Crystal structure of Hg₂SO₄ – a redetermination

The crystal structure of mercury(I) sulfate (or mercurous sulfate), Hg₂SO₄, was re-determined based on modern CCD data. In comparison with the previous determination from Weissenberg film data [Dorm (1969). Acta Chem. Scand. 23, 1607–1615], all atoms were refined with anisotropic displacement parameters, leading to higher precision in terms of bond lengths and angles [e.g. Hg—Hg = 2.5031 (7) compared to 2.500 (3)Å]. The structure consists of alternating rows along [001] of Hg₂²⁺ dumbbells (generated by inversion symmetry) and SO₄²⁻ tetra­hedra (symmetry 2). The dumbbells are linked via short O—Hg—Hg—O bonds to the sulfate tetra­hedra into chains extending parallel to [20-1]. More remote O—Hg—Hg—O bonds connect these chains into a three-dimensional framework.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](S-O) = 0.007 Å
• R factor = 0.035
• wR factor = 0.087
• Data-to-parameter ratio = 20.6

checkCIF/PLATON results

No syntax errors found



Datablock: I


Alert level B
PLAT971_ALERT_2_B Check Calcd Residual Density  1.01A From      Hg       3.36 eA-3
PLAT972_ALERT_2_B Check Calcd Residual Density  1.25A From      Hg      -3.17 eA-3

Alert level C
PLAT971_ALERT_2_C Check Calcd Residual Density  1.18A From      Hg       2.01 eA-3
PLAT971_ALERT_2_C Check Calcd Residual Density  1.74A From      Hg       1.53 eA-3
PLAT971_ALERT_2_C Check Calcd Residual Density  0.85A From      Hg       1.51 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  0.92A From      Hg      -2.48 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  1.11A From      Hg      -2.05 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  1.16A From      Hg      -1.79 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  0.66A From      Hg      -1.77 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  1.48A From      O2      -1.76 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  1.06A From      Hg      -1.66 eA-3
PLAT972_ALERT_2_C Check Calcd Residual Density  0.72A From      Hg      -1.64 eA-3

Alert level G
PLAT004_ALERT_5_G Polymeric Structure Found with Dimension .......          2 Info
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT232_ALERT_2_G Hirshfeld Test Diff (M-X)  Hg     --  O2_a    ..        5.5 su
PLAT232_ALERT_2_G Hirshfeld Test Diff (M-X)  Hg     --  O1_c    ..        5.3 su
PLAT793_ALERT_4_G The Model has Chirality at S       .............          R Verify
PLAT794_ALERT_5_G Tentative Bond Valency for Hg      (II)    .....       2.09 Note
PLAT910_ALERT_3_G Missing # of FCF Reflections Below Th(Min) .....          1 Why ?

   0 ALERT level A = Most likely a serious problem - resolve or explain
   2 ALERT level B = A potentially serious problem, consider carefully
  10 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   7 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
  14 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   3 ALERT type 5 Informative message, check

---

Related literature

Structural data of the previous refinement of Hg₂SO₄ (Dorm, 1969) were deposited with the ICSD (2014), but contain an error in the z coordinate of the sulfur atom. Other phases in the system Hg/S/O were structurally characterized by Aurivillius & Stålhandske (1980) [HgSO₄], Weil (2001) [Hg₃(SO₄)O₂] and Logemann & Wickleder (2013) [Hg(S₂O₇)]. For a review on Hg—Hg bond lengths in mercurous compounds, see: Weil et al. (2005).

S1. Experimental

1 g HgO was suspended in 20 ml water. 4 ml sulfuric acid (96%_wt) and 2 drops CS₂ were added to the mixture, transferred into a 50 ml polypropylene beaker that was sealed and heated for 12 h at 393 K. Besides a polycrystalline dirty-white solid with an unknown diffraction pattern, few colourless and transparent single crystals of the title compound were present in the reaction mixture.

S2. Refinement

The coordinates of the previous refinement (Dorm, 1969) were used as starting parameters. The highest and lowest remaining electron density is 0.84 Å and 1.25 Å, respectively, from the Hg atom. It should be noted that in the current version (01/2014) of the Inorganic Structure Data Base (ICSD, 2014), the deposited structure data of the previous refinement by Dorm (1969) contain an error: The z parameter of the sulfur atom must be 1/4, not 3/4.

Computing details

Data collection: SMART (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS for Windows (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

Fig. 1. The crystal structure of Hg2SO4 in a projection along [010]. Displacement ellipsoids are drawn at the 74% probability level; short Hg—O bonds are displayed with closed black lines, longer Hg—O bonds with open lines.

Mercury(I) sulfate

Crystal data

Hg2O4S	F(000) = 416
Mr = 497.24	Dx = 7.109 Mg m^−3
Monoclinic, P2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yc	Cell parameters from 1233 reflections
a = 6.2771 (8) Å	θ = 3.3–30.4°
b = 4.4290 (6) Å	µ = 66.35 mm^−1
c = 8.3596 (10) Å	T = 295 K
β = 91.695 (4)°	Fragment, colourless
V = 232.31 (5) Å^3	0.18 × 0.08 × 0.04 mm
Z = 2

Data collection

Bruker SMART CCD diffractometer	701 independent reflections
Radiation source: fine-focus sealed tube	629 reflections with I > 2σ(I)'
Graphite monochromator	Rint = 0.060
ω–scans	θmax = 30.4°, θmin = 4.6°
Absorption correction: numerical (HABITUS; Herrendorf, 1997)	h = −8→8
Tmin = 0.012, Tmax = 0.119	k = −6→6
1737 measured reflections	l = −11→8

