Disordered La₃Cu_4.88Se₇

The crystal structure of copper(I) lanthanum selenide, La₃Cu_4.88Se₇, obtained from the La₂Se₃-Cu₂Se quasi-binary system, has been investigated using X-ray single-crystal diffraction. The positions of the La and Se atoms are ordered and lie on mirror planes, whereas all positions for the Cu atoms are partially occupied. The crystal is built from edge-sharing [LaSe₆] and [LaSe₇] polyhedra. The five positions for the Cu atoms determine an ionic diffusion pathway in the structure.

S1. Comment

The design of functional materials with increasingly complex compositions has become a primary direction in modern science and technology. Among multicomponent systems much attention has been paid to complex rare-earth-based chalcogenides, owing to their specific thermal, electrical, magnetic and optical properties. An example is prospective applications of various chalcogenide materials in the field of infrared and nonlinear optics (Gulay & Daszkiewicz, 2011; Mitchell & Ibers, 2002).

So far, only La₅CuSe₈ and LaCuSe₂ have been synthesized from the La₂Se₃–Cu₂Se system (Julien-Pouzol & Guittard, 1968; Ijjaali et al., 2004) and been fully characterized. They crystallize in space groups I43d and P2₁/c, respectively. Julien-Pouzol & Guittard (1972) reported the existence of crystals of a compound with orthorhombic symmetry. Lattice parameters a = 7.74 Å, b = 24.67 Å, c = 7.01 Å were determined using the Weissenberg method and a formula La₅Cu₁₃Se₁₄ was proposed. However, its crystal structure was never reported until now.

The asymmetric unit of La₃Cu_4.88Se₇ contains two La sites, five Cu sites and four Se sites. The site of each copper atom is partially occupied. The non-stoichiometry here can be explained by the presence of mixed-valence Cu^I/Cu^II. The La1 and Se2 atoms lie on a mirror plane. Each of the formally La^III and Cu atoms is surrounded by four Se^2– anions at distances that agree well with the sum of the respective ionic radii (Wiberg, 1995). The selenium atoms form a distorted trigonal prism around the La1 atom and a distorted mono-capped trigonal prism around the La2 atom. Two trigonal prisms centred by La1 are surrounded on two sides by two mono-capped trigonal prisms centred by La2. These six trigonal prisms (2La1 + 4La2) form a large structural building block [La₆Se₂₈] which is related by inversion (Fig. 1). Since each lanthanum atom is connected to the adjacent lanthanum atom by two bridging selenium atoms, the crystal lattice is built by the edge-sharing [LaSe₆] and [LaSe₇] polyhedra. On the other hand, the Se atoms exhibit distorted tetrahedral coordination around the Cu1 to Cu4 atoms. The remaining Cu5 atom has triangular surroundings and it is located very close to the plane built by three Se atoms.

Overall, the crystal structure of La₃Cu_4.88Se₇ is structurally related to Pt₃Sr₇ (Fornasini & Palenzona, 1983; ICSD, 2010) (Fig. 1). In Pt₃Sr₇, the Pt1 atom is surrounded by seven Sr atoms which form a mono-capped trigonal prism [PtSr₇], and each Pt2 atom is surrounded by six Sr atoms which form a trigonal prism [PtSr₆]. Those polyhedra are connected to each other by edges creating a Pt₆Sr₂₈ building block. Since the position of platinum and strontium atoms corresponds to the position of lanthanum and selenium ions in the title compound, an identical building block of [La₆Se₂₈] exists in La₃Cu_4.88Se₇. Furthermore, since this building block is created by edge-sharing polyhedra, voids exist inside the block near the faces of [LaSe₆] and [LaSe₇] polyhedra. These voids are filled by the copper ions, because Cu⁺ has a relatively small ionic radius and the [La₆Se₂₈] building block is deficient in positive charge. So it appears that the role of voids in the stiff structural base of [La₆Se₂₈] is as important as the copper ions occupying disordered positions (Gulay & Daszkiewicz, 2011).

From the bond-valence-sum (BVS) point of view, the five copper ions are overbonded, because the BVS for these ions is greater than the formal oxidation state, +1 (Table 1) (Brown, 1996). These values remain greater than 1 even if the longest Cu–Se distance is not taken into the calculation of BVS for Cu1–Cu4. In the case of Cu5, BVS is less than 1 for two coordination spheres. However, the longest Cu–Se distance for each copper position should have to be included in the coordination sphere, because the longest Cu–Se distance still contributes 0.198 (for Cu4)–0.396 (for Cu5) of a valence unit. All the copper positions create a ring with the nearest copper–copper distances falling within the range 1.148 (11) (for Cu1–Cu2)–2.557 (10) Å [for Cu1–Cu5ⁱ; symmetry code: (i) 1/2+x, y, 3/2–z] (Fig. 2). The total occupation of the copper in the ring is 8.0 over 18 positions. The adjacent rings are joined together forming a ribbon along the a axis. The longest copper–copper distance along this direction corresponds to the longest distance in the ring, 2.557 (10) Å (for Cu1–Cu5ⁱ). The ribbon is transformed by the inversion and the shortest interribbon distance is 3.311 (6) Å [for Cu5ⁱ–Cu5^iv symmetry code: (iv) 3/2–x, 1–y, z-1/2] (Fig. 2). If the copper ions move through the Cu1–Cu5 positions, the intra-ring (Cu1–Cu5) and interribbon (Cu5–Cu5) distances appear to play an important role in ionic diffusion. If the energy barriers associated with these distances are overcome, ionic condctivity of the La₃Cu_4.88Se₇ compound will be observed.

