K₂[Hg(SO₃)₂]·2.25H₂O

The characteristic feature of the structure of the title compound, dipotassium bis­(sulfito-[kappa]S)mercurate(II) 2.25-hy­drate, is a layered arrangement parallel to (001) where each of the two independent [Hg(SO₃)₂]^2- anions are grouped into centrosymmetric pairs and are surrounded by two K⁺ cations to give the overall layer composition {K₂[Hg(SO₃)₂]₂}^2-. The remaining cations and the uncoordinated water mol­ecules are situated between these layers. Within the [Hg(SO₃)₂]^2- anions, the central Hg atoms are twofold coordinated by S atoms, with a mean Hg-S bond length of 2.384 (2) Å. The anions are slightly bent [174.26 (3) and 176.99 (3)°] due to inter­molecular O...Hg inter­actions greater than 2.8 Å. All coordination polyhedra around the K⁺ cations are considerably distorted, with coordination numbers ranging from six to nine. Although the H atoms of the five water mol­ecules (one with symmetry 2) could not be located, O...O separations between 2.80 and 2.95 Å suggest a system of medium to weak O-H...O hydrogen bonds which help to consolidate the structural set-up. Differences and similarities between the bis­(sulfito-[kappa]S)mercurate(II) anions in the title compound and those in the related salts (NH₄)₂[Hg(SO₃)₂] and Na₂[Hg(SO₃)₂]·H₂O are discussed.

S1. Comment

From a structural point of view, sulfito complexes of mercury(II) are interesting because the primary coordination of the metal is not accomplished through the oxygen atoms of the SO₃^2- anion, but through the lone-pair electrons of the S^IV atom. The κ-S coordination mode to the metal leads to an enhanced S—O π-bonding (Cruickshank, 1961) and consequently in considerably shorter S—O bond lengths (≈ 1.47 Å) in comparison with a κ-O coordination mode [d(S—O) ≈ 1.54 Å]. Structurally well characterized examples of such κ-S-bonded mercury(II) complexes include Na₂[Hg(SO₃)₂].H₂O (Nyberg & Cynkier, 1972), (NH₄)[HgCl(SO₃)], (NH₄)₂[Hg(SO₃)₂] (Weil et al., 2007), K₂[O(HgSO₃)₃] (Weil et al., 2008a) and several compounds of general composition xM[HgX(SO₃)].yHgX₂.zMX. nH₂O (M = NH₄, K; X = Cl, Br; x, y, z, n = 0–2) (Weil et al., 2008b). Continuing our studies of sulfito complexes of mercury, we have obtained single crystals of the title compound, K₂[Hg(SO₃)₂].2.25H₂O, (I), and report its crystal structure here.

The asymmetric unit of (I) (Fig. 1) contains four K, two Hg, four S and 17 O atoms, five of which are associated with water molecules. Except for one H₂O molecule (OW1) on a special position (4e, symmetry 2), all other atoms occupy general sites (8f). The two independent but very similar [Hg(SO₃)₂]^2- sulfitomercurate anions are arranged in two centrosymmetric pairs [Hg(SO₃)₂]₂^4-, which, in turn, are linked into layers parallel to (001) through weak S—O···Hg interactions. In addition, two of the four independent K⁺ cations (K1, K2) are embedded within these layers, leading to an overall layer composition of {K₂[Hg(SO₃)₂]₂}^2- (Fig. 2). The layers are stacked along [001] with an interlayer distance of sin β.c/2 = 9.0719 Å. This distance corresponds to the most intense reflection (002) in the X-ray powder pattern. These mixed anionic sheets adopt layer symmetry (a/b).1 - p 1 (Shubnikov & Koptsik, 1974). The remaining K⁺ ions (K3, K4) are spread between the anionic layers; their layer symmetry is (a:b).2 - p 2.

In the two slightly bent [Hg(SO₃)₂]^2- anions, which both approach an eclipsed conformation, the four Hg—S bonds have virtually the same lengths, with an average of 2.384 (2) Å (Table 1). The coordination spheres of the two Hg^II atoms are augmented by remote oxygen atoms at distances > 2.8 Å. When a bonding interaction between mercury and oxygen is considered to be relevant for Hg—O distances < 3.1 Å, the resulting coordination polyhedra are a distorted HgS₂O₄ octahedron for Hg1 and a distorted HgS₂O₃ trigonal bipyramid for Hg2, each with the S atoms in the respective axial positions. The four S atoms adopt a tetrahedral SHgO₃ coordination with a slight angular distortion in which the O—S—O angles [mean 110.4 (6)°] are somewhat greater than the O—S—Hg angles [mean 108.5 (18)°]. The 12 S—O bond lengths scatter marginally [¯d(S—O) = 1.472 (6) Å], as the individual O atoms are involved to a different extent in the effective coordination spheres of Hg, in the coordination to the K⁺ cations, and as acceptors in hydrogen bonds from the H₂O molecules.

