inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Redetermination of Hg2I2

aUniversité Houari-Boumedienne, Faculté de Chimie, Laboratoire Sciences des Matériaux, Bp 32 El-Alia Bab-Ezzouar, Algeria, bCentre de Diffractométrie X, Sciences Chimiques de Rennes, UMR 6226 CNRS Université de Rennes 1, Campus de Beaulieu, Avenue du Général Leclerc, France, and cDepartomento Inorgánica, Facultad C.C. Químicas, Universidad Complutense, 28040 Madrid, Spain
*Correspondence e-mail: mkarsdz@yahoo.fr

(Received 21 November 2011; accepted 31 December 2011; online 7 January 2012)

The crystal structure of mercurous iodide, Hg2I2, has been determined previously from X-ray powder diffraction data [Havighurst (1926[Havighurst, R. J. (1926). J. Am. Chem. Soc. 48, 2113-2125.]). J. Am. Chem. Soc. 48, 2113–2125]. The results of the current redetermination based on single-crystal X-ray diffraction data provide more precise geometrical data and also anisotropic displacement parameters for the Hg and I atoms, which are both situated on positions with site-symmetry 4mm. The structure consists of linear dimers I—Hg—Hg—I extending along the c axis with an Hg—Hg distance of 2.5903 (13) Å. The overall coordination sphere of the Hg+ atom is a considerably distorted octa­hedron. The crystal specimen under investigation was twinned by non-merohedry with a refined twin domain fraction of 0.853 (14):0.147 (14).

Related literature

The structures of the mercurous halides Hg2X2 (X = Cl, Br, I) were originally determined from X-ray powder data by Havighurst (1926[Havighurst, R. J. (1926). J. Am. Chem. Soc. 48, 2113-2125.]). Studies based on single crystals for X = F, Cl, Br were reported by Dorm (1970[Dorm, E. (1970). J. Chem. Soc. D, pp. 466-467.]) and for X = F also by Grdenić & Djordjević (1956[Grdenić, D. & Djordjević, C. (1956). J. Chem. Soc. pp. 1316-1319.]) and Schrötter & Müller (1992[Schrötter, F. & Müller, B. G. (1992). Z. Anorg. Allg. Chem. 618, 53-58.]). For the physical properties of mercurous halides, see: Zadokhin & Solodovnik (2004[Zadokhin, B. S. & Solodovnik, E. V. (2004). Phys. Solid State, 46, 2110-2114.]); Markov et al. (2007[Markov, Yu. F., Knorr, K. & Roginski, E. M. (2007). Ferroelectrics, 359, 82-93.], 2010[Markov, Yu. F., Roginski, E. M. & Wallacher, D. (2010). Bull. Russ. Acad. Sci. Phys. 74, 1198-1202.]); Taylor et al. (2011[Taylor, R. E., Bai, S. & Dybowski, C. (2011). J. Mol. Struct. 987, 193-198.]). For theoretical studies of the structures of mercurous halides, see: Liao & Zhang (1995[Liao, M. S. & Zhang, Q. (1995). J. Mol. Struct. (THEOCHIM), 358, 195-203.]); Liao & Schwarz (1997[Liao, M. S. & Schwarz, W. H. E. (1997). J. Alloys Compd, 246, 124-130.]).

Experimental

Crystal data
  • Hg2I2

  • Mr = 654.98

  • Tetragonal, I 4/m m m

  • a = 4.8974 (9) Å

  • c = 11.649 (2) Å

  • V = 279.40 (9) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 65.76 mm−1

  • T = 150 K

  • 0.10 × 0.06 × 0.04 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (TWINABS; Bruker, 2006[Bruker (2006). APEX2, SAINT, CELL_NOW and TWINABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.024, Tmax = 0.072

  • 448 measured reflections

  • 253 independent reflections

  • 164 reflections with I > 3σ(I)

  • Rint = 0.056

Refinement
  • R[F2 > 3σ(F2)] = 0.039

  • wR(F2) = 0.044

  • S = 1.47

  • 253 reflections

  • 9 parameters

  • Δρmax = 4.99 e Å−3

  • Δρmin = −4.73 e Å−3

Table 1
Selected bond lengths (Å)

Hg1—I1 2.7266 (17)
Hg1—I1i 3.5000 (9)
Symmetry code: (i) [-x-{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2006[Bruker (2006). APEX2, SAINT, CELL_NOW and TWINABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2006[Bruker (2006). APEX2, SAINT, CELL_NOW and TWINABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT and CELL_NOW (Bruker, 2006[Bruker (2006). APEX2, SAINT, CELL_NOW and TWINABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); program(s) used to refine structure: JANA2006 (Petříček et al., 2006[Petříček, V., Dušék, M. & Palatinus, L. (2006). JANA2006. Institute of Physics, Praha, Czech Republic.]); molecular graphics: DIAMOND (Brandenburg & Putz, 2005[Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: JANA2006.

