2,3-Bis[(3-methyl­bi­phenyl-4-yl)imino]­butane

The title compound, C₃₀H₂₈N₂, is a product of the condensation reaction of 2-methyl-4-phenyl­aniline and butane-2,3-dione. The mol­ecule lies on a crystallographic inversion centre. The C=N bond has an E conformation. The dihedral angle between the two benzene rings of the 4-phenyl-2-methyl­phenyl group is 29.19 (76)°. The 1,4-di­aza­butadiene plane makes an angle of 70.1 (10)° with the N-bonded methyl­phenyl ring and an angle of 81.08 (97)° with the terminal phenyl group.

Related literature

The title compound was synthesized as an α-di­imine ligand for applications in olefin polymerization Ni(II)-α-di­imine catalysts, see: Johnson et al. (1995); Killian et al. (1996); Wang et al. (2013); Ionkin & Marshall (2004); Meinhard et al. (2007). For the effect of the ligand structure on the activity of the catalyst and the properties of the products, see: Popeney & Guan (2005); Yuan et al. (2005); Helldörfer et al. (2003). For related structures, see: Yuan et al. (2013).

Experimental

Crystal data

• C₃₀H₂₈N₂

• M_r = 416.54

• Orthorhombic, P b c a

• a = 8.347 (3) Å

• b = 7.063 (3) Å

• c = 39.946 (16) Å

• V = 2355.0 (16) ų

• Z = 4

• Mo Kα radiation

• μ = 0.07 mm⁻¹

• T = 293 K

• 0.19 × 0.18 × 0.15 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 2004) T_min = 0.987, T_max = 0.990

• 15668 measured reflections

• 2200 independent reflections

• 1251 reflections with I > 2σ(I)

• R_int = 0.088

Refinement

• R[F² > 2σ(F²)] = 0.069

• wR(F²) = 0.135

• S = 1.01

• 2200 reflections

• 148 parameters

• H-atom parameters constrained

• Δρ_max = 0.15 e Å⁻³

• Δρ_min = −0.16 e Å⁻³

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); 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.

Supporting information

S1. Comment

In recent years, a variety of α-diimine ligands containing various ortho and para position substituted N-aryl rings (Johnson et al. 1995; Killian et al.. 1996; Popeney et al.. 2005; Yuan et al., 2005; Wang et al. 2013) and backbone effects (Helldörfer et al.. 2003) and teraryl substituted-α-diimine ligands (Ionkin et al.. 2004; Meinhard et al.. 2007) were employed to study their influence on the catalytic activity of α-diimine-Ni(II) complexes. In this study, we designed and synthesized the title compound as a bidentate ligand. The molecule lies on a crystallographic inversion centre. The single bond of 1, 4-diazabutadiene fragment is (E)-configured. The dihedral angles between the 1,4-diazabutadiene plane and the benzene ring bonded to the N atom are 70.12 (96)° and 81.08 (97)° for the terminal phenyl group, resp. The dihedral angle between both aromatic ring planes is 29.19 (76)° (Figure 1). The crystal packing shows stacking of molecules along a-axis (Figure 2), however, no significant intermolecular H-bonding is observed. A very similar molecular structure is known from Yuan et al. (2013).

Related literature

The title compound was synthesized as an α-diimine ligand for application in olefin polymerization Ni(II)-α-diimine catalysts, see: Johnson et al. (1995); Killian et al. (1996); Wang et al. (2013); Ionkin & Marshall (2004); Meinhard et al. (2007). For the effect of the ligand structure on the activity of the catalyst and the properties of the products, see: Popeney & Guan (2005); Yuan et al. (2005); Helldörfer et al. (2003). For related structures, see: Yuan et al. (2013).

