A second polymorphic form of N,N'-di­phenyl-1,4-phenyl­ene­di­amine

A new triclinic polymorphic form of N,N'-di­phenyl-1,4-phenyl­ene­di­amine (C₆H₅NHC₆H₄NHC₆H₅) has been obtained through appropriate recrystallization of the orthorhombic form. It crystallized in the centrosymmetric space group P, with two half mol­ecules as the asymmetric unit.

S1. Comment

Recent research in the conducting-polymer field pointed out the importance of preliminary studies on some related oligomers. It is now well established that conformational characteristics of the polyaniline polymer play a crucial role for its physical properties, including transport characteristics. The structure determination of N,N'-diphenyl-1,4-phenylenediamine, (I), an oligomer of polyaniline, is part of that research development.

The new triclinic polymorphic form of N,N'-diphenyl-1,4-phenylenediamine crystallized in the centrosymmetric space group P1, with two half molecules as the asymmetric unit. It differs from the orthohombic form (Povet'eva et al., 1976) not only by its moleculepacking, but also by its molecule torsion angles. Analyzed with the three Euler angles, the torsion of the two independent molecules of the triclinic form (respectively ω = 140°, χ = 42°, ϕ = 38° and ω = 133°, χ = 28°, ϕ = 43°) is much more pronounced than that of the unique molecule of the orthorhombic form (ω = 135°, χ = 4°, ϕ = 30°).

S2. Experimental

N,N'-Diphenyl-1,4-phenylenediamine (Aldrich 98%) was purified through three successive recrystallizations from toluene. Some gray crystals were obtained, with the structure corresponding to that already published (Povet'eva et al., 1976). The compound was then subsequently sublimed under vacuum at 413 K, giving rise to new transparent crystals.

S3. Refinement

H atoms bonded to C atoms were placed at calculated positions. H atoms bonded to N were located from difference Fourier syntheses and their positions refined. A unique atomic displacement parameter was refined for all H atoms.

Computing details

Data collection: EXPOSE (Stoe & Cie, 1996); cell refinement: CELL (Stoe & Cie, 1996); data reduction: INTEGRATE (Stoe & Cie, 1996); program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: JANA98 (Petricek & Dusek, 1998); software used to prepare material for publication: JANA98.

N,N'-diphenyl-1,4-phenylenediamine

Crystal data

C18H16N2	F(000) = 276
Mr = 260.3	Dx = 1.28 Mg m^−3
Triclinic, P1	Melting point: 426 K
a = 7.911 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.984 (2) Å	Cell parameters from 1631 reflections
c = 11.133 (3) Å	θ = 2–24°
α = 108.56 (3)°	µ = 0.08 mm^−1
β = 94.60 (3)°	T = 150 K
γ = 112.38 (3)°	Plate, colourless
V = 675.0 (4) Å^3	0.3 × 0.25 × 0.08 mm
Z = 2

Data collection

Stoe IPDS diffractometer	Rint = 0.057
Graphite monochromator	θmax = 24.0°, θmin = 2.0°
ω scans	h = −8→8
7072 measured reflections	k = −10→8
1931 independent reflections	l = −12→12
1450 reflections with F^2 > 2σ(F^2)

Refinement

Refinement on F^2	Weighting scheme based on measured s.u.'s w = 1/[σ^2(I) + 0.0016I^2]
R[F^2 > 2σ(F^2)] = 0.030	(Δ/σ)max = 0.0001
wR(F^2) = 0.069	Δρmax = 0.12 e Å^−3
S = 1.09	Δρmin = −0.14 e Å^−3
1931 reflections	Extinction correction: B-C type 1, Lorentzian isotropic
189 parameters	Extinction coefficient: 0.9 (1)
H atoms treated by a mixture of independent and constrained refinement

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

	x	y	z	Uiso*/Ueq
N1a	0.9757 (2)	0.2786 (2)	0.1938 (1)	0.0246 (6)
C1a	0.9838 (2)	0.1377 (2)	0.0954 (1)	0.0212 (7)
C2a	0.8898 (2)	−0.0334 (2)	0.0878 (1)	0.0229 (7)
C3a	1.0941 (2)	0.1682 (2)	0.0065 (1)	0.0228 (7)
C4a	0.8117 (2)	0.2858 (2)	0.2319 (1)	0.0219 (7)
C5a	0.8313 (2)	0.4327 (2)	0.3348 (1)	0.0277 (7)
C6a	0.6747 (2)	0.4486 (2)	0.3739 (1)	0.0339 (8)
C7a	0.4952 (2)	0.3163 (2)	0.3122 (2)	0.0338 (8)
C8a	0.4758 (2)	0.1693 (2)	0.2113 (1)	0.0296 (7)
C9a	0.6314 (2)	0.1520 (2)	0.1706 (1)	0.0253 (7)
N1b	0.2353 (2)	0.8286 (2)	0.4466 (1)	0.0295 (6)
C1b	0.1150 (2)	0.9122 (2)	0.4698 (1)	0.0233 (7)
C2b	0.0982 (2)	1.0165 (2)	0.4039 (1)	0.0263 (7)
C3b	0.0147 (2)	0.8973 (2)	0.5656 (1)	0.0260 (7)
C4b	0.2884 (2)	0.7699 (2)	0.3305 (1)	0.0245 (7)
C5b	0.4530 (2)	0.7453 (2)	0.3342 (1)	0.0302 (8)
C6b	0.5105 (2)	0.6891 (2)	0.2208 (2)	0.0359 (8)
C7b	0.4076 (2)	0.6574 (2)	0.1012 (2)	0.0323 (8)
C8b	0.2413 (2)	0.6755 (2)	0.0967 (1)	0.0296 (7)
C9b	0.1796 (2)	0.7289 (2)	0.2091 (1)	0.0260 (7)
H1a	1.065 (2)	0.381 (2)	0.209 (1)	0.036 (1)
H1b	0.287 (2)	0.820 (2)	0.512 (2)	0.036
H2a	0.810	−0.060	0.150	0.036
H3a	1.163	0.290	0.010	0.036
H5a	0.959	0.528	0.381	0.036
H6a	0.691	0.556	0.447	0.036
H7a	0.382	0.326	0.340	0.036
H8a	0.347	0.074	0.167	0.036
H9a	0.613	0.044	0.098	0.036
H2b	0.168	1.030	0.334	0.036
H3b	0.024	0.823	0.614	0.036
H5b	0.531	0.768	0.419	0.036
H6b	0.628	0.671	0.225	0.036
H7b	0.452	0.622	0.020	0.036
H8b	0.164	0.649	0.011	0.036
H9b	0.057	0.738	0.203	0.036