Related literature

For related literature, see: Brown (1996); Fornasini & Palenzona (1983); Gulay & Daszkiewicz (2011); Ijjaali et al. (2004); Julien-Pouzol & Guittard (1968); Julien-Pouzol & Guittard (1972); Julien-Pouzol et al. (1985); Mitchell & Ibers (2002); Sheldrick (2008); Spek (2009); Wiberg (1995).

S2. Experimental

The sample of composition La₃Cu_4.88Se₇ was prepared by melting of high-purity (better than 99.9 wt%) elements in an evacuated silica tube. The ampoule was heated at a rate of 30 K h^-1 in a tube furnace to a temperature of 1420 K and kept at this temperature for 3 h. Afterwards the ampoule was cooled slowly (at a rate of 10 K h^-1) to 870 K and annealed at this temperature for 720 h. After annealing, the sample was quenched in air. A diffraction-quality single crystal was selected from the sample.

S3. Refinement

Two positions for La, six for Cu and four for Se were determined. The site-occupancy factor for each Cu position was refined as a free parameter. Attempts to use a SUMP restraint to make the total number of Cu atoms integral always resulted in non-positive definite anisotropic displacement parameters. The structure was checked with PLATON (Spek, 2009) and no additional symmetry elements were found.

Computing details

Data collection: CrysAlis (Oxford Diffraction, 2007); cell refinement: CrysAlis (Oxford Diffraction, 2007); data reduction: CrysAlis (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. The unit cell and coordination polyhedra (a) of the Pt and Sr atoms in Pt3Sr7 and (b) of the La^3+ and Cu^+ ions in La3Cu4.88Se7.
	Fig. 2. Diffusion pathway of the copper ions in La3Cu4.88Se7. [Symmetry codes: (i) x + 1/2, y, -z + 3/2; (ii) x + 1/2, -y + 1/2, -z + 3/2; (iii) x, -y+1/2, z; (iv) -x+3/2, -y+1, z-1/2.]

trilanthanum pentacopper heptaselenide

Crystal data

La3Cu4.88Se7	F(000) = 2202
Mr = 1279.53	Dx = 6.516 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 1058 reflections
a = 7.6785 (11) Å	θ = 3.1–27.5°
b = 24.523 (3) Å	µ = 36.88 mm^−1
c = 6.9265 (10) Å	T = 295 K
V = 1304.3 (3) Å^3	Prism, black
Z = 4	0.06 × 0.06 × 0.03 mm

Data collection

Kuma KM-4 with CCD area-detector diffractometer	1518 independent reflections
Radiation source: fine-focus sealed tube	1058 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.102
Detector resolution: 1024x1024 with blocks 2x2, 33.133pixel/mm pixels mm^-1	θmax = 27.5°, θmin = 3.1°
ω scans	h = −9→9
Absorption correction: numerical (CrysAlis; Oxford Diffraction, 2007)	k = −31→31
Tmin = 0.110, Tmax = 0.384	l = −8→8
13882 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.041	Secondary atom site location: difference Fourier map
wR(F^2) = 0.051	w = 1/[σ^2(Fo^2) + (0.005P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
1518 reflections	Δρmax = 2.36 e Å^−3
99 parameters	Δρmin = −1.56 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
La1	0.46018 (11)	0.2500	0.06060 (14)	0.0154 (2)
La2	0.86253 (8)	0.40400 (3)	0.06238 (10)	0.01810 (18)
Se1	0.15956 (14)	0.32583 (4)	0.17598 (15)	0.0136 (3)
Se2	0.80196 (18)	0.2500	0.8402 (2)	0.0162 (4)
Se3	0.52329 (13)	0.38421 (5)	0.84856 (16)	0.0194 (3)
Se4	0.18567 (14)	0.47656 (5)	0.13470 (16)	0.0194 (3)
Cu1	0.7505 (11)	0.4402 (6)	0.6517 (14)	0.051 (5)	0.215 (8)
Cu2	0.7424 (5)	0.3983 (3)	0.5779 (8)	0.027 (2)	0.347 (7)
Cu3	0.7208 (4)	0.33687 (14)	0.6662 (4)	0.0287 (14)	0.469 (5)
Cu4	0.5874 (4)	0.29581 (15)	0.6447 (4)	0.0393 (14)	0.528 (5)
Cu5	0.5543 (3)	0.47845 (8)	0.7816 (4)	0.0741 (13)	0.880 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
La1	0.0105 (5)	0.0224 (6)	0.0133 (5)	0.000	−0.0013 (4)	0.000
La2	0.0130 (3)	0.0206 (4)	0.0207 (4)	0.0000 (3)	−0.0009 (3)	0.0014 (4)
Se1	0.0117 (5)	0.0149 (6)	0.0141 (6)	−0.0003 (5)	−0.0005 (5)	−0.0004 (5)
Se2	0.0104 (9)	0.0235 (11)	0.0146 (9)	0.000	0.0024 (7)	0.000
Se3	0.0171 (6)	0.0219 (7)	0.0192 (7)	−0.0042 (5)	−0.0054 (5)	0.0033 (5)
Se4	0.0151 (6)	0.0175 (7)	0.0257 (7)	0.0003 (5)	−0.0050 (5)	0.0003 (5)
Cu1	0.052 (6)	0.070 (11)	0.032 (6)	0.011 (5)	−0.022 (4)	0.006 (6)
Cu2	0.015 (2)	0.040 (5)	0.027 (3)	0.004 (2)	−0.006 (2)	0.000 (3)
Cu3	0.031 (2)	0.036 (3)	0.019 (2)	0.0141 (16)	0.0021 (15)	−0.0061 (16)
Cu4	0.024 (2)	0.069 (3)	0.025 (2)	0.0088 (17)	0.0080 (13)	0.0242 (18)
Cu5	0.0709 (18)	0.0292 (16)	0.122 (2)	−0.0232 (12)	−0.0733 (16)	0.0306 (14)

