Mg(NH3)2Cl2 ($E1_{3}$) Structure : A2B8CD2_oC26_65_h_r_a_i

Picture of Structure; Click for Big Picture
Prototype : Cl2H6MgN2
AFLOW prototype label : A2B8CD2_oC26_65_h_r_a_i
Strukturbericht designation : $E1_{3}$
Pearson symbol : oC26
Space group number : 65
Space group symbol : $Cmmm$
AFLOW prototype command : aflow --proto=A2B8CD2_oC26_65_h_r_a_i
--params=
$a$,$b/a$,$c/a$,$x_{2}$,$y_{3}$,$x_{4}$,$y_{4}$,$z_{4}$


Other compounds with this structure

  • Cd(NH3)2Cl2, Mg(NH3)2Cl2, Hg(NH3)2Cl2, Ni(NH3)2Br2, Ni(NH3)2Cl2, and Ni(NH3)2I2

  • (Gottfried, 1938) gave the $E1_{3}$ designation to Cd(NH3)2Cl2, and gave coordinates in the $Cmm2$ #35 space group. However, the cited reference, (MacGillavry, 1936) noted that their coordinates allowed several different space groups, with $Cmmm$ #65 having the highest symmetry. We therefore follow most authors and use the $Cmmm$ representation.
  • (MacGillavry, 1936) could not determine the positions of the hydrogen atoms, but (Leineweber, 1999) was able to do this using the isostructural compound Mg(NH3)2Cl2. Accordingly, we use Mg(NH3)2Cl2 for the prototype of $E1_{3}$.
  • Twelve hydrogen atoms are statistically distributed among the ($16r$) positions, so each site has a 75% probability of being occupied.

Base-centered Orthorhombic primitive vectors:

\[ \begin{array}{ccc} \mathbf{a}_1 & = & \frac12 \, a \, \mathbf{\hat{x}} - \frac12 \, b \, \mathbf{\hat{y}} \\ \mathbf{a}_2 & = & \frac12 \, a \, \mathbf{\hat{x}} + \frac12 \, b \, \mathbf{\hat{y}} \\ \mathbf{a}_3 & = & c \, \mathbf{\hat{z}} \\ \end{array} \]

Basis vectors:

