{4,4′,6,6′-Tetra­bromo-2,2′-[(2,2-dimethyl­propane-1,3-di­yl)bis­(nitrilo­methanylyl­idene)]diphenolato}copper(II)

Abstract

In the title compound, [Cu(C₁₉H₁₆Br₄N₂O₂)], the Cu^II ion and the substituted C atom of the diamine fragment lie on a crystallographic twofold rotation axis. The geometry around the Cu^II ion is distorted square-planar, which is defined by the N₂O₂ donor atoms of the coordinated Schiff base ligand. The dihedral angle between the symmetry-related substituted benzene rings is 25.33 (14)°. The crystal structure is stabilized by an inter­molecular π–π inter­action [centroid–centroid distance = 3.8891 (18) Å].

Related literature  

For standard bond lengths, see: Allen et al. (1987 ▶). For applications of Schiff base ligands in coordination chemistry, see: Granovski et al. (1993 ▶); Blower (1998 ▶). For a related structure, see: Kargar et al. (2008 ▶).

Experimental  

Crystal data  

• [Cu(C₁₉H₁₆Br₄N₂O₂)]

• M _r = 687.52

• Orthorhombic,

• a = 16.3594 (8) Å

• b = 15.5106 (8) Å

• c = 8.4686 (4) Å

• V = 2148.86 (18) ų

• Z = 4

• Mo Kα radiation

• μ = 8.47 mm⁻¹

• T = 291 K

• 0.21 × 0.12 × 0.08 mm

Data collection  

• Bruker SMART APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.269, T _max = 0.551

• 9913 measured reflections

• 2537 independent reflections

• 1625 reflections with I > 2σ(I)

• R _int = 0.052

Refinement  

• R[F ² > 2σ(F ²)] = 0.039

• wR(F ²) = 0.078

• S = 1.00

• 2537 reflections

• 128 parameters

• H-atom parameters constrained

• Δρ_max = 0.58 e Å⁻³

• Δρ_min = −0.59 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

Schiff base complexes are one of the most important stereochemical models in transition metal coordination chemistry, with the ease of preparation and structural variations (Granovski et al., 1993; Blower (1998)).

The asymmetric unit of the title compound, Fig. 1, comprises half of a potentially tetradentate Schiff base ligand. The bond lengths (Allen et al., 1987) and angles are within the normal ranges. The Cu1 and C9 atoms lie on crystallographic two-fold rotation axis. The crystal structure is further stabilized by the intermolecular π-π interaction, (Fig. 2), [Cg1···Cg1ⁱ = 3.8891 (18)Å; (i) 1 - X, 1 - Y, -Z; Cg1 is the centroid of Cu(1)/O(1)/C(1)/C(6)/C(7)/N(1) ring].

Experimental

The title compound was synthesized by adding 3,5-dibromo-salicylaldehyde-2,2-dimethyl-1,3- propanediamine (2 mmol) to a solution of CuCl₂. 4H₂O (2.1 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for half an hour. The resultant solution was filtered. Green single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation of the solvents at room temperature over several days.

Refinement

All hydrogen atoms were positioned geometrically with C—H = 0.93-0.97 Å and included in a riding model and treated as riding atoms: C—H = 0.93, 0.96 and 0.97 Å for CH, CH₃ and CH₂ H-atoms, respectively, with U_iso (H) = k x U_eq(C), where k = 1.5 for CH₃ H-atoms, and k = 1.2 for all other H-atoms..

Figures

Fig. 1.

The ORTEP plot of the title compound, showing 40% probability displacement ellipsoids and the atomic numbering.

Fig. 2.

The packing diagram of the title compound viewed down the b-axis showing linking of molecules through the intermolecular π-π intearctions (dashed lines). The hydrogen atoms omitted for clarity.

Crystal data

[Cu(C19H16Br4N2O2)]	F(000) = 1316
Mr = 687.52	Dx = 2.125 Mg m−3
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 1535 reflections
a = 16.3594 (8) Å	θ = 2.5–27.5°
b = 15.5106 (8) Å	µ = 8.47 mm−1
c = 8.4686 (4) Å	T = 291 K
V = 2148.86 (18) Å3	Block, green
Z = 4	0.21 × 0.12 × 0.08 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	2537 independent reflections
Radiation source: fine-focus sealed tube	1625 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
φ and ω scans	θmax = 28.0°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −21→18
Tmin = 0.269, Tmax = 0.551	k = −20→13
9913 measured reflections	l = −10→7

