1,4-Bis(2,4,6-tri­methyl­phenyl)-1,4-di­aza­buta-1,3-diene

The title compound, C₂₀H₂₄N₂, (I), has crystallographic C_i symmetry, with the central C-C bond located on a centre of inversion. The dihedral angle between the central 1,4-di­aza­buta-1,3-diene moiety and the attached substituted phenyl ring is 64.0 (2) Å.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.047
• wR factor = 0.125
• Data-to-parameter ratio = 15.4

checkCIF/PLATON results

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Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: PLATON (Spek, 1990).

(I)

Crystal data

C20H24N2	F(000) = 316
Mr = 292.41	Dx = 1.118 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4522 reflections
a = 13.486 (1) Å	θ = 1–25°
b = 4.403 (1) Å	µ = 0.07 mm^−1
c = 15.435 (1) Å	T = 173 K
β = 108.65 (1)°	Block, orange yellow
V = 868.4 (2) Å^3	0.32 × 0.30 × 0.28 mm
Z = 2

Data collection

Siemens CCD three-circle diffractometer	1167 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.044
Graphite monochromator	θmax = 25.4°, θmin = 1.6°
ω scans	h = −16→16
11184 measured reflections	k = −5→5
1597 independent reflections	l = −18→18

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.125	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0577P)^2 + 0.332P] where P = (Fo^2 + 2Fc^2)/3
1597 reflections	(Δ/σ)max < 0.001
104 parameters	Δρmax = 0.14 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

Special details

Experimental. ;

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	Occ. (<1)
N1	0.10943 (11)	0.6428 (3)	0.58628 (10)	0.0340 (4)
C1	0.04460 (13)	0.4495 (4)	0.53846 (11)	0.0324 (4)
H1	0.0542	0.2394	0.5527	0.039*
C11	0.19712 (12)	0.5314 (4)	0.65946 (11)	0.0283 (4)
C12	0.20598 (13)	0.6245 (4)	0.74896 (11)	0.0290 (4)
C13	0.29109 (13)	0.5201 (4)	0.82056 (11)	0.0310 (4)
H13	0.2972	0.5787	0.8813	0.037*
C14	0.36739 (13)	0.3331 (4)	0.80626 (11)	0.0315 (4)
C15	0.35822 (13)	0.2550 (4)	0.71676 (11)	0.0330 (4)
H15	0.4111	0.1331	0.7059	0.040*
C16	0.27403 (13)	0.3495 (4)	0.64233 (11)	0.0309 (4)
C121	0.12395 (14)	0.8237 (4)	0.76667 (13)	0.0402 (5)
H12A	0.1463	0.8820	0.8313	0.060*
H12B	0.0577	0.7124	0.7516	0.060*
H12C	0.1144	1.0065	0.7287	0.060*
C141	0.45753 (14)	0.2138 (5)	0.88530 (12)	0.0418 (5)
H14A	0.4836	0.3758	0.9304	0.063*	0.64 (2)
H14B	0.5139	0.1455	0.8626	0.063*	0.64 (2)
H14C	0.4334	0.0430	0.9140	0.063*	0.64 (2)
H14D	0.4703	0.0004	0.8743	0.063*	0.36 (2)
H14E	0.4401	0.2307	0.9421	0.063*	0.36 (2)
H14F	0.5206	0.3332	0.8907	0.063*	0.36 (2)
C161	0.26935 (15)	0.2573 (5)	0.54641 (12)	0.0420 (5)
H16A	0.2189	0.0915	0.5252	0.063*
H16B	0.3387	0.1893	0.5468	0.063*
H16C	0.2474	0.4316	0.5052	0.063*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0313 (8)	0.0322 (8)	0.0296 (8)	−0.0019 (7)	−0.0027 (6)	0.0032 (7)
C1	0.0321 (9)	0.0278 (9)	0.0303 (9)	−0.0013 (8)	0.0000 (8)	0.0029 (8)
C11	0.0262 (9)	0.0267 (9)	0.0259 (9)	−0.0052 (7)	−0.0004 (7)	0.0023 (7)
C12	0.0277 (9)	0.0268 (9)	0.0304 (9)	−0.0068 (7)	0.0063 (7)	0.0002 (7)
C13	0.0336 (10)	0.0344 (10)	0.0218 (8)	−0.0072 (8)	0.0041 (7)	−0.0011 (7)
C14	0.0280 (9)	0.0362 (10)	0.0245 (9)	−0.0054 (8)	0.0001 (7)	0.0035 (8)
C15	0.0269 (9)	0.0391 (11)	0.0308 (10)	0.0015 (8)	0.0061 (8)	0.0009 (8)
C16	0.0297 (9)	0.0350 (10)	0.0235 (9)	−0.0046 (8)	0.0022 (7)	0.0000 (8)
C121	0.0381 (10)	0.0403 (11)	0.0414 (11)	−0.0011 (9)	0.0114 (9)	−0.0028 (9)
C141	0.0351 (10)	0.0532 (12)	0.0287 (10)	−0.0005 (9)	−0.0018 (8)	0.0040 (9)
C161	0.0397 (11)	0.0560 (13)	0.0259 (10)	0.0029 (9)	0.0045 (8)	−0.0028 (9)