\[ \begin{array}{ccccccc} & & \mbox{Lattice Coordinates} & & \mbox{Cartesian Coordinates} &\mbox{Wyckoff Position} & \mbox{Atom Type} \\ \mathbf{B}_{1} & = & 0 \, \mathbf{a}_{1} + 0 \, \mathbf{a}_{2} + 0 \, \mathbf{a}_{3} & = & 0 \, \mathbf{\hat{x}} + 0 \, \mathbf{\hat{y}} + 0 \, \mathbf{\hat{z}} & \left(2a\right) & \mbox{Mg} \\ \mathbf{B}_{2} & = & x_{2} \, \mathbf{a}_{1} + x_{2} \, \mathbf{a}_{2} + \frac{1}{2} \, \mathbf{a}_{3} & = & x_{2}a \, \mathbf{\hat{x}} + \frac{1}{2}c \, \mathbf{\hat{z}} & \left(4h\right) & \mbox{Cl} \\ \mathbf{B}_{3} & = & -x_{2} \, \mathbf{a}_{1}-x_{2} \, \mathbf{a}_{2} + \frac{1}{2} \, \mathbf{a}_{3} & = & -x_{2}a \, \mathbf{\hat{x}} + \frac{1}{2}c \, \mathbf{\hat{z}} & \left(4h\right) & \mbox{Cl} \\ \mathbf{B}_{4} & = & -y_{3} \, \mathbf{a}_{1} + y_{3} \, \mathbf{a}_{2} & = & y_{3}b \, \mathbf{\hat{y}} & \left(4i\right) & \mbox{N} \\ \mathbf{B}_{5} & = & y_{3} \, \mathbf{a}_{1}-y_{3} \, \mathbf{a}_{2} & = & -y_{3}b \, \mathbf{\hat{y}} & \left(4i\right) & \mbox{N} \\ \mathbf{B}_{6} & = & \left(x_{4}-y_{4}\right) \, \mathbf{a}_{1} + \left(x_{4}+y_{4}\right) \, \mathbf{a}_{2} + z_{4} \, \mathbf{a}_{3} & = & x_{4}a \, \mathbf{\hat{x}} + y_{4}b \, \mathbf{\hat{y}} + z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{7} & = & \left(-x_{4}+y_{4}\right) \, \mathbf{a}_{1} + \left(-x_{4}-y_{4}\right) \, \mathbf{a}_{2} + z_{4} \, \mathbf{a}_{3} & = & -x_{4}a \, \mathbf{\hat{x}}-y_{4}b \, \mathbf{\hat{y}} + z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{8} & = & \left(-x_{4}-y_{4}\right) \, \mathbf{a}_{1} + \left(-x_{4}+y_{4}\right) \, \mathbf{a}_{2}-z_{4} \, \mathbf{a}_{3} & = & -x_{4}a \, \mathbf{\hat{x}} + y_{4}b \, \mathbf{\hat{y}}-z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{9} & = & \left(x_{4}+y_{4}\right) \, \mathbf{a}_{1} + \left(x_{4}-y_{4}\right) \, \mathbf{a}_{2}-z_{4} \, \mathbf{a}_{3} & = & x_{4}a \, \mathbf{\hat{x}}-y_{4}b \, \mathbf{\hat{y}}-z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{10} & = & \left(-x_{4}+y_{4}\right) \, \mathbf{a}_{1} + \left(-x_{4}-y_{4}\right) \, \mathbf{a}_{2}-z_{4} \, \mathbf{a}_{3} & = & -x_{4}a \, \mathbf{\hat{x}}-y_{4}b \, \mathbf{\hat{y}}-z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{11} & = & \left(x_{4}-y_{4}\right) \, \mathbf{a}_{1} + \left(x_{4}+y_{4}\right) \, \mathbf{a}_{2}-z_{4} \, \mathbf{a}_{3} & = & x_{4}a \, \mathbf{\hat{x}} + y_{4}b \, \mathbf{\hat{y}}-z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{12} & = & \left(x_{4}+y_{4}\right) \, \mathbf{a}_{1} + \left(x_{4}-y_{4}\right) \, \mathbf{a}_{2} + z_{4} \, \mathbf{a}_{3} & = & x_{4}a \, \mathbf{\hat{x}}-y_{4}b \, \mathbf{\hat{y}} + z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \mathbf{B}_{13} & = & \left(-x_{4}-y_{4}\right) \, \mathbf{a}_{1} + \left(-x_{4}+y_{4}\right) \, \mathbf{a}_{2} + z_{4} \, \mathbf{a}_{3} & = & -x_{4}a \, \mathbf{\hat{x}} + y_{4}b \, \mathbf{\hat{y}} + z_{4}c \, \mathbf{\hat{z}} & \left(16r\right) & \mbox{H} \\ \end{array} \]

References

  • A. Leineweber, M. W. Friedriszik, and H. Jacobs, Preparation and Crystal Structures of Mg(NH3)2Cl2, Mg(NH3)2Br2, and Mg(NH3)2I2, J. Solid State Chem. 147, 229–234 (1999), doi:10.1006/jssc.1999.8238.
  • C. H. MacGillavry and J. M. Bijvoet, Die Kristallstruktur von Zn(NH3)2Cl2 und Zn(NH3)2Br2, Zeitschrift für Kristallographie – Crystalline Materials 94, 249–255 (1936), doi:10.1524/zkri.1936.94.1.249.
  • C. Gottfried, ed., Strukturbericht Band IV 1936 (Akademische Verlagsgesellschaft M. B. H., Leipzig, 1938).

Geometry files


Prototype Generator

aflow --proto=A2B8CD2_oC26_65_h_r_a_i --params=

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