Gd₂OSe₂

Single crystals of digadolinium monooxy­gen diselenide, Gd₂OSe₂, have been obtained from a KBr flux. The compound is isostructural with the low-pressure form of Dy₂OS₂. All atoms lie on the mirror plane of Pnma. The Gd environments are a GdO₃Se₅ bicapped trigonal prism and a GdOSe₅ distorted octahedron. The two coordination polyhedra pack by face-sharing and edge-sharing to form a [Gd_8/4O_4/4Se^a_8/8-Seⁱ_8/8] fragment, which is the main motif of the structure. These fragments lie in the ac plane and form infinite chains parallel to c through the sharing of Se atoms around atom Gd1. In the a direction, these chains stack through the sharing of an Se atom around atom Gd2, thereby delimiting large pentagonal cavities.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SMART (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL/PC (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL/PC.

(I)

Crystal data

Gd2OSe2	Dx = 7.301 Mg m^−3
Mr = 488.42	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 2878 reflections
a = 16.050 (3) Å	θ = 2.5–28.3°
b = 3.9375 (8) Å	µ = 45.78 mm^−1
c = 7.0309 (14) Å	T = 153 K
V = 444.32 (15) Å^3	Rod, pale_yellow
Z = 4	0.24 × 0.02 × 0.02 mm
F(000) = 816

Data collection

Bruker Smart 1000 CCD diffractometer	623 independent reflections
Radiation source: standard-focus sealed tube	580 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ω scans	θmax = 28.3°, θmin = 2.5°
Absorption correction: numerical (face indexed; SHLEXTL/PC; Sheldrick, 1997b)	h = −20→20
Tmin = 0.065, Tmax = 0.400	k = −5→5
3870 measured reflections	l = −9→9

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.024	w = 1/[σ^2(Fo^2) + (0.04Fo^2)^2]
wR(F^2) = 0.059	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 2.96 e Å^−3
623 reflections	Δρmin = −2.30 e Å^−3
32 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0017 (2)

Special details

Experimental. Data collection covered more than a hemisphere of reciprocal space by a combination of three sets of 606 frames φ = 0°, 120°, and 240° with Δω = 0.3° and exposure times of 15 s. Crystal decay, which proved to be negligible, was monitored by repeating 50 initial frames at the end of the data collection.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Gd1	0.03937 (2)	0.2500	0.69956 (6)	0.00746 (16)
Gd2	0.16208 (3)	0.2500	0.25860 (6)	0.00901 (16)
Se1	0.31982 (5)	0.2500	0.05159 (12)	0.0088 (2)
Se2	0.40054 (4)	0.2500	0.50993 (12)	0.0082 (2)
O1	0.0314 (3)	0.2500	0.3705 (9)	0.0071 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Gd1	0.0081 (2)	0.0060 (2)	0.0083 (2)	0.000	−0.00025 (14)	0.000
Gd2	0.0093 (2)	0.0074 (2)	0.0104 (3)	0.000	0.00097 (14)	0.000
Se1	0.0087 (4)	0.0079 (4)	0.0098 (4)	0.000	0.0005 (3)	0.000
Se2	0.0105 (4)	0.0061 (4)	0.0079 (4)	0.000	0.0008 (3)	0.000
O1	0.003 (2)	0.008 (3)	0.010 (3)	0.000	−0.003 (2)	0.000

Geometric parameters (Å, º)

