N¹,N⁴-Diethynyl-N¹,N⁴-diphenyl­benzene-1,4-diamine

The title compound, C₂₂H₁₆N₂, is the first example of an ynamine with H atoms bonded to the terminal C atoms. The environment around each N atom is almost planar. The distances of the N atoms from a least squares plane fitted through each N atom and the surrounding three C atoms, are 0.087 (3) and 0.041 (4) Å. The dihedral angles between these two planes and the central phenyl­ene ring are 23.34 (14) and 34.57 (14)°. The two acetyl­ene groups have an anti conformation, keeping a conjugation through the central benzene ring. The freely refined lengths of C_sp—H are 1.00 (5) and 0.93 (4) Å, consistent with those of reported acetyl­enes. The H atoms bound to terminal C atoms have short contacts with the neighboring acetyl­enic C and N atoms. The closest contacts are an H...N distance of 2.67 (5) Å and an H...C distance of 2.74 (5) Å.

Key indicators

• Single-crystal X-ray study
• T = 93 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.043
• wR factor = 0.093
• Data-to-parameter ratio = 6.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       6.88
PLAT340_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0048 Ang
PLAT351_ALERT_3_C Long    C-H Bond (0.96A)   C10    -   H9     ...       1.15 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H1     ..  N1      ..       2.67 Ang.
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          9
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         11
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          9
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          5

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.50
           From the CIF: _reflns_number_total               1942
           Count of symmetry unique reflns         1968
           Completeness (_total/calc)             98.68%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   8 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   2 ALERT level G = General information/check it is not something unexpected

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

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S1. Comment

Ynamines, where amino groups are connected to acetylene groups, are known to be unstable because of their high reactivity. Therefore, reports of crystal structures are limited to rather stable ynamines (Galli et al., 1988; Galli et al., 1989; Mayerle & Flandera, 1978; Okuno et al., 2006;) which carry some substituents, except for H atoms, on all C– and N-terminals. When H atoms are connected to C– or N-terminals, the stability of ynamines decreases drastically. In the course of our research in ynamine compounds to develop a conjugated linker, (Tabata et al., 2011) we have succeeded in preparation and characterization of the title compound. It is the first example of ynamines with H atoms in the C-terminals.

In the molecular structure, (Fig. 1) the geometric parameters are consistent with those of other reported ynamines. (Table 1) The bond lengths of C_sp—H are 1.00 (5) Å and 0.93 (4) Å, where a marked difference is not recognized compared with those of other acetylenic compounds. The structures around the nitrogen atoms, plane (N1/C1/C7/C19) and plane (N2/C4/C13/C21), are almost planar, where the distances of the nitrogen atoms from the least squares planes are 0.087 (3) Å and 0.041 (4) Å, respectively. The dihedral angles of the plane (N1/C1/C7/C19) with the phenylene (C1/C2/C3/C4/C5/C6) and the phenyl rings (C7/C8/C9/C10/C11/C12) are 23.34 (14)° and 48.74 (15)°, respectively. The dihedral angles of the plane (N2/C4/C13/C21) with the phenylene (C1/C2/C3/C4/C5/C6) and the phenyl rings (C13/C14/C15/C16/C17/C18) are 34.57 (14)° and 29.28 (14)°, respectively. The two acetylene groups have an anti conformation, keeping a conjugation through the phenylene ring.

The H-atoms bound to C-terminals have short contacts with the neighboring acetylenic carbon and nitrogen atoms, giving C_sp—H···π interactions. (Fig. 2, Table 2) The C20—H1 bond points to the C2(-x + 1, y + 1/2, -z) atom, where the closest contact is C20—H1···N1(-x + 1, y + 1/2, -z) of 2.67 (5) Å, indicating the interaction with the lone pair of N1. The H2 atom interacts with p-orbitals of an adjacent acetylenic carbon atom. The C22—H2 bond directs to the N1(x, y, z + 1) atom, with close contact C22—H2···C20(x, y, z + 1) of 2.74 (5) Å.