Supporting information


Comment top

Les cristaux d'halogénures de mercure(I) de formulation Hg2X2 (X = F, Cl, Br et I) sont connus pour leurs propriétés physiques anisotropes (acousto-optiques, biréfringences etc). Ces dernières années, ces composés ont fait l'objet de nombreux travaux, essentiellement pour leurs propriétés dynamiques (Zadokhin & Solodovnik, 2004), ferroélastiques (Markov et al. 2007, 2010) et résonnances magnétiques nucléaires (NMR) (Taylor et al., 2011). La présence de liaisons Hg—Hg, qui est l'une des caractéristiques de ce type de composé a suscité plusieurs études quant à la nature et aux propriétés de ces liaisons (Liao & Zhang, 1995; Liao & Schwarz, 1997). La structure de ces halogènures a été déterminée au préalable par diffraction des rayons X sur poudre (Havighurst, 1926), puis sur monocristal pour Hg2X2 (X: F, Cl et Br) par Dorm (1970) et pour Hg2F2 par Schrötter & Müller (1992). La structure de Hg2I2 est analogue à celle des autres halogènures, elle est caractérisée par des chaînes linéaires I—Hg—Hg—I le long de l'axe c (Fig. 1). A la différence des autres halogènures formés par les ions Hg2+2 et X-, l'iodure de mercure(I) Hg2I2 quant à lui est caractérisé par des dimères 'HgI' (Grdenić & Djordjević, 1956).

La présente redétermination par diffraction des rayons X sur monocristal, fournit plus de précisions sur les distances interatomiques, ainsi que sur les paramètres d'agitation thermiques (ADP's). Les liaisons Hg—Hg [2.5903 (13) Å] et Hg—I [2.7266 (17) Å] sont différentes de celles observées par Havighurst (1926) [respectivement 2.694 et 2.682 Å]. Quatres longues distances Hg—I de 3.5000 (9) Å sont aussi observées, donnant aux atomes de Hg un environnement octadérique distordu (Fig. 2). Les résultats obtenus sur monocristal montrent une tendance des différentes liaisons à varier selon l'électronégativité de l'halogène (Havighurst, 1926). En effet, la liaison Hg—halogéne augmente du fluor à l'iode d'environ 0.58 et 0.78 Å respectivement pour la courte et la longue distance: Hg—F [2.14 (2) et 2.715 (5) Å]; Hg—Cl [2.43 (4) et 3.209 (6) Å]; Hg—Br [2.71 (2) et 3.32 (1) Å] et Hg—I [2.7266 (17) et 3.5000 (9) Å]; quant à liaison Hg—Hg, elle augmente seulement de 0.08 Å: F [2.507 (1) Å]; Cl [2.526 (6) Å]; Br [2.49 (1) Å] et I [2.5903 (13) Å]. Ceci contredit en partie les conclusions de Liao & Zhang, (1995) and Liao & Schwarz (1997), selon lesquelles la liaison Hg—Hg est indépendante de l'électronégativité de l'halogéne. Toutefois une redétermination structurale de Hg2Br2 semble nécessaire pour confirmer cette tendance. Enfin, il faut remarquer que comme pour les autres halogénures de mercures(I), l'agitation thermique (ADP's) autour du mercure U11(Hg) est supérieure à U33(Hg), alors qu'autour de l'iode elle est comparable à celles des autres halogènes.

Related literature top

The structures of the mercurous halides Hg2X2 (X = Cl, Br, I) were originally determined from X-ray powder data by Havighurst (1926). Studies based on single crystals for X = F, Cl, Br were reported by Dorm (1970) and for X = F also by Grdenić & Djordjević (1956) and Schrötter & Müller (1992). For the physical properties of mercurous halides, see: Zadokhin & Solodovnik (2004); Markov et al. (2007, 2010); Taylor et al. (2011). For theoretical studies of the structures of mercurous halides, see: Liao & Zhang (1995); Liao & Schwarz (1997).

Experimental top

Les monocristaux de Hg2I2 ont été obtenus lors des essais de synthèse du clathrate I8Hg10Ge36, à partir d'un mélange d'éléments purs et en présence de HgO et WO3 comme agents précurseurs. Le mélange broyé puis scellé dans un tube en quartz, est porté à une température de 1073 K pendant environ 10 jours. Des cristaux de la phase α-Ge ont été aussi identifiés.

