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Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

Crystal structure and characterization of magnesium carbonate chloride hepta­hydrate

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aInstitute of Inorganic Chemistry, TU Bergakademie Freiberg, Leipziger Strasse 29, D-09599 Freiberg, Germany, and bInstitute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
*Correspondence e-mail: christine.rincke@chemie.tu-freiberg.de

Edited by H. Uekusa, Tokyo Institute of Technology, Japan (Received 24 March 2020; accepted 19 June 2020; online 8 July 2020)

MgCO3·MgCl2·7H2O is the only known neutral magnesium carbonate con­taining chloride ions at ambient conditions. According to the literature, only small and twinned crystals of this double salt could be synthesised in a concentrated solution of MgCl2. For the crystal structure solution, single-crystal diffraction was carried out at a synchrotron radiation source. The monoclinic crystal structure (space group Cc) exhibits double chains of MgO octa­hedra linked by corners, connected by carbonate units and water mol­ecules. The chloride ions are positioned between these double chains parallel to the (100) plane. Dry MgCO3·MgCl2·7H2O decom­poses in the air to chlorartinite, Mg2(OH)Cl(CO3nH2O (n = 2 or 3). This work includes an extensive char­acterization of the title com­pound by powder X-ray diffraction, thermal analysis, SEM and vibrational spectroscopy.

1. Introduction

In the context of CO2 research, the inter­actions of CO2 with salts and brine solutions are of great inter­est. Therefore, the system MgCl2–MgCO3–H2O–CO2 has been investigated. The only nonbasic salt containing carbonate and chloride ions is MgCO3·MgCl2·7H2O (Rincke, 2018[Rincke, C. (2018). Dissertation. TU Bergakademie Freiberg, Ger­many.]).

The formation conditions of MgCO3·MgCl2·7H2O were described for the first time by Gloss (1937[Gloss, G. (1937). Dissertation. Friedrich-Wilhelms-University of Berlin, Germany.]) and Walter-Levy (1937[Walter-Levy, L. (1937). Compt. Rend. 205, 1405-1407.]). It can be synthesized at room temperature by adding MgCO3·3H2O to a highly concentrated solution of magnesium chloride saturated with CO2 (Gloss, 1937[Gloss, G. (1937). Dissertation. Friedrich-Wilhelms-University of Berlin, Germany.]; Schmidt, 1960[Schmidt, E. (1960). Bergakademie, 12, 693-697.]).

Within the scope of outbursts of CO2 in potash mines, MgCO3·MgCl2·7H2O was discussed as a storage com­pound for CO2 in the 1960s (Schmidt, 1960[Schmidt, E. (1960). Bergakademie, 12, 693-697.]; Serowy, 1963[Serowy, F. (1963). Freiberger Forschungshefte A, 267, 405-419.]; Serowy & Liebmann, 1964[Serowy, F. & Liebmann, G. (1964). Wissenschaftl. Zeitschrift der Technischen Hochschule für Chemie `Carl Schorlemmer' Leuna-Merseburg, 6, 338-342.]; Schmittler, 1964[Schmittler, H. (1964). Deut. Akad. Wiss. 6, 644-648.]; D'Ans, 1967[D'Ans, J. (1967). Kali und Steinsalz, 4, 396-401.]). This salt forms needle-like crystals, which are only stable in concentrated MgCl2 solution (Moshkina & Yaroslavtseva, 1970[Moshkina, I. A. & Yaroslavtseva, L. M. (1970). Zh. Neorg. Khim. 15, 3345-3350.]). It decom­poses immediately when it is washed with water. When it was stored in air, basic carbonate was formed (Gloss, 1937[Gloss, G. (1937). Dissertation. Friedrich-Wilhelms-University of Berlin, Germany.]).

Schmittler (1964[Schmittler, H. (1964). Deut. Akad. Wiss. 6, 644-648.]) concluded from a powder X-ray diffraction (PXRD) pattern of MgCO3·MgCl2·7H2O that its crystal structure exhibits a C-centred monoclinic lattice with parameters a = 13.27 (0), b = 11.30 (8), c = 9.22 (7) Å and β = 118.2 (6)°. Due to the low scattering power and the small size of the crystals, a crystal structure analysis of single crystals was not possible until now. Our own investigations should provide a better com­prehension of the synthesis of MgCO3·MgCl2·7H2O and provide a more detailed characterization, including a crystal structure analysis.

