Redetermination of Co₄Nb₂O₉ by single-crystal X-ray methods

A high-precision structure of tetra­cobalt diniobium nona­oxide, Co₄Nb₂O₉, is presented, based on X-ray single-crystal data. The space group and cation distribution previously obtained from powder data [Bertaut, Corliss, Forrat, Aleonard & Pauthenet (1961). J. Phys. Chem. Solids, 21, 234-251] are confirmed.

Key indicators

• Single-crystal X-ray study
• T = 297 K
• Mean [sigma](o-O) = 0.004 Å
• R factor = 0.031
• wR factor = 0.079
• Data-to-parameter ratio = 13.1

checkCIF/PLATON results

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Alert level B
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          6
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          m
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          m
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          m

Alert level C
PLAT731_ALERT_1_C Bond    Calc    2.022(5), Rep    2.022(2) ......       2.50 su-Rat
              CO1  -O1      1.555   2.665

   0 ALERT level A = In general: serious problem
   4 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
   4 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

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Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1998); program(s) used to refine structure: SHELXTL-Plus; molecular graphics: CaRIne Crystallography (Boudias & Monceau, 1998).

tetracobalt diniobium nonaoxide

Crystal data

Co4Nb2O9	Dx = 5.728 Mg m^−3
Mr = 565.54	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3c1	Cell parameters from 34 reflections
Hall symbol: -P 3 2"c	θ = 4.5–30.0°
a = 5.1736 (3) Å	µ = 13.29 mm^−1
c = 14.1457 (11) Å	T = 297 K
V = 327.90 (4) Å^3	Block, violet
Z = 2	0.12 × 0.07 × 0.05 mm
F(000) = 524

Data collection

Bruker P4 diffractometer	262 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.076
Graphite monochromator	θmax = 30.0°, θmin = 2.9°
ω scans	h = −7→7
Absorption correction: ψ scan (XSCANS; Siemens, 1996)	k = −7→7
Tmin = 0.272, Tmax = 0.510	l = −19→19
1234 measured reflections	2 standard reflections every 48 reflections
328 independent reflections	intensity decay: 1.5%

Refinement

Refinement on F^2	Primary atom site location: heavy-atom method
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	w = 1/[σ^2(Fo^2) + (0.0148P)^2 + 2.3726P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.079	(Δ/σ)max < 0.001
S = 1.28	Δρmax = 0.95 e Å^−3
328 reflections	Δρmin = −0.80 e Å^−3
25 parameters	Extinction correction: SHELXTL-Plus, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0107 (11)

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

	x	y	z	Uiso*/Ueq
Nb1	0.0000	0.0000	0.14215 (4)	0.0081 (3)
Co1	0.3333	0.6667	0.19304 (7)	0.0103 (3)
Co2	0.3333	0.6667	−0.01377 (8)	0.0101 (3)
O1	0.0000	0.2876 (9)	0.2500	0.0091 (9)
O2	0.0235 (7)	0.6821 (7)	0.0847 (2)	0.0116 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nb1	0.0087 (3)	0.0087 (3)	0.0068 (3)	0.00437 (15)	0.000	0.000
Co1	0.0097 (4)	0.0097 (4)	0.0116 (5)	0.0048 (2)	0.000	0.000
Co2	0.0102 (4)	0.0102 (4)	0.0098 (5)	0.0051 (2)	0.000	0.000
O1	0.009 (2)	0.0087 (14)	0.0095 (19)	0.0045 (10)	0.0012 (15)	0.0006 (8)
O2	0.0103 (15)	0.0104 (15)	0.0135 (15)	0.0049 (13)	−0.0005 (11)	−0.0024 (12)

Geometric parameters (Å, º)

