The crystal structure of TlMgCl3 from 290 K to 725 K

Onken, D.R.; Perrodin, D.; Vogel, S.C.; Bourret, E.D.; Moretti, F.

doi:10.1107/S2056989020013201

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Volume 76| Part 11| November 2020| Pages 1716-1719

https://doi.org/10.1107/S2056989020013201

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The crystal structure of TlMgCl₃ from 290 K to 725 K

Drew R. Onken,^a ^* Didier Perrodin,^a Sven C. Vogel,^b Edith D. Bourret ^a and Federico Moretti ^a

^aLawrence Berkeley National Laboratory, Berkeley, CA 94720, USA, and ^bLos Alamos National Laboratory, Los Alamos, NM 87545, USA
^*Correspondence e-mail: DOnken@lbl.gov

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 15 September 2020; accepted 29 September 2020; online 6 October 2020)

The title compound, thallium magnesium trichloride, has been identified as a scintillator with both moderate gamma-stopping power and moderate light yield. Knowledge of its crystal structure is needed for further development. This work determines the crystal structure of TlMgCl₃ to be hexagonal P6₃/mmc (No. 194) and isostructural with RbMgCl₃, contrary to previously reported data. This structure was obtained by single-crystal X-ray diffraction and was further confirmed by neutron diffraction measurements. Extending neutron diffraction measurements to high temperature, the data show that TlMgCl₃ maintains this crystal structure from 290 K up through 725 K, approaching the melting point of 770 K. Anisotropic thermal expansion coefficients increase over this temperature range, from 31 to 38 × 10⁻⁶ K⁻¹ along the a axis and from 19 to 34 × 10⁻⁶ K⁻¹ along the c axis.

Keywords: TlMgCl₃; scintillator; crystal structure; high-temperature neutron diffraction.

CCDC reference: 2034695

1. Chemical context

In the ongoing search for inorganic scintillators with high gamma-stopping power, TlMgCl₃ has been identified. As a result of the presence of thallium, TlMgCl₃ has a high effective atomic number, Z_eff = 67 [calculation methodology (Derenzo & Choong, 2009 ) in the supporting information], and a moderate density, ρ = 4.47 g cm⁻³ (determined in this work). A pair of initial crystal growths of TlMgCl₃ have been conducted to assess the scintillation properties: Fujimoto et al. (2016 ) measured 46,000 ph MeV⁻¹ light yield with 5% energy resolution at 662 keV, and Hawrami et al. (2017 ) measured 30,600 ph MeV⁻¹ light yield with 3.7% energy resolution at 662 keV.

To develop this compound further, a precise determination of the crystal structure is necessary. This will enable first-principles calculations of the electronic configuration and may be useful in assessing challenges that arise during synthesis (e.g. from thermal stresses). This work reports the crystal structure of TlMgCl₃ between 290 K and 725 K, approaching the melting point of 770 K. Previous work on TlMgCl₃ by Beznosikov (1978 ) used powder diffraction to report the space group at room temperature as orthorhombic (a = 6.54, b = 9.22, c = 6.99 Å). However, despite using the same synthesis procedure, the structure reported by Beznosikov does not fit the diffraction data reported herein. Arai et al. (2020 ) published diffraction data but did not provide information on the crystal structure.