2. Experimental

2.1. Synthesis and crystallization

The synthesis of MgCO3·MgCl2·7H2O is based on the information of Schmidt (1960[Schmidt, E. (1960). Bergakademie, 12, 693-697.]). MgO (1 g, Magnesia M2329, p.a.) was added to 200 g of an aqueous solution of MgCl2 (5.5 molal, Fluka, ≥98%). The suspension was stirred for 30 min. Afterwards, the undissolved MgO was filtered off. CO2 was bubbled through the stirred solution for 24 h at room tem­per­ature. The product was filtered off for further characterization.

2.2. Single-crystal diffraction

Data were collected on beamline SCD at the KIT Synchrotron Radiation Source using a Stoe IPDS diffrac­tom­eter with monochromated radiation of λ = 0.8000 Å. A crystal of MgCO3·MgCl2·7H2O was recovered from a droplet of its mother liquor and mounted rapidly in the cold (150 K) stream of nitro­gen gas of the diffractometer.

2.3. Powder X-ray diffraction (PXRD)

PXRD patterns were taken for phase identification with a laboratory Bruker D8 Discover powder diffractometer in Bragg–Brentano set up (Cu Kα1 radiation, Vantec 1 detector). The samples were prepared as flat plates and measured at room temperature.

2.4. Thermal analysis

The thermal analysis was performed with a TG/DTA 220 instrument from Seiko Instruments (reference substance: Al2O3, open platinum crucible; argon flow: 300 ml min−1; heating rate: 5 K min−1, prior period 30 min at 298.15 K in an argon flow).

2.5. Scanning electron microscopy (SEM)

The SEM images were recorded with a TESCAN Vega 5130 SB instrument (20 kV accelerating voltage). The sample was coated with gold.

2.6. Vibrational spectroscopy

For the FT–IR spectrum, a Thermo Scientific Nicolet 380 FTIR spectrometer (spectral resolution: 6 cm−1, 256 scans per measurement) with KBr blanks was used.

The Raman spectrum was recorded shortly after synthesis with a Bruker RFS100/S FT spectrometer at room temperature (Nd/YAG-laser, wavelength of the laser: 1064 nm).

2.7. Refinement

Crystal data, data collection and structure refinement details are given in Table 1[link]. Due to the small crystals and their low scattering power, the crystal structure solution was carried out by single-crystal diffraction at a synchrotron radiation source. The quality of the crystals affected the measured data set with the effect that only reflections to sin θmax/λ = 0.56 Å−1 could be considered for the structure refinement. The crystal structure was solved by direct methods. The resulting structure solution exhibits a chemically reasonable atomic arrangement, distances, angles and displacement parameters.

Table 1
Experimental details

Crystal data
Chemical formula MgCO3·MgCl2·7H2O
Mr 305.64
Crystal system, space group Monoclinic, Cc
Temperature (K) 150
a, b, c (Å) 13.368 (5), 11.262 (5), 9.266 (4)
β (°) 118.83 (3)
V3) 1222.0 (9)
Z 4
Radiation type Synchrotron, λ = 0.8000 Å
μ (mm−1) 0.93
Crystal size (mm) 0.13 × 0.07 × 0.01 × 0.02 (radius)
 
Data collection
Diffractometer Stoe IPDS II
Absorption correction For a sphere (Coppens, 1970[Coppens, P. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 255-270. Copenhagen: Munksgaard.])
No. of measured, independent and observed [I > 2σ(I)] reflections 8746, 6975, 5476
Rint 0.0613
θmax (°) 26.7
(sin θ/λ)max−1) 0.561
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.161, 1.12
No. of reflections 4791
No. of parameters 179
No. of restraints 22
H-atom treatment Only H-atom coordinates refined
Δρmax, Δρmin (e Å−3) 0.36, −0.43
Absolute structure Flack x determined using 647 quotients [(I+) − (I)]/[(I+) + (I)] (Parsons et al., 2013[Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249-259.])
Absolute structure parameter 0.43 (13)
Computer programs: X-AREA (Stoe & Cie, 2015[Stoe & Cie (2015). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany.]), X-RED (Stoe & Cie, 2015[Stoe & Cie (2015). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany.]), SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2016 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), DIAMOND (Brandenburg, 2017[Brandenburg, K. (2017). DIAMOND. Crystal Impact GbR, Bonn, Germany.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

H atoms were placed in the positions indexed by difference Fourier maps and their Uiso values were set at 1.2Ueq(O) using a riding-model approximation.

The crystal exhibits nonmerohedral twinning. The matrix that relates the individual diffraction pattern was determined as (1 0 1.38, 0 −1 0, 0 0 −1). The reflections of both domains were integrated (number of reflections in domain 1: 2829; domain 2: 3505; overlaid: 641; major twin com­ponent fraction: 56.45%).