Nb1—O2^i	1.892 (3)	Co1—O2^iii	2.247 (3)
Nb1—O2^ii	1.892 (3)	Co2—O2^vii	2.083 (3)
Nb1—O2^iii	1.892 (3)	Co2—O2^viii	2.083 (3)
Nb1—O1	2.131 (3)	Co2—O2^ix	2.083 (3)
Nb1—O1^iv	2.131 (3)	Co2—O2^vi	2.155 (3)
Nb1—O1^v	2.131 (3)	Co2—O2	2.155 (3)
Co1—O1^vi	2.022 (2)	Co2—O2^iii	2.155 (3)
Co1—O1	2.022 (2)	O1—Co1^x	2.022 (2)
Co1—O1^iii	2.022 (2)	O1—Nb1^xi	2.131 (3)
Co1—O2	2.247 (3)	O2—Nb1^xii	1.892 (3)
Co1—O2^vi	2.247 (3)	O2—Co2^vii	2.083 (3)
O2^i—Nb1—O2^ii	102.93 (11)	O2^vi—Co1—O2^iii	78.64 (13)
O2^i—Nb1—O2^iii	102.93 (11)	O2^vii—Co2—O2^viii	98.72 (12)
O2^ii—Nb1—O2^iii	102.93 (11)	O2^vii—Co2—O2^ix	98.72 (12)
O2^i—Nb1—O1	91.50 (11)	O2^viii—Co2—O2^ix	98.72 (12)
O2^ii—Nb1—O1	159.50 (13)	O2^vii—Co2—O2^vi	168.48 (10)
O2^iii—Nb1—O1	87.65 (11)	O2^viii—Co2—O2^vi	89.44 (12)
O2^i—Nb1—O1^iv	159.50 (13)	O2^ix—Co2—O2^vi	87.97 (17)
O2^ii—Nb1—O1^iv	87.65 (11)	O2^vii—Co2—O2	89.44 (12)
O2^iii—Nb1—O1^iv	91.50 (11)	O2^viii—Co2—O2	87.97 (16)
O1—Nb1—O1^iv	74.41 (13)	O2^ix—Co2—O2	168.48 (10)
O2^i—Nb1—O1^v	87.65 (11)	O2^vi—Co2—O2	82.70 (13)
O2^ii—Nb1—O1^v	91.50 (11)	O2^vii—Co2—O2^iii	87.97 (16)
O2^iii—Nb1—O1^v	159.50 (13)	O2^viii—Co2—O2^iii	168.48 (10)
O1—Nb1—O1^v	74.41 (13)	O2^ix—Co2—O2^iii	89.44 (12)
O1^iv—Nb1—O1^v	74.41 (13)	O2^vi—Co2—O2^iii	82.70 (13)
O1^vi—Co1—O1	105.17 (5)	O2—Co2—O2^iii	82.70 (13)
O1^vi—Co1—O1^iii	105.17 (5)	Co1^x—O1—Co1	114.1 (2)
O1—Co1—O1^iii	105.17 (5)	Co1^x—O1—Nb1	131.67 (5)
O1^vi—Co1—O2	81.47 (11)	Co1—O1—Nb1	95.40 (3)
O1—Co1—O2	91.63 (10)	Co1^x—O1—Nb1^xi	95.40 (3)
O1^iii—Co1—O2	159.21 (11)	Co1—O1—Nb1^xi	131.67 (5)
O1^vi—Co1—O2^vi	91.63 (10)	Nb1—O1—Nb1^xi	91.44 (17)
O1—Co1—O2^vi	159.21 (11)	Nb1^xii—O2—Co2^vii	123.06 (16)
O1^iii—Co1—O2^vi	81.47 (11)	Nb1^xii—O2—Co2	132.99 (17)
O2—Co1—O2^vi	78.64 (13)	Co2^vii—O2—Co2	90.56 (12)
O1^vi—Co1—O2^iii	159.21 (11)	Nb1^xii—O2—Co1	95.47 (13)
O1—Co1—O2^iii	81.47 (11)	Co2^vii—O2—Co1	129.54 (15)
O1^iii—Co1—O2^iii	91.63 (9)	Co2—O2—Co1	83.25 (12)
O2—Co1—O2^iii	78.64 (13)
O1^vi—Co1—O1—Co1^x	18.27 (8)	O2^vii—Co2—O2—Nb1^xii	−139.0 (3)
O2—Co1—O1—Co1^x	−63.33 (8)	O2^viii—Co2—O2—Nb1^xii	−40.3 (2)
O2^vi—Co1—O1—Co1^x	−124.6 (3)	O2^ix—Co2—O2—Nb1^xii	85.6 (8)
O2^iii—Co1—O1—Co1^x	−141.58 (9)	O2^vi—Co2—O2—Nb1^xii	49.4 (3)
O1^vi—Co1—O1—Nb1	159.01 (15)	O2^iii—Co2—O2—Nb1^xii	132.96 (18)
O1^iii—Co1—O1—Nb1	−90.22 (9)	O2^vii—Co2—O2—Co2^vii	0.0
O2—Co1—O1—Nb1	77.41 (11)	O2^viii—Co2—O2—Co2^vii	98.75 (12)
O2^vi—Co1—O1—Nb1	16.1 (3)	O2^ix—Co2—O2—Co2^vii	−135.4 (6)
O2^iii—Co1—O1—Nb1	−0.85 (10)	O2^vi—Co2—O2—Co2^vii	−171.55 (13)
O1^vi—Co1—O1—Nb1^xi	−104.22 (12)	O2^iii—Co2—O2—Co2^vii	−88.03 (17)
O1^iii—Co1—O1—Nb1^xi	6.55 (19)	O2^vii—Co2—O2—Co1	129.79 (14)
O2—Co1—O1—Nb1^xi	174.2 (2)	O2^viii—Co2—O2—Co1	−131.46 (11)
O2^vi—Co1—O1—Nb1^xi	112.9 (2)	O2^ix—Co2—O2—Co1	−5.6 (7)
O2^iii—Co1—O1—Nb1^xi	95.9 (2)	O1^vi—Co1—O2—Nb1^xii	0.95 (12)
O2^i—Nb1—O1—Co1^x	27.5 (2)	O1—Co1—O2—Nb1^xii	106.05 (14)
O2^ii—Nb1—O1—Co1^x	−107.7 (3)	O1^iii—Co1—O2—Nb1^xii	−109.6 (3)
O2^iii—Nb1—O1—Co1^x	130.4 (2)	O2^vi—Co1—O2—Nb1^xii	−92.46 (19)
O1^iv—Nb1—O1—Co1^x	−137.42 (16)	O2^iii—Co1—O2—Nb1^xii	−172.99 (15)
O1^v—Nb1—O1—Co1^x	−59.7 (2)	O1^vi—Co1—O2—Co2^vii	−141.2 (2)
O2^i—Nb1—O1—Co1	−101.88 (12)	O1—Co1—O2—Co2^vii	−36.1 (2)
O2^ii—Nb1—O1—Co1	123.0 (3)	O1^iii—Co1—O2—Co2^vii	108.3 (3)
O2^iii—Nb1—O1—Co1	1.00 (12)	O2^vi—Co1—O2—Co2^vii	125.39 (15)
O1^iv—Nb1—O1—Co1	93.21 (11)	O2^iii—Co1—O2—Co2^vii	44.9 (2)
O2^i—Nb1—O1—Nb1^xi	126.02 (10)	O1^vi—Co1—O2—Co2	133.68 (10)
O2^ii—Nb1—O1—Nb1^xi	−9.1 (3)	O1—Co1—O2—Co2	−121.22 (12)
O2^iii—Nb1—O1—Nb1^xi	−131.10 (10)	O1^iii—Co1—O2—Co2	23.2 (3)

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