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The crystal structures of two new quaternary compounds, viz. dicerium orthosilicate selenide and dicerium orthosilicate telluride, Ce2(SiO4)Q (Q = Se or Te), have been determined from single-crystal X-ray diffraction data. Each structure comprises infinite chains of SiO4 tetrahedra separated by Ce and Q atoms. The site symmetries are Ce m and 2, Si 2 and Q m. The O atoms are in general positions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104024230/sk1760sup1.cif
Contains datablocks global, II, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104024230/sk1760Isup2.hkl
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104024230/sk1760IIsup3.hkl
Contains datablock II

Comment top

Ce2(SiO4)Q (Q = Se or Te) are new members of the Ln2(SiO4)Q (Q = S, Se or Te) series [Q = S and Ln = Ho (Hartenbach et al., 2002); Q = Se and Ln = La (Brennan & Ibers, 1991), Nd (Grupe & Urland, 1990), Sm, Dy or Ho (Person et al., 2000), Er (Stöwe, 1994) or Tb (Ijjaali et al., 2002); Q = Te and Ln = Pr (Weber & Schleid, 1999), Nd (Yang & Ibers, 2000), Sm (Yang & Ibers, 2000; Person et al., 2000) or Gd (Ijjaali & Ibers, 2001)], as shown in Table 1. These compounds usually adopt an orthorhombic (Pbcm) structure, but some of the Q = Te compounds are dimorphic and also adopt a monoclinic (P21/c) structure (Table 1). Each of the two compounds reported here crystallizes in space group Pbcm and has a layered structure.

The structures of the title compounds both comprise infinite chains of SiO4 tetrahedra along [001], separated by Ln and Q atoms (as shown in Fig. 1 for Q = Se). The SiO4 tetrahedron in each structure has symmetry m but is somewhat distorted, with O—Si—O angles ranging from 104.36 (13) to 119.01 (13)° in Ce2(SiO4)Se and 103.0 (2) to 119.79 (13)° in Ce2(SiO4)Te.

Although the two structures are similar, they are not strictly isostructural, differing in the coordination about atom Ce1, which has site symmetry m and is located within the layer in each structure. In Ce2(SiO4)Se, atom Ce1 is coordinated by six O atoms and two Se atoms in a bicapped trigonal prism (Fig. 2), whereas in Ce2(SiO4)Te, atom Ce1 is coordinated by six O atoms and three Te atoms in a tricapped trigonal prism (Fig. 3). Atom Ce2 in each structure has site symmetry 2, is located between the layers, and is coordinated by six O atoms and two Se atoms in a dodecahedron (Figs. 2 and 3).

In Ce2(SiO4)Se, the Ce—O distances range from 2.475 (3) to 2.578 (2) Å, which may be compared with the range of 2.374 (3)–2.523 (5) Å observed in Ce3.67Ti2O3Se6 (Tougait & Ibers, 2000). The Ce—Se distances range from 3.0157 (7) to 3.1926 (4) Å, compared with 2.8999 (9)–3.2864 (12) Å in Ce3.67Ti2O3Se6 (Tougait & Ibers, 2000). In Ce2(SiO4)Te, the Ce—O distances range from 2.495 (3) to 2.621 (3) Å, which may also be compared with the range in Ce3.67Ti2O3Se6 (Tougait & Ibers, 2000).

The Ce—Te distances range from 3.2082 (5) to 3.3704 (5) Å, compared with 3.1898 (8)–3.3032 (11) Å in K2Ag3CeTe4 (Patschke et al., 1998).

Experimental top

The reactive flux, Cs2Se3, was prepared by the stoichiometric reaction of Cs (Aldrich, 99.5%) and Se (Aldrich, 99.5%) in liquid NH3. Most of the compounds listed in Table 1 were synthesized accidentally, and the present compounds were no exception. Clear light-red needles of Ce2(SiO4)Se were obtained accidentally in the reaction of Ce (71 mg, Alfa Aesar, 99.9%), Se (40 mg, Aldrich, 99.5%), CsCl (150 mg, Aldrich, 99.9%) and Cs2Se3 (150 mg). The materials were mixed and sealed in an unprotected fused-silica tube which was then evacuated to 10−4 Torr (1 Torr = 133.322 Pa). The tube was heated to 1173 K, kept at 1173 K for 72 h and cooled at 4 K h−1 to 473 K, and then the furnace was turned off. The reaction mixture was washed with deionized water and finally dried with acetone. Qualitative energy dispersive spectroscopy (EDS) analysis verified the presence of Ce, Si, and Se. The light-yellow needles of Ce2(SiO4)Te were grown accidentally in the reaction of Ce (70 mg, Alfa Aesar, 99.9%), Ti (48 mg, Aldrich, 99.9%), TeO2 (80 mg, Aldrich, 99.995%), Te (80 mg, Strem, 99.9%) and KCl (150 mg, Aldrich, 99.9%). The mixture was sealed in an unprotected fused-silica tube which was then evacuated to 10−4 Torr. The tube was heated to 1073 K, kept at 1073 K for 72 h and cooled at 4 K h−1 to 373 K, and then the furnace was turned off. The reaction product was washed with water and dried with actone. Qualitative EDS analysis verified the presence of Ce, Si, and Te.