3. Results and discussion

3.1. Characterization of magnesium carbonate chloride hepta­hydrate

The characterization of the unwashed product with PXRD is in accordance with the reference pattern PDF 21-1254 for MgCO3·MgCl2·7H2O (Schmittler, 1964[Schmittler, H. (1964). Deut. Akad. Wiss. 6, 644-648.]). The filtered product was stored in a sealed vessel. After 19 months, the powder pattern remained constant, i.e. the product did not alter. If the product was washed with ethanol and stored in the air, decom­position to chlorartinite [Mg2(OH)Cl(CO3)·3H2O] begins within a few days (Fig. 1[link]). This observation confirms the information of Gloss (1937[Gloss, G. (1937). Dissertation. Friedrich-Wilhelms-University of Berlin, Germany.]).

[Figure 1]
Figure 1
Powder XRD patterns of MgCO3·MgCl2·7H2O under ambient conditions (Cu Kα1 radiation) for (a) the unwashed product immediately after the synthesis, (b) the unwashed product stored in the air after 19 months, (c) the product washed with ethanol after storage in the air for 10 d and (d) the product washed with ethanol after storage in the air for 19 months. Reference data: MgCO3·MgCl2·7H2O (PDF 21-1254) and Mg2(OH)Cl(CO3)·3H2O (PDF 07-0278).

The thermal decom­position of MgCO3·MgCl2·7H2O starts as early as the heating begins and shows two main steps (Fig. 2[link]). H2O, CO­2 and HCl are evaporated off. This is in accordance with the observation of Serowy & Liebmann (1964[Serowy, F. (1963). Freiberger Forschungshefte A, 267, 405-419.]). A precise assignment of the stepwise mass loss is not possible. The characterization of the residue with PXRD at 573 K exhibits the presence of a mixture of basic magnesium carbonates, i.e. hydro­magnesite [Mg5(CO3)4(OH)2·4H2O] and amorphous phases. At 803 K the decom­position is com­plete and only MgO remains in the residue. The observed mass loss of 74.3 (1)% confirms the theoretical mass loss of 73.6%.

[Figure 2]
Figure 2
Thermal analysis of MgCO3·MgCl2·7H2O.

The SEM images of MgCO3·MgCl2·7H2O show thin needles (50 × 5 µm), which are twinned or even more inter­grown (Fig. 3[link]). Numerous crystallization experiments with the aim of obtaining larger crystals were not successful.

[Figure 3]
Figure 3
SEM images of MgCO3·MgCl2·7H2O, with the crystals exhibiting twinning or even further inter­growth.

The FT–IR (Fig. 4[link]) and Raman spectra (Fig. 5[link]) of MgCO3·MgCl2·7H2O confirm the absence of hydroxide ions in the crystal structure, because there are no bands above 3500 cm−1 as in chlorartinite, Mg2(OH)Cl(CO3)·3H2O (Ver­ga­sova et al., 1998[Vergasova, L. P., Filation, S. K., Serafimova, E. K. & Sergeeva, S. V. (1998). Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva, 127, 55-59.]). The assignment of the bands was con­cluded from a com­parison with the vibrational spectra of other neutral magnesium carbonates and chlorartinite (Coleyshaw et al., 2003[Coleyshaw, E. E., Crump, G. & Griffith, W. P. (2003). Spectrochim. Acta A Mol. Biomol. Spectrosc. 59, 2231-2239.]; Vergasova et al., 1998[Vergasova, L. P., Filation, S. K., Serafimova, E. K. & Sergeeva, S. V. (1998). Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva, 127, 55-59.]) (Table 2[link]).

Table 2
Assignment of the IR and Raman bands of MgCO3·MgCl2·7H2O

IR Raman Assignment (Coleyshaw et al., 2003[Coleyshaw, E. E., Crump, G. & Griffith, W. P. (2003). Spectrochim. Acta A Mol. Biomol. Spectrosc. 59, 2231-2239.])
3407, 3240 3386, 3250 ν(OH)W
1635 1660 δ(OH)W
1550, 1449, 1401 1544 νas(CO)
1114 1111 νs(CO)
845 794 γ(CO)
620 599 δas(CO)
457 403, 227, 181, 154, 124 lattice vibrations
Notes: ν = valence vibration, δ = deformation vibration (in the plane), γ = deformation vibration out of the plane, W = water, s = symmetric and as = asymmetric.
[Figure 4]
Figure 4
IR spectrum of MgCO3·MgCl2·7H2O under ambient conditions.
[Figure 5]
Figure 5
Raman spectrum of MgCO3·MgCl2·7H2O under ambient conditions.