S2. Experimental

Formic acid (0.5 ml) was added to a stirred solution of 2-methyl-4-phenylaniline (0.916 g, 2.2 mmol) and 2,3-Butanedione (0.086 g, 1 mmol) in 20 ml anhydrous ethanol (20 ml). The mixture was stirred at 50 ^oC for 24 h, then cooled, and the precipitate was separated by filtration. The solid was recrystallized from ethanol/dichloromethane (v/v= 8:1), washed with cold ethanol and dried under vacuum to give the title compound. Yield is 86%. Crystals suitable for X-ray structure determination were grown from a cyclohexane/dichloromethane (v:v= 1:2) solution. Anal. Calc. for C₃₀H₂₈N₂: C, 86.50; H, 6.78; N, 6.72. Found: C, 86.62; H, 6.57; N, 6.58.

S3. Refinement

Positions of the methyl H atoms were derived from Fourier maps (HFIX 137), with C–H 0.96 Å and U_iso(H) = 1.5U_eq(C). All other H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C–H distances distances of 0.93 Å and U_iso(H) = 1.2U_eq(C).

Computing details

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

Figures

	Fig. 1. The title molecule with displacement ellipsoids plotted at 50% probability level. Atoms with label "a" are related by the symmetry code (-x+1, -y+1, -z).
	Fig. 2. Crystal packing viewed along the a-axis.

2,3-Bis[(3-methylbiphenyl-4-yl)imino]butane

Crystal data

C30H28N2	Dx = 1.175 Mg m^−3
Mr = 416.54	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 1674 reflections
a = 8.347 (3) Å	θ = 2.6–21.7°
b = 7.063 (3) Å	µ = 0.07 mm^−1
c = 39.946 (16) Å	T = 293 K
V = 2355.0 (16) Å^3	Block, yellow
Z = 4	0.19 × 0.18 × 0.15 mm
F(000) = 888

Data collection

Bruker APEXII CCD diffractometer	2200 independent reflections
Radiation source: fine-focus sealed tube	1251 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.088
ϕ and ω scans	θmax = 25.5°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −10→10
Tmin = 0.987, Tmax = 0.990	k = −8→8
15668 measured reflections	l = −48→47

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.069	H-atom parameters constrained
wR(F^2) = 0.135	w = 1/[σ^2(Fo^2) + (0.0366P)^2 + 1.4273P] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
2200 reflections	Δρmax = 0.15 e Å^−3
148 parameters	Δρmin = −0.16 e Å^−3
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0025 (6)

