—Cl4	2.3024 (5)	Zn3—O4ⁱⁱ	2.0829 (16)
Zn2—O3	2.0506 (13)	Zn3—O6	2.0852 (16)
Zn2—O3ⁱ	2.0506 (13)	Zn3—O6ⁱⁱ	2.0852 (16)
Zn2—O1	2.1027 (13)	Zn3—O5ⁱⁱ	2.1045 (16)
Zn2—O1ⁱ	2.1027 (13)	Zn3—O5	2.1045 (16)

Cl2—Zn1—Cl1	115.478 (19)	O1—Zn2—O2ⁱ	87.84 (5)
Cl2—Zn1—Cl3	109.745 (18)	O1ⁱ—Zn2—O2ⁱ	92.16 (5)
Cl1—Zn1—Cl3	110.036 (19)	O2—Zn2—O2ⁱ	180.0
Cl2—Zn1—Cl4	109.947 (18)	O4—Zn3—O4ⁱⁱ	180.0
Cl1—Zn1—Cl4	104.334 (18)	O4—Zn3—O6	89.91 (7)
Cl3—Zn1—Cl4	106.860 (18)	O4ⁱⁱ—Zn3—O6	90.09 (7)
O3—Zn2—O3ⁱ	180.0	O4—Zn3—O6ⁱⁱ	90.09 (7)
O3—Zn2—O1	88.54 (5)	O4ⁱⁱ—Zn3—O6ⁱⁱ	89.91 (7)
O3ⁱ—Zn2—O1	91.46 (5)	O6—Zn3—O6ⁱⁱ	180.0
O3—Zn2—O1ⁱ	91.46 (5)	O4—Zn3—O5ⁱⁱ	91.29 (7)
O3ⁱ—Zn2—O1ⁱ	88.54 (5)	O4ⁱⁱ—Zn3—O5ⁱⁱ	88.71 (7)
O1—Zn2—O1ⁱ	180.00 (3)	O6—Zn3—O5ⁱⁱ	91.31 (7)
O3—Zn2—O2	88.50 (6)	O6ⁱⁱ—Zn3—O5ⁱⁱ	88.69 (7)
O3ⁱ—Zn2—O2	91.50 (6)	O4—Zn3—O5	88.71 (7)
O1—Zn2—O2	92.17 (5)	O4ⁱⁱ—Zn3—O5	91.29 (7)
O1ⁱ—Zn2—O2	87.83 (5)	O6—Zn3—O5	88.69 (7)
O3—Zn2—O2ⁱ	91.50 (6)	O6ⁱⁱ—Zn3—O5	91.31 (7)
O3ⁱ—Zn2—O2ⁱ	88.50 (6)	O5ⁱⁱ—Zn3—O5	180.00 (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···A	D—H	H···A	D···A	D—H···A
O1—H1B···Cl3ⁱⁱⁱ	0.84 (1)	2.42 (1)	3.2520 (14)	168 (4)
O1—H1A···Cl4^iv	0.84 (1)	2.43 (1)	3.2431 (14)	166 (3)
O2—H2A···Cl2^v	0.84 (1)	2.41 (2)	3.2260 (14)	163 (4)
O2—H2B···Cl3^vi	0.84 (1)	2.54 (2)	3.3264 (15)	157 (3)
O3—H3B···Cl2^iv	0.84 (1)	2.42 (2)	3.1715 (14)	149 (3)
O3—H3B···Cl2^vii	0.84 (1)	2.81 (3)	3.3159 (14)	120 (2)
O3—H3A···Cl4^vi	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···Cl1^viii	0.84 (1)	2.38 (1)	3.2114 (17)	167 (4)
O5—H5B···Cl3ⁱⁱ	0.84 (1)	2.91 (5)	3.4565 (17)	125 (5)
O5—H5B···Cl4ⁱⁱ	0.84 (1)	2.59 (3)	3.3527 (18)	151 (6)
O5—H5A···Cl1^iv	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···Cl3ⁱⁱⁱ	0.84 (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, y−1, z+1; (viii) x, y−1, z.

