A three-dimensional tin(II) phosphon­atobenzene­sulfonate with Sn₄O₁₂ clusters

The hydro­thermal reaction of SnCl₂·2H₂O with 4-phosphono­benzene­sulfonic acid (H₃L) and sodium hydroxide has yielded the title compound, poly[μ-hydroxido-μ₇-(4-phosphon­ato­benzene­sulfonato)-ditin(II)], [Sn₂(C₆H₄O₆PS)(OH)]_n. The inorganic building unit is an Sn₄O₁₂ cluster which is composed of edge-sharing SnO₄ and SnO₅ polyhedra. The clusters are inter­connected via P and S atoms from the organic acid to form layers in the ab plane. These layers are linked to each other through pillaring benzene groups parallel to the c axis to form a three-dimensional structure.

S1. Comment

The discovery of crystalline zirconium(IV) phosphates in 1964 sparked a surge of interest in the study of phosphate- and phosphonate-based inorganic–organic hybrid compounds (Clearfield et al., 1964). This led to the class of crystalline zirconium(IV) phosphonates in 1978 (Alberti et al., 1978). Originally, the scope of the research was focused on the synthesis of layered structures with metal(IV) ions and monophosphonic acids, but the following studies saw an expansion with the use of divalent and trivalent metal ions and diphosphonic acids to generate new types of structures (Clearfield, 1998; Poojary et al., 1996a,b). Subsequently, sulfonate groups were also incorporated in the metal phosphonates by post-synthetic sulfonation of the phenyl rings (Yang et al., 1987; Stein et al., 1996). Some of these compounds were studied with respect to their proton-conducting abilities, which are relevant for polymer electrolyte membrane (PEM) fuel cells. Inorganic–organic hybrid compounds based on such polyfunctional acids have been reported to exhibit high proton conductivities (Adani et al., 1998; Alberti et al., 1992, 2003). The presence of strong acid sites also allows the application of such compounds for catalytic purposes (Alberti et al., 1996).

Our research focuses on the use of organic linker molecules containing two or more different functional groups for the synthesis of inorganic–organic hybrid compounds. In addition to the number of functional groups their geometry, coordination modes, charge and acidity have a strong influence on the formation of the final crystal structures (Maniam et al., 2010). With the advent of phosphonoalkyl- and phosphonoarylsulfonic acids (Montoneri & Ricca, 1991a,b), many phosphonosulfonates with di- and trivalent metal ions were investigated (Sonnauer et al., 2007, 2009; Sonnauer, Lieb & Stock, 2008; Sonnauer & Stock, 2008; Du et al., 2006; Maniam et al., 2010). By utilizing a new synthesis of phosphonoarylsulfonic acids, a rigid para-substituted 4-phosphonobenzenesulfonic acid (H₃L) was recently synthesized (Montoneri et al., 2007). Employing this organic acid linker, we have synthesized five new compounds, namely [Pb₂(L)(OH)], [Cu_1.5(L)(H₂O)], NaCu(L)(H₂O)₃, [Cu₂(L)(OH)(H₂O)] and [Cu₃(L)₂(H₂O)₂] (Maniam et al., 2010).

In the present work, we describe the structure of a new Sn²⁺-based phosphonatobenzenesulfonate, poly[µ-hydroxido-µ₇-(4-phosphonatobenzenesulfonato)-ditin(II)], (I), which crystallizes in the triclinic space group P1. To the best of our knowledge, this compound is the first tin(II) phosphonosulfonate. As seen in Fig. 1, the asymmetric unit of (I) contains two Sn²⁺ ions, a fully deprotonated organic linker (L) and one hydroxide ion. The X-ray scattering factors of P and S atoms are very similar, but they were successfully distinguished by comparing the S—O [1.460 (4)–1.469 (3) Å] and P—O [1.532 (3)–1.548 (3) Å] bond lengths. The fact that S—O bonds are generally shorter than P—O bonds has also been observed in other metal phosphonosulfonates (Du et al., 2006; Sonnauer et al., 2007, 2009; Sonnauer, Lieb & Stock, 2008; Maniam et al., 2010). Looking along the P1···S1 axis, the O atoms of the phosphonate and sulfonate groups are located in a staggered conformation but, in contrast to the ideal torsion angle of 60°, the O—P···S—O torsion angles vary from 40.79 (19) to 76.92 (18)°.

