Crystal structure of tin(II) perchlorate trihydrate

The title compound, [Sn(H₂O)₃](ClO₄)₂, was synthesized by the redox reaction of copper(II) perchlorate hexa­hydrate and metallic tin in perchloric acid. Both the trigonal–pyramidal [Sn(H₂O)₃]²⁺ cations and tetra­hedral perchlorate anions lie on crystallographic threefold axes. In the crystal, the cations are linked to the anions by O—H⋯O hydrogen bonds, generating (001) sheets.

1. Chemical context

The synthesis and powder diffraction data for tin(II) perchlorate trihydrate were described by Davies & Donaldson (1968) and Schiefelbein & Daugherty (1970). With our crystal structure determination, the data of Davies & Donaldson (1968) are confirmed. The inter­est in the system tin(II)–perchloric acid-water arose from the redetermination of the redox-potential Sn²⁺/Sn⁴⁺ in perchloric acid by Gajda et al. (2009). There is no solid–liquid diagram for this binary salt–water system known in the literature.

2. Structural commentary

The tin atom lies on a crystallographic threefold rotation axis and is coordinated by three water mol­ecules as a trigonal pyramid (Fig. 1, Table 1). The perchlorate tetra­hedra are located in the gaps between the SnO₃ pyramids on their own threefold axes. A similar arrangement of the perchlorate tetra­hedra can be observed in the crystal structure of Ba(ClO₄)₂·3H₂O (Gallucci & Gerkin, 1988). The difference between the two structures is that the barium atom is sixfold coordinated by oxygen water mol­ecules. All of them are shared between two barium atoms, so that an average of three are bonded to one Ba atom.

Table 1
Selected geometric parameters (Å, °)

Sn1—O2	2.201 (7)	Cl2—O1	1.424 (12)
Cl1—O4	1.430 (4)	Cl2—O3	1.426 (5)
Cl1—O5	1.449 (10)
O2^i—Sn1—O2	76.9 (3)
Symmetry code: (i) -y, x-y, z.

Figure 1 The component ions in tin(II) perchlorate trihydrate with displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) −x + y, −x, z; (ii) −y, x − y, z; (iii) 1 − x + y, 1 − x, z; (iv) 1 − y, x − y, z; (v) 1 − y, 1 + x − y, z; (vi) −x + y, 1 − x, z.]

3. Supra­molecular features

The different coordination of Sn²⁺ in comparison with Ba²⁺ is caused by the lone-pair effect. It requires more space, so the distance to the next oxygen atoms is larger than in the barium salt structure. The perchlorate tetra­hedra are connected by O—H⋯O hydrogen bonds (Table 2) with the water mol­ecules coordinated at the tin atoms (Figs. 2 and 3), forming sheets parallel to (001).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O4^ii	0.94 (7)	1.95 (8)	2.823 (8)	152 (7)
O2—H2⋯O3^iii	0.94 (7)	2.46 (8)	2.926 (8)	110 (6)
Symmetry codes: (ii) ; (iii) -x+y, -x+1, z+1.

Figure 2 The unit-cell packing in tin(II) perchlorate trihydrate with the ions shown in polyhedral representation.

Figure 3 Larger view of the crystal structure of tin(II) perchlorate trihydrate viewed down [001]. Dashed lines indicate hydrogen bonds.

4. Database survey

For properties, thermal behavior and powder diffraction data for tin(II) perchlorate trihydrate, see: Schiefelbein & Daugherty (1970) and Davies & Donaldson (1968). For crystal structure determinations of other divalent perchlorate trihydrates, see: Gallucci & Gerkin (1988) for the barium salt and Hennings et al. (2014) for the strontium salt.

5. Synthesis and crystallization

Sn(ClO₄)₂·3H₂O was prepared by reaction of copper(II) perchlorate hexa­hydrate (15 g, Alfa Aesar, reagent grade) and elemental tin (12.04 g, VEB Feinchemikalien) in perchloric acid (50 ml, 60%, Merck, pA). After stirring the solution for 2 h the precipitated copper was filtered off and the solution was transferred into a freezer at 253 K for crystallization. All crystals are stable in the saturated aqueous solution over a period of at least four weeks.

The sample was stored in a freezer or a cryostat at low temperatures. The crystals were separated and embedded in perfluorinated ether for X-ray analysis.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The H atoms were placed in the positions indicated by difference Fourier maps. No further constraints were applied.

