(Z)-4-Bromo-N-{(Z)-3-[(4-bromo-2,6-diisopropyl­phen­yl)imino]­butan-2-yl­idene}-2,6-diisopropyl­aniline

Abstract

The title compound, C₂₈H₃₈Br₂N₂, is centrosymmetric with the mid-point of the central C—C bond of the butyl group located on an inversion center. The terminal benzene ring is approximately perpendicular to the central 1,4-diaza­butadiene mean plane [dihedral angle = 78.23 (3)°]. No hydrogen bonding or aromatic stacking is observed in the crystal structure.

Related literature  

For applications of diimine catalysts, see: Cotts et al. (2000 ▶); Ittel et al. (2000 ▶); Johnson et al. (1995 ▶); Zhang & Ye (2012 ▶).

Experimental  

Crystal data  

• C₂₈H₃₈Br₂N₂

• M _r = 562.42

• Monoclinic,

• a = 9.099 (3) Å

• b = 12.199 (4) Å

• c = 13.566 (5) Å

• β = 104.905 (5)°

• V = 1455.2 (9) ų

• Z = 2

• Mo Kα radiation

• μ = 2.80 mm⁻¹

• T = 296 K

• 0.25 × 0.23 × 0.19 mm

Data collection  

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.541, T _max = 0.618

• 7266 measured reflections

• 2685 independent reflections

• 1460 reflections with I > 2σ(I)

• R _int = 0.043

Refinement  

• R[F ² > 2σ(F ²)] = 0.052

• wR(F ²) = 0.179

• S = 0.94

• 2685 reflections

• 150 parameters

• 84 restraints

• H-atom parameters constrained

• Δρ_max = 0.46 e Å⁻³

• Δρ_min = −0.40 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); 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.

Supplementary Material

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

supplementary crystallographic information

Comment

In recent years, Ni(II)/Pd(II)-α-diimine catalysts were greatly attracted attention due to their high catalytic activity and influence on product performance in olefin polymerization (Zhang & Ye, 2012; Johnson et al., 1995). It is well known that the polymerization conditions (such as the reaction olefin pressure, temperature etc.) and ligand structure had a great impact on catalytic activity and polymer properties (Cotts et al., 2000; Ittel et al., 2000).

In the solid state, the structure exhibits trans-conformation about the central C—C bond of the ligand backbone. Bond lengths and angles are within the expected range for α-diimines. The dihedral angle between the aryl ring and 1,4-diazabutadiene plane is 78.23 (3)°(Fig. 1). In the crystal packing, there is no hydrogen-bond between the molecules.

Experimental

Formic acid (0.5 ml) was added to a stirred solution of 2,3-butanedione (0.042 g, 0.49 mmol) and 4-Bromo-2,6-diisopropyl-phenylamine (0.250 g, 0.98 mmol) in methanol (20 ml). The mixture was refluxed for 24 h, then cooled and the precipitate was separated by filtration. The solid was recrystallized from dichloromethane/cyclohexane (v/v = 8:1), washed with cold ethanol and dried under vacuum to give the title ligand 0.21 g (75%). Anal. Calcd. for C₂₈H₃₈Br₂N₂: C, 59.79; H, 6.81; N,4.98; Found: C, 60.29; H, 6.95; N, 4.74.

Refinement

All hydrogen atoms were placed in calculated positions with C—H distances of 0.93 and 0.96 Å for aryl and methyl type H-atoms. They were included in the refinement in a riding model approximation, respectively. The H-atoms were assigned Uiso = 1.2 times Ueq of the aryl C atoms and 1.5 times Ueq of the methyl C atoms.

Figures

Fig. 1.

Molecular structure of the title compound, using 30% probability level ellipsoids.

Crystal data

C28H38Br2N2	F(000) = 580
Mr = 562.42	Dx = 1.284 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1370 reflections
a = 9.099 (3) Å	θ = 2.9–21.4°
b = 12.199 (4) Å	µ = 2.80 mm−1
c = 13.566 (5) Å	T = 296 K
β = 104.905 (5)°	Block, yellow
V = 1455.2 (9) Å3	0.25 × 0.23 × 0.19 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer	2685 independent reflections
Radiation source: fine-focus sealed tube	1460 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.043
φ and ω scans	θmax = 25.5°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −10→10
Tmin = 0.541, Tmax = 0.618	k = −12→14
7266 measured reflections	l = −16→14