(ZnCl2_4halbH2O_120K) Hexaaquazinc tetrachloridozinc trihydrate top

Crystal data top

[Zn(H₂O)₆][ZnCl₄]·3H₂O	D_x = 1.814 Mg m⁻³
M_r = 434.72	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 33650 reflections
a = 6.9795 (3) Å	θ = 1.8–29.6°
b = 12.5421 (6) Å	µ = 3.70 mm⁻¹
c = 18.1849 (11) Å	T = 120 K
V = 1591.86 (14) Å³	Prism, colourless
Z = 4	1 × 0.75 × 0.09 mm
F(000) = 872

Data collection top

Stoe IPDS 2T diffractometer	4414 independent reflections
Radiation source: fine-focus sealed tube	3955 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm^-1	R_int = 0.140
rotation method scans	θ_max = 29.6°, θ_min = 2.8°
Absorption correction: integration (Coppens, 1970)	h = −9→9
T_min = 0.050, T_max = 0.708	k = −17→17
40776 measured reflections	l = −25→25

Refinement top

Refinement on F²	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F² > 2σ(F²)] = 0.021	w = 1/[σ²(F_o²) + (0.0379P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.053	(Δ/σ)_max = 0.001
S = 0.99	Δρ_max = 0.77 e Å⁻³
4414 reflections	Δρ_min = −0.64 e Å⁻³
208 parameters	Absolute structure: Flack x determined using 1730 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons & Flack, 2004)
27 restraints	Absolute structure parameter: 0.089 (8)

Crystal data top

[Zn(H₂O)₆][ZnCl₄]·3H₂O	V = 1591.86 (14) Å³
M_r = 434.72	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 6.9795 (3) Å	µ = 3.70 mm⁻¹
b = 12.5421 (6) Å	T = 120 K
c = 18.1849 (11) Å	1 × 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)
T_min = 0.050, T_max = 0.708	R_int = 0.140
40776 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.021	All H-atom parameters refined
wR(F²) = 0.053	Δρ_max = 0.77 e Å⁻³
S = 0.99	Δρ_min = −0.64 e Å⁻³
4414 reflections	Absolute structure: Flack x determined using 1730 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons & Flack, 2004)
208 parameters	Absolute structure parameter: 0.089 (8)
27 restraints