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
C1	0.6218 (4)	−0.0240 (5)	0.17712 (7)	0.0644 (9)
H1	0.7117	−0.0468	0.1640	0.077*
C2	0.6029 (4)	−0.1219 (5)	0.20680 (8)	0.0716 (10)
H2	0.6792	−0.2106	0.2133	0.086*
C3	0.4725 (4)	−0.0893 (5)	0.22677 (7)	0.0663 (9)
H3	0.4597	−0.1548	0.2468	0.080*
C4	0.3612 (4)	0.0413 (4)	0.21680 (7)	0.0594 (9)
H4	0.2726	0.0652	0.2303	0.071*
C5	0.3788 (4)	0.1375 (4)	0.18713 (6)	0.0504 (8)
H5	0.3012	0.2248	0.1807	0.061*
C6	0.5099 (3)	0.1070 (4)	0.16654 (6)	0.0442 (7)
C7	0.5276 (3)	0.2107 (4)	0.13451 (6)	0.0425 (7)
C8	0.6072 (3)	0.1298 (4)	0.10744 (7)	0.0509 (8)
H8	0.6563	0.0124	0.1099	0.061*
C9	0.6142 (3)	0.2216 (4)	0.07704 (7)	0.0532 (8)
H9	0.6678	0.1652	0.0592	0.064*
C10	0.5427 (3)	0.3961 (4)	0.07266 (6)	0.0423 (7)
C11	0.4688 (3)	0.4856 (4)	0.09956 (6)	0.0432 (7)
C12	0.4629 (3)	0.3887 (4)	0.12980 (6)	0.0443 (7)
H12	0.4126	0.4468	0.1479	0.053*
C13	0.3949 (4)	0.6774 (4)	0.09594 (8)	0.0674 (10)
H13A	0.2882	0.6648	0.0873	0.101*
H13B	0.4580	0.7522	0.0808	0.101*
H13C	0.3912	0.7384	0.1174	0.101*
C14	0.4850 (3)	0.4425 (4)	0.01552 (6)	0.0440 (7)
C15	0.3729 (4)	0.2792 (5)	0.01278 (8)	0.0773 (11)
H15A	0.3722	0.2102	0.0335	0.116*
H15B	0.4073	0.1972	−0.0050	0.116*
H15C	0.2670	0.3248	0.0081	0.116*
N1	0.5572 (3)	0.4954 (3)	0.04174 (5)	0.0486 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.068 (2)	0.078 (3)	0.0472 (19)	0.013 (2)	0.0012 (16)	0.0083 (18)
C2	0.086 (3)	0.075 (2)	0.054 (2)	0.016 (2)	−0.0096 (19)	0.012 (2)
C3	0.092 (3)	0.064 (2)	0.0429 (18)	−0.005 (2)	−0.0080 (19)	0.0083 (17)
C4	0.075 (2)	0.063 (2)	0.0400 (17)	−0.0046 (19)	0.0066 (16)	−0.0005 (16)
C5	0.0651 (19)	0.0476 (19)	0.0386 (17)	−0.0013 (16)	0.0034 (14)	0.0006 (15)
C6	0.0502 (17)	0.0475 (18)	0.0349 (15)	0.0018 (15)	−0.0037 (13)	−0.0025 (14)
C7	0.0388 (15)	0.0504 (19)	0.0381 (16)	−0.0011 (15)	−0.0014 (13)	−0.0022 (14)
C8	0.0587 (18)	0.0529 (19)	0.0410 (17)	0.0119 (16)	0.0057 (14)	0.0047 (16)
C9	0.0593 (18)	0.058 (2)	0.0424 (18)	0.0049 (17)	0.0088 (15)	−0.0019 (16)
C10	0.0417 (15)	0.0495 (18)	0.0356 (16)	−0.0052 (15)	−0.0010 (13)	0.0013 (14)
C11	0.0430 (15)	0.0456 (17)	0.0410 (17)	−0.0007 (14)	−0.0023 (13)	−0.0011 (14)
C12	0.0474 (16)	0.0479 (18)	0.0377 (16)	0.0014 (15)	0.0034 (13)	−0.0058 (14)
C13	0.088 (2)	0.055 (2)	0.059 (2)	0.0099 (19)	0.0034 (18)	0.0063 (17)
C14	0.0404 (15)	0.0522 (19)	0.0395 (16)	−0.0047 (14)	0.0022 (13)	0.0024 (13)
C15	0.090 (2)	0.086 (3)	0.055 (2)	−0.041 (2)	−0.0109 (19)	0.0185 (19)
N1	0.0521 (14)	0.0561 (16)	0.0375 (13)	−0.0075 (12)	0.0012 (12)	0.0028 (12)

Geometric parameters (Å, º)