Geometric parameters (Å, º)

La1—Se1^i	3.0217 (13)	Se3—La2^xiv	3.0354 (12)
La1—Se1^ii	3.0217 (13)	Se3—La2^iii	3.1403 (13)
La1—Se2^iii	3.0306 (18)	Se4—Cu1^iii	2.232 (8)
La1—Se2^iv	3.0359 (17)	Se4—Cu5^xvi	2.354 (2)
La1—Se1^v	3.0700 (13)	Se4—Cu5^xvii	2.376 (2)
La1—Se1	3.0700 (13)	Se4—Cu2^iii	2.458 (5)
La1—Cu3^vi	3.222 (3)	Se4—Cu1^xvi	2.569 (15)
La1—Cu3^iii	3.222 (3)	Se4—La2^iii	3.0680 (14)
La1—Cu4^vii	3.243 (3)	Se4—La2^xi	3.0941 (13)
La1—Cu4^iv	3.243 (3)	Se4—La2^ix	3.2528 (13)
La1—Cu4^vi	3.388 (3)	Cu1—Cu2	1.148 (11)
La1—Cu4^iii	3.388 (3)	Cu1—Cu5	1.990 (11)
La2—Se3^iv	3.0354 (12)	Cu1—Se4^i	2.232 (8)
La2—Se1^i	3.0640 (13)	Cu1—Se3^xii	2.504 (10)
La2—Se4^i	3.0680 (13)	Cu1—Cu3	2.545 (15)
La2—Cu2^i	3.078 (4)	Cu1—Cu5^xii	2.557 (10)
La2—Se1^viii	3.0816 (13)	Cu1—Se4^xvi	2.569 (15)
La2—Se4^viii	3.0941 (13)	Cu1—La2^xiv	3.101 (8)
La2—Cu1^iv	3.101 (8)	Cu1—La2^iii	3.444 (10)
La2—Se3^i	3.1403 (13)	Cu2—Cu3	1.635 (7)
La2—Se4^ix	3.2528 (13)	Cu2—Se3^xii	2.243 (4)
La2—Cu5^x	3.320 (2)	Cu2—Se4^i	2.458 (5)
La2—Cu5^i	3.343 (2)	Cu2—Se1^i	2.580 (7)
La2—Cu3^iv	3.380 (3)	Cu2—Cu5	2.818 (7)
Se1—Cu4^iii	2.405 (3)	Cu2—Cu4	2.820 (7)
Se1—Cu3^iii	2.431 (3)	Cu2—La2^iii	3.078 (4)
Se1—Cu2^iii	2.580 (7)	Cu2—La2^xiv	3.483 (5)
Se1—La1^iii	3.0217 (13)	Cu3—Cu4	1.444 (4)
Se1—La2^iii	3.0640 (13)	Cu3—Se1^i	2.431 (3)
Se1—La2^xi	3.0816 (13)	Cu3—Se3^xii	2.599 (4)
Se2—Cu4^v	2.410 (3)	Cu3—La1^i	3.222 (3)
Se2—Cu4	2.410 (3)	Cu3—La2^xiv	3.380 (3)
Se2—Cu4^xii	2.465 (3)	Cu3—La2^iii	3.576 (3)
Se2—Cu4^xiii	2.465 (3)	Cu4—Cu4^v	2.247 (7)
Se2—Cu3^v	2.526 (3)	Cu4—Se1^i	2.405 (3)
Se2—Cu3	2.526 (3)	Cu4—Se2^xv	2.465 (3)
Se2—La1^i	3.0306 (18)	Cu4—La1^xiv	3.243 (3)
Se2—La1^xiv	3.0359 (17)	Cu4—La1^i	3.388 (3)
Se3—Cu2^xv	2.243 (4)	Cu4—La2^iii	3.476 (3)
Se3—Cu3	2.290 (3)	Cu5—Se4^xvi	2.354 (2)
Se3—Cu5	2.369 (2)	Cu5—Se4^xviii	2.376 (2)
Se3—Cu1^xv	2.504 (10)	Cu5—Cu1^xv	2.557 (10)
Se3—Cu2	2.543 (5)	Cu5—Cu5^xix	3.311 (6)
Se3—Cu3^xv	2.599 (4)	Cu5—La2^xx	3.320 (2)
Se3—Cu1	2.605 (10)	Cu5—La2^iii	3.343 (2)
Se3—Cu4	2.634 (4)	Cu5—La2^xiv	3.566 (2)
Se1^i—La1—Se1^ii	75.96 (5)	Cu1^xvi—Se4—La2^iii	89.0 (2)
Se1^i—La1—Se2^iii	139.14 (3)	Cu1^iii—Se4—La2^xi	78.7 (3)
Se1^ii—La1—Se2^iii	139.14 (3)	Cu5^xvi—Se4—La2^xi	171.77 (7)
Se1^i—La1—Se2^iv	82.28 (4)	Cu5^xvii—Se4—La2^xi	73.42 (6)
Se1^ii—La1—Se2^iv	82.28 (4)	Cu2^iii—Se4—La2^xi	66.19 (10)
Se2^iii—La1—Se2^iv	83.45 (3)	Cu1^xvi—Se4—La2^xi	134.7 (2)
Se1^i—La1—Se1^v	126.62 (4)	La2^iii—Se4—La2^xi	97.59 (4)
Se1^ii—La1—Se1^v	81.43 (3)	Cu1^iii—Se4—La2^ix	90.7 (4)
Se2^iii—La1—Se1^v	86.39 (4)	Cu5^xvi—Se4—La2^ix	77.16 (6)