3.2. Crystal structure of magnesium carbonate chloride hepta­hydrate

The monoclinic crystal structure of MgCO3·MgCl2·7H2O with the space group Cc and the lattice parameters published by Schmittler (1964[Schmittler, H. (1964). Deut. Akad. Wiss. 6, 644-648.]) were confirmed. There are two distinguishable magnesium ions. Mg1 is coordinated by three water mol­ecules and two carbonate anions. One carbonate acts as a monodentate ligand via atom O9 and the other as a bidentate ligand via atoms O2 and O6. The octa­hedra of Mg2 are formed by four water mol­ecules and two carbonate units which are connected to the magnesium ion in a monodentate manner via atoms O2 and O6 (Fig. 6[link]). The corner-linked Mg–O octa­hedra are arranged in a zigzag manner and together with the car­bon­ate units form double chains parallel to the (100) plane (Fig. 7[link]).

[Figure 6]
Figure 6
The asymmetric unit and coordination units of MgCO3·MgCl2·7H2O [symmetry codes: (i) x, −y, z − [{1\over 2}]; (ii) x, y, z − 1; (iii) x, −y, z + [{1\over 2}]; (iv) x, y, z + 1].
[Figure 7]
Figure 7
The characteristic structural motif in MgCO3·MgCl2·7H2O, showing the double chain of MgO octa­hedra linked by corners and carbonate units parallel to the (100) plane.

All the carbonate units are crystallographically equivalent and exhibit a Cs geometry, because they are planar, but the C—O bonds have different lengths. Each carbonate unit is coordinated by three magnesium ions: monodentate to Mg1, bidentate to Mg1i and monodentate to Mg2ii (see Fig. 6[link] for symmetry codes). In addition, the carbonate units stabilize the double chains (Fig. 7[link]).

Between the double chains, which are arranged in a zigzag-like stacking order parallel to the (001) plane, are located the chloride ions Cl1 and Cl2 (Fig. 8[link]). The positions of atoms H1A and H3B are fixed by short hydrogen bonds to atoms O9iv and O4vi, and the other H atoms by inter­actions with the chloride ions (Table 3[link] and Fig. 9[link]). As a consequence, a three-dimensional network is formed.

Table 3
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1A⋯O9iv 0.82 (3) 1.94 (6) 2.688 (14) 153 (13)
O1—H1B⋯Cl2iv 0.82 (3) 2.38 (4) 3.186 (11) 167 (12)
O3—H3A⋯Cl2v 0.82 (3) 2.32 (3) 3.135 (11) 174 (17)
O3—H3B⋯O4vi 0.82 (3) 2.10 (11) 2.796 (13) 143 (17)
O4—H4A⋯Cl1vii 0.82 (3) 2.36 (3) 3.176 (10) 171 (14)
O4—H4B⋯Cl1viii 0.82 (3) 2.49 (7) 3.251 (10) 155 (13)
O5—H5A⋯Cl2viii 0.82 (3) 2.45 (7) 3.222 (11) 157 (16)
O5—H5B⋯Cl1ix 0.81 (3) 2.54 (6) 3.327 (11) 164 (17)
O7—H7A⋯Cl2viii 0.82 (3) 2.42 (6) 3.212 (11) 163 (16)
O7—H7B⋯Cl1x 0.82 (3) 2.30 (4) 3.111 (11) 169 (16)
O8—H8A⋯Cl2vi 0.82 (3) 2.46 (5) 3.254 (10) 163 (11)
O8—H8B⋯Cl2v 0.82 (3) 2.41 (3) 3.233 (10) 178 (11)
O10—H10A⋯Cl1vii 0.82 (3) 2.34 (5) 3.146 (10) 166 (15)
O10—H10B⋯Cl1xi 0.82 (3) 2.67 (7) 3.424 (10) 154 (12)
Symmetry codes: (iv) x, y, z + 1; (v) x + [{1\over 2}], y − [{1\over 2}], z + 1; (vi) x + [{1\over 2}], −y + [{1\over 2}], z + [{1\over 2}]; (vii) x, y − 1, z; (viii) x, −y + 1, z + [{1\over 2}]; (ix) x + [{1\over 2}], −y + [{3\over 2}], z + [{1\over 2}]; (x) x + [{1\over 2}], y − [{1\over 2}], z; (xi) x, −y + 1, z − [{1\over 2}].
[Figure 8]
Figure 8
Excerpt of the crystal structure of MgCO3·MgCl2·7H2O, showing the zigzag-like stacking order of the double chains and the chloride ions between them.
[Figure 9]
Figure 9
Excerpt of the crystal structure of MgCO3·MgCl2·7H2O, showing the hydrogen-bond inter­actions of the H atoms with chloride ions (dashed lines) [symmetry codes: (iv) x, y, z + 1; (v) x + [{1\over 2}], y − [{1\over 2}], z + 1; (vi) x + [{1\over 2}], −y + [{1\over 2}], z + [{1\over 2}]; (vii) x, y − 1, z; (viii) x, −y + 1, z + [{1\over 2}]; (ix) x + [{1\over 2}], −y + [{3\over 2}], z + [{1\over 2}]; (x) x + [{1\over 2}], y − [{1\over 2}], z; (xi) x, −y + 1, z − [{1\over 2}]].

