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The crystal structure of copper(I) lanthanum selenide, La3Cu4.88Se7, 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.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270111005889/fn3073sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270111005889/fn3073Isup2.hkl
Contains datablock I

Comment top

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 La3Cu4.88Se7 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 CuI/CuII. The La1 and Se2 atoms lie on a mirror plane. Each of the formally LaIII and Cu atoms is surrounded by four Se2– 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 La3Cu4.88Se7 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 La3Cu4.88Se7. 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–Cu5iv 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 La3Cu4.88Se7 compound will be observed.

Related literature top

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).

Experimental top

The sample of composition La3Cu4.88Se7 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.

Refinement top

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 top

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 top
[Figure 1] Fig. 1. The unit cell and coordination polyhedra (a) of the Pt and Sr atoms in Pt3Sr7 and (b) of the La3+ and Cu+ ions in La3Cu4.88Se7.
[Figure 2] 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 top
Crystal data top
La3Cu4.88Se7F(000) = 2202
Mr = 1279.53Dx = 6.516 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 1058 reflections
a = 7.6785 (11) Åθ = 3.1–27.5°
b = 24.523 (3) ŵ = 36.88 mm1
c = 6.9265 (10) ÅT = 295 K
V = 1304.3 (3) Å3Prism, black
Z = 40.06 × 0.06 × 0.03 mm
Data collection top
Kuma KM-4 with CCD area-detector
diffractometer
1518 independent reflections
Radiation source: fine-focus sealed tube1058 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.102
Detector resolution: 1024x1024 with blocks 2x2, 33.133pixel/mm pixels mm-1θmax = 27.5°, θmin = 3.1°
ω scansh = 99
Absorption correction: numerical
(CrysAlis; Oxford Diffraction, 2007)
k = 3131
Tmin = 0.110, Tmax = 0.384l = 88
13882 measured reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.041Secondary atom site location: difference Fourier map
wR(F2) = 0.051 w = 1/[σ2(Fo2) + (0.005P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