Refinement top

In Ce2(SiO4)Se, the highest residual electron density of 2.0 (3) e Å−3 is 0.03 Å from the Ce2 site and the deepest hole of −1.5 (3) e Å−3 is 0.69 Å from this same site. In Ce2(SiO4)Te, the highest residual electron density of 2.0 (4) e Å−3 is 0.01 Å from the Ce2 site and the deepest hole of −2.0 (4) e Å−3 is 0.61 Å from Te.

Computing details top

For both compounds, data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2003); program(s) used to refine structure: SHELXTL; molecular graphics: XP in SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The structure of Ce2(SiO4)Se, viewed along [001].
[Figure 2] Fig. 2. The coordination geometries of atoms Ce1 and Ce2 in Ce2(SiO4)Se. Displacement ellipsoids are drawn at the 90% probability level. [Symmetry codes: (b) x, y − 1, z; (f) x, 1/2 − y, −z; (h) −x, y − 1/2, 1/2 − z; (j) −x, y − 1/2, 1/2 − z; (m) 1 − x, −y, −z; (n) 1 − x, 1 − y, −z; (o) x, y − 1, 1/2 − z; (p) x, y, 1/2 − z; (r) −x, 1/2 − y, z; (t) 1 − x, y − 1/2, z; (u) 1 − x, 1/2 + y, z.]
[Figure 3] Fig. 3. The coordination geometries of atoms Ce1 and Ce2 in Ce2(SiO4)Te. Displacement ellipsoids are drawn at the 90% probability level. [Symmetry codes: (b) x, y − 1, z; (c) x, y + 1, z; (h) x, 1/2 − y, −z; (j) −x, y − 1/2, 1/2 − z; (l) 1 − x, y − 1/2, 1/2 − z; (o) 1 − x, −y, −z; (p) 1 − x, 1 − y, −z; (q) x, y − 1, 1/2 − z; (r) x, y, 1/2 − z; (t) −x, y − 1/2, z; (v) 1 − x, y − 1/2, z; (w) 1 − x, 1/2 + y, z.]
(I) Dicerium orthosilicate selenide top
Crystal data top
Ce2(SiO4)SeF(000) = 784
Mr = 451.29Dx = 6.010 Mg m3
Orthorhombic, PbcmMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2c 2bCell parameters from 5011 reflections
a = 6.2250 (6) Åθ = 2.8–29.0°
b = 7.2354 (7) ŵ = 25.46 mm1
c = 11.0739 (10) ÅT = 153 K
V = 498.77 (8) Å3Needle, light red
Z = 40.13 × 0.03 × 0.03 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
662 independent reflections
Radiation source: fine-focus sealed tube643 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
0.3° ω scansθmax = 29.0°, θmin = 3.3°
Absorption correction: numerical
(SHELXTL; Sheldrick, 2003)
h = 88
Tmin = 0.067, Tmax = 0.274k = 99
5011 measured reflectionsl = 1414
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.021 w = 1/[σ2(Fo2) + (0.03P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.059(Δ/σ)max < 0.001
S = 1.49Δρmax = 2.03 e Å3
662 reflectionsΔρmin = 1.49 e Å3
42 parametersExtinction correction: SHELXTL (Sheldrick, 2003), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0019 (3)
Crystal data top
Ce2(SiO4)SeV = 498.77 (8) Å3
Mr = 451.29Z = 4
Orthorhombic, PbcmMo Kα radiation
a = 6.2250 (6) ŵ = 25.46 mm1
b = 7.2354 (7) ÅT = 153 K
c = 11.0739 (10) Å0.13 × 0.03 × 0.03 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
662 independent reflections
Absorption correction: numerical
(SHELXTL; Sheldrick, 2003)
643 reflections with I > 2σ(I)
Tmin = 0.067, Tmax = 0.274Rint = 0.029
5011 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02142 parameters
wR(F2) = 0.0590 restraints
S = 1.49Δρmax = 2.03 e Å3
662 reflectionsΔρmin = 1.49 e Å3
Special details top

Experimental. face-indexed correction (XPREP and SADABS in SMART; Bruker, 2003)