C1—C6	1.381 (4)	C9—C10	1.380 (4)
C1—C2	1.382 (4)	C9—H9	0.9300
C1—H1	0.9300	C10—C11	1.391 (3)
C2—C3	1.369 (4)	C10—N1	1.426 (3)
C2—H2	0.9300	C11—C12	1.389 (3)
C3—C4	1.368 (4)	C11—C13	1.496 (4)
C3—H3	0.9300	C12—H12	0.9300
C4—C5	1.374 (4)	C13—H13A	0.9600
C4—H4	0.9300	C13—H13B	0.9600
C5—C6	1.386 (4)	C13—H13C	0.9600
C5—H5	0.9300	C14—N1	1.265 (3)
C6—C7	1.481 (4)	C14—C15	1.489 (4)
C7—C12	1.381 (4)	C14—C14^i	1.504 (5)
C7—C8	1.392 (3)	C15—H15A	0.9600
C8—C9	1.378 (4)	C15—H15B	0.9600
C8—H8	0.9300	C15—H15C	0.9600
C6—C1—C2	121.4 (3)	C8—C9—H9	119.6
C6—C1—H1	119.3	C9—C10—C11	120.0 (3)
C2—C1—H1	119.3	C9—C10—N1	120.8 (2)
C3—C2—C1	120.4 (3)	C11—C10—N1	118.9 (3)
C3—C2—H2	119.8	C10—C11—C12	117.6 (3)
C1—C2—H2	119.8	C10—C11—C13	121.3 (3)
C4—C3—C2	118.9 (3)	C12—C11—C13	121.1 (3)
C4—C3—H3	120.5	C7—C12—C11	123.6 (3)
C2—C3—H3	120.5	C7—C12—H12	118.2
C3—C4—C5	120.8 (3)	C11—C12—H12	118.2
C3—C4—H4	119.6	C11—C13—H13A	109.5
C5—C4—H4	119.6	C11—C13—H13B	109.5
C4—C5—C6	121.3 (3)	H13A—C13—H13B	109.5
C4—C5—H5	119.4	C11—C13—H13C	109.5
C6—C5—H5	119.4	H13A—C13—H13C	109.5
C1—C6—C5	117.2 (3)	H13B—C13—H13C	109.5
C1—C6—C7	121.9 (3)	N1—C14—C15	126.1 (3)
C5—C6—C7	120.9 (3)	N1—C14—C14^i	116.4 (3)
C12—C7—C8	117.0 (3)	C15—C14—C14^i	117.5 (3)
C12—C7—C6	121.9 (3)	C14—C15—H15A	109.5
C8—C7—C6	121.1 (3)	C14—C15—H15B	109.5
C9—C8—C7	120.8 (3)	H15A—C15—H15B	109.5
C9—C8—H8	119.6	C14—C15—H15C	109.5
C7—C8—H8	119.6	H15A—C15—H15C	109.5
C10—C9—C8	120.9 (3)	H15B—C15—H15C	109.5
C10—C9—H9	119.6	C14—N1—C10	122.1 (2)
C6—C1—C2—C3	−0.8 (5)	C8—C9—C10—C11	3.0 (4)
C1—C2—C3—C4	0.2 (5)	C8—C9—C10—N1	176.7 (3)
C2—C3—C4—C5	0.5 (5)	C9—C10—C11—C12	−3.4 (4)
C3—C4—C5—C6	−0.6 (5)	N1—C10—C11—C12	−177.2 (2)
C2—C1—C6—C5	0.7 (5)	C9—C10—C11—C13	178.0 (3)
C2—C1—C6—C7	−179.0 (3)	N1—C10—C11—C13	4.2 (4)
C4—C5—C6—C1	0.0 (4)	C8—C7—C12—C11	2.3 (4)
C4—C5—C6—C7	179.7 (3)	C6—C7—C12—C11	−176.1 (3)
C1—C6—C7—C12	−152.1 (3)	C10—C11—C12—C7	0.7 (4)
C5—C6—C7—C12	28.3 (4)	C13—C11—C12—C7	179.4 (3)
C1—C6—C7—C8	29.6 (4)	C15—C14—N1—C10	2.3 (5)
C5—C6—C7—C8	−150.0 (3)	C14^i—C14—N1—C10	−178.4 (3)
C12—C7—C8—C9	−2.7 (4)	C9—C10—N1—C14	71.9 (4)
C6—C7—C8—C9	175.7 (3)	C11—C10—N1—C14	−114.4 (3)
C7—C8—C9—C10	0.1 (4)

Symmetry code: (i) −x+1, −y+1, −z.