Table 3
Experimental details

Crystal data
Chemical formula	[Sn(H2O)3](ClO4)2
Mr	371.44
Crystal system, space group	Hexagonal, P63
Temperature (K)	180
a, c (Å)	7.0701 (10), 9.7631 (15)
V (Å^3)	422.64 (16)
Z	2
Radiation type	Mo Kα
μ (mm^−1)	3.70
Crystal size (mm)	0.70 × 0.52 × 0.22
Data collection
Diffractometer	STOE IPDS 2
Absorption correction	Integration (Coppens, 1970)
Tmin, Tmax	0.116, 0.441
No. of measured, independent and observed [I > 2σ(I)] reflections	792, 788, 742
Rint	0.152
(sin θ/λ)max (Å^−1)	0.689
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.036, 0.093, 1.08
No. of reflections	792
No. of parameters	52
No. of restraints	1
H-atom treatment	All H-atom parameters refined
Δρmax, Δρmin (e Å^−3)	0.85, −0.90
Absolute structure	Classical Flack (1983) method preferred over Parsons & Flack (2004) because s.u. lower
Absolute structure parameter	−0.04 (14)
Computer programs: X-AREA and X-RED (Stoe & Cie, 2009), SHELXS97 and SHELXL2012 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006) and publCIF (Westrip, 2010).

Supporting information

S1. Chemical context

The synthesis and powder diffraction data for tin(II) perchlorate trihydrate were described by Davies et al. (1968) and Schiefelbein et al. (1970). With our crystal structure determination, the data of Davies et al. (1968) are confirmed. The inter­est in the system tin(II)–perchloric acid-water arose from the redetermination of the redox-potential Sn²⁺/Sn⁴⁺ in perchloric acid by Gajda et al. (2009). There is no solid–liquid diagram for this binary salt–water system known in the literature.

S2. Structural commentary

The tin atom lies on a crystallographic threefold rotation axis and is coordinated by three water molecules as a trigonal pyramid (Fig. 1, Table 1). The perchlorate tetra­hedra are located in the gaps between the SnO₃ pyramids on their own threefold axes. A similar arrangement of the perchlorate tetra­hedra can be observed in the crystal structure of Ba(ClO₄)₂·3H₂O (Gallucci et al., 1988). The difference between the two structures is that the barium atom is sixfold coordinated by oxygen water molecules. All of them are shared between two barium atoms, so that an average of three are bonded to one Ba atom.

S3. Supra­molecular features

The different coordination of Sn²⁺ is caused by the lone-pair effect. It requires more space, so the distance to the next oxygen atoms is larger than in the barium salt structure. The perchlorate tetra­hedra are connected by O—H···O hydrogen bonds (Table 2) with the water molecules coordinated at the tin atoms (Figs. 2 and 3)

S4. Database survey

For properties, thermal behavior and powder diffraction data for tin(II) perchlorate trihydrate, see Schiefelbein et al. (1970) and Davies et al. (1968). For crystal structure determinations of divalent perchlorate trihydrates, see Gallucci et al. (1988) and Hennings et al. (2014).

S5. Synthesis and crystallization

Sn(ClO₄)₂·3H₂O was prepared by reaction of copper(II) perchlorate hexahydrate (15 g, Alfa Aesar, reagent grade) and elemental tin (12.04 g, VEB Feinchemikalien) in perchloric acid (50 ml, 60%, Merck, pA). After stirring the solution for 2 hours the precipitated copper was filtered off and the solution was transferred into a freezer at 253 K for crystallization. All crystals are stable in the saturated aqueous solution over a period of at least four weeks.

The sample was stored in a freezer or a cryostat at low temperatures. The crystals were separated and embedded in perfluorinated ether for X-ray analysis.

S6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3.

Related literature

For related literature, see: Davies & &Donaldson (1968); Gajda et al. (2009); Gallucci & &Gerkin (1988); Hennings et al. (2014); Schiefelbein & &Daugherty (1970).

Computing details

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

The component ions in (I) with displacement ellipsoids drawn at the 50% probability level. Symmetry codes: (i) -x+y, -x, z; (ii) -y, x-y, z; (iii) 1-x+y, 1-x, z; (iv) 1-y, x-y, z; (v) 1-y, 1+x-y, z; (vi) -x+y, 1-x, z.

The unit-cell packing in (I) with the ions shown in polyhedral representation.

Larger view of the crystal structure of (I) viewed down [001]. Dashed lines indicate hydrogen bonds.