1518 reflectionsΔρmax = 2.36 e Å3
99 parametersΔρmin = 1.56 e Å3
Crystal data top
La3Cu4.88Se7V = 1304.3 (3) Å3
Mr = 1279.53Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 7.6785 (11) ŵ = 36.88 mm1
b = 24.523 (3) ÅT = 295 K
c = 6.9265 (10) Å0.06 × 0.06 × 0.03 mm
Data collection top
Kuma KM-4 with CCD area-detector
diffractometer
1518 independent reflections
Absorption correction: numerical
(CrysAlis; Oxford Diffraction, 2007)
1058 reflections with I > 2σ(I)
Tmin = 0.110, Tmax = 0.384Rint = 0.102
13882 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.04199 parameters
wR(F2) = 0.0510 restraints
S = 1.01Δρmax = 2.36 e Å3
1518 reflectionsΔρmin = 1.56 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*/UeqOcc. (<1)
La10.46018 (11)0.25000.06060 (14)0.0154 (2)
La20.86253 (8)0.40400 (3)0.06238 (10)0.01810 (18)
Se10.15956 (14)0.32583 (4)0.17598 (15)0.0136 (3)
Se20.80196 (18)0.25000.8402 (2)0.0162 (4)
Se30.52329 (13)0.38421 (5)0.84856 (16)0.0194 (3)
Se40.18567 (14)0.47656 (5)0.13470 (16)0.0194 (3)
Cu10.7505 (11)0.4402 (6)0.6517 (14)0.051 (5)0.215 (8)
Cu20.7424 (5)0.3983 (3)0.5779 (8)0.027 (2)0.347 (7)
Cu30.7208 (4)0.33687 (14)0.6662 (4)0.0287 (14)0.469 (5)
Cu40.5874 (4)0.29581 (15)0.6447 (4)0.0393 (14)0.528 (5)
Cu50.5543 (3)0.47845 (8)0.7816 (4)0.0741 (13)0.880 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
La10.0105 (5)0.0224 (6)0.0133 (5)0.0000.0013 (4)0.000
La20.0130 (3)0.0206 (4)0.0207 (4)0.0000 (3)0.0009 (3)0.0014 (4)
Se10.0117 (5)0.0149 (6)0.0141 (6)0.0003 (5)0.0005 (5)0.0004 (5)
Se20.0104 (9)0.0235 (11)0.0146 (9)0.0000.0024 (7)0.000
Se30.0171 (6)0.0219 (7)0.0192 (7)0.0042 (5)0.0054 (5)0.0033 (5)
Se40.0151 (6)0.0175 (7)0.0257 (7)0.0003 (5)0.0050 (5)0.0003 (5)
Cu10.052 (6)0.070 (11)0.032 (6)0.011 (5)0.022 (4)0.006 (6)
Cu20.015 (2)0.040 (5)0.027 (3)0.004 (2)0.006 (2)0.000 (3)
Cu30.031 (2)0.036 (3)0.019 (2)0.0141 (16)0.0021 (15)0.0061 (16)
Cu40.024 (2)0.069 (3)0.025 (2)0.0088 (17)0.0080 (13)0.0242 (18)
Cu50.0709 (18)0.0292 (16)0.122 (2)0.0232 (12)0.0733 (16)0.0306 (14)
Geometric parameters (Å, º) top
La1—Se1i3.0217 (13)Se3—La2xiv3.0354 (12)
La1—Se1ii3.0217 (13)Se3—La2iii3.1403 (13)
La1—Se2iii3.0306 (18)Se4—Cu1iii2.232 (8)
La1—Se2iv3.0359 (17)Se4—Cu5xvi2.354 (2)
La1—Se1v3.0700 (13)Se4—Cu5xvii2.376 (2)
La1—Se13.0700 (13)Se4—Cu2iii2.458 (5)
La1—Cu3vi3.222 (3)Se4—Cu1xvi2.569 (15)