Gd1—O1	2.317 (6)	Gd2—Se1	2.9203 (10)
Gd1—O1^i	2.326 (3)	Gd2—Gd1^i	3.7968 (7)
Gd1—O1^ii	2.326 (3)	Gd2—Gd1^ii	3.7968 (7)
Gd1—Se2^iii	3.0228 (10)	Gd2—Gd2^viii	3.9375 (8)
Gd1—Se2^iv	3.0932 (8)	Gd2—Gd2^ix	3.9375 (8)
Gd1—Se2^v	3.0932 (8)	Se1—Gd2^vi	2.8642 (8)
Gd1—Se1^iv	3.1726 (8)	Se1—Gd2^vii	2.8642 (8)
Gd1—Se1^v	3.1726 (8)	Se1—Gd1^vii	3.1726 (8)
Gd1—Gd1^i	3.6535 (8)	Se1—Gd1^vi	3.1726 (8)
Gd1—Gd1^ii	3.6535 (8)	Se2—Gd2^iv	2.8183 (7)
Gd1—Gd2	3.6729 (8)	Se2—Gd2^v	2.8183 (7)
Gd1—Gd2^i	3.7968 (7)	Se2—Gd1^x	3.0228 (10)
Gd2—O1	2.240 (5)	Se2—Gd1^vi	3.0932 (8)
Gd2—Se2^vi	2.8183 (7)	Se2—Gd1^vii	3.0932 (8)
Gd2—Se2^vii	2.8183 (7)	O1—Gd1^i	2.326 (3)
Gd2—Se1^iv	2.8642 (8)	O1—Gd1^ii	2.326 (3)
Gd2—Se1^v	2.8642 (8)
O1—Gd1—O1^i	76.20 (17)	Se2^vii—Gd2—Se1^v	164.26 (3)
O1—Gd1—O1^ii	76.20 (17)	Se1^iv—Gd2—Se1^v	86.84 (3)
O1^i—Gd1—O1^ii	115.7 (2)	O1—Gd2—Se1	170.67 (15)
O1—Gd1—Se2^iii	129.35 (12)	Se2^vi—Gd2—Se1	90.00 (2)
O1^i—Gd1—Se2^iii	77.47 (14)	Se2^vii—Gd2—Se1	90.00 (2)
O1^ii—Gd1—Se2^iii	77.47 (14)	Se1^iv—Gd2—Se1	105.695 (17)
O1—Gd1—Se2^iv	136.19 (5)	Se1^v—Gd2—Se1	105.695 (17)
O1^i—Gd1—Se2^iv	147.19 (15)	O1—Gd2—Gd1	37.01 (15)
O1^ii—Gd1—Se2^iv	76.29 (13)	Se2^vi—Gd2—Gd1	109.42 (2)
Se2^iii—Gd1—Se2^iv	75.71 (2)	Se2^vii—Gd2—Gd1	109.42 (2)
O1—Gd1—Se2^v	136.19 (5)	Se1^iv—Gd2—Gd1	56.448 (18)
O1^i—Gd1—Se2^v	76.29 (13)	Se1^v—Gd2—Gd1	56.448 (18)
O1^ii—Gd1—Se2^v	147.19 (15)	Se1—Gd2—Gd1	152.32 (2)
Se2^iii—Gd1—Se2^v	75.71 (2)	O1—Gd2—Gd1^i	34.46 (6)
Se2^iv—Gd1—Se2^v	79.06 (3)	Se2^vi—Gd2—Gd1^i	51.844 (18)
O1—Gd1—Se1^iv	73.25 (9)	Se2^vii—Gd2—Gd1^i	96.12 (2)
O1^i—Gd1—Se1^iv	143.49 (14)	Se1^iv—Gd2—Gd1^i	112.77 (2)
O1^ii—Gd1—Se1^iv	75.71 (11)	Se1^v—Gd2—Gd1^i	70.989 (19)
Se2^iii—Gd1—Se1^iv	138.303 (16)	Se1—Gd2—Gd1^i	140.973 (16)
Se2^iv—Gd1—Se1^iv	67.31 (2)	Gd1—Gd2—Gd1^i	58.535 (13)
Se2^v—Gd1—Se1^iv	113.84 (2)	O1—Gd2—Gd1^ii	34.46 (6)
O1—Gd1—Se1^v	73.25 (9)	Se2^vi—Gd2—Gd1^ii	96.12 (2)
O1^i—Gd1—Se1^v	75.71 (11)	Se2^vii—Gd2—Gd1^ii	51.844 (18)
O1^ii—Gd1—Se1^v	143.49 (14)	Se1^iv—Gd2—Gd1^ii	70.989 (19)
Se2^iii—Gd1—Se1^v	138.303 (16)	Se1^v—Gd2—Gd1^ii	112.77 (2)
Se2^iv—Gd1—Se1^v	113.84 (2)	Se1—Gd2—Gd1^ii	140.974 (16)
Se2^v—Gd1—Se1^v	67.31 (2)	Gd1—Gd2—Gd1^ii	58.535 (13)
Se1^iv—Gd1—Se1^v	76.71 (2)	Gd1^i—Gd2—Gd1^ii	62.466 (17)
O1—Gd1—Gd1^i	38.19 (6)	O1—Gd2—Gd2^viii	90.0
O1^i—Gd1—Gd1^i	38.02 (15)	Se2^vi—Gd2—Gd2^viii	134.312 (15)
O1^ii—Gd1—Gd1^i	97.15 (13)	Se2^vii—Gd2—Gd2^viii	45.688 (15)
Se2^iii—Gd1—Gd1^i	105.31 (2)	Se1^iv—Gd2—Gd2^viii	46.578 (15)
Se2^iv—Gd1—Gd1^i	173.069 (15)	Se1^v—Gd2—Gd2^viii	133.421 (15)
