Retracted: μ-Oxido-bis­({4,4′-dibromo-2,2′-[ethane-1,2-diylbis(nitrilo­methyl­idyne)]diphenol­ato}chromium(III))

In the title compound, [Cr₂(C₁₆H₁₂Br₂N₂O₂)₂O], Cr^III is chelated by a Schiff base ligand through two N and two O atoms, and is penta­coordinate, with a bridging oxide ion. The coordination geometry can be described as square-based pyramidal, with the bridging oxide in the apical site, giving the shortest bond. The bridging ligand lies on a crystallographic twofold rotation axis.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.060
• wR factor = 0.155
• Data-to-parameter ratio = 14.2

checkCIF/PLATON results

No syntax errors found



Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.10
            Rint given   0.117
PLAT020_ALERT_3_C The value of Rint is greater than 0.10 .........       0.12
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.97
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.03
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          9
PLAT601_ALERT_2_C Structure Contains Solvent Accessible VOIDS of .      48.00 A   3 

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cr1         (3)       2.77

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

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

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S1. Comment

The design of Schiff base complexes has attracted long-lasting research interest due to their important role in the development of coordination chemistry as well as inorganic biochemistry, catalysis, optical materials and so on (Garnovskii et al., 1993; Huang et al., 2002). Recently, Schiff base ligands, especially relatively flexible symmetrical or unsymmetrical Schiff base ligands and their hydrogenated derivatives, have been widely employed to assemble alkoxo- or phenoxo-bridged manganese clusters and polymers with novel topological structures and interesting magnetic, catalysis and photochemical properties (Chen et al., 2006; Karacan et al., 2004). In this paper, we report the structure of the title compound, (I).

As shown in Fig. 1, Cr^III is chelated by the Schiff base ligand through two N and two O atoms. The chromium(III) ion is pentacoordinate with three oxygen atoms and two nitrogen atoms from the Schiff base ligand and a bridging oxide ion. The coordination geometry can be described as square-based pyramidal, with the bridging oxide in the apical site, giving the shortest bond. The bridging ligand lies on a crystallographic twofold rotation axis.

Related literature

For related literature, see: Chen et al. (2006); Garnovskii et al. (1993); Huang et al. (2002); Karacan et al. (2004).

S2. Experimental

A mixture of chromium(III) acetylacetonate (1 mmol, 0.35 g) and 4,4'-dibromo-2,2'-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenol (1 mmol, 0.45 g) in 20 ml me thanol was refluxed for two hours. The cooled solution was filtered and the filtrate was allowed to evaporate at room temperature. Several days later, blue blocks of (I) were obtained in a yield of 21%. Anal. Calc. for C₃₂H₂₄Br₄Cr₂N₄O₅: C 39.67, H 2.48, N 5.79%; Found: C 39.61, H 2.49, N 5.75%.

S3. Refinement

All H atoms were included in calculated positions and treated in the subsequent refinement as riding atoms, with C—H = 0.93 Å (sp²), and 0.97%A (sp³) and U_iso(H) = 1.2 or 1.5 times U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL (Bruker, 2001).

Figures

Fig. 1. The molecular structure of (I), drawn with 30% probability displacement ellipsoids for the non-hydrogen atoms. [Symmetry code for unlabelled atoms: -x, y, 1/2 - z.]

µ-Oxido-bis({4,4-dibromo-2,2-[ethane-1,2- diylbis(nitrilomethylidyne)]diphenolato}chromium(III))

Crystal data

[Cr2(C16H12Br2N2O2)2O]	F(000) = 1888
Mr = 968.19	Dx = 1.844 Mg m^−3
Orthorhombic, Pcca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2a 2ac	Cell parameters from 3073 reflections
a = 21.1067 (10) Å	θ = 3.0–25.1°
b = 13.3083 (10) Å	µ = 5.25 mm^−1
c = 12.4187 (5) Å	T = 293 K
V = 3488.3 (3) Å^3	Block, blue
Z = 4	0.12 × 0.10 × 0.08 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	3042 independent reflections
Radiation source: fine-focus sealed tube	2168 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.117
ϕ and ω scans	θmax = 25.1°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −25→25
Tmin = 0.572, Tmax = 0.679	k = −15→15
11021 measured reflections	l = 0→14

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)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.155	H-atom parameters not refined
S = 1.00	w = 1/[σ^2(Fo^2) + (0.086P)^2] where P = (Fo^2 + 2Fc^2)/3
3042 reflections	(Δ/σ)max < 0.001
214 parameters	Δρmax = 0.99 e Å^−3
0 restraints	Δρmin = −0.75 e Å^−3