The crystal structure of (I) is built of Sn—O polyhedra containing sterically active lone pairs of electrons. These are also observed in many tin(II) phosphonates, such as [Sn₂(O₃PCH₃)(C₂O₄)], [Sn₄(O₃PCH₂CH₂CO₂)₂(C₂O₄)], [Sn(C₆H₅O₃P)] and [Sn(O₃PCH₂NHC₄H₈NHCH₂PO₃)], which contain SnO₃, SnO₄ and Sn₂O₇ polyhedra (Adair et al., 1998; Stock et al., 2000; Lansky et al., 2001; Zhang et al., 2008). Depending on how the Sn—O bond distances are taken into account, the crystal structure of (I) can be described in different ways.

Including only Sn—O distances less than 2.7 Å, two distorted seesaw-type SnO₄ polyhedra are observed. Sn1 is connected to atoms O1, O2, O5 and O7, with bond lengths in the range 2.124 (3)–2.425 (3) Å (Table 1) and O—Sn1—O angles in the range 69.82 (9)–140.63 (10)°. The two longest Sn1—O bonds (to O1 and O5) lie in the pseudo-axial positions, while the two shorter Sn1—O bonds (to O2 and O7) and the lone pair are in the equatorial plane. Sn2 is connected to atoms O1, O3, O6 and O7, with bond lengths in the range 2.108 (3)–2.587 (3) Å. The O—Sn2—O angles in the distorted square-pyramidal geometry vary from 73.59 (10) to 152.13 (10)°. The observed Sn—O distances and O—Sn—O bond angles are in very good agreement with those reported in the seesaw-type SnO₄ units of the layered tin(II) phosphonate [Sn₂(O₃PCH₃)(C₂O₄)] and the three-dimensional structure of [Sn₄(O₃PCH₂CH₂CO₂)₂(C₂O₄)] (Adair et al., 1998; Stock et al., 2000). This form of polyhedron is also similar to those observed in α-SnO, with Sn—O distances of 2.223 Å and an O—Sn—O-angle range of 74.36–117.44° (Levi, 1924). Edge sharing of the two distorted seesaw-type SnO₄ polyhedra in (I) leads to dimeric units which are in close proximity to each other [Sn2—O3 = 2.726 (3) Å] and are connected through the phosphonate and sulfonate groups to form chains (Fig. 3). These chains are connected by the phenyl rings of the phosphonobenzenesulfonate ions to form a layered structure.

If the additional Sn2—O3 distance of 2.726 (3) Å is taken into account as a genuine bond, two kinds of polyhedra are observed, viz. distorted seesaw-type Sn1O₄ and irregular square-pyramidal Sn2O₅ polyhedra. The irregular SnO₅ square pyramid consists of the apical Sn2—O7 bond and the four basal Sn2—O bonds to atoms O1, O3ⁱ, O3ⁱⁱⁱ and O6^iv (symmetry codes as in Fig. 2). Associated with the influence of the lone pair, the Sn²⁺ ion is located 0.514 (1) Å below the basal plane, whereas apical atom O7 is positioned 1.591 (3) Å above the plane (Fig. 2). Although this distance is much larger than the sum of the ionic radii (2.35 Å; McDonald et al., 1980), it is much smaller than the sum of the van der Waals radii (3.70 Å; Kawamura et al., 1999). A search of the Cambridge Structural Database (Allen, 2002) for Sn—O bond lengths in tin phosphonates yields values between 1.9 and 2.8 Å, with a mean value around 2.2 Å and, in the literature, bond lengths of up to 3 Å are discussed (Ramaswamy et al., 2008; Holt et al., 1987). Accordingly, the next largest Sn—O distances in (I), which are 3.094 (3) and 3.292 (3) Å for Sn1···O4 and Sn2···O2, respectively, were not considered in the structural description. Using Sn—O distances up to 2.73 Å, edge sharing of the SnO₅ polyhedra is observed and thus Sn₄O₁₂ clusters are formed (Fig. 2). These tetrameric clusters are connected by the phosphonate and sulfonate groups to form layers in the ab plane (Fig. 3), which are further connected by the benzene rings of the phosphonobenzenesulfonate ions to form a pillared layered structure (Fig. 4). An interlayer distance of 9.932 (2) Å separates the layers from each other along the c axis. In this arrangement, the presence of narrow voids indicate the position of the sterically active lone pairs. These are observed between opposing Sn1²⁺ ions [Sn1···Sn1 = 4.335 (1) Å] (Fig. 3), whereas for Sn2²⁺ the lone pairs point towards the interlayer space occupied by the phenyl rings.