2. Structural commentary

Single crystal X-ray diffraction (SC-XRD) determined TlMgCl₃ to have a hexagonal structure (space group P6₃/mmc, No. 194) with lattice parameters a = 7.0228 (4), c = 17.4934 (15) Å at 290 K. Fig. 1 visualizes the unit cell, which shows a three-dimensional corner- and face-sharing framework of six-coordinated Mg atoms encapsulating the 12-coordinated Tl atoms. There are six formula units in the unit cell. There are two thallium, two magnesium and two chlorine atoms in the asymmetric unit of TlMgCl₃, with site symmetries of $[\overline{6}]$ m2 and 3m; 3m and $[\overline{3}]$ m; mm2 and m, respectively; key bond distances and angles are listed in Table 1. Pairs of Mg2-centered octahedra share faces (via 3 × Cl1) and these octahedral pairs share corners (via Cl2) with the Mg1 octahedra to generate an ABACBC hexagonal stacking sequence of the chloride ions in the c-axis direction with the thallium cations occupying the vacant 12-coordinate sites. The coordination polyhedra of the chloride ions are distorted ClMg₂Tl₄ octahedra with the Mg²⁺ ions in a cis disposition for Cl1 and a trans disposition for Cl2. The title compound is isostructural with RbMgCl₃ as reported by Devaney et al. (1981 ) and RbMnCl₃ as reported by Goodyear et al. (1977 ), who describe the structure in more detail. This structure is more complex than that of CsMgCl₃ (McPherson et al., 1970 ), which also has space group P6₃/mmc but only requires two formula units per unit cell and has an AB hexagonal stacking sequence of the chloride ions in the c-axis direction.

Table 1
Selected geometric parameters (Å, °)

Tl1—Cl1	3.5126 (2)	Tl2—Cl2^iv	3.622 (5)
Tl1—Cl2ⁱ	3.576 (5)	Mg1—Cl2	2.448 (6)
Tl2—Cl1ⁱⁱ	3.510 (3)	Mg1—Cl1	2.499 (6)
Tl2—Cl2ⁱⁱⁱ	3.5146 (3)	Mg2—Cl2	2.476 (4)

Mg1^v—Cl1—Mg1	78.5 (3)	Mg1—Cl2—Mg2	178.8 (3)
Symmetry codes: (i) -y+1, x-y, z; (ii) -y, x-y, z; (iii) $[x-1, y, -z+{\script{1\over 2}}]$ ; (iv) $[x-y, x, z-{\script{1\over 2}}]$ ; (v) $[x, y, -z+{\script{1\over 2}}]$ .

Figure 1
The unit cell of TlMgCl₃, with the MgCl₆ octahedra shown in polyhedral representation.

Neutron diffraction (ND) conducted on powder samples produced diffraction patterns that were in agreement with the crystal structure determined by SC-XRD. Neutron diffraction was conducted at temperatures ranging from 300 K to 725 K. TlMgCl₃ maintains the same P6₃/mmc crystal structure over this measured temperature range (see supporting information for more details on the powder ND data and fits). Fig. 2 shows the lattice parameters as a function of temperature. From these data, the thermal expansion along each axis is calculated (Fig. 3). The thermal expansion is greater along the a axis than the c axis. Besides the anisotropy in the lattice parameters, the atomic positions did not vary significantly with temperature, and therefore the bond lengths change with temperature as dictated by the lattice parameters alone.

Figure 2
The hexagonal lattice parameters of TlMgCl₃ as a function of temperature, from neutron diffraction data. Vertical error bars from Rietveld fitting are within the size of the symbols and are omitted. The dashed lines are second-order polynomial fits to the data.

Figure 3
Thermal expansion coefficients as a function of temperature, calculated from the second-order polynomial fit of the lattice parameters in Fig. 2

3. Synthesis and crystallization

Crystals of TlMgCl₃ were grown from the melt using the vertical Bridgman method. High purity beads of TlCl and MgCl₂ were combined in a stoichiometric ratio and sealed in a quartz ampoule under vacuum (10⁻⁶ Torr). The crystal was grown with a translation speed of 0.5 mm h⁻¹ and was cooled over 72 h. To protect the moisture-sensitive reactants and products, all preparations before and after synthesis were conducted inside an argon-filled glove box.