Related literature

For the related structures of ynamine compounds where a diphenylamino group is connected to diacetylene terminal, see: Galli et al. (1988, 1989). For the related structures of a diacetylene compound having 9-carbazolyl groups in both ends, see: Mayerle & Flandera (1978). For the related structures of ynamine compounds incorporating a phenothiazine-10-yl group, see: Okuno et al. (2006). For our work on the preparation and the structure of the related ynamine molecule incoporating a part of the title compound, see: Tabata et al. (2011).

S2. Experimental

N¹,N⁴-diethynyl-N¹,N⁴-diphenyl-1,4- phenylenediamine

n-BuLi in n-hexane (15.5 ml, 24.6 mmol) was added dropwise to a solution of N¹,N⁴-bis(trichloroethenyl)-N¹, N⁴-diphenyl-1,4-phenylenediamine (2.00 g, 3.85 mmol) in dry THF (100 ml) at -78 °C under an argon atmosphere. After the solution was stirred for 1 h, methanol (1.3 ml) was added to the solution. It was allowed to warm to -10 °C and poured into water (50 ml). The water layer was extracted with ether (100 ml), and the combined organic layer was washed with saturated brine (20 ml), and dried over anhydrous sodium sulfate. After the solvent was evaporated, the residue was purified by GPC to give 0.60 g (yield 50%) of the title compound as a reddish brown powder. The single crystals with sufficient quality were obtained by slow evaporation from a solution of chloroform in a refrigerator.

S3. Refinement

Friedel pairs were merged because the molecule itself was achiral and because there were not any anomalous scattering effects. Four reflections whose 2θ angles were lower than 8° were not used for refinement because of the effect of a beam stop. The C-bound H atoms were obtained from a difference Fourier map and were refined isotropically with the restriction of C_sp—H range between 0.95 (4) Å and 1.15 (4) Å.

Computing details

Data collection: CrystalClear (Rigaku, 2008); cell refinement: CrystalClear (Rigaku, 2008); data reduction: CrystalClear (Rigaku, 2008); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: CrystalStructure (Rigaku, 2010).

Figures

	Fig. 1. The asymmetric unit of the title compound with atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres.
	Fig. 2. C–H···π interactions between H-atoms of the C-terminals and the acetylenic carbon and the nitrogen atoms. [Symmetry codes: (i) -x + 1, y + 1/2, -z; (ii) x, y, z + 1]

N¹,N⁴-Diethynyl-N¹,N⁴-diphenylbenzene- 1,4-diamine

Crystal data

C22H16N2	F(000) = 324.00
Mr = 308.38	Dx = 1.283 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71075 Å
Hall symbol: P 2yb	Cell parameters from 2741 reflections
a = 9.228 (3) Å	θ = 3.2–27.5°
b = 7.752 (2) Å	µ = 0.08 mm^−1
c = 11.359 (4) Å	T = 93 K
β = 100.880 (4)°	Prism, colourless
V = 798.0 (5) Å^3	0.25 × 0.12 × 0.08 mm
Z = 2

Data collection

Rigaku Saturn724 diffractometer	1627 reflections with F^2 > 2σ(F^2)
Detector resolution: 28.445 pixels mm^-1	Rint = 0.040
ω scans	θmax = 27.5°
Absorption correction: numerical (NUMABS; Rigaku, 1999)	h = −11→11
Tmin = 0.984, Tmax = 0.994	k = −10→10
6457 measured reflections	l = −14→10
1942 independent reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.043	All H-atom parameters refined
wR(F^2) = 0.093	w = 1/[σ^2(Fo^2) + (0.010P)^2 + 0.5P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
1939 reflections	Δρmax = 0.32 e Å^−3
282 parameters	Δρmin = −0.32 e Å^−3
1 restraint	Extinction correction: SHELXL97 (Sheldrick, 2008)
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.116 (10)
Secondary atom site location: difference Fourier map

