Bis[2,4-dibromo-6-(ethyl­imino­methyl)phenolato-κ²N,O]cobalt(II)

In the title compound, [Co(C₉H₈Br₂NO)₂], the Co^II atom, located on a twofold axis, is in a pseudo-tetra­hedral environment, with two bidentate 2,4-dibromo-6-(ethyl­imino­meth­yl)phenolate Schiff base ligands acting as chelates through their phenolate O and azomethine N atoms. C—H...O hydrogen bonds link the complex mol­ecules to form a chain parallel to the b axis.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.060
• wR factor = 0.161
• Data-to-parameter ratio = 16.4

checkCIF/PLATON results

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Alert level C
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds (x 1000) Ang ..          8
PLAT971_ALERT_2_C Large Calcd. Non-Metal Positive Residual Density       1.56 eA-3
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          2

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

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

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S1. Comment

The Lewis base adducts of the 3,5-dibromosalicylidene group that are derived from the condensation of 3,5-dibromosalicylaldehyde and various primary amine are very interesting in a large number of transition metal complexes (Qiu et al., 2007; Akitsu et al., 2005; Maneiro et al., 2001; Bermejo et al., 1996). Recently, some mononuclear cobalt(II) compounds of Schiff base ligands derived from the condensation of salicylaldehyde with ethyl-, propyl- and butylamine have been structurally characterized (Li et al., 2008; Elerman et al., 1996; Bahron et al., 1994; Groombridge et al., 1992). As an extension of this work, the crystal structure of the title compound, (I), is reported here.

In (I), the Co atoms, located on a two fold axis, have pseudo-tetrahedral coordination environments with two bidentate Schiff base ligands,derived from the condensation of 3,5-dibromosalicylaldehyde and ethylamine, acting as chelates through their phenolate O and azomethine N atoms (Fig. 1). The structure is closely related to the Bis{2-[(E)-benzyliminomethyl]-4,6-dibromophenolato-κ²N, O}cobalt(II) compound (Jiang et al., 2008). The C7═N1 bond length of 1.287 (7) Å is similar to that of 1.288 (7) Å observed in the previously reported compound of Schiff base ligand, which was derived from the condensation of salicylaldehyde and isopropylamine (Elerman et al., 1996). The angle between the two O1—Co1—N1 planes of the molecule is equal to 82.80°. All bond lengths are within normal ranges (Allen et al., 1987).

In the crystal structure, the molecules are linked via intermolecular C—H···O hydrogen bonds forming a chain parallel to the b axis (Table 1, Fig. 2).

Related literature

For related Lewis base adducts, see: Akitsu et al. (2005); Bahron et al. (1994); Bermejo et al. (1996); Elerman et al. (1996); Groombridge et al. (1992); Li et al. (2008); Maneiro et al. (2001); Qiu et al. (2007). For a related structure, see: Jiang et al. (2008). For standard bond-distance values, see: Allen et al. (1987).

S2. Experimental

3,5-Dibromosalicyladehyde (560 mg, 2 mmol) and ethylamine (90 mg, 2 mmol) were dissolved in methanol (25 ml). The mixture was stirred for 30 min to give an orange solution, which was added to a methanol solution (15 ml) of Co(NO₃)₂.6H₂O (280 mg, 1 mmol). The mixture was stirred for another 20 min at room temperature to give a red solution and then filtered. The filtrate was kept in air for 5 d, forming red blocky crystals. The crystals were isolated, washed three times with distilled water and dried in a vacuum desiccator containing anhydrous CaCl₂ (yield 66%). Analysis calculated for C₁₈H₁₆Br₄CoN₂O₂: C 32.23, H 2.40, N 4.18%; found: C 32.11, H 2.55, N 4.00%. IR (KBr, cm^-1): 3447, 2956, 2925, 2868, 2363, 1736, 1616, 1581, 1505, 1436, 1406, 1343, 1309, 1210, 1156, 1090, 1058, 974, 863, 840, 750, 708, 606, 534, 477.