Geometric parameters (Å, º)

N1—C1	1.273 (2)	C16—C161	1.517 (2)
N1—C11	1.436 (2)	C121—H12A	0.9800
C1—C1^i	1.463 (3)	C121—H12B	0.9800
C1—H1	0.9500	C121—H12C	0.9800
C11—C16	1.401 (2)	C141—H14A	0.9800
C11—C12	1.409 (2)	C141—H14B	0.9800
C12—C13	1.392 (2)	C141—H14C	0.9800
C12—C121	1.504 (2)	C141—H14D	0.9800
C13—C14	1.389 (3)	C141—H14E	0.9800
C13—H13	0.9500	C141—H14F	0.9800
C14—C15	1.390 (2)	C161—H16A	0.9800
C14—C141	1.514 (2)	C161—H16B	0.9800
C15—C16	1.396 (2)	C161—H16C	0.9800
C15—H15	0.9500
C1—N1—C11	117.88 (15)	C14—C141—H14A	109.5
N1—C1—C1^i	120.1 (2)	C14—C141—H14B	109.5
N1—C1—H1	120.0	H14A—C141—H14B	109.5
C1^i—C1—H1	120.0	C14—C141—H14C	109.5
C16—C11—C12	121.04 (15)	H14A—C141—H14C	109.5
C16—C11—N1	121.35 (15)	H14B—C141—H14C	109.5
C12—C11—N1	117.54 (16)	C14—C141—H14D	109.5
C13—C12—C11	118.17 (16)	H14A—C141—H14D	141.1
C13—C12—C121	121.06 (16)	H14B—C141—H14D	56.3
C11—C12—C121	120.75 (15)	H14C—C141—H14D	56.3
C14—C13—C12	122.26 (16)	C14—C141—H14E	109.5
C14—C13—H13	118.9	H14A—C141—H14E	56.3
C12—C13—H13	118.9	H14B—C141—H14E	141.1
C13—C14—C15	117.99 (15)	H14C—C141—H14E	56.3
C13—C14—C141	121.47 (16)	H14D—C141—H14E	109.5
C15—C14—C141	120.54 (17)	C14—C141—H14F	109.5
C14—C15—C16	122.32 (17)	H14A—C141—H14F	56.3
C14—C15—H15	118.8	H14B—C141—H14F	56.3
C16—C15—H15	118.8	H14C—C141—H14F	141.1
C15—C16—C11	118.14 (15)	H14D—C141—H14F	109.5
C15—C16—C161	119.52 (16)	H14E—C141—H14F	109.5
C11—C16—C161	122.34 (15)	C16—C161—H16A	109.5
C12—C121—H12A	109.5	C16—C161—H16B	109.5
C12—C121—H12B	109.5	H16A—C161—H16B	109.5
H12A—C121—H12B	109.5	C16—C161—H16C	109.5
C12—C121—H12C	109.5	H16A—C161—H16C	109.5
H12A—C121—H12C	109.5	H16B—C161—H16C	109.5
H12B—C121—H12C	109.5
C11—N1—C1—C1^i	−178.4 (2)	C12—C13—C14—C141	−178.02 (17)
C1—N1—C11—C16	64.7 (2)	C13—C14—C15—C16	−2.1 (3)
C1—N1—C11—C12	−118.49 (18)	C141—C14—C15—C16	177.21 (17)
C16—C11—C12—C13	−2.7 (2)	C14—C15—C16—C11	0.5 (3)
N1—C11—C12—C13	−179.49 (14)	C14—C15—C16—C161	179.65 (17)
C16—C11—C12—C121	179.04 (16)	C12—C11—C16—C15	1.9 (2)
N1—C11—C12—C121	2.2 (2)	N1—C11—C16—C15	178.61 (16)
C11—C12—C13—C14	1.0 (3)	C12—C11—C16—C161	−177.15 (17)
C121—C12—C13—C14	179.29 (16)	N1—C11—C16—C161	−0.5 (3)
C12—C13—C14—C15	1.3 (3)

Symmetry code: (i) −x, −y+1, −z+1.