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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.179	H-atom parameters constrained
S = 0.94	w = 1/[σ2(Fo2) + (0.1P)2 + 0.7029P] where P = (Fo2 + 2Fc2)/3
2685 reflections	(Δ/σ)max < 0.001
150 parameters	Δρmax = 0.46 e Å−3
84 restraints	Δρmin = −0.40 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
Br1	0.35688 (8)	0.65673 (6)	0.10127 (7)	0.0922 (4)
C1	0.7029 (6)	0.8851 (4)	0.1392 (4)	0.0489 (12)
C2	0.5759 (6)	0.8270 (4)	0.1476 (4)	0.0533 (14)
H2	0.5247	0.8477	0.1958	0.064*
C3	0.5254 (6)	0.7392 (5)	0.0851 (4)	0.0539 (14)
C4	0.5971 (7)	0.7079 (4)	0.0117 (4)	0.0557 (15)
H4	0.5608	0.6482	−0.0301	0.067*
C5	0.7232 (7)	0.7651 (4)	−0.0001 (5)	0.0585 (14)
C6	0.7756 (6)	0.8543 (4)	0.0646 (4)	0.0452 (13)
C7	0.7611 (8)	0.9814 (5)	0.2083 (5)	0.0662 (14)
H7	0.8701	0.9872	0.2130	0.079*
C8	0.6907 (11)	1.0865 (6)	0.1624 (7)	0.126 (3)
H8A	0.7162	1.0991	0.0990	0.188*
H8B	0.7283	1.1459	0.2084	0.188*
H8C	0.5822	1.0819	0.1505	0.188*
C9	0.7469 (11)	0.9636 (8)	0.3149 (6)	0.120 (3)
H9A	0.8150	1.0122	0.3607	0.180*
H9B	0.7725	0.8891	0.3348	0.180*
H9C	0.6443	0.9783	0.3175	0.180*
C10	0.8059 (9)	0.7265 (6)	−0.0773 (6)	0.0804 (16)
H10	0.8666	0.7876	−0.0923	0.096*
C11	0.9126 (12)	0.6347 (7)	−0.0315 (8)	0.132 (3)
H11A	0.9847	0.6606	0.0287	0.199*
H11B	0.9656	0.6101	−0.0802	0.199*
H11C	0.8555	0.5750	−0.0139	0.199*
C12	0.6986 (12)	0.6892 (8)	−0.1768 (7)	0.126 (3)
H12A	0.6336	0.6323	−0.1632	0.189*
H12B	0.7566	0.6616	−0.2214	0.189*
H12C	0.6378	0.7500	−0.2086	0.189*
C13	0.9228 (6)	0.9765 (4)	−0.0034 (4)	0.0512 (14)
C14	0.7932 (7)	1.0159 (6)	−0.0879 (5)	0.081 (2)
H14A	0.8104	0.9956	−0.1523	0.122*
H14B	0.7856	1.0942	−0.0843	0.122*
H14C	0.7003	0.9831	−0.0812	0.122*
N1	0.9141 (5)	0.9060 (3)	0.0633 (3)	0.0504 (11)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0812 (6)	0.0846 (6)	0.1286 (8)	−0.0381 (4)	0.0595 (5)	−0.0188 (4)
C1	0.053 (3)	0.045 (3)	0.054 (3)	−0.005 (2)	0.023 (2)	−0.001 (2)
C2	0.053 (3)	0.054 (3)	0.058 (4)	−0.001 (3)	0.023 (3)	−0.001 (3)
C3	0.055 (3)	0.052 (3)	0.060 (4)	−0.011 (3)	0.026 (3)	0.005 (3)
C4	0.070 (4)	0.034 (3)	0.066 (4)	−0.014 (3)	0.024 (3)	−0.004 (3)
C5	0.075 (3)	0.043 (3)	0.070 (3)	−0.012 (3)	0.043 (3)	0.001 (3)
C6	0.046 (3)	0.037 (3)	0.055 (3)	−0.005 (2)	0.017 (3)	0.008 (2)
C7	0.076 (3)	0.062 (3)	0.067 (3)	−0.015 (3)	0.028 (3)	−0.015 (3)
C8	0.145 (7)	0.070 (5)	0.145 (6)	−0.001 (5)	0.005 (6)	−0.036 (5)
C9	0.155 (7)	0.131 (6)	0.083 (5)	−0.052 (5)	0.045 (5)	−0.038 (5)
C10	0.100 (4)	0.066 (3)	0.095 (4)	−0.016 (3)	0.060 (3)	−0.018 (3)
C11	0.131 (7)	0.129 (6)	0.163 (7)	0.022 (5)	0.085 (6)	−0.026 (6)
C12	0.153 (7)	0.147 (6)	0.100 (6)	−0.030 (6)	0.073 (5)	−0.040 (5)
C13	0.053 (3)	0.045 (3)	0.059 (4)	−0.006 (2)	0.019 (3)	0.007 (3)
C14	0.059 (4)	0.083 (5)	0.093 (5)	−0.012 (3)	0.005 (4)	0.039 (4)
N1	0.052 (3)	0.044 (3)	0.059 (3)	−0.006 (2)	0.022 (2)	0.005 (2)

Geometric parameters (Å, º)