Se2^iv—La1—Se1^v	141.34 (3)	Cu5^xvii—Se4—La2^ix	70.94 (6)
Se1^i—La1—Se1	81.43 (3)	Cu2^iii—Se4—La2^ix	118.14 (17)
Se1^ii—La1—Se1	126.62 (4)	Cu1^xvi—Se4—La2^ix	63.1 (2)
Se2^iii—La1—Se1	86.39 (4)	La2^iii—Se4—La2^ix	149.28 (4)
Se2^iv—La1—Se1	141.34 (3)	La2^xi—Se4—La2^ix	111.02 (4)
Se1^v—La1—Se1	74.56 (5)	Cu2—Cu1—Cu5	125.6 (7)
Se1^i—La1—Cu3^vi	171.95 (7)	Cu2—Cu1—Se4^i	87.1 (6)
Se1^ii—La1—Cu3^vi	100.17 (7)	Cu5—Cu1—Se4^i	92.6 (4)
Se2^iii—La1—Cu3^vi	47.53 (6)	Cu2—Cu1—Se3^xii	63.6 (5)
Se2^iv—La1—Cu3^vi	104.36 (7)	Cu5—Cu1—Se3^xii	153.1 (4)
Se1^v—La1—Cu3^vi	45.38 (6)	Se4^i—Cu1—Se3^xii	113.9 (4)
Se1—La1—Cu3^vi	95.65 (7)	Cu2—Cu1—Cu3	28.7 (4)
Se1^i—La1—Cu3^iii	100.17 (7)	Cu5—Cu1—Cu3	112.6 (4)
Se1^ii—La1—Cu3^iii	171.95 (7)	Se4^i—Cu1—Cu3	114.4 (5)
Se2^iii—La1—Cu3^iii	47.53 (6)	Se3^xii—Cu1—Cu3	61.9 (3)
Se2^iv—La1—Cu3^iii	104.36 (7)	Cu2—Cu1—Cu5^xii	117.2 (6)
Se1^v—La1—Cu3^iii	95.65 (7)	Cu5—Cu1—Cu5^xii	115.8 (6)
Se1—La1—Cu3^iii	45.38 (6)	Se4^i—Cu1—Cu5^xii	102.5 (4)
Cu3^vi—La1—Cu3^iii	82.76 (13)	Se3^xii—Cu1—Cu5^xii	55.82 (17)
Se1^i—La1—Cu4^vii	126.65 (6)	Cu3—Cu1—Cu5^xii	116.1 (4)
Se1^ii—La1—Cu4^vii	99.82 (7)	Cu2—Cu1—Se4^xvi	167.7 (6)
Se2^iii—La1—Cu4^vii	46.13 (6)	Cu5—Cu1—Se4^xvi	60.6 (4)
Se2^iv—La1—Cu4^vii	45.00 (6)	Se4^i—Cu1—Se4^xvi	103.7 (5)
Se1^v—La1—Cu4^vii	104.36 (6)	Se3^xii—Cu1—Se4^xvi	106.0 (3)
Se1—La1—Cu4^vii	131.89 (7)	Cu3—Cu1—Se4^xvi	141.8 (4)
Cu3^vi—La1—Cu4^vii	60.65 (7)	Cu5^xii—Cu1—Se4^xvi	55.2 (3)
Cu3^iii—La1—Cu4^vii	88.16 (9)	Cu2—Cu1—Se3	74.1 (6)
Se1^i—La1—Cu4^iv	99.82 (7)	Cu5—Cu1—Se3	60.3 (2)
Se1^ii—La1—Cu4^iv	126.65 (6)	Se4^i—Cu1—Se3	121.8 (4)
Se2^iii—La1—Cu4^iv	46.13 (6)	Se3^xii—Cu1—Se3	105.8 (4)
Se2^iv—La1—Cu4^iv	45.00 (6)	Cu3—Cu1—Se3	52.8 (3)
Se1^v—La1—Cu4^iv	131.89 (7)	Cu5^xii—Cu1—Se3	135.2 (3)
Se1—La1—Cu4^iv	104.36 (6)	Se4^xvi—Cu1—Se3	104.2 (4)
Cu3^vi—La1—Cu4^iv	88.16 (9)	Cu2—Cu1—La2^xiv	99.6 (6)
Cu3^iii—La1—Cu4^iv	60.65 (7)	Cu5—Cu1—La2^xiv	86.0 (3)
Cu4^vii—La1—Cu4^iv	40.54 (13)	Se4^i—Cu1—La2^xiv	172.6 (6)
Se1^i—La1—Cu4^vi	152.32 (7)	Se3^xii—Cu1—La2^xiv	67.17 (19)
Se1^ii—La1—Cu4^vi	118.52 (6)	Cu3—Cu1—La2^xiv	72.8 (2)
Se2^iii—La1—Cu4^vi	43.68 (5)	Cu5^xii—Cu1—La2^xiv	71.7 (2)
Se2^iv—La1—Cu4^vi	121.29 (6)	Se4^xvi—Cu1—La2^xiv	69.3 (2)
Se1^v—La1—Cu4^vi	43.38 (5)	Se3—Cu1—La2^xiv	63.58 (19)
Se1—La1—Cu4^vi	71.03 (7)	Cu2—Cu1—La2^iii	62.1 (4)
Cu3^vi—La1—Cu4^vi	25.07 (8)	Cu5—Cu1—La2^iii	70.2 (2)
Cu3^iii—La1—Cu4^vi	62.14 (10)	Se4^i—Cu1—La2^iii	61.8 (2)
Cu4^vii—La1—Cu4^vi	76.52 (5)	Se3^xii—Cu1—La2^iii	125.6 (5)
Cu4^iv—La1—Cu4^vi	89.80 (6)	Cu3—Cu1—La2^iii	71.5 (3)