La1—Cu3iii3.222 (3)Se4—La2iii3.0680 (14)
La1—Cu4vii3.243 (3)Se4—La2xi3.0941 (13)
La1—Cu4iv3.243 (3)Se4—La2ix3.2528 (13)
La1—Cu4vi3.388 (3)Cu1—Cu21.148 (11)
La1—Cu4iii3.388 (3)Cu1—Cu51.990 (11)
La2—Se3iv3.0354 (12)Cu1—Se4i2.232 (8)
La2—Se1i3.0640 (13)Cu1—Se3xii2.504 (10)
La2—Se4i3.0680 (13)Cu1—Cu32.545 (15)
La2—Cu2i3.078 (4)Cu1—Cu5xii2.557 (10)
La2—Se1viii3.0816 (13)Cu1—Se4xvi2.569 (15)
La2—Se4viii3.0941 (13)Cu1—La2xiv3.101 (8)
La2—Cu1iv3.101 (8)Cu1—La2iii3.444 (10)
La2—Se3i3.1403 (13)Cu2—Cu31.635 (7)
La2—Se4ix3.2528 (13)Cu2—Se3xii2.243 (4)
La2—Cu5x3.320 (2)Cu2—Se4i2.458 (5)
La2—Cu5i3.343 (2)Cu2—Se1i2.580 (7)
La2—Cu3iv3.380 (3)Cu2—Cu52.818 (7)
Se1—Cu4iii2.405 (3)Cu2—Cu42.820 (7)
Se1—Cu3iii2.431 (3)Cu2—La2iii3.078 (4)
Se1—Cu2iii2.580 (7)Cu2—La2xiv3.483 (5)
Se1—La1iii3.0217 (13)Cu3—Cu41.444 (4)
Se1—La2iii3.0640 (13)Cu3—Se1i2.431 (3)
Se1—La2xi3.0816 (13)Cu3—Se3xii2.599 (4)
Se2—Cu4v2.410 (3)Cu3—La1i3.222 (3)
Se2—Cu42.410 (3)Cu3—La2xiv3.380 (3)
Se2—Cu4xii2.465 (3)Cu3—La2iii3.576 (3)
Se2—Cu4xiii2.465 (3)Cu4—Cu4v2.247 (7)
Se2—Cu3v2.526 (3)Cu4—Se1i2.405 (3)
Se2—Cu32.526 (3)Cu4—Se2xv2.465 (3)
Se2—La1i3.0306 (18)Cu4—La1xiv3.243 (3)
Se2—La1xiv3.0359 (17)Cu4—La1i3.388 (3)
Se3—Cu2xv2.243 (4)Cu4—La2iii3.476 (3)
Se3—Cu32.290 (3)Cu5—Se4xvi2.354 (2)
Se3—Cu52.369 (2)Cu5—Se4xviii2.376 (2)
Se3—Cu1xv2.504 (10)Cu5—Cu1xv2.557 (10)
Se3—Cu22.543 (5)Cu5—Cu5xix3.311 (6)
Se3—Cu3xv2.599 (4)Cu5—La2xx3.320 (2)
Se3—Cu12.605 (10)Cu5—La2iii3.343 (2)
Se3—Cu42.634 (4)Cu5—La2xiv3.566 (2)
Se1i—La1—Se1ii75.96 (5)Cu1xvi—Se4—La2iii89.0 (2)
Se1i—La1—Se2iii139.14 (3)Cu1iii—Se4—La2xi78.7 (3)
Se1ii—La1—Se2iii139.14 (3)Cu5xvi—Se4—La2xi171.77 (7)
Se1i—La1—Se2iv82.28 (4)Cu5xvii—Se4—La2xi73.42 (6)
Se1ii—La1—Se2iv82.28 (4)Cu2iii—Se4—La2xi66.19 (10)
Se2iii—La1—Se2iv83.45 (3)Cu1xvi—Se4—La2xi134.7 (2)
Se1i—La1—Se1v126.62 (4)La2iii—Se4—La2xi97.59 (4)
Se1ii—La1—Se1v81.43 (3)Cu1iii—Se4—La2ix90.7 (4)
Se2iii—La1—Se1v86.39 (4)Cu5xvi—Se4—La2ix77.16 (6)
Se2iv—La1—Se1v141.34 (3)Cu5xvii—Se4—La2ix70.94 (6)
Se1i—La1—Se181.43 (3)Cu2iii—Se4—La2ix118.14 (17)
Se1ii—La1—Se1126.62 (4)Cu1xvi—Se4—La2ix63.1 (2)
Se2iii—La1—Se186.39 (4)La2iii—Se4—La2ix149.28 (4)
Se2iv—La1—Se1141.34 (3)La2xi—Se4—La2ix111.02 (4)
Se1v—La1—Se174.56 (5)Cu2—Cu1—Cu5125.6 (7)
Se1i—La1—Cu3vi171.95 (7)Cu2—Cu1—Se4i87.1 (6)
Se1ii—La1—Cu3vi100.17 (7)Cu5—Cu1—Se4i92.6 (4)
Se2iii—La1—Cu3vi47.53 (6)Cu2—Cu1—Se3xii63.6 (5)