The four independent K⁺ ions show different coordination behaviour. K1 is a component of the mixed anionic layer and is coordinated by six O atoms of the sulfite ligands at short distances [2.662 (3)–2.788 (3) Å] in the form of a distorted octahedron. K2 is already situated at the outer margin of the anionic layer and thus also bonds to three interlayer water molecules. This leads to an increase of the coordination number to eight with K—O distances ranging from 2.708 (3) to 3.080 (4) Å. K3 and K4 are part of the cationic layer and are coordinated both to sulfite O atoms and to water molecules. Their coordination numbers are eight and nine, with K—O distances ranging from 2.666 (3) to 3.097 (3) Å. The resulting coordination spheres are considerably distorted and difficult to derive from simple polyhedra.

Although the hydrogen atoms of the water molecules could not be located, the O···O separations (Table 2) between the water molecules and between water molecules and neighbouring O atoms of the sulfite groups are indicative of typical donor···acceptor distances for medium to weak O—H···O hydrogen bonds which leads to an additional stabilization of the structure.

In relation to the two other [Hg(SO₃)₂]^2- anions structurally characterized so far, the atomic distances and angles for the two anions in (I) are very similar (Table 1). The Hg—S bond lengths are slightly shorter than in (NH₄)₂[Hg(SO₃)₂], (II), and Na₂[Hg(SO₃)₂].H₂O, (III), due to differences in the effective coordination of Hg^II in the three structures. However, compared to the average Hg—S distance of 2.371 (19) Å in structures comprising the (halidosulfito-κ-S)-mercurate anion [HgX(SO₃)]^- (X = Br, Cl) (Weil et al., 2007, 2008b) an increase of the Hg—S bond length is observed which we ascribe to the mutual trans-influence of the two sulfito ligands in the [Hg(SO₃)₂]^2- anion. As for Hg1 in (I), the coordination polyhedra of the Hg^II atoms in (II) and (III) show a distinct [2 + 4] coordination; however, with differences with respect to the Hg—O bond lengths [2.733 (3)-[2.844 (3) Å for (II) and 2.803 (21)-[3.070 (19) Å for (III)]. In all three structures, similar angular distortions are found for the tetrahedrally coordinated S atom, whereas in (II) and (III) the mean S—O bond lengths of the sulfite moiety differ slightly from that of (I), with 1.481 (8) Å for (II) and 1.467 (16) Å for (III). The [Hg(SO₃)₂]^2- anions in all three structures are nearly linear and approach an eclipsed conformation. Comparison of the four [(bis-sulfito-κ-S)mercurate(II)] anions reveals a rather rigid structure for this unit with only slight deviations that mainly originate from the outer coordination spheres of the Hg^II atoms to remote O atoms, from the role of the sulfite O atoms as acceptors in hydrogen bonding and from bonding of the individual SO₃ units to the different counter cations (K⁺, NH₄⁺ and Na⁺) via ionic or hydrogen bonding interactions. The number of lattice water molecules and their bonding to the respective cations and further involvement in hydrogen bonding also contribute to these differences. Whereas in (I) 2.25 water molecules per anion are present, (II) contains no additional water molecules and (III) contains one water molecule per anion. The different numbers of lattice water molecules also influence the packing of the three structures. In contrast to the layered arrangement in (I) that contains a comparatively high number of water molecules, (III) includes less water and is characterized by a rod-like arrangement of the [(bis-sulfito-κ-S)mercurate(II)] anions which are separated by the Na⁺ cations and water molecules. Finally, (II), containing no water molecules, is made up of a three-dimensional anionic framework where the NH₄⁺ cations are situated in the voids.

Related literature

For related literature, see: Cruickshank (1961); Nyberg & Cynkier (1972); Shubnikov & Koptsik (1974); Weil et al. (2007, 2008a, 2008b).

S2. Experimental

All employed chemicals were of 'p.A.' quality and were purchased from Merck. Freshly prepared HgO, obtained by precipitation of a saturated aqueous HgCl₂ solution with KOH, was dissolved in a concentrated K₂SO₃ solution (molar ratio HgO:K₂SO₃ = 1:3). After filtration of unreacted HgO, the colourless solution was left to stand in a refrigerator (280 K) for several days. Colourless crystals with a typical sword-like habit and maximum edge lengths of about 0.6 mm were obtained.

S3. Refinement

Protons of the water molecules O1W—O5W were not discernible from difference Fourier maps and hence were not included in the final refinement. The highest peak in the final Fourier map is 0.65 Å from Hg2 and the deepest hole is 1.35 Å from the same atom.

Computing details

Data collection: SMART (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. The asymmetric unit of K2[Hg(SO3)2].2.25H2O showing the atom labelling and with displacement ellipsoids drawn at the 74% probability level. The additional O atoms augmenting the coordination sphere of the Hg^II atoms are also shown. K—O bonds and O···O interactions have been omitted for clarity. [Symmetry codes: (i) -x+1/2, -y+1/2, -z+1; (ii) -x, -y + 1, -z+1; (iii) -x, -y, -z+1; (iv) -x + 1/2, -y-1/2, -z+1.]