Refinement

Refinement on F^2	Primary atom site location: isomorphous structure methods
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.052P)^2 + 1.7115P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.035	(Δ/σ)max < 0.001
wR(F^2) = 0.087	Δρmax = 3.57 e Å^−3
S = 1.06	Δρmin = −3.18 e Å^−3
701 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
34 parameters	Extinction coefficient: 0.0118 (12)
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
Hg	0.19318 (5)	0.05289 (9)	−0.02034 (4)	0.0275 (2)
S	0.5000	0.5674 (5)	0.2500	0.0134 (5)
O1	0.6943 (11)	0.3901 (16)	0.2586 (8)	0.0224 (12)
O2	0.5038 (9)	0.7720 (13)	0.1058 (6)	0.0172 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Hg	0.0119 (2)	0.0392 (3)	0.0315 (3)	−0.00369 (11)	0.00211 (13)	0.00072 (13)
S	0.0125 (12)	0.0141 (11)	0.0136 (11)	0.000	0.0000 (8)	0.000
O1	0.018 (3)	0.027 (3)	0.022 (3)	0.009 (2)	−0.001 (2)	0.004 (2)
O2	0.015 (2)	0.020 (2)	0.016 (2)	0.001 (2)	0.0010 (18)	0.004 (2)

Geometric parameters (Å, º)

Hg—O2^i	2.193 (6)	S—Hg^iii	3.7082 (15)
Hg—O2^ii	2.518 (6)	S—Hg^ix	3.8936 (17)
Hg—O1^iii	2.725 (6)	S—Hg^iv	3.8936 (17)
Hg—O1^iv	2.898 (7)	O1—Hg^iii	2.725 (6)
Hg—Hg^v	2.5031 (7)	O1—Hg^iv	2.898 (7)
S—O1^iii	1.450 (7)	O1—Hg^i	3.261 (7)
S—O1	1.450 (7)	O1—Hg^vii	3.716 (7)
S—O2^iii	1.509 (6)	O1—Hg^x	4.090 (6)
S—O2	1.509 (6)	O2—Hg^i	2.193 (6)
S—Hg^vi	3.2315 (13)	O2—Hg^viii	2.518 (6)
S—Hg^i	3.2315 (13)	O2—Hg^vi	3.812 (5)
S—Hg^vii	3.6309 (15)	O2—Hg^vii	4.097 (6)
S—Hg^viii	3.6309 (15)
O2^i—Hg—Hg^v	164.47 (14)	S—O1—Hg^x	156.0 (3)
O2^i—Hg—O2^ii	69.1 (2)	Hg^iii—O1—Hg^x	36.63 (8)
Hg^v—Hg—O2^ii	126.30 (13)	Hg^iv—O1—Hg^x	77.69 (14)
O2^i—Hg—O1^iii	82.0 (2)	Hg^i—O1—Hg^x	117.52 (19)
Hg^v—Hg—O1^iii	102.86 (14)	Hg^vii—O1—Hg^x	89.04 (14)
O2^ii—Hg—O1^iii	75.8 (2)	S—O1—Hg	62.8 (3)
O2^i—Hg—O1^iv	77.5 (2)	Hg^iii—O1—Hg	115.4 (2)
Hg^v—Hg—O1^iv	102.91 (14)	Hg^iv—O1—Hg	64.22 (13)
O2^ii—Hg—O1^iv	75.64 (18)	Hg^i—O1—Hg	95.95 (15)
O1^iii—Hg—O1^iv	149.3 (3)	Hg^vii—O1—Hg	138.14 (18)
O1^iii—S—O1	114.5 (6)	Hg^x—O1—Hg	129.82 (18)
O1^iii—S—O2^iii	109.4 (3)	S—O2—Hg^i	120.5 (3)
O1—S—O2^iii	108.6 (4)	S—O2—Hg^viii	126.9 (3)
O1^iii—S—O2	108.6 (4)	Hg^i—O2—Hg^viii	110.9 (2)
O1—S—O2	109.4 (3)	S—O2—Hg^vi	56.41 (19)
O2^iii—S—O2	106.2 (5)	Hg^i—O2—Hg^vi	131.7 (2)
S—O1—Hg^iii	122.3 (4)	Hg^viii—O2—Hg^vi	80.47 (14)
S—O1—Hg^iv	123.6 (4)	S—O2—Hg	72.7 (2)
Hg^iii—O1—Hg^iv	96.8 (2)	Hg^i—O2—Hg	129.6 (2)
S—O1—Hg^i	76.0 (3)	Hg^viii—O2—Hg	85.11 (15)
Hg^iii—O1—Hg^i	148.1 (3)	Hg^vi—O2—Hg	97.20 (13)
Hg^iv—O1—Hg^i	91.77 (18)	S—O2—Hg^vii	61.6 (2)
S—O1—Hg^vii	75.3 (3)	Hg^i—O2—Hg^vii	77.46 (15)
Hg^iii—O1—Hg^vii	85.41 (17)	Hg^viii—O2—Hg^vii	122.59 (19)
Hg^iv—O1—Hg^vii	153.3 (2)	Hg^vi—O2—Hg^vii	58.72 (8)
Hg^i—O1—Hg^vii	73.82 (14)	Hg—O2—Hg^vii	134.35 (14)

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