inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoIUCrDATA
ISSN: 2414-3146

Ca2CuO2Cl2, a redetermination from single-crystal X-ray diffraction data

aInstitut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, UMR CNRS 7590 Muséum National d'Histoire Naturelle, IRD UMR 206, 4 place Jussieu, F-75005 Paris, France, bLaboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan, and cUniv. Grenoble Alpes, CNRS, Institut Néel, 38000 Grenoble, France
*Correspondence e-mail: benoit.baptiste@upmc.fr

Edited by M. Weil, Vienna University of Technology, Austria (Received 25 September 2018; accepted 19 November 2018; online 27 November 2018)

The crystal structure of Ca2CuO2Cl2, dicalcium oxidocuprate(II) dichloride, was redetermined on the basis of single-crystal X-ray diffraction data using a laboratory Mo anode. Previous structure determinations based on single-crystal X-ray data [Grande & Müller-Buschbaum (1977[Grande, B. & Müller-Buschbaum, H. (1977). Z. Anorg. Allg. Chem. 429, 88-90.]). Z. Anorg. Allg. Chem. 429, 88–90], powder X-ray diffraction data [Yamada et al. (2005[Yamada, I., Belik, A. A., Azuma, M., Harjo, S., Kamiyama, T., Shimakawa, Y. & Takano, M. (2005). Phys. Rev. B, 72, 224503, 1-5.]). Phys. Rev. B, 72, 224503–1–5] or neutron diffraction data [Argyriou et al. (1995[Argyriou, D. N., Jorgensen, J. D., Hitterman, R. L., Hiroi, Z., Kobayashi, N. & Takano, M. (1995). Phys. Rev. B, 51, 8434-8437.]). Phys. Rev. B, 51, 8434–8437] were confirmed. The present study allowed the refinement of anisotropic displacement parameters for all crystallographic sites, accompanied with higher accuracy and precision for bond lengths and angles. The layered title compound comprises of [CuO4] square-planar and [CaO4Cl4] square-anti­prismatic coordination polyhedra, and is the undoped parent compound of a high-temperature superconducting cuprate.

3D view (loading...)
[Scheme 3D1]

Structure description

The layered crystal structure of Ca2CuO2Cl2 (Fig. 1[link]) has tetra­gonal symmetry (space group I4/mmm), and is the undoped parent compound of a high-temperature superconducting cuprate (Hiroi et al., 1994[Hiroi, Z., Kobayashi, N. & Takano, M. (1994). Nature, 371, 139-141.]; Kohsaka et al., 2002[Kohsaka, Y., Azuma, M., Yamada, I., Sasagawa, T., Hanaguri, T., Takano, M. & Takagi, H. (2002). J. Am. Chem. Soc. 124, 12275-12278.]; Yamada et al., 2005[Yamada, I., Belik, A. A., Azuma, M., Harjo, S., Kamiyama, T., Shimakawa, Y. & Takano, M. (2005). Phys. Rev. B, 72, 224503, 1-5.]).

[Figure 1]
Figure 1
The crystal structure of Ca2CuO2Cl2, showing displacement ellipsoids drawn at the 90% probability level.

The principal building blocks in the structure are square-planar [CuO4] and square-anti­prismatic [CaO4Cl4] polyhedra, both with point group symmetry 4/mmm. Relevant bond lengths are listed in Table 1[link]. The building units are fused together by sharing O and Cl atoms into layers extending parallel to (001). Square-planar [CuO4] polyhedra are typical of oxocuprates(II) (Müller-Buschbaum, 1977[Müller-Buschbaum, H. (1977). Angew. Chem. Int. Ed. Engl. 16, 674-687.]), and are found in other high-temperature superconducting cuprates (Raveau et al., 1991[Raveau, B., Michel, C., Hervieu, M. & Groult, D. (1991). Crystal Chemistry of High-Tc Superconducting Copper Oxides. Berlin: Springer Verlag.]). However, here the [CuO4] units are complemented to elongated [CuO4Cl2] octa­hedra with the Cl atoms at the axial sites.