Fig. 2. The crystal structure of K2[Hg(SO3)2].2.25H2O in a projection along [010] showing the alternating anionic and cationic layers in the a–b plane.

dipotassium bis(sulfito-κS)mercurate(II) 2.25-hydrate

Crystal data

K2[Hg(SO3)2]·2.25H2O	F(000) = 3528
Mr = 479.45	Dx = 3.417 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 5331 reflections
a = 24.0774 (19) Å	θ = 2.6–31.0°
b = 8.5348 (7) Å	µ = 17.87 mm^−1
c = 19.2633 (15) Å	T = 100 K
β = 109.634 (1)°	Lath, colourless
V = 3728.4 (5) Å^3	0.30 × 0.12 × 0.02 mm
Z = 16

Data collection

Bruker SMART CCD diffractometer	5912 independent reflections
Radiation source: fine-focus sealed tube	5360 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
ω scans	θmax = 31.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2006)	h = −34→33
Tmin = 0.075, Tmax = 0.674	k = −12→12
21048 measured reflections	l = −27→27

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.023	H-atom parameters not refined
wR(F^2) = 0.058	w = 1/[σ^2(Fo^2) + (0.0275P)^2 + 2.5166P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.003
5912 reflections	Δρmax = 1.67 e Å^−3
240 parameters	Δρmin = −0.98 e Å^−3
0 restraints

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
Hg1	0.036501 (6)	0.265777 (14)	0.486165 (7)	0.01285 (4)
Hg2	0.276571 (6)	−0.003213 (14)	0.475636 (7)	0.01360 (4)
K1	0.36120 (3)	−0.39947 (9)	0.46280 (4)	0.01482 (14)
K2	0.04902 (4)	−0.35571 (9)	0.36188 (4)	0.01791 (15)
K3	0.23879 (4)	−0.42435 (10)	0.24969 (5)	0.02119 (16)
K4	0.09952 (3)	0.05704 (10)	0.31029 (4)	0.01916 (15)
S1	0.08142 (4)	0.47758 (10)	0.56635 (5)	0.01256 (15)
S2	−0.00265 (4)	0.06224 (9)	0.39867 (5)	0.01168 (14)
S3	0.21580 (4)	−0.19185 (10)	0.39359 (4)	0.01129 (14)
S4	0.33279 (4)	0.19295 (10)	0.55729 (5)	0.01320 (15)
O1	0.14181 (11)	0.4327 (3)	0.61081 (16)	0.0228 (6)
O2	0.04585 (13)	0.5124 (3)	0.61340 (16)	0.0201 (6)
O3	0.08158 (13)	0.6118 (3)	0.51848 (15)	0.0230 (6)
O4	0.04151 (12)	−0.0620 (3)	0.41178 (16)	0.0213 (6)
O5	−0.05837 (13)	−0.0006 (3)	0.40311 (17)	0.0208 (6)
O6	−0.01321 (12)	0.1340 (3)	0.32539 (15)	0.0211 (5)
O7	0.24594 (12)	−0.3443 (3)	0.40480 (15)	0.0186 (5)
O8	0.16101 (11)	−0.2003 (3)	0.41122 (15)	0.0196 (5)
O9	0.20398 (12)	−0.1359 (3)	0.31777 (14)	0.0205 (5)
O10	0.34695 (13)	0.3178 (3)	0.51409 (17)	0.0267 (6)
O11	0.38767 (12)	0.1246 (3)	0.60863 (16)	0.0243 (6)
O12	0.29695 (13)	0.2557 (3)	0.60017 (18)	0.0244 (6)
O1W	0.0000	0.4132 (5)	0.2500	0.0245 (8)
O2W	0.20764 (14)	0.1503 (4)	0.65068 (16)	0.0284 (7)
O3W	0.07218 (16)	−0.2182 (4)	0.2276 (2)	0.0353 (8)
O4W	−0.15074 (15)	0.1821 (4)	0.2988 (2)	0.0390 (8)
O5W	0.36808 (16)	0.0241 (4)	0.7400 (2)	0.0392 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Hg1	0.01303 (7)	0.01182 (6)	0.01269 (6)	−0.00016 (4)	0.00300 (5)	−0.00236 (4)
Hg2	0.01370 (7)	0.01269 (7)	0.01354 (7)	−0.00257 (4)	0.00343 (5)	−0.00150 (4)
K1	0.0122 (3)	0.0164 (3)	0.0161 (3)	0.0009 (2)	0.0051 (3)	0.0006 (3)
K2	0.0196 (4)	0.0159 (3)	0.0179 (4)	−0.0015 (3)	0.0058 (3)	−0.0019 (3)
K3	0.0192 (4)	0.0247 (4)	0.0184 (4)	0.0036 (3)	0.0047 (3)	−0.0001 (3)
K4	0.0167 (4)	0.0231 (4)	0.0172 (3)	−0.0010 (3)	0.0050 (3)	−0.0011 (3)
S1	0.0127 (4)	0.0130 (4)	0.0113 (3)	−0.0007 (3)	0.0032 (3)	−0.0017 (3)
S2	0.0112 (4)	0.0118 (4)	0.0119 (3)	0.0003 (3)	0.0038 (3)	−0.0016 (3)
S3	0.0105 (4)	0.0130 (4)	0.0102 (3)	−0.0001 (3)	0.0033 (3)	−0.0005 (3)
S4	0.0122 (4)	0.0116 (3)	0.0143 (4)	−0.0006 (3)	0.0025 (3)	−0.0007 (3)
O1	0.0137 (13)	0.0291 (15)	0.0216 (14)	0.0043 (10)	0.0007 (11)	−0.0058 (11)
O2	0.0205 (14)	0.0231 (14)	0.0192 (13)	−0.0030 (10)	0.0099 (12)	−0.0061 (10)
O3	0.0347 (16)	0.0171 (13)	0.0162 (13)	−0.0070 (11)	0.0074 (12)	0.0000 (10)
O4	0.0181 (13)	0.0171 (13)	0.0242 (14)	0.0061 (10)	0.0011 (11)	−0.0073 (10)
O5	0.0166 (13)	0.0262 (15)	0.0226 (14)	−0.0079 (10)	0.0106 (12)	−0.0066 (10)
O6	0.0279 (15)	0.0211 (13)	0.0128 (12)	−0.0035 (11)	0.0046 (11)	0.0021 (10)
O7	0.0185 (13)	0.0152 (12)	0.0204 (13)	0.0039 (10)	0.0042 (11)	−0.0015 (10)
O8	0.0139 (12)	0.0255 (14)	0.0221 (14)	−0.0051 (10)	0.0099 (11)	−0.0070 (11)
O9	0.0250 (14)	0.0249 (13)	0.0111 (12)	−0.0016 (11)	0.0056 (11)	0.0022 (10)
O10	0.0344 (17)	0.0181 (13)	0.0255 (15)	−0.0093 (11)	0.0072 (13)	0.0038 (11)
O11	0.0160 (13)	0.0241 (14)	0.0260 (15)	0.0038 (11)	−0.0022 (11)	−0.0033 (11)
O12	0.0198 (14)	0.0282 (15)	0.0274 (15)	−0.0019 (11)	0.0111 (12)	−0.0096 (12)
O1W	0.032 (2)	0.0194 (18)	0.0175 (18)	0.000	0.0022 (17)	0.000
O2W	0.0362 (17)	0.0303 (16)	0.0227 (15)	0.0135 (13)	0.0152 (13)	0.0096 (12)
O3W	0.043 (2)	0.0302 (17)	0.0318 (18)	−0.0029 (14)	0.0111 (16)	−0.0043 (14)
O4W	0.0276 (18)	0.044 (2)	0.043 (2)	0.0000 (15)	0.0088 (15)	0.0038 (16)
O5W	0.036 (2)	0.050 (2)	0.0326 (19)	−0.0040 (15)	0.0127 (16)	0.0052 (15)