Tin(II) perchlorate trihydrate

Crystal data

[Sn(H2O)3](ClO4)2	Dx = 2.919 Mg m^−3
Mr = 371.44	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63	Cell parameters from 14633 reflections
a = 7.0701 (10) Å	θ = 2.1–29.6°
c = 9.7631 (15) Å	µ = 3.70 mm^−1
V = 422.64 (16) Å^3	T = 180 K
Z = 2	Prism, colourless
F(000) = 355.8	0.70 × 0.52 × 0.22 mm

Data collection

STOE IPDS 2 diffractometer	788 independent reflections
Radiation source: fine-focus sealed tube	742 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm^-1	Rint = 0.152
rotation method scans	θmax = 29.3°, θmin = 3.3°
Absorption correction: integration (Coppens, 1970)	h = −7→9
Tmin = 0.116, Tmax = 0.441	k = 0→9
792 measured reflections	l = −13→13

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0771P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.036	(Δ/σ)max < 0.001
wR(F^2) = 0.093	Δρmax = 0.85 e Å^−3
S = 1.08	Δρmin = −0.90 e Å^−3
792 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
52 parameters	Extinction coefficient: 0.62 (5)
1 restraint	Absolute structure: Classical Flack (1983) method preferred over Parsons & Flack (2004) because s.u. lower.
Hydrogen site location: difference Fourier map	Absolute structure parameter: −0.04 (14)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Sn1	0.0000	0.0000	0.9724 (6)	0.0280 (4)
O2	0.2529 (5)	0.1712 (6)	0.8156 (8)	0.0239 (8)
O3	0.5340 (6)	0.6895 (7)	−0.0288 (9)	0.0311 (10)
Cl1	0.6667	0.3333	0.0921 (2)	0.0182 (5)
Cl2	0.3333	0.6667	0.0195 (3)	0.0197 (5)
O1	0.3333	0.6667	0.1653 (12)	0.0295 (18)
O4	0.8132 (6)	0.5490 (7)	0.1408 (7)	0.0280 (10)
O5	0.6667	0.3333	−0.0564 (10)	0.0204 (16)
H1	0.386 (19)	0.209 (16)	0.83 (2)	0.06 (3)*
H2	0.246 (11)	0.293 (10)	0.783 (8)	0.017 (17)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sn1	0.0337 (4)	0.0337 (4)	0.0164 (5)	0.0169 (2)	0.000	0.000
O2	0.0197 (15)	0.0232 (14)	0.030 (2)	0.0113 (12)	−0.0002 (19)	0.001 (2)
O3	0.0264 (16)	0.0359 (18)	0.034 (2)	0.0178 (15)	0.009 (3)	0.005 (3)
Cl1	0.0200 (7)	0.0200 (7)	0.0146 (12)	0.0100 (3)	0.000	0.000
Cl2	0.0202 (7)	0.0202 (7)	0.0187 (13)	0.0101 (3)	0.000	0.000
O1	0.038 (3)	0.038 (3)	0.013 (5)	0.0190 (15)	0.000	0.000
O4	0.0301 (18)	0.0236 (17)	0.028 (2)	0.0118 (14)	−0.003 (2)	−0.010 (2)
O5	0.023 (2)	0.023 (2)	0.016 (4)	0.0114 (11)	0.000	0.000

Geometric parameters (Å, º)

Sn1—O2^i	2.201 (7)	Cl1—O5	1.449 (10)
Sn1—O2^ii	2.201 (7)	Cl2—O1	1.424 (12)
Sn1—O2	2.201 (7)	Cl2—O3^v	1.426 (5)
Cl1—O4	1.430 (4)	Cl2—O3^vi	1.426 (5)
Cl1—O4^iii	1.430 (4)	Cl2—O3	1.426 (5)
Cl1—O4^iv	1.430 (4)
O2^i—Sn1—O2^ii	76.9 (3)	O4^iv—Cl1—O5	109.4 (3)
O2^i—Sn1—O2	76.9 (3)	O1—Cl2—O3^v	109.3 (4)
O2^ii—Sn1—O2	76.9 (3)	O1—Cl2—O3^vi	109.3 (4)
O4—Cl1—O4^iii	109.5 (3)	O3^v—Cl2—O3^vi	109.6 (4)
O4—Cl1—O4^iv	109.5 (3)	O1—Cl2—O3	109.3 (4)
O4^iii—Cl1—O4^iv	109.5 (3)	O3^v—Cl2—O3	109.6 (4)
O4—Cl1—O5	109.4 (3)	O3^vi—Cl2—O3	109.6 (4)
O4^iii—Cl1—O5	109.4 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O4^vii	0.94 (7)	1.95 (8)	2.823 (8)	152 (7)
O2—H2···O3^viii	0.94 (7)	2.46 (8)	2.926 (8)	110 (6)

Symmetry codes: (vii) −x+1, −y+1, z+1/2; (viii) −x+y, −x+1, z+1.