Se1^i—La1—Cu4^iii	118.52 (6)	Cu5^xii—Cu1—La2^iii	164.1 (3)
Se1^ii—La1—Cu4^iii	152.32 (7)	Se4^xvi—Cu1—La2^iii	128.2 (4)
Se2^iii—La1—Cu4^iii	43.68 (5)	Se3—Cu1—La2^iii	60.7 (2)
Se2^iv—La1—Cu4^iii	121.29 (6)	La2^xiv—Cu1—La2^iii	124.1 (3)
Se1^v—La1—Cu4^iii	71.03 (7)	Cu1—Cu2—Cu3	131.5 (6)
Se1—La1—Cu4^iii	43.38 (5)	Cu1—Cu2—Se3^xii	89.2 (5)
Cu3^vi—La1—Cu4^iii	62.14 (10)	Cu3—Cu2—Se3^xii	82.6 (2)
Cu3^iii—La1—Cu4^iii	25.07 (8)	Cu1—Cu2—Se4^i	65.1 (5)
Cu4^vii—La1—Cu4^iii	89.80 (6)	Cu3—Cu2—Se4^i	157.8 (3)
Cu4^iv—La1—Cu4^iii	76.52 (5)	Se3^xii—Cu2—Se4^i	115.3 (2)
Cu4^vi—La1—Cu4^iii	38.73 (12)	Cu1—Cu2—Se3	80.2 (5)
Se3^iv—La2—Se1^i	75.64 (3)	Cu3—Cu2—Se3	62.07 (17)
Se3^iv—La2—Se4^i	92.67 (3)	Se3^xii—Cu2—Se3	116.62 (19)
Se1^i—La2—Se4^i	74.53 (3)	Se4^i—Cu2—Se3	115.5 (2)
Se3^iv—La2—Cu2^i	130.69 (9)	Cu1—Cu2—Se1^i	158.8 (5)
Se1^i—La2—Cu2^i	129.83 (14)	Cu3—Cu2—Se1^i	66.1 (3)
Se4^i—La2—Cu2^i	131.43 (10)	Se3^xii—Cu2—Se1^i	106.6 (2)
Se3^iv—La2—Se1^viii	131.32 (4)	Se4^i—Cu2—Se1^i	94.91 (17)
Se1^i—La2—Se1^viii	80.57 (3)	Se3—Cu2—Se1^i	104.21 (19)
Se4^i—La2—Se1^viii	120.91 (4)	Cu1—Cu2—Cu5	35.0 (5)
Cu2^i—La2—Se1^viii	49.54 (14)	Cu3—Cu2—Cu5	113.8 (2)
Se3^iv—La2—Se4^viii	149.22 (4)	Se3^xii—Cu2—Cu5	119.1 (3)
Se1^i—La2—Se4^viii	132.22 (4)	Se4^i—Cu2—Cu5	70.41 (17)
Se4^i—La2—Se4^viii	84.88 (3)	Se3—Cu2—Cu5	52.15 (12)
Cu2^i—La2—Se4^viii	46.93 (10)	Se1^i—Cu2—Cu5	134.05 (15)
Se1^viii—La2—Se4^viii	73.91 (3)	Cu1—Cu2—Cu4	138.3 (6)
Se3^iv—La2—Cu1^iv	50.22 (18)	Cu3—Cu2—Cu4	22.15 (15)
Se1^i—La2—Cu1^iv	125.5 (2)	Se3^xii—Cu2—Cu4	103.4 (2)
Se4^i—La2—Cu1^iv	109.8 (2)	Se4^i—Cu2—Cu4	136.0 (2)
Cu2^i—La2—Cu1^iv	89.22 (18)	Se3—Cu2—Cu4	58.56 (12)
Se1^viii—La2—Cu1^iv	128.1 (2)	Se1^i—Cu2—Cu4	52.66 (14)
Se4^viii—La2—Cu1^iv	101.9 (2)	Cu5—Cu2—Cu4	108.86 (15)
Se3^iv—La2—Se3^i	82.55 (2)	Cu1—Cu2—La2^iii	98.7 (5)
Se1^i—La2—Se3^i	129.74 (4)	Cu3—Cu2—La2^iii	93.6 (2)
Se4^i—La2—Se3^i	152.07 (4)	Se3^xii—Cu2—La2^iii	171.9 (3)
Cu2^i—La2—Se3^i	48.26 (9)	Se4^i—Cu2—La2^iii	66.88 (10)
Se1^viii—La2—Se3^i	81.05 (3)	Se3—Cu2—La2^iii	67.15 (9)
Se4^viii—La2—Se3^i	85.43 (3)	Se1^i—Cu2—La2^iii	65.31 (12)
Cu1^iv—La2—Se3^i	47.3 (2)	Cu5—Cu2—La2^iii	68.93 (10)
Se3^iv—La2—Se4^ix	80.89 (3)	Cu4—Cu2—La2^iii	72.07 (13)
Se1^i—La2—Se4^ix	138.92 (4)	Cu1—Cu2—La2^xiv	61.4 (5)
Se4^i—La2—Se4^ix	73.40 (2)	Cu3—Cu2—La2^xiv	72.8 (2)
Cu2^i—La2—Se4^ix	90.92 (14)	Se3^xii—Cu2—La2^xiv	62.15 (12)
Se1^viii—La2—Se4^ix	138.73 (3)	Se4^i—Cu2—La2^xiv	126.4 (3)
Se4^viii—La2—Se4^ix	68.98 (4)	Se3—Cu2—La2^xiv	58.02 (11)
Cu1^iv—La2—Se4^ix	47.6 (3)	Se1^i—Cu2—La2^xiv	138.6 (2)