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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
Ce10.12601 (5)0.03665 (4)0.25000.00430 (15)
Ce20.60626 (5)0.25000.00000.00547 (15)
Se0.41722 (9)0.39779 (8)0.25000.00698 (17)
Si0.1111 (2)0.25000.00000.0042 (3)
O10.0504 (5)0.7673 (4)0.1173 (2)0.0074 (5)
O20.2684 (4)0.0770 (4)0.0330 (2)0.0056 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ce10.0049 (2)0.0034 (2)0.0045 (2)0.00048 (10)0.0000.000
Ce20.0019 (2)0.0052 (2)0.0093 (2)0.0000.0000.00240 (11)
Se0.0053 (3)0.0076 (3)0.0080 (3)0.0019 (2)0.0000.000
Si0.0034 (7)0.0037 (8)0.0054 (8)0.0000.0000.0006 (5)
O10.0057 (13)0.0091 (13)0.0073 (13)0.0007 (11)0.0004 (11)0.0001 (10)
O20.0047 (13)0.0050 (12)0.0072 (12)0.0001 (10)0.0011 (10)0.0009 (10)
Geometric parameters (Å, º) top
Ce1—O1i2.480 (3)Ce2—Sixiii3.1428 (15)
Ce1—O1ii2.480 (3)Ce2—Sexiv3.1926 (4)
Ce1—O1iii2.486 (3)Ce2—Se3.1926 (4)
Ce1—O1iv2.486 (3)Ce2—Ce1xv3.8398 (3)
Ce1—O2v2.578 (2)Ce2—Ce1vii3.8398 (3)
Ce1—O22.578 (2)Se—Ce1xv3.0157 (7)
Ce1—Sevi3.0157 (7)Se—Ce2v3.1926 (4)
Ce1—Siv3.1711 (3)Si—O2ix1.630 (3)
Ce1—Si3.1711 (3)Si—O21.630 (3)
Ce1—Se3.1802 (6)Si—O1xvi1.647 (3)
Ce1—Ce2vii3.8397 (3)Si—O1ii1.647 (3)
Ce1—Ce2viii3.8397 (3)Si—Ce2xvii3.1428 (15)
Ce2—O22.475 (3)Si—Ce1xiv3.1711 (3)
Ce2—O2ix2.475 (3)O1—Sixvi1.647 (3)
Ce2—O1x2.504 (3)O1—Ce1xviii2.480 (3)
Ce2—O1xi2.504 (3)O1—Ce1xix2.486 (3)
Ce2—O2xii2.518 (3)O1—Ce2xi2.504 (3)
Ce2—O2vii2.518 (3)O2—Ce2vii2.518 (3)
Ce2—Si3.0822 (15)
O1i—Ce1—O1ii72.68 (12)O1x—Ce2—Sixiii31.40 (6)
O1i—Ce1—O1iii142.57 (3)O1xi—Ce2—Sixiii31.40 (6)
O1ii—Ce1—O1iii95.36 (8)O2xii—Ce2—Sixiii71.95 (6)
O1i—Ce1—O1iv95.36 (8)O2vii—Ce2—Sixiii71.95 (6)
O1ii—Ce1—O1iv142.57 (3)Si—Ce2—Sixiii180.0
O1iii—Ce1—O1iv72.49 (12)O2—Ce2—Sexiv69.23 (6)
O1i—Ce1—O2v61.55 (9)O2ix—Ce2—Sexiv74.22 (6)
O1ii—Ce1—O2v128.93 (9)O1x—Ce2—Sexiv141.36 (6)
O1iii—Ce1—O2v134.84 (9)O1xi—Ce2—Sexiv81.26 (6)
O1iv—Ce1—O2v66.60 (8)O2xii—Ce2—Sexiv123.70 (6)
O1i—Ce1—O2128.93 (9)O2vii—Ce2—Sexiv70.95 (6)
O1ii—Ce1—O261.55 (9)Si—Ce2—Sexiv68.371 (11)
O1iii—Ce1—O266.60 (8)Sixiii—Ce2—Sexiv111.629 (11)
O1iv—Ce1—O2134.84 (9)O2—Ce2—Se74.22 (6)
O2v—Ce1—O2137.55 (12)O2ix—Ce2—Se69.23 (6)
O1i—Ce1—Sevi129.91 (6)O1x—Ce2—Se81.26 (6)
O1ii—Ce1—Sevi129.91 (6)O1xi—Ce2—Se141.36 (6)
O1iii—Ce1—Sevi85.26 (7)O2xii—Ce2—Se70.95 (6)
O1iv—Ce1—Sevi85.26 (7)O2vii—Ce2—Se123.70 (6)
O2v—Ce1—Sevi73.36 (6)Si—Ce2—Se68.371 (11)
O2—Ce1—Sevi73.36 (6)Sixiii—Ce2—Se111.629 (11)
O1i—Ce1—Siv30.92 (7)Sexiv—Ce2—Se136.74 (2)
O1ii—Ce1—Siv100.19 (6)O2—Ce2—Ce1xv122.38 (5)
O1iii—Ce1—Siv153.16 (6)O2ix—Ce2—Ce1xv101.67 (6)