Only one hydrogen bond is observed in (I) which involves the bond between the µ(O—H) hydroxide ion and an O atom of the sulfonate group (Fig. 3 and Table 2). This bond can be considered as a weak hydrogen bond, with an O—H···O distance of 2.874 (4) Å and an O—H···O angle of 139.02 (22)° (Libowitzky, 1999).

Related literature

For related literature, see: Adair et al. (1998); Adani et al. (1998); Alberti & Casciola (2003); Alberti et al. (1978, 1992, 1996); Clearfield (1998); Clearfield & Stynes (1964); Du et al. (2006); Holt et al. (1987); Kawamura et al. (1999); Lansky et al. (2001); Levi (1924); Libowitzky (1999); Maniam et al. (2010); McDonald & Eriks (1980); Montoneri & Ricca (1991a,b); Montoneri et al. (2007); Poojary et al. (1996a,b); Ramaswamy et al. (2008); Sonnauer & Stock (2008); Sonnauer, Lieb & Stock (2008); Sonnauer et al. (2007, 2009); Stein et al. (1996); Stock (2010); Stock et al. (2000); Yang & Clearfield (1987); Zhang et al. (2008).

S2. Experimental

All reagents and solvents were obtained commercially and used without further purification. 4-Phosphonobenzenesulfonic acid dihydrate (H₃L) was synthesized according to Montoneri et al. (2007). The reaction mixture consisted of tin(II) chloride dihydrate (6.8 mg, 0.03 mmol), H₃L (5.48 mg, 0.02 mmol), NaOH (0.06 mmol) and deionized water (200 µl). The mixture was heated in a 300 µl Teflon-lined high-throughput reactor at 423 K for 36 h (Stock, 2010). The mixture was cooled to room temperature over a period of 8 h, and colourless plate-like crystals were formed.

S3. Refinement

All H atoms were located in difference Fourier maps. Idealized values for the bond lengths (C—H = 0.93 Å and O—H = 0.84 Å) and angles were used and H-atom parameters were refined using a riding model. This led to very similar Sn1—O7—H7 and Sn2—O7—H7 bond-angle values. The highest peak of 0.82 e Å^-33 in the residual electron-density map is located 1.34 Å from H3 and the deepest hole of 1.10 e Å^-3 is located 0.72 Å from Sn2.

Computing details

Data collection: X-AREA (Stoe & Cie, 2008); cell refinement: X-AREA (Stoe & Cie, 2008); data reduction: X-AREA (Stoe & Cie, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: XCIF in SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The asymmetric unit of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Coordinative Sn—O bonds are marked as broken lines.
	Fig. 2. The coordination environment of the Sn1 and Sn2 atoms. Including only bond lengths < 2.7 Å, two distorted seesaw-type polyhedra are observed. Edge sharing leads to the formation of dimeric Sn2O6 clusters (solid lines). By considering the Sn2—O3 bond of 2.726 (3) Å (dashed line), one distorted seesaw SnO4 and one distorted square-pyramidal SnO5 polyhedra are observed. Edge sharing leads to tetrameric Sn4O12 clusters. [Symmetry codes: (i) -x, -y + 1, -z + 1; (ii) x - 1, y, z + 1; (iii) x - 1, y, z; (iv) -x, -y + 2, -z; (vi) -x - 1, -y + 1, -z + 1; (vii) x - 1, y - 1, z + 1; (viii) -x, -y + 1, -z.]
	Fig. 3. Packing diagram showing the interconnection of dimeric clusters via phosphonate and sulfonate groups to form chains. Taking the Sn2—O3 bond of 2.726 (3) Å (black dashed lines) into account, tetrameric Sn4O12 clusters are formed and the formerly described chains are connected to form layers in the ab plane. The positions of lone pairs are indicated by the narrow voids between the opposing Sn1^2+ ions. Hydrogen bonds are shown as grey dashed lines. The layers are then linked to each other by the benzene groups along the c axis. Atoms C2, C3, C5 and C6 and their respective H atoms have been omitted for clarity.
	Fig. 4. Schematic representation of the three-dimensional pillared–layered structure of (I) viewed along the a axis with an interlayer distance of 9.932 (2) Å. Aromatic H atoms have been omitted for clarity.