4. Refinement

SC-XRD was conducted on a Bruker Kappa APEXII CCD diffractometer. The crystal was protected from moisture by oil during mounting and by an Oxford dry nitrogen gas cryostream system during data collection at 290 K. Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	TlMgCl₃
M_r	335.03
Crystal system, space group	Hexagonal, P6₃/mmc
Temperature (K)	290
a, c (Å)	7.0228 (4), 17.4934 (15)
V (Å³)	747.18 (11)
Z	6
Radiation type	Mo Kα
μ (mm⁻¹)	33.97
Crystal size (mm)	0.10 × 0.10 × 0.10

Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2004 )
T_min, T_max	0.578, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	4109, 489, 387
R_int	0.047
(sin θ/λ)_max (Å⁻¹)	0.718

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.047, 0.113, 1.42
No. of reflections	489
No. of parameters	21
Δρ_max, Δρ_min (e Å⁻³)	1.88, −2.11
Computer programs: APEX2 and SAINT (Bruker, 2004), SHELXT2014/4 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ) and VESTA (Momma & Izumi, 2011 ).

Powder high-temperature ND measurements were obtained using the high-pressure preferred orientation (HIPPO) neutron diffractometer at the short-pulsed spallation neutron source of the Lujan Neutron Scattering Center at Los Alamos National Laboratory (Wenk et al., 2003 ; Vogel et al., 2004 ). Powder samples were sealed under argon in vanadium tubes to protect from moisture during data collection. Time-of-flight data were collected with HIPPO detector panels of ³He detector tubes arranged on five rings with nominal diffraction angles of 2θ = 39, 60, 90, 120, and 144°. Count times were 90 minutes per dwell time. ND data were analyzed for all five rings simultaneously using the Rietveld method implemented in the GSAS code (Larson & Von Dreele, 2004 ) and automated by scripts through gsaslanguage (Vogel, 2011 ). To yield reliable absolute lattice parameters, the DIFC instrument calibration parameters were fitted for the room-temperature data using the lattice parameters from SC-XRD and were kept constant for the rest of the ND data at higher temperatures. For more details on the data collection and refinement of these neutron diffraction data, see Onken et al. (2018 ).

The thermal expansion tensor was generated using a quadratic fit to the lattice parameters (R² = 0.999), using the Thermal Expansion Visualization (TEV) program (Langreiter & Kahlenberg, 2015 ).

Supporting information

CCDC reference: 2034695

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2056989020013201/hb7945sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020013201/hb7945Isup2.hkl

Supporting information includes additional details, plots, and tables describing the high-temperature neutron diffraction data and refinements. DOI: https://doi.org/10.1107/S2056989020013201/hb7945sup3.odt

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXT2014/4 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: VESTA (Momma & Izumi, 2011); software used to prepare material for publication: SHELXL2018/3 (Sheldrick, 2015b).

Thallium magnesium trichloride top

Crystal data top

TlMgCl₃	D_x = 4.467 Mg m⁻³
M_r = 335.03	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6₃/mmc	Cell parameters from 1053 reflections
a = 7.0228 (4) Å	θ = 3.6–28.2°
c = 17.4934 (15) Å	µ = 33.97 mm⁻¹
V = 747.18 (11) Å³	T = 290 K
Z = 6	Block, colorless
F(000) = 864	0.10 × 0.10 × 0.10 mm

Data collection top

Bruker Kappa APEXII CCD diffractometer	387 reflections with I > 2σ(I)
ω scans	R_int = 0.047
Absorption correction: multi-scan (SADABS; Bruker, 2004)	θ_max = 30.7°, θ_min = 2.3°
T_min = 0.578, T_max = 0.746	h = −8→9
4109 measured reflections	k = −8→8
489 independent reflections	l = −23→25

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Primary atom site location: dual
R[F² > 2σ(F²)] = 0.047	w = 1/[σ²(F_o²) + 23.1798P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.113	(Δ/σ)_max < 0.001
S = 1.42	Δρ_max = 1.88 e Å⁻³
489 reflections	Δρ_min = −2.11 e Å⁻³
21 parameters