Se2^v—Gd1—Gd1^i	107.863 (17)	Se1—Gd2—Gd2^viii	90.0
Se1^iv—Gd1—Gd1^i	109.20 (3)	Gd1—Gd2—Gd2^viii	90.0
Se1^v—Gd1—Gd1^i	70.13 (2)	Gd1^i—Gd2—Gd2^viii	121.233 (8)
O1—Gd1—Gd1^ii	38.19 (6)	Gd1^ii—Gd2—Gd2^viii	58.767 (8)
O1^i—Gd1—Gd1^ii	97.15 (13)	O1—Gd2—Gd2^ix	90.0
O1^ii—Gd1—Gd1^ii	38.02 (15)	Se2^vi—Gd2—Gd2^ix	45.688 (15)
Se2^iii—Gd1—Gd1^ii	105.31 (2)	Se2^vii—Gd2—Gd2^ix	134.312 (15)
Se2^iv—Gd1—Gd1^ii	107.863 (17)	Se1^iv—Gd2—Gd2^ix	133.422 (15)
Se2^v—Gd1—Gd1^ii	173.069 (15)	Se1^v—Gd2—Gd2^ix	46.578 (15)
Se1^iv—Gd1—Gd1^ii	70.13 (2)	Se1—Gd2—Gd2^ix	90.0
Se1^v—Gd1—Gd1^ii	109.20 (3)	Gd1—Gd2—Gd2^ix	90.0
Gd1^i—Gd1—Gd1^ii	65.213 (19)	Gd1^i—Gd2—Gd2^ix	58.767 (8)
O1—Gd1—Gd2	35.59 (12)	Gd1^ii—Gd2—Gd2^ix	121.233 (8)
O1^i—Gd1—Gd2	94.76 (14)	Gd2^viii—Gd2—Gd2^ix	180.0
O1^ii—Gd1—Gd2	94.76 (14)	Gd2^vi—Se1—Gd2^vii	86.84 (3)
Se2^iii—Gd1—Gd2	164.93 (2)	Gd2^vi—Se1—Gd2	116.51 (2)
Se2^iv—Gd1—Gd2	115.36 (2)	Gd2^vii—Se1—Gd2	116.51 (2)
Se2^v—Gd1—Gd2	115.36 (2)	Gd2^vi—Se1—Gd1^vii	126.17 (3)
Se1^iv—Gd1—Gd2	48.797 (16)	Gd2^vii—Se1—Gd1^vii	74.755 (18)
Se1^v—Gd1—Gd2	48.797 (16)	Gd2—Se1—Gd1^vii	117.01 (3)
Gd1^i—Gd1—Gd2	62.428 (17)	Gd2^vi—Se1—Gd1^vi	74.755 (18)
Gd1^ii—Gd1—Gd2	62.428 (17)	Gd2^vii—Se1—Gd1^vi	126.17 (3)
O1—Gd1—Gd2^i	91.74 (10)	Gd2—Se1—Gd1^vi	117.01 (3)
O1^i—Gd1—Gd2^i	33.02 (12)	Gd1^vii—Se1—Gd1^vi	76.71 (2)
O1^ii—Gd1—Gd2^i	92.26 (10)	Gd2^iv—Se2—Gd2^v	88.62 (3)
Se2^iii—Gd1—Gd2^i	47.150 (15)	Gd2^iv—Se2—Gd1^x	81.01 (2)
Se2^iv—Gd1—Gd2^i	122.74 (2)	Gd2^v—Se2—Gd1^x	81.01 (2)
Se2^v—Gd1—Gd2^i	83.155 (17)	Gd2^iv—Se2—Gd1^vi	173.44 (3)
Se1^iv—Gd1—Gd2^i	162.50 (2)	Gd2^v—Se2—Gd1^vi	95.982 (17)
Se1^v—Gd1—Gd2^i	108.072 (18)	Gd1^x—Se2—Gd1^vi	104.29 (2)
Gd1^i—Gd1—Gd2^i	59.037 (13)	Gd2^iv—Se2—Gd1^vii	95.982 (17)
Gd1^ii—Gd1—Gd2^i	92.541 (17)	Gd2^v—Se2—Gd1^vii	173.44 (3)
Gd2—Gd1—Gd2^i	121.465 (13)	Gd1^x—Se2—Gd1^vii	104.29 (2)
O1—Gd2—Se2^vi	83.34 (11)	Gd1^vi—Se2—Gd1^vii	79.06 (3)
O1—Gd2—Se2^vii	83.34 (11)	Gd2—O1—Gd1	107.4 (2)
Se2^vi—Gd2—Se2^vii	88.62 (3)	Gd2—O1—Gd1^i	112.51 (15)
O1—Gd2—Se1^iv	80.93 (11)	Gd1—O1—Gd1^i	103.80 (17)
Se2^vi—Gd2—Se1^iv	164.26 (3)	Gd2—O1—Gd1^ii	112.51 (15)
Se2^vii—Gd2—Se1^iv	90.12 (2)	Gd1—O1—Gd1^ii	103.80 (17)
O1—Gd2—Se1^v	80.93 (11)	Gd1^i—O1—Gd1^ii	115.7 (2)
Se2^vi—Gd2—Se1^v	90.12 (2)

Symmetry codes: (i) −x, −y, −z+1; (ii) −x, −y+1, −z+1; (iii) x−1/2, y, −z+3/2; (iv) −x+1/2, −y+1, z+1/2; (v) −x+1/2, −y, z+1/2; (vi) −x+1/2, −y, z−1/2; (vii) −x+1/2, −y+1, z−1/2; (viii) x, y+1, z; (ix) x, y−1, z; (x) x+1/2, y, −z+3/2.