O1iv—Ce1—Siv81.95 (6)O1x—Ce2—Ce1xv39.52 (6)
O2v—Ce1—Siv30.80 (6)O1xi—Ce2—Ce1xv91.75 (6)
O2—Ce1—Siv140.24 (6)O2xii—Ce2—Ce1xv41.70 (6)
Sevi—Ce1—Siv100.94 (3)O2vii—Ce2—Ce1xv118.53 (6)
O1i—Ce1—Si100.19 (6)Si—Ce2—Ce1xv115.725 (6)
O1ii—Ce1—Si30.92 (7)Sixiii—Ce2—Ce1xv64.275 (7)
O1iii—Ce1—Si81.95 (6)Sexiv—Ce2—Ce1xv165.044 (10)
O1iv—Ce1—Si153.16 (6)Se—Ce2—Ce1xv49.749 (12)
O2v—Ce1—Si140.24 (6)O2—Ce2—Ce1vii101.67 (6)
O2—Ce1—Si30.80 (6)O2ix—Ce2—Ce1vii122.38 (5)
Sevi—Ce1—Si100.94 (3)O1x—Ce2—Ce1vii91.75 (6)
Siv—Ce1—Si121.624 (12)O1xi—Ce2—Ce1vii39.52 (6)
O1i—Ce1—Se72.51 (7)O2xii—Ce2—Ce1vii118.53 (6)
O1ii—Ce1—Se72.51 (7)O2vii—Ce2—Ce1vii41.70 (6)
O1iii—Ce1—Se138.77 (6)Si—Ce2—Ce1vii115.725 (7)
O1iv—Ce1—Se138.77 (6)Sixiii—Ce2—Ce1vii64.275 (7)
O2v—Ce1—Se73.20 (6)Sexiv—Ce2—Ce1vii49.749 (12)
O2—Ce1—Se73.20 (6)Se—Ce2—Ce1vii165.044 (10)
Sevi—Ce1—Se74.709 (10)Ce1xv—Ce2—Ce1vii128.550 (13)
Siv—Ce1—Se67.461 (18)Ce1xv—Se—Ce1144.21 (2)
Si—Ce1—Se67.461 (18)Ce1xv—Se—Ce2v76.352 (12)
O1i—Ce1—Ce2vii169.39 (6)Ce1—Se—Ce2v86.268 (12)
O1ii—Ce1—Ce2vii97.38 (6)Ce1xv—Se—Ce276.352 (12)
O1iii—Ce1—Ce2vii39.87 (6)Ce1—Se—Ce286.268 (12)
O1iv—Ce1—Ce2vii94.88 (6)Ce2v—Se—Ce2120.259 (19)
O2v—Ce1—Ce2vii125.74 (6)O2ix—Si—O2106.2 (2)
O2—Ce1—Ce2vii40.53 (6)O2ix—Si—O1xvi104.36 (13)
Sevi—Ce1—Ce2vii53.899 (8)O2—Si—O1xvi119.01 (13)
Siv—Ce1—Ce2vii154.83 (3)O2ix—Si—O1ii119.01 (13)
Si—Ce1—Ce2vii69.278 (14)O2—Si—O1ii104.36 (13)
Se—Ce1—Ce2vii101.326 (10)O1xvi—Si—O1ii104.8 (2)
O1i—Ce1—Ce2viii97.38 (6)O2ix—Si—Ce253.10 (10)
O1ii—Ce1—Ce2viii169.39 (6)O2—Si—Ce253.10 (10)
O1iii—Ce1—Ce2viii94.88 (6)O1xvi—Si—Ce2127.61 (11)
O1iv—Ce1—Ce2viii39.87 (6)O1ii—Si—Ce2127.61 (11)
O2v—Ce1—Ce2viii40.53 (6)O2ix—Si—Ce2xvii126.90 (10)
O2—Ce1—Ce2viii125.74 (6)O2—Si—Ce2xvii126.90 (10)
Sevi—Ce1—Ce2viii53.899 (8)O1xvi—Si—Ce2xvii52.39 (11)
Siv—Ce1—Ce2viii69.278 (14)O1ii—Si—Ce2xvii52.39 (11)
Si—Ce1—Ce2viii154.83 (3)Ce2—Si—Ce2xvii180.0
Se—Ce1—Ce2viii101.326 (10)O2ix—Si—Ce1123.49 (9)
Ce2vii—Ce1—Ce2viii92.275 (10)O2—Si—Ce154.06 (8)
O2—Ce2—O2ix63.59 (13)O1xvi—Si—Ce1132.01 (10)
O2—Ce2—O1x132.39 (8)O1ii—Si—Ce150.69 (9)
O2ix—Ce2—O1x140.97 (8)Ce2—Si—Ce188.33 (3)
O2—Ce2—O1xi140.97 (8)Ce2xvii—Si—Ce191.67 (3)
O2ix—Ce2—O1xi132.39 (8)O2ix—Si—Ce1xiv54.06 (8)
O1x—Ce2—O1xi62.80 (12)O2—Si—Ce1xiv123.49 (9)
O2—Ce2—O2xii135.82 (8)O1xvi—Si—Ce1xiv50.69 (9)
O2ix—Ce2—O2xii79.02 (10)O1ii—Si—Ce1xiv132.01 (10)
O1x—Ce2—O2xii67.25 (9)Ce2—Si—Ce1xiv88.33 (3)
O1xi—Ce2—O2xii81.82 (9)Ce2xvii—Si—Ce1xiv91.67 (3)
O2—Ce2—O2vii79.02 (10)Ce1—Si—Ce1xiv176.65 (5)
O2ix—Ce2—O2vii135.82 (8)Sixvi—O1—Ce1xviii98.39 (12)