Se2iv—La1—Cu3vi104.36 (7)Cu5—Cu1—Se3xii153.1 (4)
Se1v—La1—Cu3vi45.38 (6)Se4i—Cu1—Se3xii113.9 (4)
Se1—La1—Cu3vi95.65 (7)Cu2—Cu1—Cu328.7 (4)
Se1i—La1—Cu3iii100.17 (7)Cu5—Cu1—Cu3112.6 (4)
Se1ii—La1—Cu3iii171.95 (7)Se4i—Cu1—Cu3114.4 (5)
Se2iii—La1—Cu3iii47.53 (6)Se3xii—Cu1—Cu361.9 (3)
Se2iv—La1—Cu3iii104.36 (7)Cu2—Cu1—Cu5xii117.2 (6)
Se1v—La1—Cu3iii95.65 (7)Cu5—Cu1—Cu5xii115.8 (6)
Se1—La1—Cu3iii45.38 (6)Se4i—Cu1—Cu5xii102.5 (4)
Cu3vi—La1—Cu3iii82.76 (13)Se3xii—Cu1—Cu5xii55.82 (17)
Se1i—La1—Cu4vii126.65 (6)Cu3—Cu1—Cu5xii116.1 (4)
Se1ii—La1—Cu4vii99.82 (7)Cu2—Cu1—Se4xvi167.7 (6)
Se2iii—La1—Cu4vii46.13 (6)Cu5—Cu1—Se4xvi60.6 (4)
Se2iv—La1—Cu4vii45.00 (6)Se4i—Cu1—Se4xvi103.7 (5)
Se1v—La1—Cu4vii104.36 (6)Se3xii—Cu1—Se4xvi106.0 (3)
Se1—La1—Cu4vii131.89 (7)Cu3—Cu1—Se4xvi141.8 (4)
Cu3vi—La1—Cu4vii60.65 (7)Cu5xii—Cu1—Se4xvi55.2 (3)
Cu3iii—La1—Cu4vii88.16 (9)Cu2—Cu1—Se374.1 (6)
Se1i—La1—Cu4iv99.82 (7)Cu5—Cu1—Se360.3 (2)
Se1ii—La1—Cu4iv126.65 (6)Se4i—Cu1—Se3121.8 (4)
Se2iii—La1—Cu4iv46.13 (6)Se3xii—Cu1—Se3105.8 (4)
Se2iv—La1—Cu4iv45.00 (6)Cu3—Cu1—Se352.8 (3)
Se1v—La1—Cu4iv131.89 (7)Cu5xii—Cu1—Se3135.2 (3)
Se1—La1—Cu4iv104.36 (6)Se4xvi—Cu1—Se3104.2 (4)
Cu3vi—La1—Cu4iv88.16 (9)Cu2—Cu1—La2xiv99.6 (6)
Cu3iii—La1—Cu4iv60.65 (7)Cu5—Cu1—La2xiv86.0 (3)
Cu4vii—La1—Cu4iv40.54 (13)Se4i—Cu1—La2xiv172.6 (6)
Se1i—La1—Cu4vi152.32 (7)Se3xii—Cu1—La2xiv67.17 (19)
Se1ii—La1—Cu4vi118.52 (6)Cu3—Cu1—La2xiv72.8 (2)
Se2iii—La1—Cu4vi43.68 (5)Cu5xii—Cu1—La2xiv71.7 (2)
Se2iv—La1—Cu4vi121.29 (6)Se4xvi—Cu1—La2xiv69.3 (2)
Se1v—La1—Cu4vi43.38 (5)Se3—Cu1—La2xiv63.58 (19)
Se1—La1—Cu4vi71.03 (7)Cu2—Cu1—La2iii62.1 (4)
Cu3vi—La1—Cu4vi25.07 (8)Cu5—Cu1—La2iii70.2 (2)
Cu3iii—La1—Cu4vi62.14 (10)Se4i—Cu1—La2iii61.8 (2)
Cu4vii—La1—Cu4vi76.52 (5)Se3xii—Cu1—La2iii125.6 (5)
Cu4iv—La1—Cu4vi89.80 (6)Cu3—Cu1—La2iii71.5 (3)
Se1i—La1—Cu4iii118.52 (6)Cu5xii—Cu1—La2iii164.1 (3)
Se1ii—La1—Cu4iii152.32 (7)Se4xvi—Cu1—La2iii128.2 (4)
Se2iii—La1—Cu4iii43.68 (5)Se3—Cu1—La2iii60.7 (2)
Se2iv—La1—Cu4iii121.29 (6)La2xiv—Cu1—La2iii124.1 (3)
Se1v—La1—Cu4iii71.03 (7)Cu1—Cu2—Cu3131.5 (6)
Se1—La1—Cu4iii43.38 (5)Cu1—Cu2—Se3xii89.2 (5)
Cu3vi—La1—Cu4iii62.14 (10)Cu3—Cu2—Se3xii82.6 (2)
Cu3iii—La1—Cu4iii25.07 (8)Cu1—Cu2—Se4i65.1 (5)
Cu4vii—La1—Cu4iii89.80 (6)Cu3—Cu2—Se4i157.8 (3)
Cu4iv—La1—Cu4iii76.52 (5)Se3xii—Cu2—Se4i115.3 (2)
Cu4vi—La1—Cu4iii38.73 (12)Cu1—Cu2—Se380.2 (5)