The structural motifs of such double chains are similar in MgCO3·MgCl2·7H2O and MgCO3·3H2O (Giester et al., 2000[Giester, G., Lengauer, C. L. & Rieck, B. (2000). Mineral. Petrol. 70, 153-163.]), but in contrast to MgCO3·3H2O in MgCO3·MgCl2·7H2O, only two of three carbonate units and three and four water mol­ecules instead of two water mol­ecules are linked to each Mg atom. Furthermore, no free water mol­ecules are positioned between these double chains in MgCO3·MgCl2·7H2O. The crystal structures of other neutral magnesium carbonates, e.g. MgCO3·5H2O, MgCO3·6H2O and the chloride-containing magnesium carbonates Mg2(OH)Cl(CO3)·2H2O (chlorartinite) and Mg2(OH)Cl(CO3)·H2O (dehydrated clorarti­nite), do not exhibit such double chains (Liu et al., 1990[Liu, B., Zhou, X., Cui, X. & Tang, J. (1990). Sci. China Ser. B, 33, 1350-1356.]; Rincke et al., 2020[Rincke, C., Schmidt, H. & Voigt, W. (2020). Acta Cryst. C76, 244-249.]; Sugimoto et al., 2006[Sugimoto, K., Dinnebier, R. E. & Schlecht, T. (2006). J. Appl. Cryst. 39, 739-744.], 2007[Sugimoto, K., Dinnebier, R. E. & Schlecht, T. (2007). Powder Diff. 22(1), 739-744.]). Therefore, the crystal structure of MgCO3·MgCl2·7H2O is unique.

Supporting information


Computing details top

Data collection: X-AREA (Stoe & Cie, 2015); cell refinement: X-AREA (Stoe & Cie, 2015); data reduction: X-RED (Stoe & Cie, 2015); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2017); software used to prepare material for publication: publCIF (Westrip, 2010).

Magnesium carbonate chloride heptahydrate top
Crystal data top
MgCO3·MgCl2·7H2OF(000) = 632
Mr = 305.64Dx = 1.661 Mg m3
Monoclinic, CcSynchrotron radiation, λ = 0.8000 Å
a = 13.368 (5) ÅCell parameters from 4192 reflections
b = 11.262 (5) Åθ = 2.7–29.5°
c = 9.266 (4) ŵ = 0.93 mm1
β = 118.83 (3)°T = 150 K
V = 1222.0 (9) Å3Needle, colourless
Z = 40.13 × 0.07 × 0.01 × 0.02 (radius) mm
Data collection top
Stoe IPDS II
diffractometer
5476 reflections with I > 2σ(I)
Radiation source: synchrotronRint = 0.061
rotation method scansθmax = 26.7°, θmin = 3.3°
Absorption correction: for a sphere
(Coppens, 1970)
h = 1414
k = 1212
8746 measured reflectionsl = 1010
6975 independent reflections
Refinement top
Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullOnly H-atom coordinates refined
R[F2 > 2σ(F2)] = 0.053 w = 1/[σ2(Fo2) + (0.094P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.161(Δ/σ)max < 0.001
S = 1.12Δρmax = 0.36 e Å3
4791 reflectionsΔρmin = 0.43 e Å3
179 parametersAbsolute structure: Flack x determined using 647 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
22 restraintsAbsolute structure parameter: 0.43 (13)
Primary atom site location: structure-invariant direct methods
Special details top