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Tl1	0.000000	0.000000	0.250000	0.0375 (5)
Tl2	0.333333	0.666667	0.09002 (7)	0.0395 (4)
Mg1	0.666667	0.333333	0.3404 (4)	0.0115 (14)
Mg2	1.000000	1.000000	0.500000	0.017 (2)
Cl1	0.5075 (4)	0.0150 (8)	0.250000	0.0211 (9)
Cl2	0.8336 (4)	0.6671 (9)	0.4185 (2)	0.0379 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Tl1	0.0378 (7)	0.0378 (7)	0.0369 (8)	0.0189 (3)	0.000	0.000
Tl2	0.0353 (5)	0.0353 (5)	0.0479 (7)	0.0176 (2)	0.000	0.000
Mg1	0.011 (2)	0.011 (2)	0.013 (3)	0.0053 (11)	0.000	0.000
Mg2	0.019 (4)	0.019 (4)	0.014 (5)	0.0094 (19)	0.000	0.000
Cl1	0.0224 (18)	0.011 (2)	0.0261 (19)	0.0055 (10)	0.000	0.000
Cl2	0.0418 (18)	0.027 (2)	0.0399 (18)	0.0135 (10)	−0.0123 (9)	−0.0246 (18)

Geometric parameters (Å, º) top

Tl1—Cl1ⁱ	3.5126 (2)	Tl2—Cl2^x	3.5146 (3)
Tl1—Cl1ⁱⁱ	3.5126 (2)	Tl2—Cl2^xvi	3.5146 (3)
Tl1—Cl1ⁱⁱⁱ	3.5126 (2)	Tl2—Cl2^xvii	3.622 (5)
Tl1—Cl1	3.5126 (2)	Tl2—Cl2^xviii	3.622 (5)
Tl1—Cl1^iv	3.5126 (2)	Tl2—Cl2^xix	3.622 (5)
Tl1—Cl1^v	3.5126 (2)	Mg1—Cl2	2.448 (6)
Tl1—Cl2^vi	3.576 (5)	Mg1—Cl2ⁱⁱ	2.448 (6)
Tl1—Cl2^vii	3.576 (5)	Mg1—Cl2^vii	2.448 (6)
Tl1—Cl2^viii	3.576 (5)	Mg1—Cl1^vii	2.499 (6)
Tl1—Cl2^ix	3.576 (5)	Mg1—Cl1	2.499 (6)
Tl1—Cl2^x	3.576 (5)	Mg1—Cl1ⁱⁱ	2.499 (6)
Tl1—Cl2^xi	3.576 (5)	Mg1—Mg1^xvi	3.162 (13)
Tl2—Cl1ⁱⁱ	3.510 (3)	Mg2—Cl2^xx	2.476 (4)
Tl2—Cl1^xii	3.510 (3)	Mg2—Cl2^xxi	2.476 (4)
Tl2—Cl1^iv	3.510 (3)	Mg2—Cl2^xxii	2.476 (4)
Tl2—Cl2^xiii	3.5146 (3)	Mg2—Cl2^xxiii	2.476 (4)
Tl2—Cl2^xiv	3.5146 (3)	Mg2—Cl2^xxiv	2.476 (4)
Tl2—Cl2^viii	3.5146 (3)	Mg2—Cl2	2.476 (4)
Tl2—Cl2^xv	3.5146 (3)