Se3iv—La2—Se1i75.64 (3)Cu3—Cu2—Se362.07 (17)
Se3iv—La2—Se4i92.67 (3)Se3xii—Cu2—Se3116.62 (19)
Se1i—La2—Se4i74.53 (3)Se4i—Cu2—Se3115.5 (2)
Se3iv—La2—Cu2i130.69 (9)Cu1—Cu2—Se1i158.8 (5)
Se1i—La2—Cu2i129.83 (14)Cu3—Cu2—Se1i66.1 (3)
Se4i—La2—Cu2i131.43 (10)Se3xii—Cu2—Se1i106.6 (2)
Se3iv—La2—Se1viii131.32 (4)Se4i—Cu2—Se1i94.91 (17)
Se1i—La2—Se1viii80.57 (3)Se3—Cu2—Se1i104.21 (19)
Se4i—La2—Se1viii120.91 (4)Cu1—Cu2—Cu535.0 (5)
Cu2i—La2—Se1viii49.54 (14)Cu3—Cu2—Cu5113.8 (2)
Se3iv—La2—Se4viii149.22 (4)Se3xii—Cu2—Cu5119.1 (3)
Se1i—La2—Se4viii132.22 (4)Se4i—Cu2—Cu570.41 (17)
Se4i—La2—Se4viii84.88 (3)Se3—Cu2—Cu552.15 (12)
Cu2i—La2—Se4viii46.93 (10)Se1i—Cu2—Cu5134.05 (15)
Se1viii—La2—Se4viii73.91 (3)Cu1—Cu2—Cu4138.3 (6)
Se3iv—La2—Cu1iv50.22 (18)Cu3—Cu2—Cu422.15 (15)
Se1i—La2—Cu1iv125.5 (2)Se3xii—Cu2—Cu4103.4 (2)
Se4i—La2—Cu1iv109.8 (2)Se4i—Cu2—Cu4136.0 (2)
Cu2i—La2—Cu1iv89.22 (18)Se3—Cu2—Cu458.56 (12)
Se1viii—La2—Cu1iv128.1 (2)Se1i—Cu2—Cu452.66 (14)
Se4viii—La2—Cu1iv101.9 (2)Cu5—Cu2—Cu4108.86 (15)
Se3iv—La2—Se3i82.55 (2)Cu1—Cu2—La2iii98.7 (5)
Se1i—La2—Se3i129.74 (4)Cu3—Cu2—La2iii93.6 (2)
Se4i—La2—Se3i152.07 (4)Se3xii—Cu2—La2iii171.9 (3)
Cu2i—La2—Se3i48.26 (9)Se4i—Cu2—La2iii66.88 (10)
Se1viii—La2—Se3i81.05 (3)Se3—Cu2—La2iii67.15 (9)
Se4viii—La2—Se3i85.43 (3)Se1i—Cu2—La2iii65.31 (12)
Cu1iv—La2—Se3i47.3 (2)Cu5—Cu2—La2iii68.93 (10)
Se3iv—La2—Se4ix80.89 (3)Cu4—Cu2—La2iii72.07 (13)
Se1i—La2—Se4ix138.92 (4)Cu1—Cu2—La2xiv61.4 (5)
Se4i—La2—Se4ix73.40 (2)Cu3—Cu2—La2xiv72.8 (2)
Cu2i—La2—Se4ix90.92 (14)Se3xii—Cu2—La2xiv62.15 (12)
Se1viii—La2—Se4ix138.73 (3)Se4i—Cu2—La2xiv126.4 (3)
Se4viii—La2—Se4ix68.98 (4)Se3—Cu2—La2xiv58.02 (11)
Cu1iv—La2—Se4ix47.6 (3)Se1i—Cu2—La2xiv138.6 (2)
Se3i—La2—Se4ix78.67 (4)Cu5—Cu2—La2xiv68.01 (14)
Se3iv—La2—Cu5x121.81 (5)Cu4—Cu2—La2xiv89.39 (13)
Se1i—La2—Cu5x111.75 (5)La2iii—Cu2—La2xiv123.60 (15)
Se4i—La2—Cu5x43.02 (4)Cu4—Cu3—Cu2132.6 (3)
Cu2i—La2—Cu5x90.08 (11)Cu4—Cu3—Se386.61 (19)
Se1viii—La2—Cu5x106.31 (6)Cu2—Cu3—Se378.8 (2)
Se4viii—La2—Cu5x43.31 (4)Cu4—Cu3—Se1i71.62 (17)
Cu1iv—La2—Cu5x103.0 (3)Cu2—Cu3—Se1i76.0 (2)
Se3i—La2—Cu5x118.24 (5)Se3—Cu3—Se1i117.79 (13)
Se4ix—La2—Cu5x55.39 (5)Cu4—Cu3—Se268.65 (18)
Se3iv—La2—Cu5i96.75 (5)Cu2—Cu3—Se2158.6 (2)
Se1i—La2—Cu5i170.81 (5)Se3—Cu3—Se2109.13 (13)
Se4i—La2—Cu5i111.44 (5)Se1i—Cu3—Se2114.78 (13)
Cu2i—La2—Cu5i51.86 (14)Cu4—Cu3—Cu1138.9 (3)
Se1viii—La2—Cu5i101.29 (5)Cu2—Cu3—Cu119.7 (2)