O1x—Ce2—O2vii81.82 (9)Sixvi—O1—Ce1xix129.89 (14)
O1xi—Ce2—O2vii67.25 (9)Ce1xviii—O1—Ce1xix105.13 (10)
O2xii—Ce2—O2vii143.89 (13)Sixvi—O1—Ce2xi96.21 (12)
O2—Ce2—Si31.79 (6)Ce1xviii—O1—Ce2xi130.66 (11)
O2ix—Ce2—Si31.79 (6)Ce1xix—O1—Ce2xi100.61 (10)
O1x—Ce2—Si148.60 (6)Si—O2—Ce295.11 (13)
O1xi—Ce2—Si148.60 (6)Si—O2—Ce2vii151.02 (14)
O2xii—Ce2—Si108.05 (6)Ce2—O2—Ce2vii100.98 (10)
O2vii—Ce2—Si108.05 (6)Si—O2—Ce195.14 (11)
O2—Ce2—Sixiii148.21 (6)Ce2—O2—Ce1119.16 (10)
O2ix—Ce2—Sixiii148.21 (6)Ce2vii—O2—Ce197.78 (9)
Symmetry codes: (i) x, y1/2, z+1/2; (ii) x, y1/2, z; (iii) x, y1, z; (iv) x, y1, z+1/2; (v) x, y, z+1/2; (vi) x+1, y1/2, z+1/2; (vii) x+1, y, z; (viii) x+1, y, z+1/2; (ix) x, y+1/2, z; (x) x+1, y1/2, z; (xi) x+1, y+1, z; (xii) x+1, y+1/2, z; (xiii) x+1, y, z; (xiv) x, y+1/2, z1/2; (xv) x+1, y+1/2, z+1/2; (xvi) x, y+1, z; (xvii) x1, y, z; (xviii) x, y+1/2, z+1/2; (xix) x, y+1, z.
(II) Dicerium orthosilicate telluride top
Crystal data top
Ce2(SiO4)TeF(000) = 856
Mr = 499.93Dx = 6.356 Mg m3
Orthorhombic, PbcmMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2c 2bCell parameters from 5770 reflections
a = 6.3647 (6) Åθ = 3.2–28.9°
b = 7.2807 (7) ŵ = 22.82 mm1
c = 11.2743 (10) ÅT = 153 K
V = 522.45 (8) Å3Needle, light yellow
Z = 40.08 × 0.05 × 0.04 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
690 independent reflections
Radiation source: fine-focus sealed tube666 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.034
0.3° ω scansθmax = 28.9°, θmin = 3.2°
Absorption correction: numerical
(SHELXTL; Sheldrick, 2003)
h = 88
Tmin = 0.244, Tmax = 0.423k = 99
5770 measured reflectionsl = 1514
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.023 w = 1/[σ2(Fo2) + (0.031P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.057(Δ/σ)max < 0.001
S = 1.34Δρmax = 1.99 e Å3
690 reflectionsΔρmin = 2.03 e Å3
42 parametersExtinction correction: SHELXTL (Sheldrick, 2003), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0071 (4)
Crystal data top
Ce2(SiO4)TeV = 522.45 (8) Å3
Mr = 499.93Z = 4
Orthorhombic, PbcmMo Kα radiation
a = 6.3647 (6) ŵ = 22.82 mm1
b = 7.2807 (7) ÅT = 153 K
c = 11.2743 (10) Å0.08 × 0.05 × 0.04 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
690 independent reflections
Absorption correction: numerical
(SHELXTL; Sheldrick, 2003)
666 reflections with I > 2σ(I)
Tmin = 0.244, Tmax = 0.423Rint = 0.034
5770 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02342 parameters
wR(F2) = 0.0570 restraints
S = 1.34Δρmax = 1.99 e Å3
690 reflectionsΔρmin = 2.03 e Å3
Special details top