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

Refinement. Refined as a 2-component twin

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Mg10.4801 (4)0.1376 (3)0.5771 (6)0.0178 (9)
Mg20.4708 (3)0.1837 (4)0.9931 (5)0.0182 (10)
Cl10.1825 (3)0.9715 (3)0.5763 (4)0.0262 (9)
Cl20.2944 (3)0.5078 (3)0.0497 (4)0.0249 (8)
C10.4795 (10)0.0190 (12)0.2714 (13)0.017 (3)
O10.4661 (9)0.2884 (9)1.1718 (12)0.028 (2)
H1B0.419 (11)0.341 (10)1.152 (18)0.034*
H1A0.468 (13)0.250 (11)1.247 (14)0.034*
O20.4771 (7)0.0395 (8)1.1333 (10)0.0196 (19)
O30.6440 (9)0.1968 (9)1.1050 (12)0.028 (2)
H3B0.680 (13)0.211 (16)1.203 (6)0.034*
H3A0.688 (12)0.153 (13)1.09 (2)0.034*
O40.2896 (8)0.1586 (9)0.8686 (11)0.025 (2)
H4B0.264 (12)0.148 (13)0.932 (14)0.029*
H4A0.255 (12)0.112 (11)0.792 (12)0.029*
O50.4634 (9)0.3447 (9)0.8750 (12)0.029 (2)
H5A0.433 (12)0.371 (12)0.781 (7)0.034*
H5B0.509 (12)0.395 (10)0.933 (13)0.034*
O60.4774 (8)0.0931 (8)0.8055 (12)0.0184 (19)
O70.4802 (9)0.3153 (9)0.5418 (13)0.028 (2)
H7A0.427 (8)0.361 (9)0.52 (2)0.034*
H7B0.536 (7)0.358 (10)0.57 (2)0.034*
O80.6599 (8)0.1449 (9)0.7010 (12)0.025 (2)
H8B0.694 (12)0.111 (12)0.790 (8)0.029*
H8A0.686 (11)0.116 (12)0.645 (12)0.029*
O90.4820 (8)0.1034 (8)0.3651 (11)0.022 (2)
O100.3036 (8)0.1571 (9)0.4583 (11)0.024 (2)
H10B0.278 (11)0.150 (13)0.359 (5)0.029*
H10A0.262 (10)0.117 (12)0.481 (14)0.029*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mg10.023 (2)0.017 (2)0.0156 (18)0.0018 (19)0.0114 (15)0.004 (2)
Mg20.022 (2)0.019 (2)0.0152 (18)0.0026 (17)0.0102 (16)0.0000 (17)
Cl10.0248 (16)0.0273 (19)0.0302 (17)0.0052 (14)0.0162 (14)0.0031 (15)
Cl20.0242 (15)0.0255 (16)0.0257 (15)0.0023 (14)0.0126 (12)0.0018 (14)
C10.021 (6)0.023 (8)0.010 (7)0.001 (5)0.008 (6)0.009 (6)
O10.048 (6)0.021 (5)0.024 (5)0.008 (4)0.023 (5)0.009 (4)
O20.027 (5)0.017 (5)0.017 (4)0.005 (4)0.013 (4)0.003 (4)
O30.030 (6)0.032 (6)0.023 (5)0.005 (4)0.013 (5)0.001 (4)
O40.028 (5)0.030 (5)0.017 (5)0.002 (4)0.012 (4)0.001 (4)
O50.040 (6)0.023 (5)0.020 (5)0.006 (4)0.013 (4)0.001 (4)
O60.025 (5)0.016 (5)0.017 (4)0.000 (4)0.012 (4)0.002 (4)
O70.030 (5)0.022 (5)0.038 (7)0.006 (4)0.021 (5)0.004 (4)
O80.024 (5)0.029 (5)0.020 (5)0.003 (4)0.010 (4)0.003 (4)
O90.034 (6)0.018 (5)0.020 (5)0.002 (4)0.018 (4)0.005 (4)
O100.025 (5)0.029 (6)0.019 (5)0.001 (4)0.012 (4)0.002 (4)
Geometric parameters (Å, º) top
Mg1—O92.014 (10)Mg2—O22.055 (10)
Mg1—O72.028 (11)Mg2—O12.058 (11)
Mg1—O2i2.066 (9)Mg2—O52.095 (11)
Mg1—O102.079 (11)Mg2—O42.140 (11)
Mg1—O82.107 (11)C1—O91.277 (15)
Mg1—O62.192 (10)C1—O2ii1.285 (15)
Mg2—O32.036 (11)C1—O6i1.305 (17)
Mg2—O62.054 (11)
O9—Mg1—O791.7 (4)O3—Mg2—O191.0 (5)
O9—Mg1—O2i94.2 (4)O6—Mg2—O1174.8 (5)
O7—Mg1—O2i174.1 (5)O2—Mg2—O187.3 (4)
O9—Mg1—O1092.8 (4)O3—Mg2—O587.6 (4)
O7—Mg1—O1084.2 (4)O6—Mg2—O589.9 (4)
O2i—Mg1—O1094.6 (4)O2—Mg2—O5172.2 (4)
O9—Mg1—O889.5 (4)O1—Mg2—O585.0 (4)
O7—Mg1—O887.7 (4)O3—Mg2—O4176.1 (5)
O2i—Mg1—O893.2 (4)O6—Mg2—O488.7 (4)
O10—Mg1—O8171.6 (4)O2—Mg2—O485.8 (4)
O9—Mg1—O6155.8 (4)O1—Mg2—O492.5 (5)
O7—Mg1—O6112.5 (4)O5—Mg2—O494.4 (4)
O2i—Mg1—O661.6 (4)O3—Mg2—Mg1iii92.8 (3)