S3. Refinement

All the H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances of 0.93–0.97 Å, and with U_iso(H) = 1.2U_eq(carrier) or 1.5U_eq(methyl groups).

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009).; software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The structure of the title compound (I), with the atom labeling scheme. Ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. [Symmetry code: (i) 1 - x, y, 1/2 - z.]
	Fig. 2. Partial packing view showing the chain formed through C—H···O hydrogen bonds. H atoms not involved in hydrogen bondings have been omitted for clarity. H bonds are shown as dashed lines. [Symmetry code: (ii) -x + 1, y - 1, -z + 1/2.]

Bis[2,4-dibromo-6-(ethyliminomethyl)phenolato-κ²N,O]cobalt(II)

Crystal data

[Co(C9H8Br2NO)2]	F(000) = 1284
Mr = 670.90	Dx = 2.140 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2472 reflections
a = 22.116 (3) Å	θ = 2.6–27.2°
b = 4.8645 (5) Å	µ = 8.52 mm^−1
c = 19.652 (2) Å	T = 298 K
β = 100.038 (3)°	Block, red
V = 2081.9 (4) Å^3	0.30 × 0.21 × 0.11 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	2028 independent reflections
Radiation source: fine-focus sealed tube	1607 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.099
φ and ω scans	θmax = 26.0°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −26→26
Tmin = 0.089, Tmax = 0.392	k = −6→5
6537 measured reflections	l = −24→22

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) = 0.161	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0865P)^2] where P = (Fo^2 + 2Fc^2)/3
2028 reflections	(Δ/σ)max < 0.001
124 parameters	Δρmax = 1.39 e Å^−3
0 restraints	Δρmin = −1.08 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
Co1	0.5000	0.9495 (3)	0.2500	0.0396 (3)
N1	0.44643 (19)	0.7331 (11)	0.3012 (2)	0.0394 (11)
O1	0.43303 (17)	1.1213 (9)	0.1898 (2)	0.0423 (10)
Br1	0.36561 (3)	1.36837 (14)	0.05745 (3)	0.0477 (3)
Br2	0.18010 (3)	0.63810 (17)	0.10502 (4)	0.0595 (3)
C1	0.3544 (2)	0.8138 (12)	0.2155 (3)	0.0354 (12)
C2	0.3778 (2)	1.0161 (13)	0.1750 (3)	0.0343 (12)
C3	0.3371 (3)	1.1041 (12)	0.1146 (3)	0.0354 (13)
C4	0.2796 (2)	0.9972 (13)	0.0949 (3)	0.0398 (13)
H4	0.2549	1.0568	0.0544	0.048*
C5	0.2587 (2)	0.8016 (14)	0.1352 (3)	0.0405 (14)
C6	0.2942 (3)	0.7099 (14)	0.1949 (3)	0.0438 (14)
H6	0.2789	0.5792	0.2219	0.053*
C7	0.3891 (3)	0.6970 (13)	0.2770 (3)	0.0406 (13)
H7	0.3677	0.5820	0.3023	0.049*
C8	0.4728 (3)	0.5890 (14)	0.3657 (3)	0.0508 (16)
H8A	0.5098	0.4929	0.3593	0.061*
H8B	0.4437	0.4538	0.3767	0.061*
C9	0.4878 (4)	0.7869 (17)	0.4243 (3)	0.064 (2)
H9A	0.5131	0.9319	0.4116	0.096*
H9B	0.5094	0.6928	0.4642	0.096*
H9C	0.4505	0.8634	0.4349	0.096*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0224 (5)	0.0503 (8)	0.0437 (6)	0.000	−0.0009 (4)	0.000
N1	0.026 (2)	0.043 (3)	0.048 (3)	0.006 (2)	0.0011 (19)	0.001 (2)
O1	0.0245 (19)	0.047 (3)	0.051 (2)	−0.0072 (16)	−0.0047 (17)	0.0032 (19)
Br1	0.0393 (4)	0.0488 (5)	0.0511 (4)	−0.0047 (2)	−0.0036 (3)	0.0089 (3)
Br2	0.0276 (4)	0.0697 (6)	0.0769 (5)	−0.0128 (3)	−0.0030 (3)	−0.0035 (4)
C1	0.022 (2)	0.040 (3)	0.043 (3)	0.002 (2)	0.000 (2)	−0.006 (2)
C2	0.026 (2)	0.032 (3)	0.042 (3)	0.003 (2)	−0.004 (2)	−0.006 (2)
C3	0.029 (3)	0.041 (4)	0.035 (3)	0.002 (2)	0.003 (2)	−0.002 (2)
C4	0.031 (3)	0.043 (4)	0.043 (3)	0.003 (2)	−0.003 (2)	−0.005 (3)
C5	0.022 (2)	0.051 (4)	0.046 (3)	0.000 (2)	−0.001 (2)	−0.008 (3)
C6	0.029 (3)	0.044 (4)	0.059 (4)	−0.003 (3)	0.010 (3)	−0.002 (3)
C7	0.032 (3)	0.041 (4)	0.048 (3)	−0.002 (2)	0.007 (2)	0.003 (3)
C8	0.039 (3)	0.049 (4)	0.058 (4)	0.006 (3)	−0.007 (3)	0.010 (3)
C9	0.071 (5)	0.077 (6)	0.044 (4)	0.016 (4)	0.009 (3)	0.009 (4)