Experimental. Face-indexed correction (XPREP and SADABS in SMART; Bruker, 2003)

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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
Ce10.11220 (4)0.04046 (4)0.25000.00394 (15)
Ce20.61066 (4)0.25000.00000.00481 (15)
Te0.40014 (5)0.42897 (5)0.25000.00560 (15)
Si0.1131 (2)0.25000.00000.0036 (3)
O10.0487 (4)0.7712 (3)0.1139 (2)0.0052 (5)
O20.2672 (5)0.0795 (3)0.0361 (2)0.0063 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ce10.0036 (2)0.0040 (2)0.0042 (2)0.00022 (9)0.0000.000
Ce20.0022 (2)0.0051 (2)0.0072 (2)0.0000.0000.00119 (11)
Te0.0041 (2)0.0066 (2)0.0061 (2)0.00070 (12)0.0000.000
Si0.0030 (8)0.0043 (8)0.0036 (8)0.0000.0000.0007 (5)
O10.0053 (13)0.0049 (12)0.0056 (12)0.0006 (10)0.0002 (11)0.0000 (10)
O20.0054 (13)0.0045 (11)0.0091 (12)0.0001 (10)0.0016 (10)0.0015 (10)
Geometric parameters (Å, º) top
Ce1—O1i2.495 (3)Ce2—Texiii3.3819 (3)
Ce1—O1ii2.495 (3)Ce2—Te3.3819 (3)
Ce1—O1iii2.522 (3)Ce2—Tevi3.6623 (3)
Ce1—O1iv2.522 (3)Ce2—Teviii3.6623 (3)
Ce1—O2v2.621 (3)Te—Ce1xiv3.2082 (5)
Ce1—O22.621 (3)Te—Ce1xv3.3604 (5)
Ce1—Siv3.2050 (3)Te—Ce2v3.3819 (3)
Ce1—Si3.2050 (3)Te—Ce2xvi3.6623 (3)
Ce1—Tevi3.2082 (5)Te—Ce2viii3.6623 (3)
Ce1—Tei3.3604 (5)Si—O21.633 (3)
Ce1—Te3.3704 (5)Si—O2ix1.633 (3)
Ce1—Ce1i3.9105 (4)Si—O1xvii1.653 (3)
Ce2—O1vii2.524 (3)Si—O1ii1.653 (3)
Ce2—O1viii2.524 (3)Si—Ce2xviii3.1977 (14)
Ce2—O22.547 (3)Si—Ce1xiii3.2050 (3)
Ce2—O2ix2.547 (3)O1—Sixvii1.653 (3)
Ce2—O2x2.555 (3)O1—Ce1xv2.495 (3)
Ce2—O2xi2.555 (3)O1—Ce1xix2.522 (3)
Ce2—Si3.1670 (14)O1—Ce2viii2.524 (3)
Ce2—Sixii3.1977 (14)O2—Ce2x2.555 (3)
O1i—Ce1—O1ii75.90 (12)O2ix—Ce2—Texiii73.40 (6)
O1i—Ce1—O1iii146.28 (3)O2x—Ce2—Texiii68.03 (6)
O1ii—Ce1—O1iii94.79 (9)O2xi—Ce2—Texiii127.97 (6)
O1i—Ce1—O1iv94.79 (9)Si—Ce2—Texiii66.659 (8)
O1ii—Ce1—O1iv146.28 (3)Sixii—Ce2—Texiii113.340 (8)
O1iii—Ce1—O1iv74.94 (12)O1vii—Ce2—Te83.84 (6)
O1i—Ce1—O2v61.03 (9)O1viii—Ce2—Te141.98 (6)
O1ii—Ce1—O2v130.33 (8)O2—Ce2—Te73.40 (6)
O1iii—Ce1—O2v134.78 (8)O2ix—Ce2—Te66.76 (6)
O1iv—Ce1—O2v65.48 (8)O2x—Ce2—Te127.97 (6)
O1i—Ce1—O2130.33 (8)O2xi—Ce2—Te68.03 (6)
O1ii—Ce1—O261.03 (9)Si—Ce2—Te66.660 (8)
O1iii—Ce1—O265.48 (8)Sixii—Ce2—Te113.340 (8)
O1iv—Ce1—O2134.78 (8)Texiii—Ce2—Te133.319 (15)
O2v—Ce1—O2133.87 (13)O1vii—Ce2—Tevi70.34 (6)
O1i—Ce1—Siv30.62 (6)O1viii—Ce2—Tevi111.63 (6)
O1ii—Ce1—Siv102.77 (6)O2—Ce2—Tevi63.24 (6)
O1iii—Ce1—Siv154.86 (6)O2ix—Ce2—Tevi114.71 (6)
O1iv—Ce1—Siv80.52 (6)O2x—Ce2—Tevi61.90 (6)
O2v—Ce1—Siv30.52 (6)O2xi—Ce2—Tevi118.84 (6)
O2—Ce1—Siv139.18 (6)Si—Ce2—Tevi88.924 (7)
O1i—Ce1—Si102.77 (6)Sixii—Ce2—Tevi91.076 (7)
O1ii—Ce1—Si30.62 (6)Texiii—Ce2—Tevi112.835 (7)
O1iii—Ce1—Si80.52 (6)Te—Ce2—Tevi66.236 (7)
O1iv—Ce1—Si154.86 (6)O1vii—Ce2—Teviii111.63 (6)
O2v—Ce1—Si139.18 (6)O1viii—Ce2—Teviii70.34 (6)
O2—Ce1—Si30.52 (6)O2—Ce2—Teviii114.71 (6)
Siv—Ce1—Si123.151 (12)O2ix—Ce2—Teviii63.24 (6)
O1i—Ce1—Tevi124.58 (6)O2x—Ce2—Teviii118.84 (6)
O1ii—Ce1—Tevi124.58 (6)O2xi—Ce2—Teviii61.90 (6)
O1iii—Ce1—Tevi87.61 (6)Si—Ce2—Teviii88.924 (7)
O1iv—Ce1—Tevi87.61 (6)Sixii—Ce2—Teviii91.076 (7)
O2v—Ce1—Tevi70.33 (7)Texiii—Ce2—Teviii66.236 (7)
O2—Ce1—Tevi70.33 (7)Te—Ce2—Teviii112.835 (7)
Siv—Ce1—Tevi96.82 (3)Tevi—Ce2—Teviii177.848 (13)
Si—Ce1—Tevi96.82 (3)Ce1xiv—Te—Ce1xv151.364 (17)