poly[µ-hydroxido-µ₇-(4-phosphonatobenzenesulfonato)-ditin(II)]

Crystal data

[Sn2(C6H4O6PS)(OH)]	Z = 2
Mr = 489.56	F(000) = 456
Triclinic, P1	Dx = 2.847 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.0045 (14) Å	Cell parameters from 1556 reflections
b = 8.487 (2) Å	θ = 1.9–28.2°
c = 10.0570 (17) Å	µ = 4.72 mm^−1
α = 81.10 (2)°	T = 293 K
β = 86.17 (2)°	Plate, colourless
γ = 75.25 (3)°	0.14 × 0.10 × 0.07 mm
V = 571.0 (2) Å^3

Data collection

Stoe IPDS-1 diffractometer	2550 independent reflections
Radiation source: fine-focus sealed tube	2146 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.048
ϕ scans	θmax = 28.1°, θmin = 2.5°
Absorption correction: numerical (X-RED and X-SHAPE; Stoe & Cie, 2008)	h = −9→9
Tmin = 0.380, Tmax = 0.581	k = −11→11
6691 measured reflections	l = −13→13

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.026	H-atom parameters constrained
wR(F^2) = 0.071	w = 1/[σ^2(Fo^2) + (0.0432P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max = 0.001
2550 reflections	Δρmax = 0.82 e Å^−3
155 parameters	Δρmin = −1.10 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0123 (10)

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.

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

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

	x	y	z	Uiso*/Ueq
Sn1	−0.18613 (4)	0.83666 (3)	0.57935 (3)	0.01836 (11)
Sn2	−0.35359 (4)	0.61742 (3)	0.35282 (2)	0.01959 (11)
P1	0.12974 (15)	0.57545 (11)	0.34659 (8)	0.0149 (2)
S1	0.37173 (16)	0.93629 (12)	−0.21630 (9)	0.0162 (2)
O1	−0.0714 (4)	0.6751 (3)	0.3977 (2)	0.0150 (5)
O2	0.1080 (4)	0.4085 (3)	0.3189 (2)	0.0178 (6)
O3	0.2896 (4)	0.5662 (4)	0.4464 (3)	0.0174 (6)
O4	0.2573 (5)	0.9067 (5)	−0.3219 (3)	0.0326 (8)
O5	0.5818 (5)	0.8540 (4)	−0.2320 (3)	0.0270 (7)
O6	0.3416 (5)	1.1094 (4)	−0.2014 (3)	0.0292 (7)
O7	−0.4333 (4)	0.7918 (3)	0.4878 (3)	0.0166 (5)
H7	−0.5511	0.8396	0.5045	0.025*
C1	0.1890 (6)	0.6801 (5)	0.1857 (3)	0.0156 (7)
C2	0.2371 (11)	0.5966 (6)	0.0754 (5)	0.0483 (17)
H2	0.2360	0.4862	0.0840	0.058*
C3	0.2867 (12)	0.6764 (7)	−0.0470 (5)	0.058 (2)
H3	0.3155	0.6206	−0.1213	0.070*
C4	0.2937 (7)	0.8399 (5)	−0.0595 (4)	0.0213 (8)
C5	0.2428 (8)	0.9260 (6)	0.0478 (4)	0.0251 (9)
H5	0.2452	1.0362	0.0390	0.030*
C6	0.1874 (8)	0.8456 (5)	0.1700 (4)	0.0258 (10)
H6	0.1488	0.9039	0.2424	0.031*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sn1	0.02093 (19)	0.01540 (15)	0.01949 (15)	−0.00647 (12)	−0.00124 (10)	−0.00118 (10)
Sn2	0.01849 (19)	0.02489 (17)	0.01553 (15)	−0.00268 (12)	−0.00037 (10)	−0.00788 (10)
P1	0.0153 (5)	0.0175 (4)	0.0105 (4)	−0.0037 (4)	0.0025 (3)	0.0003 (3)
S1	0.0178 (6)	0.0206 (5)	0.0068 (4)	−0.0024 (4)	0.0045 (3)	0.0025 (3)
O1	0.0122 (15)	0.0193 (13)	0.0124 (11)	−0.0031 (11)	0.0037 (9)	−0.0020 (10)
O2	0.0250 (17)	0.0139 (12)	0.0136 (12)	−0.0048 (12)	−0.0019 (10)	0.0011 (9)
O3	0.0151 (16)	0.0227 (13)	0.0137 (12)	−0.0052 (12)	−0.0020 (10)	0.0016 (10)
O4	0.031 (2)	0.050 (2)	0.0155 (13)	−0.0126 (17)	0.0003 (12)	0.0010 (13)
O5	0.0226 (18)	0.0365 (18)	0.0167 (13)	0.0001 (14)	0.0059 (11)	−0.0029 (12)
O6	0.038 (2)	0.0234 (15)	0.0186 (14)	−0.0015 (14)	0.0081 (13)	0.0045 (11)
O7	0.0108 (15)	0.0216 (13)	0.0161 (12)	−0.0015 (11)	0.0032 (10)	−0.0047 (10)
C1	0.017 (2)	0.0192 (18)	0.0098 (15)	−0.0049 (16)	0.0027 (13)	0.0004 (13)
C2	0.103 (5)	0.022 (2)	0.022 (2)	−0.024 (3)	0.027 (3)	−0.0073 (18)
C3	0.128 (7)	0.027 (2)	0.020 (2)	−0.026 (3)	0.032 (3)	−0.0095 (19)
C4	0.023 (2)	0.027 (2)	0.0111 (16)	−0.0057 (18)	0.0057 (14)	0.0015 (14)
C5	0.041 (3)	0.0224 (19)	0.0139 (17)	−0.0129 (19)	0.0086 (16)	−0.0031 (15)
C6	0.046 (3)	0.022 (2)	0.0119 (17)	−0.013 (2)	0.0103 (17)	−0.0048 (15)