Geometric parameters (Å, º)

Hg1—S2	2.3831 (8)	K4—O4W^vii	2.969 (4)
Hg1—S1	2.3876 (9)	K4—O9	2.969 (3)
Hg1—O10^i	2.897 (3)	K4—O12^i	2.975 (3)
Hg1—O2^ii	2.939 (3)	K4—O8	2.977 (3)
Hg1—O3^ii	3.002 (3)	K4—O11^i	3.097 (3)
Hg1—O5^iii	3.032 (3)	S1—O1	1.469 (3)
Hg1—O11^i	3.128 (3)	S1—O2	1.471 (3)
Hg2—S3	2.3826 (8)	S1—O3	1.472 (3)
Hg2—S4	2.3829 (9)	S2—O4	1.462 (3)
Hg2—O12^i	2.827 (3)	S2—O5	1.474 (3)
Hg2—O7^iv	2.852 (3)	S2—O6	1.480 (3)
Hg2—O1^i	3.033 (3)	S3—O7	1.470 (3)
Hg2—O8	3.129 (3)	S3—O8	1.470 (3)
Hg2—O9	3.164 (3)	S3—O9	1.471 (3)
K1—O7	2.662 (3)	S4—O10	1.461 (3)
K1—O10^v	2.673 (3)	S4—O11	1.479 (3)
K1—O5^vi	2.704 (3)	S4—O12	1.481 (3)
K1—O4^iv	2.762 (3)	O1—O2W	2.845 (4)
K1—O3^i	2.779 (3)	O1—O5W^x	3.064 (5)
K1—O8^iv	2.788 (3)	O2—O5W^x	2.889 (5)
K1—O2W^iv	3.110 (3)	O4—O3W^vii	3.397 (5)
K1—O4W^vi	3.153 (4)	O5—O4W	2.901 (5)
K2—O11^iv	2.708 (3)	O5—O3W^vii	3.056 (4)
K2—O4	2.713 (3)	O6—O1W	2.863 (4)
K2—O2^iii	2.822 (3)	O10—O2W^i	3.012 (4)
K2—O3^v	2.864 (3)	O11—O5W	2.857 (5)
K2—O8	2.865 (3)	O12—O2W	2.790 (4)
K2—O1W^v	2.867 (3)	O1W—O6^vii	2.863 (4)
K2—O3W	3.057 (4)	O1W—O11^i	3.144 (3)
K2—O3W^vii	3.080 (4)	O1W—O11^xi	3.144 (3)
K3—O4W^vi	2.666 (3)	O1W—O5W^i	3.162 (4)
K3—O2W^iv	2.721 (3)	O2W—O10^i	3.012 (4)
K3—O5W^iv	2.780 (4)	O2W—O7^iv	3.165 (4)
K3—O9^viii	2.837 (3)	O3W—O5W^iv	2.945 (5)
K3—O1^ix	2.901 (3)	O3W—O5^vii	3.056 (4)
K3—O2W^ix	2.951 (3)	O4W—O5W^xi	2.849 (5)
K3—O7	3.013 (3)	O5W—O4W^xii	2.849 (5)
K3—O9	3.037 (3)	O5W—O2^xiii	2.889 (5)
K4—O3W	2.790 (3)	O5W—O3W^iv	2.945 (5)
K4—O6^vii	2.816 (3)	O5W—O1^xiii	3.064 (5)
K4—O6	2.901 (3)	O5W—O1W^i	3.162 (4)
K4—O4	2.939 (3)
O1···O2W	2.845 (4)	O11···O5W	2.857 (5)
O2···O5W^x	2.889 (5)	O12···O2W	2.790 (4)
O5···O4W	2.901 (5)	O3W···O5W^iv	2.945 (5)
O6···O1W	2.863 (4)	O4W···O5W^xi	2.849 (5)
S2—Hg1—S1	174.26 (3)	O3W—K4—O11^i	172.27 (10)
S2—Hg1—O10^i	88.42 (6)	O6^vii—K4—O11^i	100.41 (8)
S1—Hg1—O10^i	87.66 (6)	O6—K4—O11^i	71.86 (8)
S2—Hg1—O2^ii	89.32 (6)	O4—K4—O11^i	87.52 (8)
S1—Hg1—O2^ii	89.67 (6)	O4W^vii—K4—O11^i	92.68 (9)
O10^i—Hg1—O2^ii	126.80 (8)	O9—K4—O11^i	121.53 (8)
S2—Hg1—O3^ii	94.99 (5)	O12^i—K4—O11^i	46.72 (7)
S1—Hg1—O3^ii	88.53 (5)	O8—K4—O11^i	111.99 (8)
O10^i—Hg1—O3^ii	173.66 (7)	O3W—K4—O10^i	141.13 (9)