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.078	H-atom parameters constrained
S = 1.00	w = 1/[σ2(Fo2) + (0.0202P)2 + 1.7635P] where P = (Fo2 + 2Fc2)/3
2537 reflections	(Δ/σ)max = 0.001
128 parameters	Δρmax = 0.58 e Å−3
0 restraints	Δρmin = −0.59 e Å−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
Br1	0.33450 (3)	0.74146 (3)	0.18143 (5)	0.05098 (16)
Br2	0.10313 (3)	0.54552 (4)	−0.15415 (7)	0.0733 (2)
Cu1	0.5000	0.48415 (4)	0.2500	0.03410 (18)
N1	0.4444 (2)	0.39656 (19)	0.1258 (3)	0.0332 (7)
O1	0.42323 (17)	0.57112 (16)	0.1958 (3)	0.0395 (7)
C1	0.3547 (2)	0.5618 (2)	0.1192 (4)	0.0341 (9)
C2	0.3023 (2)	0.6335 (2)	0.0965 (4)	0.0341 (9)
C3	0.2301 (2)	0.6285 (3)	0.0162 (4)	0.0406 (10)
H3	0.1982	0.6776	0.0030	0.049*
C4	0.2042 (2)	0.5504 (3)	−0.0458 (5)	0.0417 (10)
C5	0.2520 (3)	0.4788 (3)	−0.0299 (4)	0.0425 (10)
H5	0.2348	0.4267	−0.0730	0.051*
C6	0.3270 (2)	0.4831 (2)	0.0511 (4)	0.0342 (9)
C7	0.3757 (3)	0.4058 (2)	0.0534 (4)	0.0368 (10)
H7	0.3560	0.3585	−0.0022	0.044*
C8	0.4911 (3)	0.3163 (2)	0.1017 (4)	0.0404 (10)
H8A	0.5453	0.3310	0.0635	0.048*
H8B	0.4644	0.2825	0.0204	0.048*
C9	0.5000	0.2606 (3)	0.2500	0.0390 (14)
C10	0.5749 (3)	0.2038 (3)	0.2270 (5)	0.0574 (13)
H10A	0.6231	0.2391	0.2253	0.086*
H10B	0.5703	0.1733	0.1288	0.086*
H10C	0.5786	0.1633	0.3123	0.086*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0710 (3)	0.0317 (2)	0.0503 (3)	0.0104 (2)	−0.0024 (2)	−0.0063 (2)
Br2	0.0527 (3)	0.0645 (4)	0.1027 (4)	0.0055 (3)	−0.0303 (3)	0.0001 (3)
Cu1	0.0387 (4)	0.0275 (3)	0.0361 (4)	0.000	−0.0012 (3)	0.000
N1	0.041 (2)	0.0256 (17)	0.0334 (17)	0.0063 (16)	0.0008 (15)	−0.0012 (14)
O1	0.0416 (17)	0.0295 (14)	0.0475 (16)	0.0014 (13)	−0.0063 (13)	−0.0027 (13)
C1	0.042 (3)	0.031 (2)	0.030 (2)	0.002 (2)	0.0088 (18)	0.0010 (18)
C2	0.043 (2)	0.029 (2)	0.031 (2)	0.0058 (19)	0.0072 (18)	−0.0018 (18)
C3	0.044 (3)	0.039 (2)	0.039 (2)	0.013 (2)	0.0078 (19)	0.002 (2)
C4	0.035 (2)	0.046 (3)	0.045 (2)	0.006 (2)	−0.0028 (19)	0.001 (2)
C5	0.045 (3)	0.039 (2)	0.043 (2)	−0.002 (2)	−0.002 (2)	−0.002 (2)
C6	0.041 (2)	0.029 (2)	0.032 (2)	0.005 (2)	0.0022 (17)	0.0001 (18)
C7	0.049 (3)	0.029 (2)	0.032 (2)	0.001 (2)	0.0022 (19)	−0.0042 (18)
C8	0.052 (3)	0.031 (2)	0.038 (2)	0.012 (2)	−0.0001 (19)	−0.0050 (19)
C9	0.047 (4)	0.026 (3)	0.044 (3)	0.000	−0.007 (3)	0.000
C10	0.064 (3)	0.046 (3)	0.062 (3)	0.017 (3)	−0.013 (2)	0.005 (2)

Geometric parameters (Å, º)