O10—Mg1—O689.6 (4)O6—Mg2—Mg1iii71.4 (3)
O8—Mg1—O691.6 (4)O2—Mg2—Mg1iii26.5 (3)
O9—Mg1—C1iii124.7 (4)O1—Mg2—Mg1iii113.8 (3)
O7—Mg1—C1iii143.6 (5)O5—Mg2—Mg1iii161.2 (3)
O2i—Mg1—C1iii30.5 (4)O4—Mg2—Mg1iii84.2 (3)
O10—Mg1—C1iii93.4 (4)O9—C1—O2ii121.5 (12)
O8—Mg1—C1iii92.0 (4)O9—C1—O6i123.5 (10)
O6—Mg1—C1iii31.1 (4)O2ii—C1—O6i115.0 (10)
O9—Mg1—Mg2i67.8 (3)O9—C1—Mg1i175.9 (10)
O7—Mg1—Mg2i159.4 (3)O2ii—C1—Mg1i54.7 (6)
O2i—Mg1—Mg2i26.4 (2)O6i—C1—Mg1i60.3 (6)
O10—Mg1—Mg2i94.5 (3)C1iv—O2—Mg2138.1 (8)
O8—Mg1—Mg2i93.9 (3)C1iv—O2—Mg1iii94.7 (8)
O6—Mg1—Mg2i88.0 (3)Mg2—O2—Mg1iii127.1 (4)
C1iii—Mg1—Mg2i56.9 (3)C1iii—O6—Mg2134.5 (8)
O3—Mg2—O687.9 (4)C1iii—O6—Mg188.5 (7)
O3—Mg2—O292.6 (4)Mg2—O6—Mg1137.0 (5)
O6—Mg2—O297.9 (4)C1—O9—Mg1142.8 (8)
Symmetry codes: (i) x, y, z1/2; (ii) x, y, z1; (iii) x, y, z+1/2; (iv) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···O9iv0.82 (3)1.94 (6)2.688 (14)153 (13)
O1—H1B···Cl2iv0.82 (3)2.38 (4)3.186 (11)167 (12)
O3—H3A···Cl2v0.82 (3)2.32 (3)3.135 (11)174 (17)
O3—H3B···O4vi0.82 (3)2.10 (11)2.796 (13)143 (17)
O4—H4A···Cl1vii0.82 (3)2.36 (3)3.176 (10)171 (14)
O4—H4B···Cl1viii0.82 (3)2.49 (7)3.251 (10)155 (13)
O5—H5A···Cl2viii0.82 (3)2.45 (7)3.222 (11)157 (16)
O5—H5B···Cl1ix0.81 (3)2.54 (6)3.327 (11)164 (17)
O7—H7A···Cl2viii0.82 (3)2.42 (6)3.212 (11)163 (16)
O7—H7B···Cl1x0.82 (3)2.30 (4)3.111 (11)169 (16)
O8—H8A···Cl2vi0.82 (3)2.46 (5)3.254 (10)163 (11)
O8—H8B···Cl2v0.82 (3)2.41 (3)3.233 (10)178 (11)
O10—H10A···Cl1vii0.82 (3)2.34 (5)3.146 (10)166 (15)
O10—H10B···Cl1xi0.82 (3)2.67 (7)3.424 (10)154 (12)
Symmetry codes: (iv) x, y, z+1; (v) x+1/2, y1/2, z+1; (vi) x+1/2, y+1/2, z+1/2; (vii) x, y1, z; (viii) x, y+1, z+1/2; (ix) x+1/2, y+3/2, z+1/2; (x) x+1/2, y1/2, z; (xi) x, y+1, z1/2.
Assignment of the IR- and Raman-bands of MgCO3·MgCl2·7H2O top
IRRamanAssignment (Coleyshaw et al., 2003)
3407, 32403386, 3250ν(OH)W
16351660δ(OH)W
1550, 1449, 14011544νas(CO)
11141111νs(CO)
845794γ(CO)
620599δas(CO)
457403, 227, 181, 154, 124lattice vibrations
Notes: ν valence vibration, δ deformation vibration (in the plane), γ deformation vibration out of the plane, W = water, s = symmetric and as = asymmetric.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···O9iv0.82 (3)1.94 (6)2.688 (14)153 (13)
O1—H1B···Cl2iv0.82 (3)2.38 (4)3.186 (11)167 (12)
O3—H3A···Cl2v0.82 (3)2.32 (3)3.135 (11)174 (17)
O3—H3B···O4vi0.82 (3)2.10 (11)2.796 (13)143 (17)
O4—H4A···Cl1vii0.82 (3)2.36 (3)3.176 (10)171 (14)
O4—H4B···Cl1viii0.82 (3)2.49 (7)3.251 (10)155 (13)
O5—H5A···Cl2viii0.82 (3)2.45 (7)3.222 (11)157 (16)
O5—H5B···Cl1ix0.81 (3)2.54 (6)3.327 (11)164 (17)
O7—H7A···Cl2viii0.82 (3)2.42 (6)3.212 (11)163 (16)
O7—H7B···Cl1x0.82 (3)2.30 (4)3.111 (11)169 (16)
O8—H8A···Cl2vi0.82 (3)2.46 (5)3.254 (10)163 (11)
O8—H8B···Cl2v0.82 (3)2.41 (3)3.233 (10)178 (11)
O10—H10A···Cl1vii0.82 (3)2.34 (5)3.146 (10)166 (15)
O10—H10B···Cl1xi0.82 (3)2.67 (7)3.424 (10)154 (12)
Symmetry codes: (iv) x, y, z+1; (v) x+1/2, y-1/2, z+1; (vii) x+1/2, -y+1/2, z+1/2; (vii) x, y-1, z; (viii) x, -y+1, z+1/2; (ix) x+1/2, -y+3/2, z+1/2; (x) x+1/2, y-1/2, z; (xi) x, -y+1, z-1/2.
 