O2^ii—Hg1—O3^ii	48.08 (7)	O6^vii—K4—O10^i	140.64 (8)
S2—Hg1—O5^iii	83.53 (6)	O6—K4—O10^i	83.25 (8)
S1—Hg1—O5^iii	100.15 (6)	O4—K4—O10^i	63.13 (7)
O10^i—Hg1—O5^iii	82.99 (8)	O4W^vii—K4—O10^i	119.18 (9)
O2^ii—Hg1—O5^iii	149.25 (7)	O9—K4—O10^i	95.46 (8)
O3^ii—Hg1—O5^iii	102.69 (7)	O12^i—K4—O10^i	44.21 (8)
S2—Hg1—O11^i	88.56 (5)	O8—K4—O10^i	68.84 (7)
S1—Hg1—O11^i	85.70 (6)	O11^i—K4—O10^i	43.51 (7)
O10^i—Hg1—O11^i	46.92 (7)	S4^i—K4—O10^i	25.29 (5)
O2^ii—Hg1—O11^i	79.89 (7)	O3W—K4—S2	102.89 (8)
O3^ii—Hg1—O11^i	127.69 (7)	O1—S1—O2	111.14 (17)
O5^iii—Hg1—O11^i	129.52 (7)	O1—S1—O3	110.97 (17)
S3—Hg2—S4	176.99 (3)	O2—S1—O3	110.69 (16)
S3—Hg2—O12^i	91.37 (6)	O1—S1—Hg1	108.91 (12)
S4—Hg2—O12^i	86.23 (6)	O2—S1—Hg1	108.71 (11)
S3—Hg2—O7^iv	89.22 (6)	O3—S1—Hg1	106.26 (11)
S4—Hg2—O7^iv	90.43 (6)	O4—S2—O5	110.47 (16)
O12^i—Hg2—O7^iv	120.15 (8)	O4—S2—O6	110.29 (17)
S3—Hg2—O1^i	97.86 (6)	O5—S2—O6	109.74 (17)
S4—Hg2—O1^i	83.90 (6)	O4—S2—Hg1	108.34 (11)
O12^i—Hg2—O1^i	88.67 (8)	O5—S2—Hg1	112.06 (11)
O7^iv—Hg2—O1^i	150.26 (7)	O6—S2—Hg1	105.85 (11)
S3—Hg2—O8	26.83 (5)	O7—S3—O8	111.07 (17)
S4—Hg2—O8	150.65 (5)	O7—S3—O9	110.77 (16)
O12^i—Hg2—O8	82.98 (8)	O8—S3—O9	110.86 (16)
O7^iv—Hg2—O8	71.93 (7)	O7—S3—Hg2	109.74 (11)
O1^i—Hg2—O8	122.88 (7)	O8—S3—Hg2	106.18 (11)
S3—Hg2—O9	26.22 (5)	O9—S3—Hg2	108.07 (11)
S4—Hg2—O9	153.33 (5)	O10—S4—O11	109.97 (18)
O12^i—Hg2—O9	73.93 (8)	O10—S4—O12	110.18 (18)
O7^iv—Hg2—O9	114.79 (7)	O11—S4—O12	109.08 (18)
O1^i—Hg2—O9	78.11 (7)	O10—S4—Hg2	109.03 (13)
O8—Hg2—O9	45.26 (7)	O11—S4—Hg2	110.26 (12)
O7—K1—O10^v	93.99 (9)	O12—S4—Hg2	108.31 (12)
O7—K1—O5^vi	132.25 (9)	S1—O1—K3^xv	151.20 (16)
O10^v—K1—O5^vi	93.92 (9)	O2W—O1—K3^xv	61.80 (9)
O7—K1—O4^iv	147.80 (9)	S1—O1—Hg2^i	108.98 (15)
O10^v—K1—O4^iv	75.27 (9)	O2W—O1—Hg2^i	84.91 (9)
O5^vi—K1—O4^iv	79.39 (9)	K3^xv—O1—Hg2^i	92.40 (8)
O7—K1—O3^i	107.44 (9)	O2W—O1—Hg1	93.15 (10)
O10^v—K1—O3^i	150.38 (9)	K3^xv—O1—Hg1	151.04 (11)
O5^vi—K1—O3^i	86.70 (8)	Hg2^i—O1—Hg1	100.00 (8)
O4^iv—K1—O3^i	75.75 (8)	O5W^x—O1—Hg1	121.90 (11)
O7—K1—O8^iv	80.41 (8)	S1—O2—K2^iii	132.82 (15)
O10^v—K1—O8^iv	82.42 (9)	S1—O2—Hg1^ii	97.64 (14)
O5^vi—K1—O8^iv	147.33 (9)	K2^iii—O2—Hg1^ii	90.49 (8)
O4^iv—K1—O8^iv	68.25 (8)	O5W^x—O2—Hg1^ii	136.11 (11)