Br1—C2	1.897 (4)	C4—C5	1.364 (6)
Br2—C4	1.893 (4)	C5—C6	1.407 (5)
Cu1—O1i	1.899 (3)	C5—H5	0.9300
Cu1—O1	1.899 (3)	C6—C7	1.440 (5)
Cu1—N1i	1.944 (3)	C7—H7	0.9300
Cu1—N1	1.944 (3)	C8—C9	1.531 (5)
N1—C7	1.288 (5)	C8—H8A	0.9700
N1—C8	1.475 (5)	C8—H8B	0.9700
O1—C1	1.303 (5)	C9—C10i	1.522 (5)
C1—C2	1.418 (5)	C9—C10	1.522 (5)
C1—C6	1.425 (5)	C9—C8i	1.531 (5)
C2—C3	1.364 (5)	C10—H10A	0.9600
C3—C4	1.387 (6)	C10—H10B	0.9600
C3—H3	0.9300	C10—H10C	0.9600
O1i—Cu1—O1	89.50 (16)	C5—C6—C1	121.0 (4)
O1i—Cu1—N1i	93.23 (12)	C5—C6—C7	116.8 (4)
O1—Cu1—N1i	159.45 (11)	C1—C6—C7	122.1 (4)
O1i—Cu1—N1	159.45 (11)	N1—C7—C6	125.6 (4)
O1—Cu1—N1	93.23 (12)	N1—C7—H7	117.2
N1i—Cu1—N1	91.32 (18)	C6—C7—H7	117.2
C7—N1—C8	118.7 (3)	N1—C8—C9	114.3 (3)
C7—N1—Cu1	126.0 (3)	N1—C8—H8A	108.7
C8—N1—Cu1	115.0 (3)	C9—C8—H8A	108.7
C1—O1—Cu1	127.6 (2)	N1—C8—H8B	108.7
O1—C1—C2	120.1 (4)	C9—C8—H8B	108.7
O1—C1—C6	124.8 (4)	H8A—C8—H8B	107.6
C2—C1—C6	115.1 (4)	C10i—C9—C10	109.2 (5)
C3—C2—C1	123.2 (4)	C10i—C9—C8i	107.3 (2)
C3—C2—Br1	118.7 (3)	C10—C9—C8i	110.8 (2)
C1—C2—Br1	118.2 (3)	C10i—C9—C8	110.8 (2)
C2—C3—C4	120.2 (4)	C10—C9—C8	107.3 (2)
C2—C3—H3	119.9	C8i—C9—C8	111.3 (4)
C4—C3—H3	119.9	C9—C10—H10A	109.5
C5—C4—C3	119.9 (4)	C9—C10—H10B	109.5
C5—C4—Br2	121.1 (3)	H10A—C10—H10B	109.5
C3—C4—Br2	119.0 (3)	C9—C10—H10C	109.5
C4—C5—C6	120.6 (4)	H10A—C10—H10C	109.5
C4—C5—H5	119.7	H10B—C10—H10C	109.5
C6—C5—H5	119.7
O1i—Cu1—N1—C7	−102.7 (4)	C2—C3—C4—Br2	179.2 (3)
O1—Cu1—N1—C7	−5.5 (3)	C3—C4—C5—C6	1.0 (6)
N1i—Cu1—N1—C7	154.5 (4)	Br2—C4—C5—C6	−179.9 (3)
O1i—Cu1—N1—C8	70.7 (4)	C4—C5—C6—C1	0.3 (6)
O1—Cu1—N1—C8	167.9 (2)	C4—C5—C6—C7	−176.2 (4)
N1i—Cu1—N1—C8	−32.2 (2)	O1—C1—C6—C5	180.0 (3)
O1i—Cu1—O1—C1	167.4 (3)	C2—C1—C6—C5	−0.9 (5)
N1i—Cu1—O1—C1	−94.7 (4)	O1—C1—C6—C7	−3.7 (6)
N1—Cu1—O1—C1	7.8 (3)	C2—C1—C6—C7	175.4 (3)
Cu1—O1—C1—C2	176.5 (2)	C8—N1—C7—C6	−173.3 (3)
Cu1—O1—C1—C6	−4.5 (5)	Cu1—N1—C7—C6	−0.1 (6)
O1—C1—C2—C3	179.4 (3)	C5—C6—C7—N1	−177.5 (4)
C6—C1—C2—C3	0.2 (5)	C1—C6—C7—N1	6.1 (6)
O1—C1—C2—Br1	−0.4 (5)	C7—N1—C8—C9	−115.0 (4)
C6—C1—C2—Br1	−179.5 (3)	Cu1—N1—C8—C9	71.1 (4)
C1—C2—C3—C4	1.0 (6)	N1—C8—C9—C10i	83.8 (4)
Br1—C2—C3—C4	−179.2 (3)	N1—C8—C9—C10	−157.0 (4)
C2—C3—C4—C5	−1.7 (6)	N1—C8—C9—C8i	−35.6 (2)

Symmetry code: (i) −x+1, y, −z+1/2.