Se4viii—La2—Cu5i56.51 (5)Se3—Cu3—Cu164.9 (2)
Cu1iv—La2—Cu5i46.56 (19)Se1i—Cu3—Cu195.2 (2)
Se3i—La2—Cu5i42.72 (4)Se2—Cu3—Cu1146.7 (2)
Se4ix—La2—Cu5i42.20 (4)Cu4—Cu3—Se3xii160.3 (2)
Cu5x—La2—Cu5i76.53 (7)Cu2—Cu3—Se3xii58.84 (17)
Se3iv—La2—Cu3iv41.39 (5)Se3—Cu3—Se3xii112.78 (14)
Se1i—La2—Cu3iv90.67 (7)Se1i—Cu3—Se3xii100.62 (12)
Se4i—La2—Cu3iv134.04 (6)Se2—Cu3—Se3xii100.08 (11)
Cu2i—La2—Cu3iv91.53 (10)Cu1—Cu3—Se3xii58.3 (2)
Se1viii—La2—Cu3iv98.20 (6)Cu4—Cu3—La1i83.87 (18)
Se4viii—La2—Cu3iv132.05 (7)Cu2—Cu3—La1i111.7 (2)
Cu1iv—La2—Cu3iv46.0 (3)Se3—Cu3—La1i169.07 (16)
Se3i—La2—Cu3iv46.80 (6)Se1i—Cu3—La1i63.99 (7)
Se4ix—La2—Cu3iv93.51 (6)Se2—Cu3—La1i62.25 (7)
Cu5x—La2—Cu3iv148.89 (8)Cu1—Cu3—La1i126.0 (2)
Cu5i—La2—Cu3iv80.16 (7)Se3xii—Cu3—La1i76.49 (8)
Cu4iii—Se1—Cu2iii68.78 (14)Cu4—Cu3—La2xiv130.7 (2)
Cu4iii—Se1—La1iii104.64 (9)Cu2—Cu3—La2xiv79.7 (2)
Cu3iii—Se1—La1iii139.03 (10)Se3—Cu3—La2xiv61.21 (7)
Cu2iii—Se1—La1iii163.84 (10)Se1i—Cu3—La2xiv155.21 (15)
Cu4iii—Se1—La2iii148.76 (10)Se2—Cu3—La2xiv86.78 (9)
Cu3iii—Se1—La2iii114.11 (9)Cu1—Cu3—La2xiv61.2 (2)
Cu2iii—Se1—La2iii81.18 (10)Se3xii—Cu3—La2xiv61.74 (7)
La1iii—Se1—La2iii106.59 (4)La1i—Cu3—La2xiv122.28 (10)
Cu4iii—Se1—La175.36 (8)Cu4—Cu3—La2iii74.33 (16)
Cu3iii—Se1—La170.63 (8)Cu2—Cu3—La2iii59.22 (16)
Cu2iii—Se1—La193.12 (10)Se3—Cu3—La2iii60.09 (7)
La1iii—Se1—La199.52 (4)Se1i—Cu3—La2iii58.05 (7)
La2iii—Se1—La198.66 (4)Se2—Cu3—La2iii142.14 (13)
Cu4iii—Se1—La2xi77.53 (8)Cu1—Cu3—La2iii66.00 (19)
Cu3iii—Se1—La2xi79.92 (8)Se3xii—Cu3—La2iii117.68 (12)
Cu2iii—Se1—La2xi65.16 (9)La1i—Cu3—La2iii121.83 (9)
La1iii—Se1—La2xi99.33 (4)La2xiv—Cu3—La2iii112.52 (9)
La2iii—Se1—La2xi97.95 (4)Cu3—Cu4—Cu4v134.22 (17)
La1—Se1—La2xi150.09 (4)Cu3—Cu4—Se1i73.64 (17)
Cu4v—Se2—Cu455.56 (18)Cu4v—Cu4—Se1i107.83 (9)
Cu4v—Se2—Cu4xii147.54 (8)Cu3—Cu4—Se277.44 (17)
Cu4—Se2—Cu4xii114.78 (14)Cu4v—Cu4—Se262.22 (9)
Cu4v—Se2—Cu4xiii114.78 (14)Se1i—Cu4—Se2120.29 (12)
Cu4—Se2—Cu4xiii147.54 (8)Cu3—Cu4—Se2xv160.7 (2)
Cu4xii—Se2—Cu4xiii54.21 (16)Cu4v—Cu4—Se2xv62.89 (8)
Cu4—Se2—Cu3v87.49 (14)Se1i—Cu4—Se2xv112.54 (12)
Cu4xii—Se2—Cu3v128.60 (11)Se2—Cu4—Se2xv111.81 (12)
Cu4xiii—Se2—Cu3v81.68 (12)Cu3—Cu4—Se360.22 (17)
Cu4v—Se2—Cu387.49 (14)Cu4v—Cu4—Se3145.40 (7)
Cu4xii—Se2—Cu381.68 (12)Se1i—Cu4—Se3106.64 (13)
Cu4xiii—Se2—Cu3128.60 (11)Se2—Cu4—Se3102.13 (12)
Cu3v—Se2—Cu3115.00 (16)Se2xv—Cu4—Se3100.72 (10)