O3^i—K1—O8^iv	81.31 (8)	K2^iii—O2—Hg1	87.97 (7)
O7—K1—O2W^iv	65.96 (8)	O5W^x—O2—Hg1	128.16 (12)
O10^v—K1—O2W^iv	62.23 (9)	Hg1^ii—O2—Hg1	93.78 (8)
O5^vi—K1—O2W^iv	76.71 (8)	S1—O3—K1^i	135.41 (16)
O4^iv—K1—O2W^iv	128.89 (8)	S1—O3—K2^xvi	132.68 (15)
O3^i—K1—O2W^iv	145.41 (8)	K1^i—O3—K2^xvi	89.97 (8)
O8^iv—K1—O2W^iv	127.53 (8)	S1—O3—Hg1^ii	95.03 (13)
O7—K1—O4W^vi	79.00 (9)	K1^i—O3—Hg1^ii	96.88 (8)
O10^v—K1—O4W^vi	126.16 (10)	K2^xvi—O3—Hg1^ii	90.78 (8)
O5^vi—K1—O4W^vi	58.77 (9)	K1^i—O3—Hg1	168.90 (11)
O4^iv—K1—O4W^vi	131.90 (9)	K2^xvi—O3—Hg1	85.87 (7)
O3^i—K1—O4W^vi	79.00 (9)	Hg1^ii—O3—Hg1	93.48 (8)
O8^iv—K1—O4W^vi	145.61 (9)	S1—O3—Hg2^i	88.94 (13)
O2W^iv—K1—O4W^vi	66.43 (9)	K1^i—O3—Hg2^i	78.12 (7)
O11^iv—K2—O4	143.99 (9)	K2^xvi—O3—Hg2^i	88.77 (7)
O11^iv—K2—O2^iii	89.62 (9)	Hg1^ii—O3—Hg2^i	174.98 (9)
O4—K2—O2^iii	102.95 (8)	Hg1—O3—Hg2^i	91.48 (7)
O11^iv—K2—O3^v	76.20 (9)	S2—O4—K2	137.75 (16)
O4—K2—O3^v	75.13 (8)	S2—O4—K1^iv	126.24 (15)
O2^iii—K2—O3^v	74.16 (8)	K2—O4—K1^iv	93.55 (8)
O11^iv—K2—O8	85.53 (9)	S2—O4—K4	96.61 (14)
O4—K2—O8	67.80 (8)	K2—O4—K4	88.89 (8)
O2^iii—K2—O8	152.65 (9)	K1^iv—O4—K4	99.79 (9)
O3^v—K2—O8	78.54 (8)	K2—O4—Hg1	174.20 (11)
O11^iv—K2—O1W^v	68.60 (8)	K1^iv—O4—Hg1	81.91 (7)
O4—K2—O1W^v	147.41 (8)	K4—O4—Hg1	95.43 (8)
O2^iii—K2—O1W^v	69.43 (6)	S2—O4—Hg1^iii	87.82 (12)
O3^v—K2—O1W^v	128.55 (8)	K2—O4—Hg1^iii	81.71 (7)
O8—K2—O1W^v	132.19 (6)	K1^iv—O4—Hg1^iii	84.80 (8)
O11^iv—K2—O3W	104.66 (9)	K4—O4—Hg1^iii	169.80 (9)
O4—K2—O3W	89.88 (9)	Hg1—O4—Hg1^iii	94.23 (7)
O2^iii—K2—O3W	135.45 (9)	O3W^vii—O4—Hg1^iii	79.16 (8)
O3^v—K2—O3W	149.89 (9)	S2—O5—K1^xvii	134.80 (15)
O8—K2—O3W	71.59 (9)	S2—O5—Hg1^iii	111.46 (15)
O1W^v—K2—O3W	76.95 (8)	K1^xvii—O5—Hg1^iii	85.35 (8)
O11^iv—K2—O3W^vii	143.24 (9)	O4W—O5—Hg1^iii	143.15 (12)
O4—K2—O3W^vii	71.50 (9)	K1^xvii—O5—Hg1	93.04 (8)
O2^iii—K2—O3W^vii	66.83 (9)	O4W—O5—Hg1	102.38 (11)
O3^v—K2—O3W^vii	119.94 (9)	Hg1^iii—O5—Hg1	104.45 (9)
O8—K2—O3W^vii	128.20 (9)	O3W^vii—O5—Hg1	134.19 (11)
O1W^v—K2—O3W^vii	76.58 (8)	S2—O6—K4^vii	128.70 (15)
O3W—K2—O3W^vii	77.76 (11)	S2—O6—K4	97.76 (13)
O11^iv—K2—O5W^iv	52.39 (9)	K4^vii—O6—K4	106.12 (9)
O4—K2—O5W^iv	133.54 (9)	O1W—O6—K4	82.56 (8)
O2^iii—K2—O5W^iv	122.69 (8)	K4^vii—O6—Hg1	156.88 (11)