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Zn1	0.77065 (5)	0.00714 (2)	0.06201 (2)	0.01250 (7)
Zn2	0.31706 (5)	0.03464 (3)	0.81771 (2)	0.01309 (7)
Cl3	0.27768 (11)	−0.08062 (5)	0.91458 (4)	0.01637 (13)
Cl4	0.22957 (11)	−0.06620 (6)	0.71906 (4)	0.01873 (14)
Cl1	0.62302 (10)	0.09178 (6)	0.80989 (4)	0.01949 (14)
Cl2	0.11859 (11)	0.17633 (6)	0.83407 (4)	0.01869 (14)
O5	0.7005 (4)	0.0248 (2)	0.17173 (12)	0.0221 (4)
O6	1.0486 (3)	−0.03761 (19)	0.08567 (14)	0.0194 (4)
O4	0.6863 (4)	−0.15048 (17)	0.05792 (14)	0.0230 (5)
O7	0.8639 (3)	0.17112 (16)	0.06267 (13)	0.0155 (4)
O2	0.7609 (3)	0.27476 (16)	0.93613 (13)	0.0180 (4)
O3	0.0251 (4)	0.25556 (19)	0.66850 (15)	0.0233 (5)
O1	0.6408 (4)	0.75102 (19)	0.91896 (15)	0.0216 (5)
O8	0.5001 (3)	0.05893 (19)	0.03098 (15)	0.0216 (5)
O9	0.8442 (3)	−0.00564 (19)	−0.04927 (12)	0.0193 (4)
H6A	1.106 (7)	−0.008 (3)	0.1205 (18)	0.027 (12)*
H1A	0.732 (5)	0.761 (4)	0.890 (2)	0.030 (12)*
H4B	0.681 (8)	−0.188 (3)	0.0199 (16)	0.031 (12)*
H7A	0.829 (8)	0.201 (4)	0.0235 (16)	0.033 (13)*
H9A	0.784 (6)	0.017 (4)	−0.0860 (17)	0.029 (12)*
H5A	0.747 (7)	−0.006 (4)	0.2084 (19)	0.043 (15)*
H5B	0.586 (3)	0.032 (4)	0.184 (3)	0.041 (14)*
H8A	0.433 (6)	0.015 (3)	0.008 (2)	0.031 (13)*
H7B	0.816 (9)	0.204 (4)	0.099 (2)	0.054 (18)*
H8B	0.423 (6)	0.106 (3)	0.045 (3)	0.028 (12)*
H6B	1.069 (8)	−0.1034 (13)	0.084 (3)	0.038 (15)*
H9B	0.959 (3)	−0.014 (5)	−0.061 (3)	0.050 (16)*
H4A	0.629 (7)	−0.181 (4)	0.092 (2)	0.035 (14)*
H2A	0.780 (9)	0.239 (4)	0.8979 (19)	0.049 (17)*
H3A	0.046 (8)	0.228 (4)	0.7098 (15)	0.040 (15)*
H1B	0.550 (6)	0.791 (4)	0.906 (3)	0.047 (17)*
H2B	0.645 (3)	0.292 (4)	0.939 (4)	0.050 (17)*
H3B	−0.041 (7)	0.310 (3)	0.676 (4)	0.047 (16)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn1	0.01058 (15)	0.01326 (13)	0.01365 (14)	0.00118 (11)	−0.00037 (11)	0.00004 (10)
Zn2	0.00971 (15)	0.01571 (13)	0.01386 (14)	−0.00083 (11)	−0.00053 (11)	−0.00135 (11)
Cl3	0.0161 (3)	0.0176 (3)	0.0154 (3)	−0.0007 (2)	−0.0006 (2)	0.0012 (2)
Cl4	0.0175 (3)	0.0241 (3)	0.0146 (3)	−0.0049 (3)	−0.0008 (3)	−0.0039 (2)
Cl1	0.0108 (3)	0.0288 (3)	0.0189 (3)	−0.0047 (2)	0.0008 (3)	−0.0050 (3)
Cl2	0.0137 (3)	0.0185 (3)	0.0239 (4)	0.0027 (2)	−0.0013 (3)	−0.0032 (2)
O5	0.0198 (11)	0.0340 (11)	0.0126 (9)	0.0063 (10)	0.0007 (8)	0.0015 (8)
O6	0.0161 (10)	0.0193 (10)	0.0227 (11)	0.0046 (9)	−0.0063 (8)	−0.0035 (9)
O4	0.0319 (13)	0.0176 (10)	0.0195 (11)	−0.0053 (9)	0.0026 (11)	−0.0007 (8)
O7	0.0147 (10)	0.0154 (9)	0.0164 (10)	0.0004 (7)	0.0007 (8)	−0.0009 (8)
O2	0.0170 (11)	0.0175 (9)	0.0194 (10)	−0.0004 (8)	0.0005 (9)	−0.0012 (8)
O3	0.0220 (12)	0.0236 (11)	0.0245 (13)	0.0060 (9)	−0.0043 (10)	−0.0005 (9)
O1	0.0189 (12)	0.0199 (10)	0.0260 (12)	−0.0012 (9)	0.0012 (9)	−0.0014 (9)
O8	0.0122 (10)	0.0244 (11)	0.0281 (13)	0.0056 (8)	−0.0062 (9)	−0.0088 (9)
O9	0.0157 (10)	0.0294 (11)	0.0127 (9)	0.0038 (9)	0.0025 (8)	0.0012 (8)

Geometric parameters (Å, º) top

Zn1—O4	2.064 (2)	Zn1—O7	2.157 (2)
Zn1—O6	2.065 (2)	Zn2—Cl1	2.2570 (8)
Zn1—O5	2.066 (2)	Zn2—Cl2	2.2728 (8)
Zn1—O8	2.075 (2)	Zn2—Cl4	2.2783 (8)
Zn1—O9	2.094 (2)	Zn2—Cl3	2.2953 (8)