Geometric parameters (Å, º)

Co1—O1^i	1.918 (4)	C3—C4	1.366 (8)
Co1—O1	1.918 (4)	C4—C5	1.370 (9)
Co1—N1^i	1.985 (5)	C4—H4	0.9300
Co1—N1	1.985 (5)	C5—C6	1.367 (9)
N1—C7	1.287 (7)	C6—H6	0.9300
N1—C8	1.477 (8)	C7—H7	0.9300
O1—C2	1.310 (6)	C8—C9	1.493 (10)
Br1—C3	1.886 (6)	C8—H8A	0.9700
Br2—C5	1.909 (5)	C8—H8B	0.9700
C1—C6	1.414 (8)	C9—H9A	0.9600
C1—C2	1.419 (8)	C9—H9B	0.9600
C1—C7	1.432 (8)	C9—H9C	0.9600
C2—C3	1.424 (8)
O1^i—Co1—O1	128.3 (3)	C6—C5—C4	121.4 (5)
O1^i—Co1—N1^i	94.52 (17)	C6—C5—Br2	119.2 (5)
O1—Co1—N1^i	112.53 (19)	C4—C5—Br2	119.4 (4)
O1^i—Co1—N1	112.53 (19)	C5—C6—C1	120.0 (6)
O1—Co1—N1	94.52 (17)	C5—C6—H6	120.0
N1^i—Co1—N1	116.0 (3)	C1—C6—H6	120.0
C7—N1—C8	118.0 (5)	N1—C7—C1	127.3 (6)
C7—N1—Co1	121.5 (4)	N1—C7—H7	116.3
C8—N1—Co1	120.4 (4)	C1—C7—H7	116.3
C2—O1—Co1	123.9 (4)	N1—C8—C9	110.9 (6)
C6—C1—C2	120.3 (5)	N1—C8—H8A	109.5
C6—C1—C7	116.0 (6)	C9—C8—H8A	109.5
C2—C1—C7	123.7 (5)	N1—C8—H8B	109.5
O1—C2—C1	124.3 (5)	C9—C8—H8B	109.5
O1—C2—C3	119.8 (5)	H8A—C8—H8B	108.0
C1—C2—C3	115.9 (5)	C8—C9—H9A	109.5
C4—C3—C2	122.9 (6)	C8—C9—H9B	109.5
C4—C3—Br1	118.8 (4)	H9A—C9—H9B	109.5
C2—C3—Br1	118.3 (4)	C8—C9—H9C	109.5
C3—C4—C5	119.5 (5)	H9A—C9—H9C	109.5
C3—C4—H4	120.2	H9B—C9—H9C	109.5
C5—C4—H4	120.2

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8A···O1^ii	0.97	2.49	3.389 (8)	154

Symmetry code: (ii) −x+1, y−1, −z+1/2.