O3^v—K2—O5W^iv	122.60 (9)	O1W—O6—Hg1	97.60 (9)
O8—K2—O5W^iv	74.27 (8)	K4—O6—Hg1	96.95 (8)
O1W^v—K2—O5W^iv	58.02 (6)	S3—O7—K1	127.72 (15)
O3W—K2—O5W^iv	52.40 (9)	S3—O7—Hg2^iv	107.71 (13)
O3W^vii—K2—O5W^iv	116.68 (9)	K1—O7—Hg2^iv	91.98 (8)
O4W^vi—K3—O2W^iv	79.14 (10)	S3—O7—K3	101.19 (13)
O4W^vi—K3—O5W^iv	156.40 (12)	K1—O7—K3	94.60 (8)
O2W^iv—K3—O5W^iv	87.89 (10)	Hg2^iv—O7—K3	137.25 (9)
O4W^vi—K3—O9^viii	78.41 (10)	K1—O7—Hg2	85.61 (7)
O2W^iv—K3—O9^viii	71.58 (8)	Hg2^iv—O7—Hg2	98.64 (8)
O5W^iv—K3—O9^viii	116.19 (10)	K3—O7—Hg2	123.94 (9)
O4W^vi—K3—O1^ix	137.17 (10)	O2W^iv—O7—Hg2	147.07 (11)
O2W^iv—K3—O1^ix	132.61 (9)	S3—O8—K1^iv	129.45 (15)
O5W^iv—K3—O1^ix	65.22 (9)	S3—O8—K2	139.77 (15)
O9^viii—K3—O1^ix	85.78 (8)	K1^iv—O8—K2	89.76 (7)
O4W^vi—K3—O2W^ix	88.02 (10)	S3—O8—K4	95.78 (13)
O2W^iv—K3—O2W^ix	167.14 (6)	K1^iv—O8—K4	98.30 (8)
O5W^iv—K3—O2W^ix	104.40 (10)	K2—O8—K4	85.34 (8)
O9^viii—K3—O2W^ix	105.39 (8)	K1^iv—O8—Hg2	84.01 (7)
O1^ix—K3—O2W^ix	58.16 (8)	K2—O8—Hg2	173.04 (10)
O4W^vi—K3—O7	81.56 (10)	K4—O8—Hg2	92.47 (7)
O2W^iv—K3—O7	66.77 (8)	S3—O8—Hg2^iv	86.92 (12)
O5W^iv—K3—O7	75.20 (9)	K1^iv—O8—Hg2^iv	80.78 (7)
O9^viii—K3—O7	136.37 (8)	K2—O8—Hg2^iv	91.87 (7)
O1^ix—K3—O7	132.85 (8)	K4—O8—Hg2^iv	177.08 (9)
O2W^ix—K3—O7	112.25 (8)	Hg2—O8—Hg2^iv	90.19 (7)
O4W^vi—K3—O9	87.58 (10)	S3—O9—K3^xviii	134.40 (15)
O2W^iv—K3—O9	113.84 (8)	S3—O9—K4	96.11 (12)
O5W^iv—K3—O9	79.69 (9)	K3^xviii—O9—K4	99.13 (8)
O9^viii—K3—O9	163.87 (7)	S3—O9—K3	100.16 (13)
O1^ix—K3—O9	99.48 (8)	K3^xviii—O9—K3	94.08 (7)
O2W^ix—K3—O9	65.77 (7)	K4—O9—K3	141.35 (10)
O7—K3—O9	47.15 (7)	K3^xviii—O9—Hg2	90.91 (8)
O4W^vi—K3—O4W^xiv	140.65 (11)	K4—O9—Hg2	91.92 (7)
O2W^iv—K3—O4W^xiv	69.54 (9)	K3—O9—Hg2	124.18 (9)
O5W^iv—K3—O4W^xiv	46.68 (9)	O3W—O9—Hg2	137.75 (11)
O9^viii—K3—O4W^xiv	69.65 (8)	S4—O10—K1^xvi	162.26 (19)
O1^ix—K3—O4W^xiv	63.60 (8)	S4—O10—Hg1^i	103.46 (15)
O2W^ix—K3—O4W^xiv	121.76 (8)	K1^xvi—O10—Hg1^i	88.68 (8)
O7—K3—O4W^xiv	106.08 (8)	K1^xvi—O10—Hg2	144.83 (11)
O9—K3—O4W^xiv	126.35 (8)	Hg1^i—O10—Hg2	103.20 (9)
S3—K3—O4W^xiv	116.46 (6)	O2W^i—O10—Hg2	79.77 (9)
O4W^vi—K3—O3W	133.41 (9)	S4—O10—K4^i	75.09 (12)
O2W^iv—K3—O3W	124.70 (8)	K1^xvi—O10—K4^i	91.82 (8)
O5W^iv—K3—O3W	43.28 (9)	Hg1^i—O10—K4^i	92.05 (8)