O4—Zn1—O6	90.86 (10)	O6—Zn1—O7	88.54 (9)
O4—Zn1—O5	94.02 (10)	O5—Zn1—O7	87.92 (10)
O6—Zn1—O5	92.91 (10)	O8—Zn1—O7	88.72 (9)
O4—Zn1—O8	91.75 (10)	O9—Zn1—O7	90.25 (9)
O6—Zn1—O8	175.34 (10)	Cl1—Zn2—Cl2	109.67 (3)
O5—Zn1—O8	90.76 (10)	Cl1—Zn2—Cl4	112.35 (3)
O4—Zn1—O9	87.81 (10)	Cl2—Zn2—Cl4	111.95 (3)
O6—Zn1—O9	87.15 (9)	Cl1—Zn2—Cl3	111.20 (3)
O5—Zn1—O9	178.17 (10)	Cl2—Zn2—Cl3	108.60 (3)
O8—Zn1—O9	89.09 (10)	Cl4—Zn2—Cl3	102.86 (3)
O4—Zn1—O7	178.00 (10)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	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···Cl2^iv	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···Cl2^iv	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···Cl3^v	0.84 (1)	2.71 (5)	3.312 (3)	130 (5)
O3—H3B···Cl4^v	0.84 (1)	2.79 (4)	3.512 (3)	146 (6)
O4—H4B···O1^vi	0.84 (1)	2.01 (2)	2.831 (4)	167 (5)
O4—H4A···O3^vii	0.84 (1)	1.99 (2)	2.821 (4)	175 (6)
O5—H5A···Cl1^viii	0.84 (1)	2.32 (1)	3.157 (2)	180 (6)
O5—H5B···Cl4^vii	0.84 (1)	2.33 (2)	3.165 (3)	175 (5)
O6—H6A···Cl4^viii	0.84 (1)	2.32 (1)	3.159 (2)	177 (4)
O6—H6B···O1^ix	0.84 (1)	1.92 (2)	2.754 (3)	175 (6)
O7—H7A···O2^x	0.84 (1)	1.90 (1)	2.739 (3)	176 (5)
O7—H7B···Cl2^ix	0.84 (1)	2.38 (3)	3.181 (2)	160 (6)
O8—H8A···Cl3^x	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···Cl1^x	0.84 (1)	2.39 (1)	3.230 (2)	176 (4)
O9—H9B···Cl3^xi	0.84 (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) x−1/2, −y+1/2, −z+1; (iv) x+1, y, z; (v) −x, y+1/2, −z+3/2; (vi) x, y−1, z−1; (vii) −x+1/2, −y, z−1/2; (viii) −x+3/2, −y, z−1/2; (ix) x+1/2, −y+1/2, −z+1; (x) x, y, z−1; (xi) x+1, y, z−1.

Hydrogen-bond geometry (Å, º) for (ZnCl2_2halbH2O_150K) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···Cl2ⁱ	0.832 (10)	2.426 (13)	3.243 (2)	167 (3)
O1—H1B···O5ⁱⁱ	0.835 (10)	2.018 (11)	2.853 (3)	178 (4)
O2—H2A···Cl2ⁱⁱⁱ	0.834 (10)	2.511 (15)	3.299 (2)	158 (3)
O2—H2B···Cl4ⁱⁱ	0.840 (10)	2.414 (14)	3.2212 (19)	162 (3)
O3—H3B···Cl1^iv	0.830 (10)	2.418 (13)	3.225 (2)	164 (3)
O3—H3A···Cl4^v	0.832 (10)	2.381 (11)	3.205 (2)	171 (3)
O4—H4B···Cl2^v	0.833 (10)	2.349 (10)	3.181 (2)	177 (3)
O4—H4A···Cl1ⁱⁱⁱ	0.833 (10)	2.450 (16)	3.2349 (19)	157 (3)
O5—H5A···Cl4ⁱ	0.829 (10)	2.55 (2)	3.233 (2)	141 (3)
O5—H5B···Cl1	0.827 (10)	2.560 (14)	3.359 (3)	163 (3)

Symmetry codes: (i) x+1, y, z; (ii) −x+3/2, y−1/2, −z+1/2; (iii) −x+3/2, y+1/2, −z+1/2; (iv) x−1/2, −y+3/2, z−1/2; (v) x+1/2, −y+3/2, z−1/2.

