The crystal structures of (CH
3NH
3)
2Cu(Cl
1–xBr
x)
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:
P2
1/
c –
C) induced by the co-operative orbital ordering produced by the Jahn–Teller distortion characterizing the 3
d9 Cu
2+ 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
CCDC references: 2155905; 2155906; 2155907
For all structures, program(s) used to refine structure: FULLPROF.
Crystal data top
Monoclinic, P21/c | c = 7.293427 (3) Å |
Hall symbol: -P 2ybc | β = 111.30598 (8)° |
a = 10.031269 (6) Å | V = 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: Synchrotron | 2θmin = 0.016°, 2θmax = 47.916°, 2θstep = 0.002° |
Refinement top
Rp = 7.245 | 23951 data points |
Rwp = 10.088 | 112 parameters |
Rexp = 3.278 | 0 restraints |
RBragg = 8.289 | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Cu1 | 0.00000 | 0.00000 | 0.00000 | 0.04780 (7)* | |
N1 | 0.77953 (6) | 0.02029 (17) | 0.3825 (2) | 0.0036 (2)* | 0.87912 |
C1 | 0.63496 (8) | 0.53006 (17) | 0.7935 (2) | 0.0138 (4)* | 0.87912 |
Cl1 | 0.75569 (2) | 0.01878 (8) | 0.88404 (12) | 0.06860 (11)* | 0.95448 |
Cl2 | 0.02043 (5) | 0.22903 (6) | 0.23997 (6) | 0.06458 (13)* | 0.92466 |
Crystal data top
Monoclinic, P21/a | c = 10.311401 (8) Å |
Hall symbol: -P 2yab | β = 110.92194 (9)° |
a = 7.370110 (3) Å | V = 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: Synchrotron | 2θmin = 0.006°, 2θmax = 47.916°, 2θstep = 0.002° |
Refinement top
Rp = 5.038 | 23956 data points |
Rwp = 6.920 | 141 parameters |
Rexp = 5.680 | 0 restraints |
RBragg = 5.386 | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Cu1 | 0.00000 | 0.00000 | 0.00000 | 0.03468 (7)* | |
N1 | 0.61639 (12) | 0.0012 (3) | 0.21010 (3) | −0.0001 (2)* | 0.86975 |
C1 | 0.6712 (2) | 0.9932 (4) | 0.35757 (5) | 0.0211 (4)* | 0.86975 |
Cl2 | 0.23248 (4) | 0.23328 (4) | 0.01227 (5) | 0.07338 (15)* | 0.94068 |
Br2 | 0.23248 (4) | 0.23328 (4) | 0.01227 (5) | 0.07338 (15)* | 0.03233 |
Br1 | 0.11459 (3) | −0.00098 (7) | 0.255058 (9) | 0.07828 (8)* | 0.89674 |
Crystal data top
Monoclinic, P21/a | c = 10.369632 (17) Å |
Hall symbol: -P 2yab | β = 111.0013 (2)° |
a = 7.418941 (10) Å | V = 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: Synchrotron | 2θmin = 0.017°, 2θmax = 47.917°, 2θstep = 0.002° |
Refinement top
Rp = 7.575 | 23951 data points |
Rwp = 10.660 | 114 parameters |
Rexp = 2.850 | 0 restraints |
RBragg = 11.375 | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Cu1 | 0.00000 | 0.00000 | 0.00000 | 0.01803 (12)* | |
Br1 | 0.13225 (11) | 0.01126 (12) | 0.25866 (3) | 0.10733 (14)* | |
Br2 | 0.25968 (17) | 0.25723 (17) | 0.00392 (11) | 0.1903 (3)* | 0.5693 (7) |
Cl2 | 0.25968 (17) | 0.25723 (17) | 0.00392 (11) | 0.1903 (3)* | 0.4307 (7) |
N1 | 0.6157 (5) | 0.0013 (6) | 0.23075 (11) | 0.0058 (3)* | |
C1 | −0.1878 (3) | 0.6834 (3) | 0.2678 (2) | −0.0489 (5)* | |