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The crystal structures of (CH3NH3)2Cu(Cl1–xBrx)4 compounds have been investigated by means of synchrotron powder X-ray diffraction and pair distribution function analysis at room temperature. As a result, new insights are gained about the structural properties of these compounds, suggesting a monoclinic symmetry (space group No. 14: P21/cC_{2h}^{5}) induced by the co-operative orbital ordering produced by the Jahn–Teller distortion characterizing the 3d9 Cu2+ ion. In contrast to previous studies, a significant amount of vacancies is found at halogen positions, a feature that can be likely ascribed to the synthesis technique adopted in the present study. Br atoms preferentially occupy axial positions, likely on account of reduced steric hindrance at these sites.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520622002438/ra5107sup1.cif
Contains datablocks global_1, CH3NH3CuCl4, global_2, Structure, global_3, CH3NH32CuC11Br3

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S2052520622002438/ra5107sup2.rtv
Contains datablocks hc3840_7_Cu1, hc3840_9_Cu3, hc3840_10_Cu4

CCDC references: 2155905; 2155906; 2155907

Computing details top

For all structures, program(s) used to refine structure: FULLPROF.

(CH3NH3CuCl4) top
Crystal data top
Monoclinic, P21/cc = 7.293427 (3) Å
Hall symbol: -P 2ybcβ = 111.30598 (8)°
a = 10.031269 (6) ÅV = 501.86 (1) Å3
b = 7.362769 (3) Å? # Put here the name of the beam-line and site radiation
Data collection top
Radiation source: Synchrotron2θmin = 0.016°, 2θmax = 47.916°, 2θstep = 0.002°
Refinement top
Rp = 7.24523951 data points
Rwp = 10.088112 parameters
Rexp = 3.2780 restraints
RBragg = 8.289
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cu10.000000.000000.000000.04780 (7)*
N10.77953 (6)0.02029 (17)0.3825 (2)0.0036 (2)*0.87912
C10.63496 (8)0.53006 (17)0.7935 (2)0.0138 (4)*0.87912
Cl10.75569 (2)0.01878 (8)0.88404 (12)0.06860 (11)*0.95448
Cl20.02043 (5)0.22903 (6)0.23997 (6)0.06458 (13)*0.92466
(Structure) top
Crystal data top
Monoclinic, P21/ac = 10.311401 (8) Å
Hall symbol: -P 2yabβ = 110.92194 (9)°
a = 7.370110 (3) ÅV = 523.08 (1) Å3
b = 7.368856 (4) Å? # Put here the name of the beam-line and site radiation
Data collection top
Radiation source: Synchrotron2θmin = 0.006°, 2θmax = 47.916°, 2θstep = 0.002°
Refinement top
Rp = 5.03823956 data points
Rwp = 6.920141 parameters
Rexp = 5.6800 restraints
RBragg = 5.386
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cu10.000000.000000.000000.03468 (7)*
N10.61639 (12)0.0012 (3)0.21010 (3)0.0001 (2)*0.86975
C10.6712 (2)0.9932 (4)0.35757 (5)0.0211 (4)*0.86975
Cl20.23248 (4)0.23328 (4)0.01227 (5)0.07338 (15)*0.94068
Br20.23248 (4)0.23328 (4)0.01227 (5)0.07338 (15)*0.03233
Br10.11459 (3)0.00098 (7)0.255058 (9)0.07828 (8)*0.89674
(CH3NH32CuC11Br3) top
Crystal data top
Monoclinic, P21/ac = 10.369632 (17) Å
Hall symbol: -P 2yabβ = 111.0013 (2)°
a = 7.418941 (10) ÅV = 533.26 (1) Å3
b = 7.424763 (12) Å? # Put here the name of the beam-line and site radiation
Data collection top
Radiation source: Synchrotron2θmin = 0.017°, 2θmax = 47.917°, 2θstep = 0.002°
Refinement top
Rp = 7.57523951 data points
Rwp = 10.660114 parameters
Rexp = 2.8500 restraints
RBragg = 11.375
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cu10.000000.000000.000000.01803 (12)*
Br10.13225 (11)0.01126 (12)0.25866 (3)0.10733 (14)*
Br20.25968 (17)0.25723 (17)0.00392 (11)0.1903 (3)*0.5693 (7)
Cl20.25968 (17)0.25723 (17)0.00392 (11)0.1903 (3)*0.4307 (7)
N10.6157 (5)0.0013 (6)0.23075 (11)0.0058 (3)*
C10.1878 (3)0.6834 (3)0.2678 (2)0.0489 (5)*
 

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