Br1—C3	1.894 (5)	C9—H9A	0.9600
C1—C2	1.384 (7)	C9—H9B	0.9600
C1—C6	1.396 (7)	C9—H9C	0.9600
C1—C7	1.511 (8)	C10—C11	1.507 (11)
C2—C3	1.371 (7)	C10—C12	1.517 (11)
C2—H2	0.9300	C10—H10	0.9800
C3—C4	1.376 (8)	C11—H11A	0.9600
C4—C5	1.387 (7)	C11—H11B	0.9600
C4—H4	0.9300	C11—H11C	0.9600
C5—C6	1.402 (7)	C12—H12A	0.9600
C5—C10	1.513 (8)	C12—H12B	0.9600
C6—N1	1.414 (7)	C12—H12C	0.9600
C7—C8	1.495 (10)	C13—N1	1.265 (6)
C7—C9	1.501 (9)	C13—C14	1.497 (8)
C7—H7	0.9800	C13—C13i	1.498 (10)
C8—H8A	0.9600	C14—H14A	0.9600
C8—H8B	0.9600	C14—H14B	0.9600
C8—H8C	0.9600	C14—H14C	0.9600
C2—C1—C6	118.8 (5)	H9A—C9—H9B	109.5
C2—C1—C7	120.9 (5)	C7—C9—H9C	109.5
C6—C1—C7	120.2 (5)	H9A—C9—H9C	109.5
C3—C2—C1	120.2 (5)	H9B—C9—H9C	109.5
C3—C2—H2	119.9	C11—C10—C5	109.2 (6)
C1—C2—H2	119.9	C11—C10—C12	110.1 (7)
C2—C3—C4	121.2 (5)	C5—C10—C12	112.8 (6)
C2—C3—Br1	119.7 (4)	C11—C10—H10	108.2
C4—C3—Br1	119.0 (4)	C5—C10—H10	108.2
C3—C4—C5	120.3 (5)	C12—C10—H10	108.2
C3—C4—H4	119.8	C10—C11—H11A	109.5
C5—C4—H4	119.8	C10—C11—H11B	109.5
C4—C5—C6	118.4 (5)	H11A—C11—H11B	109.5
C4—C5—C10	119.8 (5)	C10—C11—H11C	109.5
C6—C5—C10	121.7 (5)	H11A—C11—H11C	109.5
C1—C6—C5	121.1 (5)	H11B—C11—H11C	109.5
C1—C6—N1	118.6 (5)	C10—C12—H12A	109.5
C5—C6—N1	119.9 (5)	C10—C12—H12B	109.5
C8—C7—C9	113.0 (7)	H12A—C12—H12B	109.5
C8—C7—C1	111.3 (5)	C10—C12—H12C	109.5
C9—C7—C1	112.5 (5)	H12A—C12—H12C	109.5
C8—C7—H7	106.5	H12B—C12—H12C	109.5
C9—C7—H7	106.5	N1—C13—C14	125.7 (5)
C1—C7—H7	106.5	N1—C13—C13i	116.6 (6)
C7—C8—H8A	109.5	C14—C13—C13i	117.8 (6)
C7—C8—H8B	109.5	C13—C14—H14A	109.5
H8A—C8—H8B	109.5	C13—C14—H14B	109.5
C7—C8—H8C	109.5	H14A—C14—H14B	109.5
H8A—C8—H8C	109.5	C13—C14—H14C	109.5
H8B—C8—H8C	109.5	H14A—C14—H14C	109.5
C7—C9—H9A	109.5	H14B—C14—H14C	109.5
C7—C9—H9B	109.5	C13—N1—C6	122.2 (4)
C6—C1—C2—C3	1.6 (8)	C4—C5—C6—N1	172.3 (5)
C7—C1—C2—C3	−179.3 (5)	C10—C5—C6—N1	−4.1 (9)
C1—C2—C3—C4	−1.3 (9)	C2—C1—C7—C8	−90.6 (8)
C1—C2—C3—Br1	177.3 (4)	C6—C1—C7—C8	88.5 (8)
C2—C3—C4—C5	0.2 (9)	C2—C1—C7—C9	37.4 (8)
Br1—C3—C4—C5	−178.4 (4)	C6—C1—C7—C9	−143.5 (6)
C3—C4—C5—C6	0.4 (9)	C4—C5—C10—C11	−81.6 (8)
C3—C4—C5—C10	176.9 (6)	C6—C5—C10—C11	94.7 (8)
C2—C1—C6—C5	−0.9 (8)	C4—C5—C10—C12	41.1 (9)
C7—C1—C6—C5	180.0 (5)	C6—C5—C10—C12	−142.6 (7)
C2—C1—C6—N1	−173.4 (5)	C14—C13—N1—C6	0.5 (9)
C7—C1—C6—N1	7.5 (8)	C13i—C13—N1—C6	−179.2 (6)
C4—C5—C6—C1	−0.1 (8)	C1—C6—N1—C13	−106.2 (6)
C10—C5—C6—C1	−176.4 (6)	C5—C6—N1—C13	81.2 (7)

Symmetry code: (i) −x+2, −y+2, −z.