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.3719 (3)	0.3729 (3)	0.1482 (2)	0.0205 (6)
N2	0.7581 (3)	0.3249 (4)	0.5970 (2)	0.0199 (6)
C1	0.4697 (3)	0.3595 (4)	0.2614 (3)	0.0179 (7)
C2	0.4381 (3)	0.2478 (4)	0.3489 (3)	0.0185 (7)
C3	0.5345 (3)	0.2341 (4)	0.4589 (3)	0.0189 (7)
C4	0.6630 (3)	0.3317 (4)	0.4816 (3)	0.0169 (7)
C5	0.6951 (3)	0.4417 (4)	0.3933 (3)	0.0178 (7)
C6	0.5999 (3)	0.4552 (4)	0.2837 (3)	0.0190 (7)
C7	0.2146 (3)	0.3531 (4)	0.1369 (3)	0.0193 (7)
C8	0.1366 (4)	0.2700 (4)	0.0355 (3)	0.0240 (8)
C9	−0.0163 (4)	0.2602 (5)	0.0191 (3)	0.0291 (9)
C10	−0.0907 (4)	0.3317 (5)	0.1017 (3)	0.0286 (9)
C11	−0.0121 (4)	0.4117 (4)	0.2036 (3)	0.0249 (8)
C12	0.1407 (3)	0.4234 (4)	0.2211 (3)	0.0208 (7)
C13	0.9137 (3)	0.3538 (4)	0.6126 (3)	0.0194 (7)
C14	0.9879 (3)	0.4337 (4)	0.7169 (3)	0.0226 (8)
C15	1.1393 (4)	0.4586 (4)	0.7329 (3)	0.0263 (8)
C16	1.2172 (4)	0.4105 (4)	0.6452 (3)	0.0262 (8)
C17	1.1418 (3)	0.3325 (4)	0.5412 (3)	0.0229 (8)
C18	0.9911 (3)	0.3013 (4)	0.5250 (3)	0.0212 (7)
C19	0.4187 (3)	0.4520 (4)	0.0562 (3)	0.0223 (7)
C20	0.4608 (4)	0.5242 (4)	−0.0232 (3)	0.0266 (9)
C21	0.6955 (3)	0.3114 (4)	0.6945 (3)	0.0208 (7)
C22	0.6419 (4)	0.3023 (4)	0.7811 (3)	0.0258 (8)
H1	0.498 (5)	0.586 (6)	−0.089 (4)	0.056 (13)*
H2	0.601 (4)	0.299 (6)	0.850 (3)	0.039 (10)*
H3	0.352 (4)	0.178 (5)	0.330 (3)	0.017 (8)*
H4	0.502 (4)	0.162 (5)	0.523 (3)	0.024 (9)*
H5	0.785 (4)	0.509 (5)	0.404 (3)	0.021 (8)*
H6	0.624 (4)	0.529 (5)	0.223 (3)	0.033 (10)*
H7	0.194 (3)	0.217 (4)	−0.021 (3)	0.014 (7)*
H8	−0.064 (4)	0.207 (5)	−0.054 (3)	0.025 (9)*
H9	−0.218 (4)	0.329 (6)	0.084 (3)	0.038 (10)*
H10	−0.065 (4)	0.464 (5)	0.262 (3)	0.028 (9)*
H11	0.191 (4)	0.486 (5)	0.294 (3)	0.033 (10)*
H12	0.934 (4)	0.468 (5)	0.779 (3)	0.028 (9)*
H13	1.195 (4)	0.509 (5)	0.811 (3)	0.033 (10)*
H14	1.336 (4)	0.424 (6)	0.662 (3)	0.038 (10)*
H15	1.196 (4)	0.298 (5)	0.478 (3)	0.025 (8)*