O9^viii—K3—O3W	143.26 (8)	O2W^i—O10—K4^i	156.23 (12)
O1^ix—K3—O3W	58.67 (8)	Hg2—O10—K4^i	120.17 (9)
O2W^ix—K3—O3W	65.34 (8)	S4—O10—Hg2^i	86.04 (13)
O7—K3—O3W	75.17 (7)	K1^xvi—O10—Hg2^i	80.01 (8)
O9—K3—O3W	47.34 (7)	Hg1^i—O10—Hg2^i	166.43 (10)
S3—K3—O3W	57.79 (5)	O2W^i—O10—Hg2^i	86.53 (9)
O4W^xiv—K3—O3W	85.08 (7)	Hg2—O10—Hg2^i	90.37 (7)
K1—K3—O3W	113.95 (5)	K4^i—O10—Hg2^i	80.92 (7)
O3W—K4—O6^vii	73.00 (10)	S4—O11—K2^iv	142.02 (16)
O3W—K4—O6	101.46 (10)	S4—O11—K4^i	84.64 (12)
O6^vii—K4—O6	67.46 (9)	K2^iv—O11—K4^i	133.17 (10)
O3W—K4—O4	90.85 (9)	O5W—O11—K4^i	80.49 (11)
O6^vii—K4—O4	109.30 (8)	S4—O11—Hg1^i	93.29 (14)
O6—K4—O4	48.84 (7)	K2^iv—O11—Hg1^i	88.75 (8)
O3W—K4—O4W^vii	88.48 (11)	O5W—O11—Hg1^i	155.41 (13)
O6^vii—K4—O4W^vii	67.16 (9)	K4^i—O11—Hg1^i	93.06 (8)
O6—K4—O4W^vii	127.92 (9)	K2^iv—O11—Hg2	97.97 (8)
O4—K4—O4W^vii	176.43 (9)	O5W—O11—Hg2	105.27 (11)
O3W—K4—O9	66.06 (9)	K4^i—O11—Hg2	128.00 (9)
O6^vii—K4—O9	121.56 (8)	Hg1^i—O11—Hg2	97.42 (8)
O6—K4—O9	157.93 (8)	S4—O12—Hg2^i	111.30 (17)
O4—K4—O9	111.11 (7)	S4—O12—K4^i	89.20 (13)
O4W^vii—K4—O9	71.78 (9)	Hg2^i—O12—K4^i	98.93 (8)
O3W—K4—O12^i	140.73 (10)	Hg2^i—O12—Hg2	102.63 (10)
O6^vii—K4—O12^i	128.75 (9)	K4^i—O12—Hg2	134.29 (10)
O6—K4—O12^i	116.75 (8)	K2^xvi—O1W—K2^xix	93.06 (12)
O4—K4—O12^i	107.03 (8)	K3^iv—O2W—K3^xv	98.54 (9)
O4W^vii—K4—O12^i	75.57 (9)	K3^iv—O2W—K1^iv	91.28 (9)
O9—K4—O12^i	74.86 (8)	K3^xv—O2W—K1^iv	163.62 (11)
O3W—K4—O8	73.84 (9)	K4—O3W—K2	85.15 (10)
O6^vii—K4—O8	145.91 (8)	K4—O3W—K2^vii	129.63 (13)
O6—K4—O8	112.24 (7)	K2—O3W—K2^vii	85.38 (9)
O4—K4—O8	63.50 (7)	K3^xvii—O4W—K4^vii	103.22 (13)
O4W^vii—K4—O8	119.59 (9)	K3^xvii—O4W—K1^xvii	91.38 (10)
O9—K4—O8	48.07 (7)	K4^vii—O4W—K1^xvii	135.23 (13)
O12^i—K4—O8	83.21 (8)

Symmetry codes: (i) −x+1/2, −y+1/2, −z+1; (ii) −x, −y+1, −z+1; (iii) −x, −y, −z+1; (iv) −x+1/2, −y−1/2, −z+1; (v) x, y−1, z; (vi) x+1/2, y−1/2, z; (vii) −x, y, −z+1/2; (viii) −x+1/2, y−1/2, −z+1/2; (ix) x, −y, z−1/2; (x) −x+1/2, y+1/2, −z+3/2; (xi) x−1/2, −y+1/2, z−1/2; (xii) x+1/2, −y+1/2, z+1/2; (xiii) −x+1/2, y−1/2, −z+3/2; (xiv) −x, y−1, −z+1/2; (xv) x, −y, z+1/2; (xvi) x, y+1, z; (xvii) x−1/2, y+1/2, z; (xviii) −x+1/2, y+1/2, −z+1/2; (xix) −x, y+1, −z+1/2.