Table 1
Selected bond lengths (Å)

Cu1—Cl1 2.7452 (14) Ca1—Cl1i 2.9775 (7)
Cu1—O1 1.9340 (1) Ca1—O1ii 2.4900 (7)
Symmetry codes: (i) [-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (ii) [x-{\script{1\over 2}}, y-{\script{1\over 2}}, z-{\script{1\over 2}}].

Previous structure determinations of Ca2CuO2Cl2 based on single-crystal X-ray data (Grande & Müller-Buschbaum, 1977[Grande, B. & Müller-Buschbaum, H. (1977). Z. Anorg. Allg. Chem. 429, 88-90.]), powder X-ray diffraction data (Yamada et al., 2005[Yamada, I., Belik, A. A., Azuma, M., Harjo, S., Kamiyama, T., Shimakawa, Y. & Takano, M. (2005). Phys. Rev. B, 72, 224503, 1-5.]) or neutron diffraction data (Argyriou et al., 1995[Argyriou, D. N., Jorgensen, J. D., Hitterman, R. L., Hiroi, Z., Kobayashi, N. & Takano, M. (1995). Phys. Rev. B, 51, 8434-8437.]) are confirmed by the current study. The first determination of the crystal structure of Ca2CuO2Cl2 converged with rather high residuals (R1 = 0.105; Grande & Müller-Buschbaum, 1977[Grande, B. & Müller-Buschbaum, H. (1977). Z. Anorg. Allg. Chem. 429, 88-90.]). Another previous attempt to determine anisotropic displacement parameters for all crystallographic sites has been made on basis of neutron powder diffraction data (Argyriou et al., 1995[Argyriou, D. N., Jorgensen, J. D., Hitterman, R. L., Hiroi, Z., Kobayashi, N. & Takano, M. (1995). Phys. Rev. B, 51, 8434-8437.]). We note that most of the refined values are compatible with our refinement within uncertainty, with the notable exception of U33 for the chlorine and oxygen sites, which have larger values in our refinement. Although a direct comparison between the results of the two techniques is difficult, we note that neutrons are more sensitive to oxygen but the number of measured reflections is much smaller in powder diffraction. The much higher redundancy resulting from single-crystal X-ray data collection allows a better data-to-parameter ratio and hence a more reliable refinement. We also estimate that our model shows a lower correlation between fitted parameters.

Synthesis and crystallization

Powders of CaO and CuCl2 were mixed in a molar ratio of 2:1 and put into an alumina crucible. The mixed powder was heated at 1053 K for 24 h with inter­mediate grindings. Subsequently, the as-obtained Ca2CuO2Cl2 material was again heated to 1053 K at a ramp rate of 60 K h−1 and kept at this temperature for 5 h. It was then heated to 1203 K at a ramp rate of 60 K h−1 and kept at that temperature for 10 h. Finally, it was cooled down to room temperature at a ramp rate of 60 K h−1. Single crystals with a size up to 2 mm × 2 mm × 0.1 mm could be harvested by cleaving the as-grown bulks.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Coordinates from an isotypic compound were used in the structure solution.

Table 2
Experimental details

Crystal data
Chemical formula Ca2CuO2Cl2
Mr 246.60
Crystal system, space group Tetragonal, I4/mmm
Temperature (K) 293
a, c (Å) 3.8680 (2), 15.0321 (15)
V3) 224.90 (3)
Z 2
Radiation type Mo Kα
μ (mm−1) 8.16
Crystal size (mm) 0.80 × 0.40 × 0.16
 
Data collection
Diffractometer Agilent Xcalibur, Sapphire3
Absorption correction Analytical [CrysAlis PRO (Agilent, 2013[Agilent (2013). CrysAlis PRO. Agilent Technologies Ltd, Yarnton, England.]), using a multi-faceted crystal model based on expressions derived by Clark & Reid (1995[Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897.])]
Tmin, Tmax 0.056, 0.287
No. of measured, independent and observed [I > 2σ(I)] reflections 634, 101, 101
Rint 0.019
(sin θ/λ)max−1) 0.652
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.047, 1.24
No. of reflections 101
No. of parameters 12
Δρmax, Δρmin (e Å−3) 0.51, −0.43
Computer programs: CrysAlis PRO (Agilent, 2013[Agilent (2013). CrysAlis PRO. Agilent Technologies Ltd, Yarnton, England.]), OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]), VESTA (Momma & Izumi, 2011[Momma, K. & Izumi, F. (2011). J. Appl. Cryst. 44, 1272-1276.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Structural data