Hydrogen-bond geometry (Å, º) for (zncl2_3H2O_150K) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1B···Cl3ⁱ	0.843 (10)	2.423 (13)	3.2520 (14)	168 (4)
O1—H1A···Cl4ⁱⁱ	0.836 (10)	2.427 (12)	3.2431 (14)	166 (3)
O2—H2A···Cl2ⁱⁱⁱ	0.840 (10)	2.412 (16)	3.2260 (14)	163 (4)
O2—H2B···Cl3^iv	0.837 (10)	2.538 (15)	3.3264 (15)	157 (3)
O3—H3B···Cl2ⁱⁱ	0.840 (10)	2.422 (18)	3.1715 (14)	149 (3)
O3—H3B···Cl2^v	0.840 (10)	2.81 (3)	3.3159 (14)	120 (2)
O3—H3A···Cl4^iv	0.831 (10)	2.454 (13)	3.2552 (15)	162 (3)
O4—H4A···Cl4	0.838 (10)	2.432 (19)	3.2307 (18)	159 (4)
O4—H4B···Cl1^vi	0.843 (10)	2.385 (13)	3.2114 (17)	167 (4)
O5—H5B···Cl3^vii	0.838 (10)	2.91 (5)	3.4565 (17)	125 (5)
O5—H5B···Cl4^vii	0.838 (10)	2.59 (3)	3.3527 (18)	151 (6)
O5—H5A···Cl1ⁱⁱ	0.842 (10)	2.483 (14)	3.3159 (18)	170 (5)
O6—H6A···Cl1	0.843 (10)	2.52 (2)	3.3142 (18)	158 (4)
O6—H6B···Cl3ⁱ	0.841 (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, y−1, z+1; (vi) x, y−1, z; (vii) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) for (ZnCl2_4halbH2O_120K) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1B···Cl3ⁱ	0.838 (14)	2.50 (2)	3.300 (3)	161 (6)
O1—H1A···O3ⁱⁱ	0.839 (14)	2.000 (17)	2.823 (4)	167 (5)
O2—H2B···O7ⁱⁱⁱ	0.838 (14)	2.017 (15)	2.853 (3)	176 (6)
O2—H2A···Cl2^iv	0.834 (13)	2.75 (5)	3.347 (2)	130 (5)
O2—H2A···Cl1	0.834 (13)	2.68 (4)	3.386 (2)	143 (6)
O2—H2A···Cl2^iv	0.834 (13)	2.75 (5)	3.347 (2)	130 (5)
O2—H2B···O7ⁱⁱⁱ	0.838 (14)	2.017 (15)	2.853 (3)	176 (6)
O3—H3A···Cl2	0.839 (13)	2.406 (16)	3.237 (3)	171 (5)
O3—H3B···Cl3^v	0.835 (13)	2.71 (5)	3.312 (3)	130 (5)
O3—H3B···Cl4^v	0.835 (13)	2.79 (4)	3.512 (3)	146 (6)
O4—H4B···O1^vi	0.837 (13)	2.008 (18)	2.831 (4)	167 (5)
O4—H4A···O3^vii	0.838 (13)	1.985 (15)	2.821 (4)	175 (6)
O5—H5A···Cl1^viii	0.838 (13)	2.319 (14)	3.157 (2)	180 (6)
O5—H5B···Cl4^vii	0.838 (13)	2.330 (15)	3.165 (3)	175 (5)
O6—H6A···Cl4^viii	0.841 (13)	2.319 (14)	3.159 (2)	177 (4)
O6—H6B···O1^ix	0.837 (13)	1.920 (15)	2.754 (3)	175 (6)
O7—H7A···O2^x	0.839 (13)	1.901 (14)	2.739 (3)	176 (5)
O7—H7B···Cl2^ix	0.840 (13)	2.38 (3)	3.181 (2)	160 (6)
O8—H8A···Cl3^x	0.841 (13)	2.339 (19)	3.155 (3)	164 (5)
O8—H8B···O2ⁱⁱⁱ	0.839 (13)	1.907 (16)	2.738 (3)	170 (5)
O9—H9A···Cl1^x	0.840 (13)	2.392 (14)	3.230 (2)	176 (4)
O9—H9B···Cl3^xi	0.838 (13)	2.415 (19)	3.236 (2)	167 (5)

Experimental details

	[Zn₂Cl₄(H₂O)₅]	[Zn(H₂O)₆][ZnCl₄]	[Zn(H₂O)₆][ZnCl₄]·3H₂O
Crystal data
M_r	362.66	380.68	434.72
Crystal system, space group	Monoclinic, P2₁/n	Triclinic, P1	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
V (Å³)	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 × 0.75 × 0.09

Data collection
Diffractometer	Stoe IPDS 2 diffractometer	Stoe IPDS 2T diffractometer	Stoe IPDS 2T diffractometer
Absorption correction	Integration (Coppens, 1970)	Integration (Coppens, 1970)	Integration (Coppens, 1970)
T_min, T_max	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
R_int	0.043	0.091	0.140
(sin θ/λ)_max (Å⁻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
Δρ_max, Δρ_min (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)
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).

References

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ISSN: 2056-9890

Volume 70| Part 12| December 2014| Pages 515-518

doi:10.1107/S1600536814024738

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