Cl1ⁱ—Tl1—Cl1ⁱⁱ	120.0	Cl1^iv—Tl2—Cl2^xvi	123.81 (8)
Cl1ⁱ—Tl1—Cl1ⁱⁱⁱ	57.02 (16)	Cl2^xiii—Tl2—Cl2^xvi	175.12 (14)
Cl1ⁱⁱ—Tl1—Cl1ⁱⁱⁱ	177.02 (16)	Cl2^xiv—Tl2—Cl2^xvi	119.820 (11)
Cl1ⁱ—Tl1—Cl1	62.98 (16)	Cl2^viii—Tl2—Cl2^xvi	119.820 (10)
Cl1ⁱⁱ—Tl1—Cl1	57.02 (16)	Cl2^xv—Tl2—Cl2^xvi	59.85 (17)
Cl1ⁱⁱⁱ—Tl1—Cl1	120.0	Cl2^x—Tl2—Cl2^xvi	60.03 (17)
Cl1ⁱ—Tl1—Cl1^iv	177.02 (16)	Cl1ⁱⁱ—Tl2—Cl2^xvii	176.96 (10)
Cl1ⁱⁱ—Tl1—Cl1^iv	62.98 (16)	Cl1^xii—Tl2—Cl2^xvii	119.42 (7)
Cl1ⁱⁱⁱ—Tl1—Cl1^iv	120.0	Cl1^iv—Tl2—Cl2^xvii	119.42 (7)
Cl1—Tl1—Cl1^iv	120.000 (1)	Cl2^xiii—Tl2—Cl2^xvii	58.64 (11)
Cl1ⁱ—Tl1—Cl1^v	120.000 (1)	Cl2^xiv—Tl2—Cl2^xvii	58.64 (11)
Cl1ⁱⁱ—Tl1—Cl1^v	119.999 (1)	Cl2^viii—Tl2—Cl2^xvii	88.00 (9)
Cl1ⁱⁱⁱ—Tl1—Cl1^v	62.98 (16)	Cl2^xv—Tl2—Cl2^xvii	88.00 (9)
Cl1—Tl1—Cl1^v	177.02 (16)	Cl2^x—Tl2—Cl2^xvii	116.71 (6)
Cl1^iv—Tl1—Cl1^v	57.02 (16)	Cl2^xvi—Tl2—Cl2^xvii	116.71 (6)
Cl1ⁱ—Tl1—Cl2^vi	60.17 (6)	Cl1ⁱⁱ—Tl2—Cl2^xviii	119.42 (7)
Cl1ⁱⁱ—Tl1—Cl2^vi	118.86 (6)	Cl1^xii—Tl2—Cl2^xviii	176.96 (10)
Cl1ⁱⁱⁱ—Tl1—Cl2^vi	60.17 (6)	Cl1^iv—Tl2—Cl2^xviii	119.42 (7)
Cl1—Tl1—Cl2^vi	90.84 (4)	Cl2^xiii—Tl2—Cl2^xviii	88.00 (9)
Cl1^iv—Tl1—Cl2^vi	118.86 (6)	Cl2^xiv—Tl2—Cl2^xviii	116.71 (6)
Cl1^v—Tl1—Cl2^vi	90.84 (5)	Cl2^viii—Tl2—Cl2^xviii	58.64 (11)
Cl1ⁱ—Tl1—Cl2^vii	90.84 (4)	Cl2^xv—Tl2—Cl2^xviii	116.71 (6)
Cl1ⁱⁱ—Tl1—Cl2^vii	60.17 (6)	Cl2^x—Tl2—Cl2^xviii	58.64 (11)
Cl1ⁱⁱⁱ—Tl1—Cl2^vii	118.86 (6)	Cl2^xvi—Tl2—Cl2^xviii	88.00 (9)
Cl1—Tl1—Cl2^vii	60.17 (6)	Cl2^xvii—Tl2—Cl2^xviii	58.07 (11)
Cl1^iv—Tl1—Cl2^vii	90.84 (4)	Cl1ⁱⁱ—Tl2—Cl2^xix	119.42 (7)
Cl1^v—Tl1—Cl2^vii	118.86 (6)	Cl1^xii—Tl2—Cl2^xix	119.42 (8)
Cl2^vi—Tl1—Cl2^vii	147.12 (6)	Cl1^iv—Tl2—Cl2^xix	176.96 (10)
Cl1ⁱ—Tl1—Cl2^viii	118.86 (6)	Cl2^xiii—Tl2—Cl2^xix	116.71 (6)
Cl1ⁱⁱ—Tl1—Cl2^viii	90.84 (5)	Cl2^xiv—Tl2—Cl2^xix	88.00 (9)
Cl1ⁱⁱⁱ—Tl1—Cl2^viii	90.84 (5)	Cl2^viii—Tl2—Cl2^xix	116.71 (6)
Cl1—Tl1—Cl2^viii	118.86 (6)	Cl2^xv—Tl2—Cl2^xix	58.64 (11)