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
Cr1	0.07193 (4)	0.12984 (5)	0.31472 (6)	0.0285 (3)
Br2	0.28253 (4)	−0.28112 (6)	0.48703 (7)	0.0693 (3)
Br1	0.10796 (4)	0.66037 (5)	0.24484 (7)	0.0820 (4)
C16	0.1642 (3)	−0.0344 (4)	0.3175 (4)	0.0388 (12)
C15	0.2037 (3)	−0.0951 (4)	0.2516 (5)	0.0451 (14)
H15	0.2059	−0.0854	0.1775	0.054*
C14	0.2376 (3)	−0.1671 (4)	0.3006 (5)	0.0508 (16)
H14	0.2657	−0.2059	0.2608	0.061*
C13	0.2305 (3)	−0.1852 (4)	0.4171 (5)	0.0471 (15)
C12	0.1905 (3)	−0.1316 (4)	0.4828 (5)	0.0455 (15)
H12	0.1868	−0.1452	0.5559	0.055*
C11	0.1560 (3)	−0.0555 (4)	0.4328 (5)	0.0398 (13)
C4	0.1148 (3)	−0.0005 (4)	0.5090 (4)	0.0403 (13)
H4	0.1150	−0.0191	0.5812	0.048*
C2	0.0463 (3)	0.1212 (4)	0.5716 (5)	0.0459 (14)
H2A	0.0231	0.0725	0.6143	0.055*
H2B	0.0765	0.1554	0.6176	0.055*
C1	0.0011 (3)	0.1961 (5)	0.5201 (5)	0.0464 (15)
H1A	−0.0380	0.1631	0.4992	0.056*
H1B	−0.0089	0.2498	0.5702	0.056*
C3	0.0406 (3)	0.3283 (4)	0.4142 (5)	0.0432 (14)
H3	0.0242	0.3697	0.4676	0.052*
C5	0.0737 (3)	0.3750 (4)	0.3201 (5)	0.0419 (13)
C10	0.0742 (3)	0.4751 (4)	0.3226 (5)	0.0504 (15)
H10	0.0556	0.5103	0.3790	0.061*
C9	0.1039 (3)	0.5252 (5)	0.2371 (6)	0.0560 (17)
C8	0.1315 (3)	0.4779 (5)	0.1450 (6)	0.0587 (18)
H8	0.1497	0.5155	0.0899	0.070*
C7	0.1302 (3)	0.3797 (5)	0.1412 (5)	0.0548 (16)
H7	0.1466	0.3455	0.0821	0.066*
C6	0.1030 (3)	0.3258 (4)	0.2299 (5)	0.0444 (14)
N2	0.0797 (2)	0.0704 (3)	0.4795 (4)	0.0399 (11)
N1	0.0344 (2)	0.2372 (3)	0.4230 (4)	0.0393 (11)
O3	0.0000	0.0842 (4)	0.2500	0.0404 (13)
O1	0.1370 (2)	0.0412 (3)	0.2689 (3)	0.0443 (10)
O2	0.10570 (19)	0.2323 (3)	0.2222 (3)	0.0470 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr1	0.0374 (5)	0.0172 (4)	0.0310 (4)	0.0006 (3)	0.0006 (4)	−0.0001 (3)
Br2	0.0685 (5)	0.0550 (5)	0.0845 (6)	0.0219 (3)	0.0092 (4)	0.0254 (4)
Br1	0.1113 (8)	0.0274 (4)	0.1074 (7)	−0.0027 (3)	0.0294 (5)	0.0094 (4)
C16	0.046 (3)	0.026 (3)	0.044 (3)	−0.002 (2)	0.003 (3)	0.000 (2)
C15	0.054 (4)	0.032 (3)	0.049 (3)	0.004 (3)	0.001 (3)	0.001 (3)
C14	0.051 (4)	0.033 (3)	0.068 (4)	0.005 (3)	0.008 (3)	0.004 (3)
C13	0.044 (3)	0.037 (3)	0.061 (4)	0.006 (3)	0.008 (3)	0.015 (3)
C12	0.052 (4)	0.035 (3)	0.050 (3)	0.000 (3)	0.000 (3)	0.011 (3)
C11	0.044 (3)	0.029 (3)	0.047 (3)	0.000 (2)	−0.003 (3)	0.003 (2)
C4	0.054 (4)	0.027 (3)	0.041 (3)	−0.003 (3)	−0.003 (3)	0.002 (2)
C2	0.055 (4)	0.036 (3)	0.046 (3)	−0.002 (3)	0.010 (3)	−0.001 (3)
C1	0.054 (4)	0.035 (3)	0.050 (4)	−0.001 (3)	0.011 (3)	0.004 (3)
C3	0.046 (4)	0.035 (3)	0.048 (3)	0.002 (2)	0.000 (3)	−0.005 (3)
C5	0.046 (3)	0.026 (3)	0.053 (3)	0.000 (2)	0.000 (3)	0.003 (3)
C10	0.052 (4)	0.032 (3)	0.068 (4)	0.001 (3)	0.006 (3)	0.000 (3)
C9	0.064 (4)	0.028 (3)	0.076 (4)	0.000 (3)	0.009 (4)	0.015 (3)
C8	0.069 (5)	0.034 (3)	0.073 (4)	−0.004 (3)	0.010 (4)	0.007 (3)
C7	0.068 (4)	0.039 (3)	0.058 (4)	−0.002 (3)	0.010 (3)	0.010 (3)
C6	0.044 (4)	0.031 (3)	0.058 (4)	−0.001 (2)	0.005 (3)	0.001 (3)
N2	0.049 (3)	0.028 (2)	0.042 (3)	0.001 (2)	0.002 (2)	−0.002 (2)
N1	0.045 (3)	0.023 (2)	0.049 (3)	−0.0050 (19)	0.006 (2)	0.002 (2)
O3	0.045 (3)	0.025 (3)	0.052 (3)	0.000	−0.008 (3)	0.000
O1	0.059 (3)	0.030 (2)	0.044 (2)	0.0110 (18)	−0.0010 (19)	0.0033 (17)
O2	0.059 (3)	0.028 (2)	0.054 (2)	−0.0008 (17)	0.012 (2)	0.0030 (18)