Cu4v—Se2—La1i76.06 (8)Cu3—Cu4—Cu225.27 (16)
Cu4—Se2—La1i76.06 (8)Cu4v—Cu4—Cu2153.08 (12)
Cu4xii—Se2—La1i71.48 (7)Se1i—Cu4—Cu258.56 (14)
Cu4xiii—Se2—La1i71.48 (7)Se2—Cu4—Cu2102.66 (14)
Cu3v—Se2—La1i70.22 (7)Se2xv—Cu4—Cu2142.04 (15)
Cu3—Se2—La1i70.22 (7)Se3—Cu4—Cu255.46 (14)
Cu4v—Se2—La1xiv72.05 (8)Cu3—Cu4—La1xiv111.3 (2)
Cu4—Se2—La1xiv72.05 (8)Cu4v—Cu4—La1xiv69.73 (6)
Cu4xii—Se2—La1xiv138.36 (8)Se1i—Cu4—La1xiv174.90 (14)
Cu4xiii—Se2—La1xiv138.36 (8)Se2—Cu4—La1xiv62.95 (7)
Cu3v—Se2—La1xiv91.53 (8)Se2xv—Cu4—La1xiv62.40 (7)
Cu3—Se2—La1xiv91.53 (8)Se3—Cu4—La1xiv75.67 (7)
La1i—Se2—La1xiv143.81 (6)Cu2—Cu4—La1xiv125.57 (16)
Cu2xv—Se3—Cu3147.17 (16)Cu3—Cu4—La1i71.06 (15)
Cu2xv—Se3—Cu589.45 (19)Cu4v—Cu4—La1i70.63 (6)
Cu3—Se3—Cu5108.67 (12)Se1i—Cu4—La1i61.26 (7)
Cu3—Se3—Cu1xv146.2 (2)Se2—Cu4—La1i60.26 (7)
Cu5—Se3—Cu1xv63.2 (3)Se2xv—Cu4—La1i128.16 (13)
Cu2xv—Se3—Cu2141.51 (18)Se3—Cu4—La1i131.00 (12)
Cu5—Se3—Cu269.91 (17)Cu2—Cu4—La1i82.54 (12)
Cu1xv—Se3—Cu2118.6 (3)La1xiv—Cu4—La1i120.84 (9)
Cu3—Se3—Cu3xv110.11 (13)Cu3—Cu4—La2iii82.10 (18)
Cu5—Se3—Cu3xv121.18 (9)Cu4v—Cu4—La2iii139.76 (6)
Cu1xv—Se3—Cu3xv59.8 (3)Se1i—Cu4—La2iii59.97 (7)
Cu2—Se3—Cu3xv128.56 (16)Se2—Cu4—La2iii158.01 (15)
Cu2xv—Se3—Cu1133.0 (4)Se2xv—Cu4—La2iii85.61 (8)
Cu3—Se3—Cu162.3 (3)Se3—Cu4—La2iii60.00 (7)
Cu5—Se3—Cu146.9 (3)Cu2—Cu4—La2iii57.41 (10)
Cu1xv—Se3—Cu1105.7 (5)La1xiv—Cu4—La2iii118.77 (9)
Cu3xv—Se3—Cu1144.4 (2)La1i—Cu4—La2iii119.98 (8)
Cu2xv—Se3—Cu4115.37 (16)Cu1—Cu5—Se4xvi72.0 (4)
Cu5—Se3—Cu4132.79 (11)Cu1—Cu5—Se372.8 (4)
Cu1xv—Se3—Cu4127.4 (2)Se4xvi—Cu5—Se3119.61 (9)
Cu2—Se3—Cu465.98 (18)Cu1—Cu5—Se4xviii127.8 (3)
Cu3xv—Se3—Cu477.19 (10)Se4xvi—Cu5—Se4xviii123.06 (10)
Cu1—Se3—Cu491.6 (3)Se3—Cu5—Se4xviii117.32 (8)
Cu2xv—Se3—La2xiv133.61 (13)Cu1—Cu5—Cu1xv126.8 (6)
Cu3—Se3—La2xiv77.40 (9)Se4xvi—Cu5—Cu1xv154.4 (2)
Cu5—Se3—La2xiv81.57 (5)Se3—Cu5—Cu1xv61.0 (3)
Cu1xv—Se3—La2xiv129.1 (2)Se4xviii—Cu5—Cu1xv62.6 (3)
Cu2—Se3—La2xiv76.70 (11)Cu1—Cu5—Cu219.3 (3)
Cu3xv—Se3—La2xiv149.05 (8)Se4xvi—Cu5—Cu290.87 (13)
Cu1—Se3—La2xiv66.20 (19)Se3—Cu5—Cu257.93 (12)
Cu4—Se3—La2xiv103.46 (7)Se4xviii—Cu5—Cu2120.46 (13)
Cu2xv—Se3—La2iii78.69 (15)Cu1xv—Cu5—Cu2107.6 (3)
Cu3—Se3—La2iii80.71 (9)Cu1—Cu5—La2xx93.3 (3)
Cu5—Se3—La2iii73.22 (6)Se4xvi—Cu5—La2xx62.77 (5)
Cu1xv—Se3—La2iii65.5 (2)Se3—Cu5—La2xx162.89 (12)
Cu2—Se3—La2iii64.59 (10)Se4xviii—Cu5—La2xx63.27 (5)