Cl1^iv—Tl1—Cl2^viii	60.17 (6)	Cl2^x—Tl2—Cl2^xix	88.00 (9)
Cl1^v—Tl1—Cl2^viii	60.17 (6)	Cl2^xvi—Tl2—Cl2^xix	58.64 (11)
Cl2^vi—Tl1—Cl2^viii	58.71 (11)	Cl2^xvii—Tl2—Cl2^xix	58.07 (11)
Cl2^vii—Tl1—Cl2^viii	147.12 (6)	Cl2^xviii—Tl2—Cl2^xix	58.07 (11)
Cl1ⁱ—Tl1—Cl2^ix	118.86 (6)	Cl2—Mg1—Cl2ⁱⁱ	91.8 (2)
Cl1ⁱⁱ—Tl1—Cl2^ix	90.84 (5)	Cl2—Mg1—Cl2^vii	91.8 (2)
Cl1ⁱⁱⁱ—Tl1—Cl2^ix	90.84 (5)	Cl2ⁱⁱ—Mg1—Cl2^vii	91.8 (2)
Cl1—Tl1—Cl2^ix	118.86 (6)	Cl2—Mg1—Cl1^vii	91.84 (10)
Cl1^iv—Tl1—Cl2^ix	60.17 (6)	Cl2ⁱⁱ—Mg1—Cl1^vii	91.84 (10)
Cl1^v—Tl1—Cl2^ix	60.17 (6)	Cl2^vii—Mg1—Cl1^vii	174.7 (3)
Cl2^vi—Tl1—Cl2^ix	147.12 (6)	Cl2—Mg1—Cl1	174.7 (3)
Cl2^vii—Tl1—Cl2^ix	58.71 (11)	Cl2ⁱⁱ—Mg1—Cl1	91.84 (10)
Cl2^viii—Tl1—Cl2^ix	111.04 (14)	Cl2^vii—Mg1—Cl1	91.84 (10)
Cl1ⁱ—Tl1—Cl2^x	90.84 (4)	Cl1^vii—Mg1—Cl1	84.3 (2)
Cl1ⁱⁱ—Tl1—Cl2^x	60.17 (6)	Cl2—Mg1—Cl1ⁱⁱ	91.84 (10)
Cl1ⁱⁱⁱ—Tl1—Cl2^x	118.86 (6)	Cl2ⁱⁱ—Mg1—Cl1ⁱⁱ	174.7 (3)
Cl1—Tl1—Cl2^x	60.17 (6)	Cl2^vii—Mg1—Cl1ⁱⁱ	91.84 (10)
Cl1^iv—Tl1—Cl2^x	90.84 (5)	Cl1^vii—Mg1—Cl1ⁱⁱ	84.3 (2)
Cl1^v—Tl1—Cl2^x	118.86 (6)	Cl1—Mg1—Cl1ⁱⁱ	84.3 (2)
Cl2^vi—Tl1—Cl2^x	58.71 (11)	Cl2^xx—Mg2—Cl2^xxi	90.17 (16)
Cl2^vii—Tl1—Cl2^x	111.04 (14)	Cl2^xx—Mg2—Cl2^xxii	89.83 (16)
Cl2^viii—Tl1—Cl2^x	58.71 (11)	Cl2^xxi—Mg2—Cl2^xxii	180.0
Cl2^ix—Tl1—Cl2^x	147.12 (6)	Cl2^xx—Mg2—Cl2^xxiii	90.17 (16)
Cl1ⁱ—Tl1—Cl2^xi	60.17 (6)	Cl2^xxi—Mg2—Cl2^xxiii	90.17 (17)
Cl1ⁱⁱ—Tl1—Cl2^xi	118.86 (6)	Cl2^xxii—Mg2—Cl2^xxiii	89.83 (17)
Cl1ⁱⁱⁱ—Tl1—Cl2^xi	60.17 (6)	Cl2^xx—Mg2—Cl2^xxiv	89.83 (16)
Cl1—Tl1—Cl2^xi	90.84 (4)	Cl2^xxi—Mg2—Cl2^xxiv	89.83 (17)
Cl1^iv—Tl1—Cl2^xi	118.86 (6)	Cl2^xxii—Mg2—Cl2^xxiv	90.17 (17)
Cl1^v—Tl1—Cl2^xi	90.84 (5)	Cl2^xxiii—Mg2—Cl2^xxiv	180.0
Cl2^vi—Tl1—Cl2^xi	111.04 (14)	Cl2^xx—Mg2—Cl2	180.0
Cl2^vii—Tl1—Cl2^xi	58.71 (11)	Cl2^xxi—Mg2—Cl2	89.83 (17)
Cl2^viii—Tl1—Cl2^xi	147.12 (6)	Cl2^xxii—Mg2—Cl2	90.17 (17)