Computing details top

Data collection: CrysAlis PRO (Agilent, 2013); cell refinement: CrysAlis PRO (Agilent, 2013); data reduction: CrysAlis PRO (Agilent, 2013); program(s) used to solve structure: coordinates from isotypic compound; program(s) used to refine structure: OLEX2 (Dolomanov et al., 2009); molecular graphics: VESTA (Momma & Izumi, 2011); software used to prepare material for publication: publCIF (Westrip, 2010).

Dicalcium oxidocuprate(II) dichloride top
Crystal data top
Ca2CuO2Cl2Dx = 3.641 Mg m3
Mr = 246.60Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4/mmmCell parameters from 440 reflections
a = 3.8680 (2) Åθ = 5.4–27.4°
c = 15.0321 (15) ŵ = 8.16 mm1
V = 224.90 (3) Å3T = 293 K
Z = 2Block, black
F(000) = 2380.80 × 0.4 × 0.16 mm
Data collection top
Agilent Xcalibur, Sapphire3
diffractometer
101 independent reflections
Radiation source: Enhance (Mo) X-ray Source101 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.019
Detector resolution: 16.0318 pixels mm-1θmax = 27.6°, θmin = 5.4°
ω scansh = 44
Absorption correction: analytical
[CrysAlis PRO (Agilent, 2013), using a multi-faceted crystal model based on expressions derived by Clark & Reid (1995)]
k = 44
Tmin = 0.056, Tmax = 0.287l = 1818
634 measured reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.018Secondary atom site location: difference Fourier map
wR(F2) = 0.047 w = 1/[σ2(Fo2) + (0.0248P)2 + 0.4487P]
where P = (Fo2 + 2Fc2)/3
S = 1.24(Δ/σ)max < 0.001
101 reflectionsΔρmax = 0.51 e Å3
12 parametersΔρmin = 0.43 e Å3
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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cu10.00000.00000.50000.0090 (3)
Cl10.00000.00000.31738 (9)0.0158 (4)
Ca10.00000.00000.10434 (7)0.0128 (3)
O10.50000.00000.50000.0120 (7)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.0049 (4)0.0049 (4)0.0171 (5)0.0000.0000.000
Cl10.0152 (5)0.0152 (5)0.0171 (6)0.0000.0000.000
Ca10.0101 (4)0.0101 (4)0.0183 (6)0.0000.0000.000
O10.0049 (16)0.0114 (17)0.0198 (16)0.0000.0000.000
Geometric parameters (Å, º) top
Cu1—Cl1i2.7451 (14)Ca1—Cl1vi2.9775 (7)
Cu1—Cl12.7452 (14)Ca1—Cl1vii2.9775 (7)
Cu1—O1ii1.9340 (1)Ca1—Cl1viii2.9775 (7)
Cu1—O1iii1.9340 (1)Ca1—O1ix2.4900 (7)
Cu1—O1iv1.9340 (1)Ca1—O1x2.4900 (7)
Cu1—O11.9340 (1)Ca1—O1xi2.4900 (7)
Ca1—Cl1v2.9775 (7)Ca1—O1xii2.4900 (7)
Cl1i—Cu1—Cl1180.0Ca1vii—Cl1—Ca1viii133.44 (6)
O1ii—Cu1—Cl190.0Ca1viii—Cl1—Ca1vi81.01 (2)
O1iii—Cu1—Cl190.0Ca1vii—Cl1—Ca1v81.01 (2)
O1—Cu1—Cl190.0Ca1viii—Cl1—Ca1v81.01 (2)
O1iv—Cu1—Cl190.0O1ix—Ca1—O1xi66.63 (2)
O1iv—Cu1—Cl1i90.0O1x—Ca1—O1xi101.92 (4)
O1—Cu1—Cl1i90.0O1x—Ca1—O1ix66.63 (2)
O1ii—Cu1—Cl1i90.0O1xi—Ca1—O1xii66.63 (2)
O1iii—Cu1—Cl1i90.0O1ix—Ca1—O1xii101.92 (4)
O1ii—Cu1—O190.0O1x—Ca1—O1xii66.63 (2)
O1iii—Cu1—O190.0Cu1xiii—O1—Cu1180.0
O1iii—Cu1—O1ii180.0Cu1xiii—O1—Ca1vii90.0
O1—Cu1—O1iv180.0Cu1—O1—Ca1vii90.0
O1ii—Cu1—O1iv90.0Cu1—O1—Ca1xiv90.0
O1iii—Cu1—O1iv90.0Cu1xiii—O1—Ca1xiv90.0
Cu1—Cl1—Ca1vi66.72 (3)Cu1—O1—Ca1v90.0
Cu1—Cl1—Ca1v66.72 (3)Cu1xiii—O1—Ca1xv90.0
Cu1—Cl1—Ca1180.0Cu1xiii—O1—Ca1v90.0
Cu1—Cl1—Ca1viii66.72 (3)Cu1—O1—Ca1xv90.0
Cu1—Cl1—Ca1vii66.72 (3)Ca1v—O1—Ca1xiv78.08 (4)
Ca1v—Cl1—Ca1113.28 (3)Ca1xv—O1—Ca1xiv101.92 (4)
Ca1vii—Cl1—Ca1113.28 (3)Ca1vii—O1—Ca1xiv180.0
Ca1vi—Cl1—Ca1113.28 (3)Ca1v—O1—Ca1xv180.0
Ca1vi—Cl1—Ca1v133.44 (6)Ca1v—O1—Ca1vii101.92 (4)
Ca1viii—Cl1—Ca1113.28 (3)Ca1xv—O1—Ca1vii78.08 (4)
Ca1vii—Cl1—Ca1vi81.01 (2)
Symmetry codes: (i) x, y, z+1; (ii) y, x1, z; (iii) y, x, z; (iv) x1, y, z; (v) x+1/2, y1/2, z+1/2; (vi) x1/2, y+1/2, z+1/2; (vii) x+1/2, y+1/2, z+1/2; (viii) x1/2, y1/2, z+1/2; (ix) x1/2, y1/2, z1/2; (x) y1/2, x1/2, z1/2; (xi) y+1/2, x1/2, z1/2; (xii) x1/2, y+1/2, z1/2; (xiii) x+1, y, z; (xiv) x+1/2, y1/2, z+1/2; (xv) x+1/2, y+1/2, z+1/2.
 

