Electron density in the sodium vanadium oxide bronze β-Na_xV₂O₅ at 9 K

The crystal structure and electron density in sodium vanadium oxide bronze, β-Na_xV₂O₅ [x = 0.282 (3)], have been studied by accurate Mo Kα X-ray diffraction measurements at 9.6 (3) K. No noticeable difference in the crystal structures at room temperature and 9.6 K has been observed. No superstructure reflections, previously found by Kanai, Kagoshima & Nagasawa [(1982), J. Phys. Soc. Jpn, 51, 697–698], have been detected at low temperature. Analysis of the deformation electron density has revealed the presence of the quasi-two-dimensional sheets of the —V—O—V—O— bonds in the structure. The electron density in the different chemical bonds within each of the three crystallographically independent VO₆ polyhedra noticeably varies, although there is no clear evidence that the three crystallographically independent V atoms have different valence states.

Computing details

Program(s) used to refine structure: Koritsanszky et al., (1995); molecular graphics: Koritsanszky et al., (1995); software used to prepare material for publication: Koritsanszky et al., (1995).

Figures

(NaV2O5)

Crystal data

Na0.282V2O5	Dx = 3.594 Mg m^−3
Mr = 188.36	Mo Kα radiation, λ = 0.71069 Å
Monoclinic, C2/m	Cell parameters from 12 reflections
a = 15.3500 (1) Å	θ = 37.8–39.1°
b = 3.6115 (4) Å	µ = 5.25 mm^−1
c = 10.058 (1) Å	T = 10 K
β = 109.560 (7)°	, black
V = 525.40 (9) Å^3	0.21 × 0.14 × 0.05 mm
Z = 6

Data collection

Huber 512 diffractometer	Rint = 0.028
ω–2θ scans	θmax = 50°
Absorption correction: analytical ?	h = −32→32
Tmin = 0.473, Tmax = 0.776	k = −7→7
10461 measured reflections	l = −21→21
2938 independent reflections	3 standard reflections every 100 reflections
2897 reflections with I > 2/σ(I)	intensity decay: 2%

Refinement

Refinement on F	253 parameters
R[F^2 > 2σ(F^2)] = 0.016	w = 1/σ^2(F)
wR(F^2) = 0.0110
2897 reflections	Extinction correction: Becker & Coppens

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

	x	y	z	Uiso*/Ueq
V(1)	0.337844 (7)	0.000000	0.100038 (11)	0.004
V(2)	0.116550 (8)	0.000000	0.119918 (12)	0.005
V(3)	0.288107 (8)	0.000000	0.409916 (12)	0.004
Na(1)	0.00100 (5)	0.00000	0.40311 (8)	0.007
O(1)	0.00000	0.00000	0.00000	0.007
O(2)	0.18561 (4)	0.00000	−0.05486 (5)	0.007
O(3)	0.36577 (3)	0.00000	−0.07900 (5)	0.006
O(4)	0.43750 (4)	0.00000	0.21868 (6)	0.009
O(5)	0.26336 (4)	0.00000	0.22320 (5)	0.006
O(6)	0.10644 (4)	0.00000	0.27384 (6)	0.007
O(7)	0.24317 (3)	0.00000	0.57449 (5)	0.006
O(8)	0.39856 (4)	0.00000	0.47136 (5)	0.008

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
V(1)	0.00436 (3)	0.00401 (4)	0.00423 (3)	0.00000	0.00158 (3)	0.00000
V(2)	0.00713 (4)	0.00393 (4)	0.00506 (4)	0.00000	0.00310 (3)	0.00000
V(3)	0.00480 (4)	0.00405 (4)	0.00422 (3)	0.00000	0.00199 (3)	0.00000
Na(1)	0.0074 (2)	0.0066 (3)	0.0073 (2)	0.0000	0.0022 (2)	0.0000
O(1)	0.0050 (2)	0.0066 (2)	0.0085 (2)	0.0000	0.0007 (2)	0.0000
O(2)	0.0077 (2)	0.0048 (2)	0.0068 (2)	0.0000	0.0027 (1)	0.0000
O(3)	0.0066 (2)	0.0045 (2)	0.0053 (1)	0.0000	0.0023 (1)	0.0000
O(4)	0.0055 (2)	0.0149 (2)	0.0063 (2)	0.0000	0.0011 (1)	0.0000
O(5)	0.0055 (1)	0.0063 (2)	0.0046 (1)	0.0000	0.0020 (1)	0.0000
O(6)	0.0077 (2)	0.0077 (2)	0.0054 (2)	0.0000	0.0028 (1)	0.0000
O(7)	0.0087 (2)	0.0040 (2)	0.0064 (1)	0.0000	0.0039 (1)	0.0000
O(8)	0.0056 (2)	0.0118 (2)	0.0069 (2)	0.0000	0.0017 (1)	0.0000

Bond lengths (Å)

V(1)—O(2)^i	1.8674 (1)	V(2)—O(3)^iii	1.8917 (2)
V(1)—O(2)^ii	1.8674 (1)	V(2)—O(3)^iv	1.8917 (1)
V(1)—O(2)^iii	1.8674 (1)	V(2)—O(6)	1.6067 (5)
V(1)—O(2)^iv	1.8674 (1)	V(2)—O(6)^v	1.6067 (5)
V(1)—O(4)	1.5942 (5)	V(3)—O(5)	1.7871 (5)
V(1)—O(4)^v	1.5942 (5)	V(3)—O(5)^v	1.7871 (5)
V(1)—O(5)	1.9467 (5)	V(3)—O(7)^viii	1.8885 (2)
V(1)—O(5)^v	1.9467 (5)	V(3)—O(7)^ix	1.8885 (2)
V(2)—O(1)	1.7918 (1)	V(3)—O(7)^x	1.8885 (2)
V(2)—O(1)^vi	1.7918 (1)	V(3)—O(7)^xi	1.8885 (2)
V(2)—O(1)^vii	1.7918 (1)	V(3)—O(8)	1.5985 (5)
V(2)—O(1)^v	1.7918 (1)	V(3)—O(8)^v	1.5985 (5)
V(2)—O(3)^i	1.8917 (2)	Na(1)—Na(1)^xii	1.9596 (14)
V(2)—O(3)^ii	1.8917 (1)	Na(1)—Na(1)^xiii	1.9596 (14)

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