Cu3xv—Se3—La2iii71.46 (7)Cu1xv—Cu5—La2xx125.2 (3)
Cu1—Se3—La2iii72.99 (19)Cu2—Cu5—La2xx106.13 (13)
Cu4—Se3—La2iii73.43 (7)Cu1—Cu5—La2iii75.7 (3)
La2xiv—Se3—La2iii139.01 (4)Se4xvi—Cu5—La2iii143.61 (12)
Cu1iii—Se4—Cu5xvi102.5 (3)Se3—Cu5—La2iii64.06 (5)
Cu1iii—Se4—Cu5xvii137.7 (2)Se4xviii—Cu5—La2iii66.86 (5)
Cu5xvi—Se4—Cu5xvii109.55 (8)Cu1xv—Cu5—La2iii61.73 (19)
Cu5xvi—Se4—Cu2iii111.29 (12)Cu2—Cu5—La2iii59.21 (11)
Cu5xvii—Se4—Cu2iii139.16 (11)La2xx—Cu5—La2iii103.47 (7)
Cu1iii—Se4—Cu1xvi141.9 (3)Cu1—Cu5—La2xiv60.2 (2)
Cu5xvi—Se4—Cu1xvi47.44 (19)Se4xvi—Cu5—La2xiv62.78 (5)
Cu5xvii—Se4—Cu1xvi62.12 (19)Se3—Cu5—La2xiv57.35 (5)
Cu2iii—Se4—Cu1xvi158.7 (2)Se4xviii—Cu5—La2xiv170.33 (11)
Cu1iii—Se4—La2iii106.1 (3)Cu1xv—Cu5—La2xiv108.6 (3)
Cu5xvi—Se4—La2iii74.21 (6)Cu2—Cu5—La2xiv64.89 (10)
Cu5xvii—Se4—La2iii108.63 (8)La2xx—Cu5—La2xiv124.48 (6)
Cu2iii—Se4—La2iii83.03 (15)La2iii—Cu5—La2xiv113.66 (7)
Symmetry codes: (i) x+1/2, y, z+1/2; (ii) x+1/2, y+1/2, z+1/2; (iii) x1/2, y, z+1/2; (iv) x, y, z1; (v) x, y+1/2, z; (vi) x1/2, y+1/2, z+1/2; (vii) x, y+1/2, z1; (viii) x+1, y, z; (ix) x+1, y+1, z; (x) x+3/2, y+1, z1/2; (xi) x1, 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) x1/2, y, z+3/2; (xvi) x+1, y+1, z+1; (xvii) x+1/2, y+1, z1/2; (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.

Experimental details

Crystal data
Chemical formulaLa3Cu4.88Se7
Mr1279.53
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)295
a, b, c (Å)7.6785 (11), 24.523 (3), 6.9265 (10)
V3)1304.3 (3)
Z4
Radiation typeMo Kα
µ (mm1)36.88
Crystal size (mm)0.06 × 0.06 × 0.03
Data collection
DiffractometerKuma KM-4 with CCD area-detector
diffractometer
Absorption correctionNumerical
(CrysAlis; Oxford Diffraction, 2007)
Tmin, Tmax0.110, 0.384
No. of measured, independent and
observed [I > 2σ(I)] reflections
13882, 1518, 1058
Rint0.102
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.051, 1.01
No. of reflections1518
No. of parameters99
Δρmax, Δρmin (e Å3)2.36, 1.56

Computer programs: CrysAlis (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2009), publCIF (Westrip, 2010).

Bond-valence-sums (BSV) for the symmetry-independent Cu+ and La3+ ions in La3Cu4.88Se7. top
AtomCNBVSatomCNBVS
Cu131.103Cu431.041
Cu141.317Cu441.238
Cu231.139Cu520.825
Cu241.368Cu531.221
Cu331.107La162.845
Cu341.324La272.835
 

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