Geometric parameters (Å, º)

Cr1—O3	1.8220 (19)	C2—N2	1.503 (7)
Cr1—O1	1.897 (4)	C2—H2A	0.970
Cr1—O2	1.920 (4)	C2—H2B	0.970
Cr1—N1	2.116 (5)	C1—N1	1.499 (8)
Cr1—N2	2.200 (5)	C1—H1A	0.970
Br2—C13	1.894 (6)	C1—H1B	0.970
Br1—C9	1.803 (6)	C3—N1	1.224 (7)
C16—O1	1.307 (6)	C3—C5	1.497 (8)
C16—C15	1.420 (8)	C3—H3	0.930
C16—C11	1.470 (8)	C5—C10	1.332 (8)
C15—C14	1.342 (8)	C5—C6	1.437 (8)
C15—H15	0.930	C10—C9	1.402 (9)
C14—C13	1.474 (9)	C10—H10	0.930
C14—H14	0.930	C9—C8	1.431 (9)
C13—C12	1.373 (9)	C8—C7	1.308 (8)
C12—C11	1.394 (8)	C8—H8	0.930
C12—H12	0.930	C7—C6	1.434 (8)
C11—C4	1.478 (8)	C7—H7	0.930
C4—N2	1.255 (7)	C6—O2	1.250 (7)
C4—H4	0.930	O3—Cr1^i	1.8220 (19)
C2—C1	1.521 (9)
O3—Cr1—O1	105.27 (18)	N1—C1—C2	106.4 (5)
O3—Cr1—O2	106.37 (17)	N1—C1—H1A	110.4
O1—Cr1—O2	89.60 (17)	C2—C1—H1A	110.4
O3—Cr1—N1	101.15 (16)	N1—C1—H1B	110.5
O1—Cr1—N1	151.81 (18)	C2—C1—H1B	110.5
O2—Cr1—N1	92.28 (17)	H1A—C1—H1B	108.6
O3—Cr1—N2	110.63 (15)	N1—C3—C5	122.1 (5)
O1—Cr1—N2	90.13 (17)	N1—C3—H3	119.0
O2—Cr1—N2	141.66 (19)	C5—C3—H3	119.0
N1—Cr1—N2	71.29 (17)	C10—C5—C6	118.0 (6)
O1—C16—C15	115.5 (5)	C10—C5—C3	113.6 (6)
O1—C16—C11	123.0 (5)	C6—C5—C3	128.3 (5)
C15—C16—C11	121.5 (5)	C5—C10—C9	117.5 (6)
C14—C15—C16	117.2 (6)	C5—C10—H10	121.2
C14—C15—H15	121.4	C9—C10—H10	121.2
C16—C15—H15	121.4	C10—C9—C8	125.3 (6)
C15—C14—C13	120.6 (6)	C10—C9—Br1	117.1 (5)
C15—C14—H14	119.7	C8—C9—Br1	117.5 (5)
C13—C14—H14	119.7	C7—C8—C9	117.4 (6)
C12—C13—C14	124.0 (5)	C7—C8—H8	121.3
C12—C13—Br2	115.7 (4)	C9—C8—H8	121.3
C14—C13—Br2	120.1 (4)	C8—C7—C6	118.7 (6)
C13—C12—C11	115.8 (5)	C8—C7—H7	120.6
C13—C12—H12	122.1	C6—C7—H7	120.6
C11—C12—H12	122.1	O2—C6—C5	122.2 (5)
C12—C11—C4	112.5 (5)	O2—C6—C7	114.9 (5)
C12—C11—C16	120.7 (5)	C5—C6—C7	122.9 (5)
C4—C11—C16	126.8 (5)	C4—N2—C2	113.1 (5)
N2—C4—C11	122.2 (5)	C4—N2—Cr1	125.9 (4)
N2—C4—H4	118.9	C2—N2—Cr1	120.7 (3)
C11—C4—H4	118.9	C3—N1—C1	118.9 (5)
C1—C2—N2	105.6 (5)	C3—N1—Cr1	124.9 (4)
C1—C2—H2A	110.6	C1—N1—Cr1	116.1 (3)
N2—C2—H2A	110.6	Cr1—O3—Cr1^i	141.1 (3)
C1—C2—H2B	110.6	C16—O1—Cr1	131.2 (4)
N2—C2—H2B	110.6	C6—O2—Cr1	130.1 (4)
H2A—C2—H2B	108.8

Symmetry code: (i) −x, y, −z+1/2.