References

First citationAgilent (2013). CrysAlis PRO. Agilent Technologies Ltd, Yarnton, England.  Google Scholar
First citationArgyriou, D. N., Jorgensen, J. D., Hitterman, R. L., Hiroi, Z., Kobayashi, N. & Takano, M. (1995). Phys. Rev. B, 51, 8434–8437.  CrossRef Google Scholar
First citationClark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887–897.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationDolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationGrande, B. & Müller-Buschbaum, H. (1977). Z. Anorg. Allg. Chem. 429, 88–90.  CrossRef Google Scholar
First citationHiroi, Z., Kobayashi, N. & Takano, M. (1994). Nature, 371, 139–141.  CrossRef Google Scholar
First citationKohsaka, Y., Azuma, M., Yamada, I., Sasagawa, T., Hanaguri, T., Takano, M. & Takagi, H. (2002). J. Am. Chem. Soc. 124, 12275–12278.  CrossRef Google Scholar
First citationMomma, K. & Izumi, F. (2011). J. Appl. Cryst. 44, 1272–1276.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationMüller-Buschbaum, H. (1977). Angew. Chem. Int. Ed. Engl. 16, 674–687.  Google Scholar
First citationRaveau, B., Michel, C., Hervieu, M. & Groult, D. (1991). Crystal Chemistry of High-Tc Superconducting Copper Oxides. Berlin: Springer Verlag.  Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationYamada, I., Belik, A. A., Azuma, M., Harjo, S., Kamiyama, T., Shimakawa, Y. & Takano, M. (2005). Phys. Rev. B, 72, 224503, 1–5.  Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoIUCrDATA
ISSN: 2414-3146
Follow IUCr Journals
Sign up for e-alerts
Follow IUCr on Twitter
Follow us on facebook
Sign up for RSS feeds