Refinement top

La structure a été déterminée par isotypie aux halogénures de mercure(I) dans le groupe d'espace I4/mmm. Le cristal étudié correspond à une macle non-mériédrique, contitué de deux individus mis en évidence par le programme CELL_NOW (Bruker, 2006) avec une matrice de macle de [0.137 0.983 0.053, 0.984 -0.149 0.038, 0.250 0.262 -0.988]. La structure a été affinée avec JANA2006 en utilisant un fichier de type HKL5 crée par le programme TWINABS (Bruker, 2006) et contenant la contribution de ces deux individus. En fin d'affinement, la fraction en volume des composants est de: 0.853 (14): 0.147 (14), et la carte de densité électronique est de: ρmax = 4.99 e Å-3 (localisée à 0.88 Å de I) et ρmin = -4.73 e Å-3 (localisée à 1.99 Å de Hg).

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006) and CELL_NOW (Bruker, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: JANA2006 (Petříček et al., 2006); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: JANA2006 (Petříček et al., 2006).

Figures top
[Figure 1] Fig. 1. Structure de Hg2I2 montrant les chaînes linéaire I—Hg—Hg—I le long de l'axe c, avec un déplacement des ellipsoīdes à 80% de probabilité.
[Figure 2] Fig. 2. Environnement octaédrique distordu des atomes de Hg, avec un déplacement des ellipsoīdes à 80% de probabilité.
mercury(I) iodide top
Crystal data top
Hg2I2Dx = 7.783 Mg m3
Mr = 654.98Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4/mmmCell parameters from 274 reflections
Hall symbol: -I 4 2θ = 4.5–32.9°
a = 4.8974 (9) ŵ = 65.76 mm1
c = 11.649 (2) ÅT = 150 K
V = 279.40 (9) Å3Prism, black
Z = 20.10 × 0.06 × 0.04 mm
F(000) = 532
Data collection top
Bruker APEXII CCD
diffractometer
253 independent reflections
Radiation source: X-ray tube164 reflections with I > 3σ(I)
Graphite monochromatorRint = 0.056
ω and ϕm scansθmax = 39.6°, θmin = 3.5°
Absorption correction: multi-scan
(TWINABS; Bruker, 2006)
h = 56
Tmin = 0.024, Tmax = 0.072k = 08
448 measured reflectionsl = 020
Refinement top
Refinement on F0 constraints
R[F2 > 2σ(F2)] = 0.039Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2)
wR(F2) = 0.044(Δ/σ)max = 0.0003
S = 1.47Δρmax = 4.99 e Å3
253 reflectionsΔρmin = 4.73 e Å3
9 parametersExtinction correction: B-C type 1 Gaussian isotropic (Becker & Coppens, 1974)
0 restraintsExtinction coefficient: 27 (7)
Crystal data top
Hg2I2Z = 2
Mr = 654.98Mo Kα radiation
Tetragonal, I4/mmmµ = 65.76 mm1
a = 4.8974 (9) ÅT = 150 K
c = 11.649 (2) Å0.10 × 0.06 × 0.04 mm
V = 279.40 (9) Å3
Data collection top
Bruker APEXII CCD
diffractometer
253 independent reflections
Absorption correction: multi-scan
(TWINABS; Bruker, 2006)
164 reflections with I > 3σ(I)
Tmin = 0.024, Tmax = 0.072Rint = 0.056
448 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0399 parameters
wR(F2) = 0.0440 restraints
S = 1.47Δρmax = 4.99 e Å3
253 reflectionsΔρmin = 4.73 e Å3
Special details top