Cl2^ix—Tl1—Cl2^xi	58.71 (11)	Cl2^xxiii—Mg2—Cl2	89.83 (16)
Cl2^x—Tl1—Cl2^xi	147.12 (6)	Cl2^xxiv—Mg2—Cl2	90.17 (16)
Cl1ⁱⁱ—Tl2—Cl1^xii	63.03 (10)	Mg1^xvi—Cl1—Mg1	78.5 (3)
Cl1ⁱⁱ—Tl2—Cl1^iv	63.03 (10)	Mg1^xvi—Cl1—Tl2^xxv	87.89 (12)
Cl1^xii—Tl2—Cl1^iv	63.03 (10)	Mg1—Cl1—Tl2^xxv	166.36 (18)
Cl1ⁱⁱ—Tl2—Cl2^xiii	123.81 (8)	Mg1^xvi—Cl1—Tl2^xxvi	166.36 (18)
Cl1^xii—Tl2—Cl2^xiii	91.92 (9)	Mg1—Cl1—Tl2^xxvi	87.89 (12)
Cl1^iv—Tl2—Cl2^xiii	60.79 (8)	Tl2^xxv—Cl1—Tl2^xxvi	105.74 (13)
Cl1ⁱⁱ—Tl2—Cl2^xiv	123.81 (8)	Mg1^xvi—Cl1—Tl1^xxvii	91.16 (6)
Cl1^xii—Tl2—Cl2^xiv	60.79 (8)	Mg1—Cl1—Tl1^xxvii	91.15 (6)
Cl1^iv—Tl2—Cl2^xiv	91.92 (9)	Tl2^xxv—Cl1—Tl1^xxvii	89.10 (5)
Cl2^xiii—Tl2—Cl2^xiv	59.85 (17)	Tl2^xxvi—Cl1—Tl1^xxvii	89.10 (5)
Cl1ⁱⁱ—Tl2—Cl2^viii	91.92 (9)	Mg1^xvi—Cl1—Tl1	91.15 (6)
Cl1^xii—Tl2—Cl2^viii	123.81 (8)	Mg1—Cl1—Tl1	91.15 (6)
Cl1^iv—Tl2—Cl2^viii	60.79 (8)	Tl2^xxv—Cl1—Tl1	89.10 (5)
Cl2^xiii—Tl2—Cl2^viii	60.03 (17)	Tl2^xxvi—Cl1—Tl1	89.10 (5)
Cl2^xiv—Tl2—Cl2^viii	119.820 (10)	Tl1^xxvii—Cl1—Tl1	177.02 (16)
Cl1ⁱⁱ—Tl2—Cl2^xv	91.92 (9)	Mg1—Cl2—Mg2	178.8 (3)
Cl1^xii—Tl2—Cl2^xv	60.79 (8)	Mg1—Cl2—Tl2^xvi	88.60 (7)
Cl1^iv—Tl2—Cl2^xv	123.81 (8)	Mg2—Cl2—Tl2^xvi	91.44 (7)
Cl2^xiii—Tl2—Cl2^xv	119.820 (10)	Mg1—Cl2—Tl2^xxviii	88.60 (7)
Cl2^xiv—Tl2—Cl2^xv	60.03 (17)	Mg2—Cl2—Tl2^xxviii	91.44 (7)
Cl2^viii—Tl2—Cl2^xv	175.12 (14)	Tl2^xvi—Cl2—Tl2^xxviii	175.12 (14)
Cl1ⁱⁱ—Tl2—Cl2^x	60.79 (8)	Mg1—Cl2—Tl1^xxix	90.52 (17)
Cl1^xii—Tl2—Cl2^x	123.81 (8)	Mg2—Cl2—Tl1^xxix	90.67 (16)
Cl1^iv—Tl2—Cl2^x	91.92 (9)	Tl2^xvi—Cl2—Tl1^xxix	88.02 (8)
Cl2^xiii—Tl2—Cl2^x	119.820 (11)	Tl2^xxviii—Cl2—Tl1^xxix	88.02 (8)
Cl2^xiv—Tl2—Cl2^x	175.12 (14)	Mg1—Cl2—Tl2^xxx	89.9 (2)
Cl2^viii—Tl2—Cl2^x	59.85 (17)	Mg2—Cl2—Tl2^xxx	88.94 (11)
Cl2^xv—Tl2—Cl2^x	119.820 (11)	Tl2^xvi—Cl2—Tl2^xxx	91.99 (9)
Cl1ⁱⁱ—Tl2—Cl2^xvi	60.79 (8)	Tl2^xxviii—Cl2—Tl2^xxx	91.99 (9)
Cl1^xii—Tl2—Cl2^xvi	91.92 (9)	Tl1^xxix—Cl2—Tl2^xxx	179.61 (13)

