Reinvestigation of CuSe₂O₅

The crystal structure of the title compound, copper(II) diselenium(IV) pentoxide [Meunier, Svensson & Carpy, (1976). Acta Cryst. B32, 2664-2667], has been reinvestigated and confirmed to much higher precision, and anisotropic displacement parameters has been refined. The structure consists of CuO₄ planar squares and Se₂O₅E₂ (E = lone pair) dimers. The Cu atom has site symmetry and one O atom has site symmetry 2.

Key indicators

• Single-crystal X-ray study
• T = 292 K
• Mean [sigma](u-O) = 0.004 Å
• R factor = 0.028
• wR factor = 0.070
• Data-to-parameter ratio = 16.4

checkCIF/PLATON results

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Alert level C
PLAT021_ALERT_1_C Ratio Unique / Expected Reflections too High ...       1.01

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: SHELXL97.

Copper(II) diselenium(IV) pentaoxide

Crystal data

CuO5Se2	F(000) = 548
Mr = 301.46	Dx = 4.478 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C2yc	Cell parameters from 1839 reflections
a = 12.3869 (19) Å	θ = 0.2–0.6°
b = 4.8699 (7) Å	µ = 21.08 mm^−1
c = 7.9917 (13) Å	T = 292 K
β = 111.953 (15)°	Needle, green
V = 447.13 (12) Å^3	0.32 × 0.08 × 0.04 mm
Z = 4

Data collection

Oxford Xcalibur3 Diffractometer	655 independent reflections
Radiation source: fine-focus sealed tube	571 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.071
ω scans at different φ	θmax = 29.9°, θmin = 4.5°
Absorption correction: numerical [X-RED32 (Stoe, 2001) and X-SHAPE (Stoe, 1999)'	h = −17→17
Tmin = 0.218, Tmax = 0.642	k = −6→6
1839 measured reflections	l = −11→7

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)] = 0.028	w = 1/[σ^2(Fo^2) + (0.0331P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.070	(Δ/σ)max < 0.001
S = 0.99	Δρmax = 1.15 e Å^−3
655 reflections	Δρmin = −0.95 e Å^−3
40 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0038 (6)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Se	0.13990 (4)	0.06450 (9)	0.82983 (5)	0.01230 (18)
Cu	0.0000	0.5000	0.5000	0.0148 (2)
O1	0.0000	−0.1180 (10)	0.7500	0.0151 (9)
O2	0.1256 (3)	0.2753 (8)	0.6593 (4)	0.0222 (7)
O3	0.1262 (3)	0.2725 (7)	0.9874 (4)	0.0206 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Se	0.0089 (2)	0.0126 (3)	0.0148 (2)	0.00123 (15)	0.00365 (15)	−0.00009 (14)
Cu	0.0102 (4)	0.0165 (4)	0.0168 (4)	−0.0014 (3)	0.0042 (3)	0.0030 (3)
O1	0.0093 (19)	0.016 (2)	0.0192 (19)	0.000	0.0039 (16)	0.000
O2	0.0140 (15)	0.0255 (19)	0.0246 (15)	0.0026 (14)	0.0044 (12)	0.0140 (14)
O3	0.0120 (14)	0.0213 (18)	0.0267 (15)	0.0020 (13)	0.0052 (12)	−0.0098 (14)

Geometric parameters (Å, º)

Se—O2	1.662 (3)	Cu—O1^v	2.730 (3)
Se—O3	1.673 (3)	O1—Se^iii	1.837 (2)
Se—O1	1.837 (2)	O1—Cu^vi	2.730 (3)
Cu—O2^i	1.938 (3)	O1—Cu^vii	2.730 (3)
Cu—O2	1.938 (3)	O1—Cu^iii	3.612 (4)
Cu—O3^ii	1.949 (3)	O2—Cu^iii	3.768 (3)
Cu—O3^iii	1.949 (3)	O3—Cu^iii	1.949 (3)
Cu—O1^iv	2.730 (3)	O3—Se^viii	2.827 (3)
O2—Se—O3	103.50 (19)	Se—O1—Cu^vii	109.49 (6)
O2—Se—O1	102.50 (14)	Se^iii—O1—Cu^vii	109.02 (6)
O3—Se—O1	101.91 (14)	Cu^vi—O1—Cu^vii	94.09 (15)
O2^i—Cu—O2	180.000 (1)	Se—O1—Cu^iii	66.41 (12)
O2^i—Cu—O3^ii	96.16 (14)	Se^iii—O1—Cu^iii	66.04 (12)
O2—Cu—O3^ii	83.84 (14)	Cu^vi—O1—Cu^iii	166.53 (11)
O2^i—Cu—O3^iii	83.84 (14)	Cu^vii—O1—Cu^iii	99.38 (3)
O2—Cu—O3^iii	96.16 (14)	Se—O1—Cu	66.04 (12)
O3^ii—Cu—O3^iii	180.0 (2)	Se^iii—O1—Cu	66.41 (12)
O2^i—Cu—O1^iv	82.90 (11)	Cu^vi—O1—Cu	99.38 (3)
O2—Cu—O1^iv	97.10 (11)	Cu^vii—O1—Cu	166.53 (11)
O3^ii—Cu—O1^iv	82.52 (11)	Cu^iii—O1—Cu	67.16 (8)
O3^iii—Cu—O1^iv	97.48 (11)	Se—O2—Cu	134.49 (19)
O2^i—Cu—O1^v	97.10 (11)	Se—O2—Cu^iii	62.17 (10)
O2—Cu—O1^v	82.90 (11)	Cu—O2—Cu^iii	82.18 (11)
O3^ii—Cu—O1^v	97.48 (11)	Se—O3—Cu^iii	133.77 (17)
O3^iii—Cu—O1^v	82.52 (11)	Se—O3—Se^viii	100.73 (13)
O1^iv—Cu—O1^v	180.0	Cu^iii—O3—Se^viii	120.04 (14)
Se—O1—Se^iii	122.1 (3)	Se—O3—Cu	61.39 (9)
Se—O1—Cu^vi	109.02 (6)	Cu^iii—O3—Cu	81.71 (10)
Se^iii—O1—Cu^vi	109.49 (6)	Se^viii—O3—Cu	113.52 (10)

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