Refinement. The refinement was carried out against all reflections. The conventional R-factor is always based on F. The goodness of fit as well as the weighted R-factor are based on F and F2 for refinement carried out on F and F2, respectively. The threshold expression is used only for calculating R-factors etc. and it is not relevant to the choice of reflections for refinement. The crystal studied was twinned by non-merohedry with a refined twin domain fraction of 0.853 (14): 0.147 (14). The program used for refinement, Jana2006, uses the weighting scheme based on the experimental expectations, see _refine_ls_weighting_details, that does not force S to be one. Therefore the values of S are usually larger than the ones from the SHELX program.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Hg1000.11118 (6)0.0263 (2)
I1000.34524 (10)0.0207 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg10.0356 (4)0.0356 (4)0.0078 (3)000
I10.0271 (6)0.0271 (6)0.0079 (5)000
Geometric parameters (Å, º) top
Hg1—Hg1i2.5903 (13)Hg1—I1iii3.5000 (9)
Hg1—I12.7266 (17)Hg1—I1iv3.5000 (9)
Hg1—I1ii3.5000 (9)Hg1—I1v3.5000 (9)
Hg1i—Hg1—I1180.0 (5)I1iv—Hg1—I1v88.795 (15)
Hg1i—Hg1—I1ii98.34 (2)Hg1—I1—Hg1ii98.34 (2)
Hg1i—Hg1—I1iii98.34 (2)Hg1—I1—Hg1iii98.34 (2)
Hg1i—Hg1—I1iv98.34 (2)Hg1—I1—Hg1iv98.34 (2)
Hg1i—Hg1—I1v98.34 (2)Hg1—I1—Hg1v98.34 (2)
I1—Hg1—I1ii81.66 (2)Hg1—I1—I1vi180.0 (5)
I1—Hg1—I1iii81.66 (2)Hg1ii—I1—Hg1iii88.795 (16)
I1—Hg1—I1iv81.66 (2)Hg1ii—I1—Hg1iv88.795 (16)
I1—Hg1—I1v81.66 (2)Hg1ii—I1—Hg1v163.32 (4)
I1ii—Hg1—I1iii88.795 (15)Hg1ii—I1—I1vi81.66 (2)
I1ii—Hg1—I1iv88.795 (15)Hg1iii—I1—Hg1iv163.32 (4)
I1ii—Hg1—I1v163.32 (4)Hg1iii—I1—Hg1v88.795 (16)
I1iii—Hg1—I1iv163.32 (4)Hg1iii—I1—I1vi81.66 (2)
I1iii—Hg1—I1v88.795 (15)Hg1iv—I1—Hg1v88.795 (16)
Symmetry codes: (i) x, y, z; (ii) x1/2, y1/2, z+1/2; (iii) x1/2, y+1/2, z+1/2; (iv) x+1/2, y1/2, z+1/2; (v) x+1/2, y+1/2, z+1/2; (vi) x, y, z+1.

Experimental details

Crystal data
Chemical formulaHg2I2
Mr654.98
Crystal system, space groupTetragonal, I4/mmm
Temperature (K)150
a, c (Å)4.8974 (9), 11.649 (2)
V3)279.40 (9)
Z2
Radiation typeMo Kα
µ (mm1)65.76
Crystal size (mm)0.10 × 0.06 × 0.04
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(TWINABS; Bruker, 2006)
Tmin, Tmax0.024, 0.072
No. of measured, independent and
observed [I > 3σ(I)] reflections
448, 253, 164
Rint0.056
(sin θ/λ)max1)0.897
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.039, 0.044, 1.47
No. of reflections253
No. of parameters9
Δρmax, Δρmin (e Å3)4.99, 4.73

Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006) and CELL_NOW (Bruker, 2006), SIR97 (Altomare et al., 1999), JANA2006 (Petříček et al., 2006), DIAMOND (Brandenburg & Putz, 2005).

Selected bond lengths (Å) top
Hg1—I12.7266 (17)Hg1—I1i3.5000 (9)
Symmetry code: (i) x1/2, y1/2, z+1/2.
 

References

First citationAltomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationBrandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2006). APEX2, SAINT, CELL_NOW and TWINABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationDorm, E. (1970). J. Chem. Soc. D, pp. 466–467.  Google Scholar
First citationGrdenić, D. & Djordjević, C. (1956). J. Chem. Soc. pp. 1316–1319.  Google Scholar
First citationHavighurst, R. J. (1926). J. Am. Chem. Soc. 48, 2113–2125.  CrossRef CAS Google Scholar
First citationLiao, M. S. & Schwarz, W. H. E. (1997). J. Alloys Compd, 246, 124–130.  CrossRef CAS Web of Science Google Scholar
First citationLiao, M. S. & Zhang, Q. (1995). J. Mol. Struct. (THEOCHIM), 358, 195–203.  CrossRef CAS Google Scholar
First citationMarkov, Yu. F., Knorr, K. & Roginski, E. M. (2007). Ferroelectrics, 359, 82–93.  Web of Science CrossRef CAS Google Scholar
First citationMarkov, Yu. F., Roginski, E. M. & Wallacher, D. (2010). Bull. Russ. Acad. Sci. Phys. 74, 1198–1202.  CrossRef Google Scholar
First citationPetříček, V., Dušék, M. & Palatinus, L. (2006). JANA2006. Institute of Physics, Praha, Czech Republic.  Google Scholar
First citationSchrötter, F. & Müller, B. G. (1992). Z. Anorg. Allg. Chem. 618, 53–58.  Google Scholar
First citationTaylor, R. E., Bai, S. & Dybowski, C. (2011). J. Mol. Struct. 987, 193–198.  Web of Science CrossRef CAS Google Scholar
First citationZadokhin, B. S. & Solodovnik, E. V. (2004). Phys. Solid State, 46, 2110–2114.  Web of Science CrossRef CAS Google Scholar

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ISSN: 2056-9890
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