Se3^i—La2—Se4^ix	78.67 (4)	Cu5—Cu2—La2^xiv	68.01 (14)
Se3^iv—La2—Cu5^x	121.81 (5)	Cu4—Cu2—La2^xiv	89.39 (13)
Se1^i—La2—Cu5^x	111.75 (5)	La2^iii—Cu2—La2^xiv	123.60 (15)
Se4^i—La2—Cu5^x	43.02 (4)	Cu4—Cu3—Cu2	132.6 (3)
Cu2^i—La2—Cu5^x	90.08 (11)	Cu4—Cu3—Se3	86.61 (19)
Se1^viii—La2—Cu5^x	106.31 (6)	Cu2—Cu3—Se3	78.8 (2)
Se4^viii—La2—Cu5^x	43.31 (4)	Cu4—Cu3—Se1^i	71.62 (17)
Cu1^iv—La2—Cu5^x	103.0 (3)	Cu2—Cu3—Se1^i	76.0 (2)
Se3^i—La2—Cu5^x	118.24 (5)	Se3—Cu3—Se1^i	117.79 (13)
Se4^ix—La2—Cu5^x	55.39 (5)	Cu4—Cu3—Se2	68.65 (18)
Se3^iv—La2—Cu5^i	96.75 (5)	Cu2—Cu3—Se2	158.6 (2)
Se1^i—La2—Cu5^i	170.81 (5)	Se3—Cu3—Se2	109.13 (13)
Se4^i—La2—Cu5^i	111.44 (5)	Se1^i—Cu3—Se2	114.78 (13)
Cu2^i—La2—Cu5^i	51.86 (14)	Cu4—Cu3—Cu1	138.9 (3)
Se1^viii—La2—Cu5^i	101.29 (5)	Cu2—Cu3—Cu1	19.7 (2)
Se4^viii—La2—Cu5^i	56.51 (5)	Se3—Cu3—Cu1	64.9 (2)
Cu1^iv—La2—Cu5^i	46.56 (19)	Se1^i—Cu3—Cu1	95.2 (2)
Se3^i—La2—Cu5^i	42.72 (4)	Se2—Cu3—Cu1	146.7 (2)
Se4^ix—La2—Cu5^i	42.20 (4)	Cu4—Cu3—Se3^xii	160.3 (2)
Cu5^x—La2—Cu5^i	76.53 (7)	Cu2—Cu3—Se3^xii	58.84 (17)
Se3^iv—La2—Cu3^iv	41.39 (5)	Se3—Cu3—Se3^xii	112.78 (14)
Se1^i—La2—Cu3^iv	90.67 (7)	Se1^i—Cu3—Se3^xii	100.62 (12)
Se4^i—La2—Cu3^iv	134.04 (6)	Se2—Cu3—Se3^xii	100.08 (11)
Cu2^i—La2—Cu3^iv	91.53 (10)	Cu1—Cu3—Se3^xii	58.3 (2)
Se1^viii—La2—Cu3^iv	98.20 (6)	Cu4—Cu3—La1^i	83.87 (18)
Se4^viii—La2—Cu3^iv	132.05 (7)	Cu2—Cu3—La1^i	111.7 (2)
Cu1^iv—La2—Cu3^iv	46.0 (3)	Se3—Cu3—La1^i	169.07 (16)
Se3^i—La2—Cu3^iv	46.80 (6)	Se1^i—Cu3—La1^i	63.99 (7)
Se4^ix—La2—Cu3^iv	93.51 (6)	Se2—Cu3—La1^i	62.25 (7)
Cu5^x—La2—Cu3^iv	148.89 (8)	Cu1—Cu3—La1^i	126.0 (2)
Cu5^i—La2—Cu3^iv	80.16 (7)	Se3^xii—Cu3—La1^i	76.49 (8)
Cu4^iii—Se1—Cu2^iii	68.78 (14)	Cu4—Cu3—La2^xiv	130.7 (2)
Cu4^iii—Se1—La1^iii	104.64 (9)	Cu2—Cu3—La2^xiv	79.7 (2)
Cu3^iii—Se1—La1^iii	139.03 (10)	Se3—Cu3—La2^xiv	61.21 (7)
Cu2^iii—Se1—La1^iii	163.84 (10)	Se1^i—Cu3—La2^xiv	155.21 (15)
Cu4^iii—Se1—La2^iii	148.76 (10)	Se2—Cu3—La2^xiv	86.78 (9)
Cu3^iii—Se1—La2^iii	114.11 (9)	Cu1—Cu3—La2^xiv	61.2 (2)
Cu2^iii—Se1—La2^iii	81.18 (10)	Se3^xii—Cu3—La2^xiv	61.74 (7)
La1^iii—Se1—La2^iii	106.59 (4)	La1^i—Cu3—La2^xiv	122.28 (10)
Cu4^iii—Se1—La1	75.36 (8)	Cu4—Cu3—La2^iii	74.33 (16)
Cu3^iii—Se1—La1	70.63 (8)	Cu2—Cu3—La2^iii	59.22 (16)
Cu2^iii—Se1—La1	93.12 (10)	Se3—Cu3—La2^iii	60.09 (7)
La1^iii—Se1—La1	99.52 (4)	Se1^i—Cu3—La2^iii	58.05 (7)
La2^iii—Se1—La1	98.66 (4)	Se2—Cu3—La2^iii	142.14 (13)
Cu4^iii—Se1—La2^xi	77.53 (8)	Cu1—Cu3—La2^iii	66.00 (19)
Cu3^iii—Se1—La2^xi	79.92 (8)	Se3^xii—Cu3—La2^iii	117.68 (12)
