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Crystal Lab › Prototype structures › Orthorhombic

Mg(NH₃)₂Cl₂ (E1₃)

Orthorhombic · space group Cmmm (No. 65) · Pearson oC26 · Strukturbericht E13

Symmetry elements and Wyckoff positions (interactive)

Mg(NH₃)₂Cl₂ (E1₃) in Cmmm

Setting
Loading the group…
x = 0.10, y = 0.17, z = 0.08

Unit cell

Lattice constants
a = 8.181 Å, b = 8.207 Å, c = 3.755 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
252.1 ų
Atoms in the conventional cell
26 (Mg 2, Cl 4, N 4, H 16)
Formula units Z
2
Pearson symbol
oC26 — orthorhombic, base-centred lattice, 26 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Mg3Mg2a20.00000.00000.0000
Cl1Cl4h40.21330.00000.5000
N4N4i40.00000.25950.0000
H2H16r160.54500.81200.1580

The multiplicity and the Wyckoff letter say how many copies of the site the group makes in one cell and on which kind of symmetry element the site sits; the 26 atoms drawn above are these sites multiplied by all 16 operations. Press Wyckoff under Colour to see the sites, and tick a symmetry element on the left to see which atoms lie on it.

How to read the label

A2B8CD2_oC26_65_h_r_a_i-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC26, then the space-group number 65, then the Wyckoff letters occupied by each element in turn (Mg: 2a; Cl: 4h; N: 4i; H: 16r). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Cd(NH₃)₂Cl₂, Mg(NH₃)₂Cl₂, Hg(NH₃)₂Cl₂, Ni(NH₃)₂Br₂, Ni(NH₃)₂Cl₂, Ni(NH₃)₂I₂ <!--beginning with an

Note: E1₃.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B8CD2_oC26_65_h_r_a_i-001 (M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017); D. Hicks et al., ibid. 161, S1 (2019) and 199, 110450 (2021); S. Eckert et al., ibid. 240, 112988 (2024)). Symmetry elements, Wyckoff assignment and the diagram are computed on this page from the group operations.

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