H16	0.939 (4)	0.242 (5)	0.449 (3)	0.028 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0205 (12)	0.0205 (12)	0.0205 (12)	−0.0003 (10)	0.0036 (10)	0.0013 (10)
N2	0.0194 (11)	0.0194 (12)	0.0194 (12)	0.0000 (10)	0.0000 (9)	0.0000 (10)
C1	0.0179 (13)	0.0179 (14)	0.0179 (13)	0.0027 (11)	0.0034 (11)	−0.0016 (11)
C2	0.0186 (14)	0.0186 (14)	0.0186 (14)	−0.0024 (11)	0.0039 (11)	−0.0004 (11)
C3	0.0192 (14)	0.0192 (13)	0.0192 (14)	0.0003 (11)	0.0056 (11)	0.0029 (11)
C4	0.0170 (13)	0.0170 (13)	0.0170 (13)	0.0017 (11)	0.0040 (10)	−0.0007 (12)
C5	0.0179 (14)	0.0179 (13)	0.0179 (13)	−0.0012 (12)	0.0039 (11)	−0.0003 (11)
C6	0.0194 (14)	0.0194 (14)	0.0194 (13)	−0.0005 (12)	0.0070 (11)	0.0025 (12)
C7	0.0192 (14)	0.0192 (14)	0.0192 (14)	−0.0002 (12)	0.0031 (11)	0.0032 (11)
C8	0.0238 (15)	0.0238 (15)	0.0238 (15)	0.0005 (12)	0.0027 (13)	−0.0014 (12)
C9	0.0278 (16)	0.0278 (17)	0.0278 (17)	−0.0046 (13)	−0.0046 (14)	0.0009 (13)
C10	0.0280 (17)	0.0280 (16)	0.0280 (17)	−0.0030 (14)	0.0005 (13)	0.0080 (15)
C11	0.0254 (16)	0.0254 (15)	0.0254 (15)	0.0012 (13)	0.0088 (13)	0.0054 (13)
C12	0.0207 (14)	0.0207 (14)	0.0207 (14)	−0.0018 (12)	0.0030 (12)	0.0017 (12)
C13	0.0190 (14)	0.0190 (14)	0.0190 (14)	−0.0004 (12)	0.0009 (11)	0.0029 (11)
C14	0.0225 (15)	0.0225 (14)	0.0225 (15)	−0.0008 (13)	0.0034 (12)	−0.0011 (13)
C15	0.0253 (16)	0.0253 (16)	0.0253 (16)	−0.0015 (13)	−0.0031 (13)	0.0007 (13)
C16	0.0256 (16)	0.0256 (16)	0.0256 (16)	0.0004 (13)	0.0000 (13)	0.0055 (13)
C17	0.0232 (15)	0.0232 (15)	0.0232 (14)	0.0068 (13)	0.0068 (12)	0.0067 (13)
C18	0.0208 (14)	0.0208 (14)	0.0208 (14)	0.0021 (12)	0.0005 (12)	0.0015 (12)
C19	0.0221 (14)	0.0221 (14)	0.0221 (14)	−0.0003 (12)	0.0028 (11)	−0.0043 (12)
C20	0.0267 (17)	0.0267 (16)	0.0267 (16)	−0.0017 (13)	0.0057 (13)	0.0010 (13)
C21	0.0203 (14)	0.0203 (14)	0.0203 (14)	0.0000 (12)	0.0000 (11)	0.0000 (12)
C22	0.0260 (15)	0.0260 (16)	0.0260 (15)	−0.0004 (13)	0.0067 (13)	0.0003 (13)