Symmetry codes: (i) −y, x−y−1, z; (ii) −x+y+1, −x+1, z; (iii) −x+y, −x, z; (iv) −y, x−y, z; (v) x−1, y, z; (vi) x−1, y−1, −z+1/2; (vii) −y+1, x−y, z; (viii) −x+y, −x+1, −z+1/2; (ix) −x+y, −x+1, z; (x) −y+1, x−y, −z+1/2; (xi) x−1, y−1, z; (xii) x, y+1, z; (xiii) x−1, y, −z+1/2; (xiv) −y+1, x−y+1, −z+1/2; (xv) −x+y+1, −x+2, −z+1/2; (xvi) x, y, −z+1/2; (xvii) x−y, x, z−1/2; (xviii) −x+1, −y+1, z−1/2; (xix) y, −x+y+1, z−1/2; (xx) −x+2, −y+2, −z+1; (xxi) x−y+1, x, −z+1; (xxii) −x+y+1, −x+2, z; (xxiii) y, −x+y+1, −z+1; (xxiv) −y+2, x−y+1, z; (xxv) x, y−1, z; (xxvi) x, y−1, −z+1/2; (xxvii) x+1, y, z; (xxviii) x+1, y, −z+1/2; (xxix) x+1, y+1, z; (xxx) −x+1, −y+1, z+1/2.

Acknowledgements

The single-crystal structure determination was provided by the X-ray Analytical Facility at the University of California, Santa Barbara (Dr Guang Wu, Lab Manager).

Funding information

Funding for this research was provided by: U.S. Defense Threat Reduction Agency (DTRA) [contract No. HDTRA19-31194 to Lawrence Berkeley National Laboratory (LBNL) authors]; U.S. Department of Energy, National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (DNN) (contract No. AC02-05CH11231 to LBNL authors); U.S. Department of Energy, NNSA [contract No. 89233218NCA000001 to Los Alamos National Laboratory (LANL)].

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