Acknowledgements

The award of synchrotron beamtime at KIT Synchrotron Radiation Source, Karlsruhe, Germany, is gratefully acknowledged.

References

First citationBrandenburg, K. (2017). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationColeyshaw, E. E., Crump, G. & Griffith, W. P. (2003). Spectrochim. Acta A Mol. Biomol. Spectrosc. 59, 2231–2239.  Web of Science CrossRef PubMed Google Scholar
First citationCoppens, P. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 255–270. Copenhagen: Munksgaard.  Google Scholar
First citationD'Ans, J. (1967). Kali und Steinsalz, 4, 396–401.  CAS Google Scholar
First citationGiester, G., Lengauer, C. L. & Rieck, B. (2000). Mineral. Petrol. 70, 153–163.  Web of Science CrossRef ICSD CAS Google Scholar
First citationGloss, G. (1937). Dissertation. Friedrich-Wilhelms-University of Berlin, Germany.  Google Scholar
First citationLiu, B., Zhou, X., Cui, X. & Tang, J. (1990). Sci. China Ser. B, 33, 1350–1356.  CAS Google Scholar
First citationMoshkina, I. A. & Yaroslavtseva, L. M. (1970). Zh. Neorg. Khim. 15, 3345–3350.  CAS Google Scholar
First citationParsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249–259.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationRincke, C. (2018). Dissertation. TU Bergakademie Freiberg, Ger­many.  Google Scholar
First citationRincke, C., Schmidt, H. & Voigt, W. (2020). Acta Cryst. C76, 244–249.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSchmidt, E. (1960). Bergakademie, 12, 693–697.  CAS Google Scholar
First citationSchmittler, H. (1964). Deut. Akad. Wiss. 6, 644–648.  CAS Google Scholar
First citationSerowy, F. (1963). Freiberger Forschungshefte A, 267, 405–419.  Google Scholar
First citationSerowy, F. & Liebmann, G. (1964). Wissenschaftl. Zeitschrift der Technischen Hochschule für Chemie `Carl Schorlemmer' Leuna-Merseburg, 6, 338–342.  CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationStoe & Cie (2015). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany.  Google Scholar
First citationSugimoto, K., Dinnebier, R. E. & Schlecht, T. (2006). J. Appl. Cryst. 39, 739–744.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationSugimoto, K., Dinnebier, R. E. & Schlecht, T. (2007). Powder Diff. 22(1), 739–744.  Google Scholar
First citationVergasova, L. P., Filation, S. K., Serafimova, E. K. & Sergeeva, S. V. (1998). Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva, 127, 55–59.  CAS Google Scholar
First citationWalter-Levy, L. (1937). Compt. Rend. 205, 1405–1407.  CAS Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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