O1i—Ce1—Tei76.37 (6)Ce1xiv—Te—Ce1137.596 (15)
O1ii—Ce1—Tei76.37 (6)Ce1xv—Te—Ce171.039 (10)
O1iii—Ce1—Tei69.93 (6)Ce1xiv—Te—Ce2v73.393 (8)
O1iv—Ce1—Tei69.93 (6)Ce1xv—Te—Ce2v118.524 (8)
O2v—Ce1—Tei113.05 (7)Ce1—Te—Ce2v83.804 (9)
O2—Ce1—Tei113.05 (7)Ce1xiv—Te—Ce273.393 (9)
Siv—Ce1—Tei96.70 (3)Ce1xv—Te—Ce2118.524 (8)
Si—Ce1—Tei96.70 (3)Ce1—Te—Ce283.805 (9)
Tevi—Ce1—Tei151.364 (17)Ce2v—Te—Ce2112.903 (14)
O1i—Ce1—Te70.01 (6)Ce1xiv—Te—Ce2xvi81.760 (9)
O1ii—Ce1—Te70.01 (6)Ce1xv—Te—Ce2xvi80.073 (8)
O1iii—Ce1—Te137.69 (6)Ce1—Te—Ce2xvi121.696 (8)
O1iv—Ce1—Te137.69 (6)Ce2v—Te—Ce2xvi67.165 (7)
O2v—Ce1—Te72.79 (6)Ce2—Te—Ce2xvi153.478 (11)
O2—Ce1—Te72.79 (6)Ce1xiv—Te—Ce2viii81.760 (9)
Siv—Ce1—Te66.396 (16)Ce1xv—Te—Ce2viii80.073 (8)
Si—Ce1—Te66.395 (16)Ce1—Te—Ce2viii121.696 (8)
Tevi—Ce1—Te71.717 (10)Ce2v—Te—Ce2viii153.478 (11)
Tei—Ce1—Te136.919 (15)Ce2—Te—Ce2viii67.165 (7)
O1i—Ce1—Ce1i118.48 (6)Ce2xvi—Te—Ce2viii100.641 (12)
O1ii—Ce1—Ce1i118.48 (6)O2—Si—O2ix106.2 (2)
O1iii—Ce1—Ce1i38.54 (6)O2—Si—O1xvii119.79 (13)
O1iv—Ce1—Ce1i38.54 (6)O2ix—Si—O1xvii104.55 (13)
O2v—Ce1—Ce1i103.80 (6)O2—Si—O1ii104.55 (13)
O2—Ce1—Ce1i103.80 (6)O2ix—Si—O1ii119.79 (13)
Siv—Ce1—Ce1i116.343 (12)O1xvii—Si—O1ii103.0 (2)
Si—Ce1—Ce1i116.344 (12)O2—Si—Ce253.09 (10)
Tevi—Ce1—Ce1i96.765 (12)O2ix—Si—Ce253.10 (10)
Tei—Ce1—Ce1i54.599 (11)O1xvii—Si—Ce2128.52 (10)
Te—Ce1—Ce1i168.482 (15)O1ii—Si—Ce2128.52 (10)
O1vii—Ce2—O1viii61.64 (12)O2—Si—Ce2xviii126.91 (10)
O1vii—Ce2—O2133.28 (9)O2ix—Si—Ce2xviii126.90 (10)
O1viii—Ce2—O2142.07 (8)O1xvii—Si—Ce2xviii51.48 (10)
O1vii—Ce2—O2ix142.07 (8)O1ii—Si—Ce2xviii51.48 (10)
O1viii—Ce2—O2ix133.28 (9)Ce2—Si—Ce2xviii180.0
O2—Ce2—O2ix61.71 (12)O2—Si—Ce154.56 (9)
O1vii—Ce2—O2x82.95 (9)O2ix—Si—Ce1125.59 (10)
O1viii—Ce2—O2x66.43 (8)O1xvii—Si—Ce1129.61 (10)
O2—Ce2—O2x80.16 (10)O1ii—Si—Ce150.23 (9)
O2ix—Ce2—O2x133.90 (9)Ce2—Si—Ce190.10 (3)
O1vii—Ce2—O2xi66.43 (8)Ce2xviii—Si—Ce189.90 (3)
O1viii—Ce2—O2xi82.94 (9)O2—Si—Ce1xiii125.59 (10)
O2—Ce2—O2xi133.90 (9)O2ix—Si—Ce1xiii54.55 (9)
O2ix—Ce2—O2xi80.16 (10)O1xvii—Si—Ce1xiii50.22 (9)
O2x—Ce2—O2xi144.57 (13)O1ii—Si—Ce1xiii129.61 (10)
O1vii—Ce2—Si149.18 (6)Ce2—Si—Ce1xiii90.10 (3)
O1viii—Ce2—Si149.18 (6)Ce2xviii—Si—Ce1xiii89.90 (3)
O2—Ce2—Si30.86 (6)Ce1—Si—Ce1xiii179.80 (5)
O2ix—Ce2—Si30.86 (6)Sixvii—O1—Ce1xv99.16 (11)
O2x—Ce2—Si107.72 (7)Sixvii—O1—Ce1xix130.16 (13)
O2xi—Ce2—Si107.72 (7)Ce1xv—O1—Ce1xix102.42 (10)
O1vii—Ce2—Sixii30.82 (6)Sixvii—O1—Ce2viii97.70 (13)
O1viii—Ce2—Sixii30.82 (6)Ce1xv—O1—Ce2viii128.62 (11)
O2—Ce2—Sixii149.14 (6)Ce1xix—O1—Ce2viii102.68 (9)
O2ix—Ce2—Sixii149.14 (6)Si—O2—Ce296.05 (12)
O2x—Ce2—Sixii72.28 (7)Si—O2—Ce2x148.92 (16)
O2xi—Ce2—Sixii72.28 (7)Ce2—O2—Ce2x99.84 (10)
Si—Ce2—Sixii180.0Si—O2—Ce194.93 (12)
O1vii—Ce2—Texiii141.98 (6)Ce2—O2—Ce1121.55 (11)
O1viii—Ce2—Texiii83.84 (6)Ce2x—O2—Ce199.16 (9)
O2—Ce2—Texiii66.76 (6)
Symmetry codes: (i) x, y1/2, z+1/2; (ii) x, y1/2, z; (iii) x, y1, z; (iv) x, y1, z+1/2; (v) x, y, z+1/2; (vi) x+1, y1/2, z+1/2; (vii) x+1, y1/2, z; (viii) x+1, y+1, z; (ix) x, y+1/2, z; (x) x+1, y, z; (xi) x+1, y+1/2, z; (xii) x+1, y, z; (xiii) x, y+1/2, z1/2; (xiv) x+1, y+1/2, z+1/2; (xv) x, y+1/2, z+1/2; (xvi) x+1, y+1, z+1/2; (xvii) x, y+1, z; (xviii) x1, y, z; (xix) x, y+1, z.