Geometric parameters (Å, º)

N1—C1	1.428 (4)	C15—C16	1.385 (6)
N1—C7	1.441 (4)	C16—C17	1.391 (5)
N1—C19	1.351 (5)	C17—C18	1.389 (4)
N2—C4	1.434 (4)	C19—C20	1.187 (5)
N2—C13	1.431 (4)	C21—C22	1.184 (6)
N2—C21	1.346 (5)	C2—H3	0.95 (4)
C1—C2	1.390 (5)	C3—H4	1.01 (4)
C1—C6	1.394 (4)	C5—H5	0.97 (4)
C2—C3	1.394 (5)	C6—H6	0.95 (4)
C3—C4	1.389 (4)	C8—H7	0.99 (4)
C4—C5	1.390 (5)	C9—H8	0.96 (4)
C5—C6	1.386 (5)	C10—H9	1.15 (4)
C7—C8	1.395 (5)	C11—H10	0.98 (4)
C7—C12	1.387 (5)	C12—H11	1.00 (4)
C8—C9	1.390 (6)	C14—H12	0.97 (4)
C9—C10	1.379 (6)	C15—H13	1.02 (4)
C10—C11	1.391 (5)	C16—H14	1.08 (4)
C11—C12	1.389 (5)	C17—H15	0.99 (4)
C13—C14	1.396 (5)	C18—H16	1.02 (4)
C13—C18	1.391 (5)	C20—H1	1.00 (5)
C14—C15	1.388 (5)	C22—H2	0.93 (4)
C1—N1—C7	121.8 (3)	N1—C19—C20	178.7 (4)
C1—N1—C19	119.3 (3)	N2—C21—C22	178.7 (4)
C7—N1—C19	116.3 (3)	C1—C2—H3	118 (2)
C4—N2—C13	122.3 (3)	C3—C2—H3	122 (2)
C4—N2—C21	118.1 (3)	C2—C3—H4	117.6 (19)
C13—N2—C21	119.1 (3)	C4—C3—H4	121.9 (19)
N1—C1—C2	120.4 (3)	C4—C5—H5	122 (2)
N1—C1—C6	120.1 (3)	C6—C5—H5	117 (2)
C2—C1—C6	119.4 (3)	C1—C6—H6	120 (2)
C1—C2—C3	120.2 (3)	C5—C6—H6	120 (2)
C2—C3—C4	120.2 (3)	C7—C8—H7	118.0 (16)
N2—C4—C3	120.2 (3)	C9—C8—H7	122.8 (16)
N2—C4—C5	120.3 (3)	C8—C9—H8	115 (3)
C3—C4—C5	119.4 (3)	C10—C9—H8	124 (3)
C4—C5—C6	120.6 (3)	C9—C10—H9	119.7 (19)
C1—C6—C5	120.1 (3)	C11—C10—H9	120 (2)
N1—C7—C8	118.5 (3)	C10—C11—H10	120 (2)
N1—C7—C12	121.0 (3)	C12—C11—H10	120 (2)
C8—C7—C12	120.4 (3)	C7—C12—H11	124 (3)
C7—C8—C9	119.2 (4)	C11—C12—H11	117 (3)
C8—C9—C10	120.7 (3)	C13—C14—H12	120 (2)
C9—C10—C11	119.8 (4)	C15—C14—H12	120 (2)
C10—C11—C12	120.3 (4)	C14—C15—H13	120 (3)
C7—C12—C11	119.6 (3)	C16—C15—H13	119 (3)
N2—C13—C14	119.6 (3)	C15—C16—H14	120 (2)
N2—C13—C18	120.3 (3)	C17—C16—H14	121 (2)
C14—C13—C18	120.1 (3)	C16—C17—H15	120 (2)
C13—C14—C15	119.5 (3)	C18—C17—H15	119 (2)
C14—C15—C16	121.0 (3)	C13—C18—H16	121 (3)
C15—C16—C17	118.9 (4)	C17—C18—H16	120 (3)
C16—C17—C18	121.1 (4)	C19—C20—H1	179 (3)
C13—C18—C17	119.4 (3)	C21—C22—H2	178 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C20—H1···N1^i	1.00 (5)	2.67 (5)	3.540 (5)	145 (4)
C22—H2···C20^ii	0.93 (4)	2.74 (5)	3.478 (6)	137 (4)

Symmetry codes: (i) −x+1, y+1/2, −z; (ii) x, y, z+1.