Geometric parameters (Å, º)

Sn1—O1	2.425 (3)	S1—C4	1.780 (4)
Sn1—O2^i	2.124 (3)	O2—Sn1^i	2.124 (3)
Sn1—O5^ii	2.412 (3)	O3—Sn2^i	2.345 (3)
Sn1—O7	2.156 (3)	O5—Sn1^v	2.412 (3)
Sn2—O1	2.243 (3)	O7—H7	0.8400
Sn2—O3^i	2.345 (3)	C1—C2	1.384 (6)
Sn2—O3^iii	2.726 (3)	C1—C6	1.387 (5)
Sn2—O6^iv	2.587 (3)	C2—C3	1.378 (6)
Sn2—O7	2.108 (3)	C2—H2	0.9300
P1—O1	1.548 (3)	C3—C4	1.387 (7)
P1—O2	1.532 (3)	C3—H3	0.9300
P1—O3	1.532 (3)	C4—C5	1.373 (6)
P1—C1	1.798 (3)	C5—C6	1.392 (5)
S1—O4	1.460 (3)	C5—H5	0.9300
S1—O5	1.469 (4)	C6—H6	0.9300
S1—O6	1.460 (3)
O2^i—Sn1—O7	91.86 (11)	P1—O1—Sn1	136.33 (16)
O2^i—Sn1—O5^ii	78.78 (11)	Sn2—O1—Sn1	100.03 (10)
O7—Sn1—O5^ii	80.57 (11)	P1—O2—Sn1^i	135.20 (16)
O2^i—Sn1—O1	76.92 (10)	P1—O3—Sn2^i	126.01 (15)
O7—Sn1—O1	69.82 (10)	S1—O5—Sn1^v	133.86 (17)
O5^ii—Sn1—O1	140.63 (10)	Sn2—O7—Sn1	114.14 (13)
O1—Sn2—O3^i	83.12 (9)	Sn2—O7—H7	122.9
O3^i—Sn2—O3^iii	74.32 (10)	Sn1—O7—H7	122.9
O3^iii—Sn2—O6^iv	119.16 (10)	C2—C1—C6	118.9 (3)
O6^iv—Sn2—O1	73.59 (10)	C2—C1—P1	120.5 (3)
O7—Sn2—O1	74.32 (10)	C6—C1—P1	120.5 (3)
O6^iv—Sn2—O3^i	152.13 (10)	C3—C2—C1	120.3 (4)
O1—Sn2—O3^iii	147.69 (10)	C3—C2—H2	119.8
O2—P1—O3	114.86 (16)	C1—C2—H2	119.8
O2—P1—O1	109.21 (16)	C2—C3—C4	120.1 (4)
O3—P1—O1	109.44 (16)	C2—C3—H3	120.0
O2—P1—C1	105.38 (16)	C4—C3—H3	120.0
O3—P1—C1	109.51 (17)	C5—C4—C3	120.5 (4)
O1—P1—C1	108.20 (17)	C5—C4—S1	120.4 (3)
O4—S1—O6	114.6 (2)	C3—C4—S1	119.1 (3)
O4—S1—O5	110.8 (2)	C4—C5—C6	118.9 (4)
O6—S1—O5	112.1 (2)	C4—C5—H5	120.5
O4—S1—C4	108.0 (2)	C6—C5—H5	120.5