Cu2^iii—Se1—La2^xi	65.16 (9)	La1^i—Cu3—La2^iii	121.83 (9)
La1^iii—Se1—La2^xi	99.33 (4)	La2^xiv—Cu3—La2^iii	112.52 (9)
La2^iii—Se1—La2^xi	97.95 (4)	Cu3—Cu4—Cu4^v	134.22 (17)
La1—Se1—La2^xi	150.09 (4)	Cu3—Cu4—Se1^i	73.64 (17)
Cu4^v—Se2—Cu4	55.56 (18)	Cu4^v—Cu4—Se1^i	107.83 (9)
Cu4^v—Se2—Cu4^xii	147.54 (8)	Cu3—Cu4—Se2	77.44 (17)
Cu4—Se2—Cu4^xii	114.78 (14)	Cu4^v—Cu4—Se2	62.22 (9)
Cu4^v—Se2—Cu4^xiii	114.78 (14)	Se1^i—Cu4—Se2	120.29 (12)
Cu4—Se2—Cu4^xiii	147.54 (8)	Cu3—Cu4—Se2^xv	160.7 (2)
Cu4^xii—Se2—Cu4^xiii	54.21 (16)	Cu4^v—Cu4—Se2^xv	62.89 (8)
Cu4—Se2—Cu3^v	87.49 (14)	Se1^i—Cu4—Se2^xv	112.54 (12)
Cu4^xii—Se2—Cu3^v	128.60 (11)	Se2—Cu4—Se2^xv	111.81 (12)
Cu4^xiii—Se2—Cu3^v	81.68 (12)	Cu3—Cu4—Se3	60.22 (17)
Cu4^v—Se2—Cu3	87.49 (14)	Cu4^v—Cu4—Se3	145.40 (7)
Cu4^xii—Se2—Cu3	81.68 (12)	Se1^i—Cu4—Se3	106.64 (13)
Cu4^xiii—Se2—Cu3	128.60 (11)	Se2—Cu4—Se3	102.13 (12)
Cu3^v—Se2—Cu3	115.00 (16)	Se2^xv—Cu4—Se3	100.72 (10)
Cu4^v—Se2—La1^i	76.06 (8)	Cu3—Cu4—Cu2	25.27 (16)
Cu4—Se2—La1^i	76.06 (8)	Cu4^v—Cu4—Cu2	153.08 (12)
Cu4^xii—Se2—La1^i	71.48 (7)	Se1^i—Cu4—Cu2	58.56 (14)
Cu4^xiii—Se2—La1^i	71.48 (7)	Se2—Cu4—Cu2	102.66 (14)
Cu3^v—Se2—La1^i	70.22 (7)	Se2^xv—Cu4—Cu2	142.04 (15)
Cu3—Se2—La1^i	70.22 (7)	Se3—Cu4—Cu2	55.46 (14)
Cu4^v—Se2—La1^xiv	72.05 (8)	Cu3—Cu4—La1^xiv	111.3 (2)
Cu4—Se2—La1^xiv	72.05 (8)	Cu4^v—Cu4—La1^xiv	69.73 (6)
Cu4^xii—Se2—La1^xiv	138.36 (8)	Se1^i—Cu4—La1^xiv	174.90 (14)
Cu4^xiii—Se2—La1^xiv	138.36 (8)	Se2—Cu4—La1^xiv	62.95 (7)
Cu3^v—Se2—La1^xiv	91.53 (8)	Se2^xv—Cu4—La1^xiv	62.40 (7)
Cu3—Se2—La1^xiv	91.53 (8)	Se3—Cu4—La1^xiv	75.67 (7)
La1^i—Se2—La1^xiv	143.81 (6)	Cu2—Cu4—La1^xiv	125.57 (16)
Cu2^xv—Se3—Cu3	147.17 (16)	Cu3—Cu4—La1^i	71.06 (15)
Cu2^xv—Se3—Cu5	89.45 (19)	Cu4^v—Cu4—La1^i	70.63 (6)
Cu3—Se3—Cu5	108.67 (12)	Se1^i—Cu4—La1^i	61.26 (7)
Cu3—Se3—Cu1^xv	146.2 (2)	Se2—Cu4—La1^i	60.26 (7)
Cu5—Se3—Cu1^xv	63.2 (3)	Se2^xv—Cu4—La1^i	128.16 (13)
Cu2^xv—Se3—Cu2	141.51 (18)	Se3—Cu4—La1^i	131.00 (12)
Cu5—Se3—Cu2	69.91 (17)	Cu2—Cu4—La1^i	82.54 (12)
Cu1^xv—Se3—Cu2	118.6 (3)	La1^xiv—Cu4—La1^i	120.84 (9)
Cu3—Se3—Cu3^xv	110.11 (13)	Cu3—Cu4—La2^iii	82.10 (18)
Cu5—Se3—Cu3^xv	121.18 (9)	Cu4^v—Cu4—La2^iii	139.76 (6)
Cu1^xv—Se3—Cu3^xv	59.8 (3)	Se1^i—Cu4—La2^iii	59.97 (7)
Cu2—Se3—Cu3^xv	128.56 (16)	Se2—Cu4—La2^iii	158.01 (15)
Cu2^xv—Se3—Cu1	133.0 (4)	Se2^xv—Cu4—La2^iii	85.61 (8)
Cu3—Se3—Cu1	62.3 (3)	Se3—Cu4—La2^iii	60.00 (7)
Cu5—Se3—Cu1	46.9 (3)	Cu2—Cu4—La2^iii	57.41 (10)
Cu1^xv—Se3—Cu1	105.7 (5)	La1^xiv—Cu4—La2^iii	118.77 (9)
Cu3^xv—Se3—Cu1	144.4 (2)	La1^i—Cu4—La2^iii	119.98 (8)