Experimental details

(I)(II)
Crystal data
Chemical formulaCe2(SiO4)SeCe2(SiO4)Te
Mr451.29499.93
Crystal system, space groupOrthorhombic, PbcmOrthorhombic, Pbcm
Temperature (K)153153
a, b, c (Å)6.2250 (6), 7.2354 (7), 11.0739 (10)6.3647 (6), 7.2807 (7), 11.2743 (10)
V3)498.77 (8)522.45 (8)
Z44
Radiation typeMo KαMo Kα
µ (mm1)25.4622.82
Crystal size (mm)0.13 × 0.03 × 0.030.08 × 0.05 × 0.04
Data collection
DiffractometerBruker SMART 1000 CCD area-detector
diffractometer
Bruker SMART 1000 CCD area-detector
diffractometer
Absorption correctionNumerical
(SHELXTL; Sheldrick, 2003)
Numerical
(SHELXTL; Sheldrick, 2003)
Tmin, Tmax0.067, 0.2740.244, 0.423
No. of measured, independent and
observed [I > 2σ(I)] reflections
5011, 662, 643 5770, 690, 666
Rint0.0290.034
(sin θ/λ)max1)0.6830.680
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.059, 1.49 0.023, 0.057, 1.34
No. of reflections662690
No. of parameters4242
Δρmax, Δρmin (e Å3)2.03, 1.491.99, 2.03

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SAINT, SHELXTL (Sheldrick, 2003), XP in SHELXTL.

Selected geometric parameters (Å, º) for (I) top
Ce1—O1i2.480 (3)Ce2—O1iv2.504 (3)
Ce1—O1ii2.486 (3)Ce2—O2v2.518 (3)
Ce1—O22.578 (2)Ce2—Se3.1926 (4)
Ce1—Seiii3.0157 (7)Si—O21.630 (3)
Ce1—Se3.1802 (6)Si—O1i1.647 (3)
Ce2—O22.475 (3)
O2vi—Si—O2106.2 (2)O2—Si—O1i104.36 (13)
O2vi—Si—O1i119.01 (13)O1vii—Si—O1i104.8 (2)
Symmetry codes: (i) x, y1/2, z; (ii) x, y1, z; (iii) x+1, y1/2, z+1/2; (iv) x+1, y1/2, z; (v) x+1, y+1/2, z; (vi) x, y+1/2, z; (vii) x, y+1, z.
The known Ln2(SiO4)Q (Q = Te, Se, S) compounds top
Q = TeQ = SeQ = S
Ce2(SiO4)Tea (Pbcm)La2(SiO4)Sef (Pbcm)Ho2SiO4Sj (Pbcm)
Pr2(SiO4)Teb (Pbcm and P21/c)Ce2(SiO4)Sea (Pbcm)
Nd2(SiO4)Tec (Pbcm and P21/c)Nd2(SiO4)Seg (Pbcm)
Sm2(SiO4)Tec,d (Pbcm and P21/c)Sm2(SiO4)Sed (Pbcm)
Gd2(SiO4)Tee (Pbcm)Tb2(SiO4)Seh (Pbcm)
Dy2(SiO4)Sed (Pbcm)
Ho2(SiO4)Sed (Pbcm)
Er2(SiO4)Sei (Pbcm)
Notes: (a) this work; (b) Weber & Schleid (1999); (c) Yang & Ibers (2000); (d) Person et al. (2000); (e) Ijjalli & Ibers (2001); (f) Brennan & Ibers (1991); (g) Grupe & Urland (1990); (h) Ijjaali et al. (2002); (i) Stöwe (1994); (j) Hartenbach et al. (2002).
Selected geometric parameters (Å, º) for (II) top
Ce1—O1i2.495 (3)Ce2—O1v2.524 (3)
Ce1—O1ii2.522 (3)Ce2—O2vi2.547 (3)
Ce1—O22.621 (3)Ce2—O2vii2.555 (3)
Ce1—Teiii3.2082 (5)Ce2—Teviii3.3819 (3)
Ce1—Teiv3.3604 (5)Si—O21.633 (3)
Ce1—Te3.3704 (5)Si—O1i1.653 (3)
O2—Si—O2vi106.2 (2)O2vi—Si—O1i119.79 (13)
O2—Si—O1i104.55 (13)O1ix—Si—O1i103.0 (2)
Symmetry codes: (i) x, y1/2, z; (ii) x, y1, z; (iii) x+1, y1/2, z+1/2; (iv) x, y1/2, z+1/2; (v) x+1, y1/2, z; (vi) x, y+1/2, z; (vii) x+1, y, z; (viii) x, y+1/2, z1/2; (ix) x, y+1, z.
 

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