O6—S1—C4	105.58 (19)	C1—C6—C5	121.1 (4)
O5—S1—C4	105.10 (19)	C1—C6—H6	119.5
P1—O1—Sn2	120.56 (15)	C5—C6—H6	119.5
O2—P1—O1—Sn2	−22.09 (19)	O3^i—Sn2—O7—Sn1	73.82 (13)
O3—P1—O1—Sn2	−148.61 (15)	O2^i—Sn1—O7—Sn2	−64.71 (13)
C1—P1—O1—Sn2	92.13 (19)	O5^ii—Sn1—O7—Sn2	−143.01 (14)
O2—P1—O1—Sn1	133.60 (19)	O1—Sn1—O7—Sn2	10.62 (10)
O3—P1—O1—Sn1	7.1 (2)	O2—P1—C1—C2	−10.6 (5)
C1—P1—O1—Sn1	−112.2 (2)	O3—P1—C1—C2	113.5 (5)
O7—Sn2—O1—P1	172.43 (18)	O1—P1—C1—C2	−127.3 (5)
O3^i—Sn2—O1—P1	88.70 (16)	O2—P1—C1—C6	169.4 (4)
O7—Sn2—O1—Sn1	9.21 (9)	O3—P1—C1—C6	−66.5 (4)
O3^i—Sn2—O1—Sn1	−74.52 (10)	O1—P1—C1—C6	52.7 (4)
O2^i—Sn1—O1—P1	−71.2 (2)	C6—C1—C2—C3	1.4 (9)
O7—Sn1—O1—P1	−168.1 (2)	P1—C1—C2—C3	−178.6 (6)
O5^ii—Sn1—O1—P1	−124.5 (2)	C1—C2—C3—C4	1.7 (11)
O2^i—Sn1—O1—Sn2	87.70 (11)	C2—C3—C4—C5	−3.0 (10)
O7—Sn1—O1—Sn2	−9.24 (9)	C2—C3—C4—S1	176.5 (6)
O5^ii—Sn1—O1—Sn2	34.4 (2)	O4—S1—C4—C5	−129.8 (4)
O3—P1—O2—Sn1^i	20.6 (3)	O6—S1—C4—C5	−6.8 (5)
O1—P1—O2—Sn1^i	−102.8 (2)	O5—S1—C4—C5	111.9 (4)
C1—P1—O2—Sn1^i	141.2 (2)	O4—S1—C4—C3	50.8 (6)
O2—P1—O3—Sn2^i	−41.9 (2)	O6—S1—C4—C3	173.8 (5)
O1—P1—O3—Sn2^i	81.3 (2)	O5—S1—C4—C3	−67.5 (5)
C1—P1—O3—Sn2^i	−160.25 (19)	C3—C4—C5—C6	1.1 (8)
O4—S1—O5—Sn1^v	46.7 (3)	S1—C4—C5—C6	−178.3 (4)
O6—S1—O5—Sn1^v	−82.7 (3)	C2—C1—C6—C5	−3.3 (8)
C4—S1—O5—Sn1^v	163.1 (3)	P1—C1—C6—C5	176.7 (4)
O1—Sn2—O7—Sn1	−11.20 (11)	C4—C5—C6—C1	2.0 (8)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O7—H7···O4^ii	0.84	2.19	2.874 (4)	139

Symmetry code: (ii) x−1, y, z+1.