Cu2^xv—Se3—Cu4	115.37 (16)	Cu1—Cu5—Se4^xvi	72.0 (4)
Cu5—Se3—Cu4	132.79 (11)	Cu1—Cu5—Se3	72.8 (4)
Cu1^xv—Se3—Cu4	127.4 (2)	Se4^xvi—Cu5—Se3	119.61 (9)
Cu2—Se3—Cu4	65.98 (18)	Cu1—Cu5—Se4^xviii	127.8 (3)
Cu3^xv—Se3—Cu4	77.19 (10)	Se4^xvi—Cu5—Se4^xviii	123.06 (10)
Cu1—Se3—Cu4	91.6 (3)	Se3—Cu5—Se4^xviii	117.32 (8)
Cu2^xv—Se3—La2^xiv	133.61 (13)	Cu1—Cu5—Cu1^xv	126.8 (6)
Cu3—Se3—La2^xiv	77.40 (9)	Se4^xvi—Cu5—Cu1^xv	154.4 (2)
Cu5—Se3—La2^xiv	81.57 (5)	Se3—Cu5—Cu1^xv	61.0 (3)
Cu1^xv—Se3—La2^xiv	129.1 (2)	Se4^xviii—Cu5—Cu1^xv	62.6 (3)
Cu2—Se3—La2^xiv	76.70 (11)	Cu1—Cu5—Cu2	19.3 (3)
Cu3^xv—Se3—La2^xiv	149.05 (8)	Se4^xvi—Cu5—Cu2	90.87 (13)
Cu1—Se3—La2^xiv	66.20 (19)	Se3—Cu5—Cu2	57.93 (12)
Cu4—Se3—La2^xiv	103.46 (7)	Se4^xviii—Cu5—Cu2	120.46 (13)
Cu2^xv—Se3—La2^iii	78.69 (15)	Cu1^xv—Cu5—Cu2	107.6 (3)
Cu3—Se3—La2^iii	80.71 (9)	Cu1—Cu5—La2^xx	93.3 (3)
Cu5—Se3—La2^iii	73.22 (6)	Se4^xvi—Cu5—La2^xx	62.77 (5)
Cu1^xv—Se3—La2^iii	65.5 (2)	Se3—Cu5—La2^xx	162.89 (12)
Cu2—Se3—La2^iii	64.59 (10)	Se4^xviii—Cu5—La2^xx	63.27 (5)
Cu3^xv—Se3—La2^iii	71.46 (7)	Cu1^xv—Cu5—La2^xx	125.2 (3)
Cu1—Se3—La2^iii	72.99 (19)	Cu2—Cu5—La2^xx	106.13 (13)
Cu4—Se3—La2^iii	73.43 (7)	Cu1—Cu5—La2^iii	75.7 (3)
La2^xiv—Se3—La2^iii	139.01 (4)	Se4^xvi—Cu5—La2^iii	143.61 (12)
Cu1^iii—Se4—Cu5^xvi	102.5 (3)	Se3—Cu5—La2^iii	64.06 (5)
Cu1^iii—Se4—Cu5^xvii	137.7 (2)	Se4^xviii—Cu5—La2^iii	66.86 (5)
Cu5^xvi—Se4—Cu5^xvii	109.55 (8)	Cu1^xv—Cu5—La2^iii	61.73 (19)
Cu5^xvi—Se4—Cu2^iii	111.29 (12)	Cu2—Cu5—La2^iii	59.21 (11)
Cu5^xvii—Se4—Cu2^iii	139.16 (11)	La2^xx—Cu5—La2^iii	103.47 (7)
Cu1^iii—Se4—Cu1^xvi	141.9 (3)	Cu1—Cu5—La2^xiv	60.2 (2)
Cu5^xvi—Se4—Cu1^xvi	47.44 (19)	Se4^xvi—Cu5—La2^xiv	62.78 (5)
Cu5^xvii—Se4—Cu1^xvi	62.12 (19)	Se3—Cu5—La2^xiv	57.35 (5)
Cu2^iii—Se4—Cu1^xvi	158.7 (2)	Se4^xviii—Cu5—La2^xiv	170.33 (11)
Cu1^iii—Se4—La2^iii	106.1 (3)	Cu1^xv—Cu5—La2^xiv	108.6 (3)
Cu5^xvi—Se4—La2^iii	74.21 (6)	Cu2—Cu5—La2^xiv	64.89 (10)
Cu5^xvii—Se4—La2^iii	108.63 (8)	La2^xx—Cu5—La2^xiv	124.48 (6)
Cu2^iii—Se4—La2^iii	83.03 (15)	La2^iii—Cu5—La2^xiv	113.66 (7)

Symmetry codes: (i) x+1/2, y, −z+1/2; (ii) x+1/2, −y+1/2, −z+1/2; (iii) x−1/2, y, −z+1/2; (iv) x, y, z−1; (v) x, −y+1/2, z; (vi) x−1/2, −y+1/2, −z+1/2; (vii) x, −y+1/2, z−1; (viii) x+1, y, z; (ix) −x+1, −y+1, −z; (x) −x+3/2, −y+1, z−1/2; (xi) x−1, y, z; (xii) x+1/2, y, −z+3/2; (xiii) x+1/2, −y+1/2, −z+3/2; (xiv) x, y, z+1; (xv) x−1/2, y, −z+3/2; (xvi) −x+1, −y+1, −z+1; (xvii) −x+1/2, −y+1, z−1/2; (xviii) −x+1/2, −y+1, z+1/2; (xix) −x+1, −y+1, −z+2; (xx) −x+3/2, −y+1, z+1/2.