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1a	0.0223 (7)	0.0178 (8)	0.0295 (7)	0.0071 (5)	0.0055 (5)	0.0057 (6)
C1a	0.0209 (7)	0.019 (1)	0.0216 (7)	0.0098 (6)	0.0013 (6)	0.0052 (7)
C2a	0.0228 (7)	0.023 (1)	0.0240 (8)	0.0104 (7)	0.0071 (6)	0.0099 (7)
C3a	0.0205 (7)	0.020 (1)	0.0275 (8)	0.0077 (6)	0.0043 (6)	0.0107 (7)
C4a	0.0262 (8)	0.024 (1)	0.0204 (7)	0.0128 (7)	0.0062 (6)	0.0116 (7)
C5a	0.0305 (8)	0.022 (1)	0.0260 (8)	0.0093 (7)	0.0060 (6)	0.0065 (7)
C6a	0.043 (1)	0.025 (1)	0.0319 (8)	0.0163 (8)	0.0160 (7)	0.0051 (7)
C7a	0.0340 (9)	0.035 (1)	0.0397 (9)	0.0189 (8)	0.0191 (7)	0.0149 (8)
C8a	0.0265 (8)	0.030 (1)	0.0322 (8)	0.0117 (7)	0.0087 (7)	0.0116 (8)
C9a	0.0274 (8)	0.023 (1)	0.0231 (8)	0.0108 (7)	0.0036 (6)	0.0060 (7)
N1b	0.0321 (7)	0.0353 (9)	0.0242 (7)	0.0191 (6)	0.0024 (6)	0.0107 (6)
C1b	0.0215 (7)	0.0207 (9)	0.0221 (7)	0.0074 (6)	−0.0007 (6)	0.0043 (6)
C2b	0.0296 (8)	0.024 (1)	0.0236 (8)	0.0089 (7)	0.0075 (6)	0.0104 (7)
C3b	0.0321 (8)	0.023 (1)	0.0220 (7)	0.0110 (7)	0.0031 (6)	0.0094 (7)
C4b	0.0232 (8)	0.0170 (9)	0.0283 (8)	0.0050 (6)	0.0039 (6)	0.0073 (7)
C5b	0.0244 (8)	0.026 (1)	0.0375 (9)	0.0103 (7)	0.0028 (7)	0.0110 (8)
C6b	0.0282 (9)	0.032 (1)	0.053 (1)	0.0160 (8)	0.0134 (8)	0.0180 (9)
C7b	0.0376 (9)	0.025 (1)	0.0394 (9)	0.0151 (7)	0.0179 (8)	0.0140 (8)
C8b	0.0346 (9)	0.023 (1)	0.0299 (8)	0.0115 (7)	0.0074 (7)	0.0105 (7)
C9b	0.0248 (8)	0.024 (1)	0.0297 (8)	0.0106 (7)	0.0053 (6)	0.0106 (7)

Geometric parameters (Å, º)

N1a—C1a	1.413 (2)	N1b—C1b	1.413 (3)
N1a—C4a	1.415 (2)	N1b—C4b	1.395 (2)
N1a—H1a	0.87 (2)	N1b—H1b	0.85 (2)
C1a—C2a	1.400 (2)	C1b—C2b	1.397 (3)
C1a—C3a	1.395 (2)	C1b—C3b	1.390 (2)
C2a—C3a^i	1.384 (2)	C2b—C3b^ii	1.386 (3)
C2a—H2a	1.000	C2b—H2b	1.000
C3a—H3a	1.000	C3b—H3b	1.000
C4a—C5a	1.390 (2)	C4b—C5b	1.401 (3)
C4a—C9a	1.400 (2)	C4b—C9b	1.400 (2)
C5a—C6a	1.388 (3)	C5b—C6b	1.384 (2)
C5a—H5a	0.998	C5b—H5b	0.998
C6a—C7a	1.393 (2)	C6b—C7b	1.388 (3)
C6a—H6a	0.999	C6b—H6b	1.000
C7a—C8a	1.379 (2)	C7b—C8b	1.385 (3)
C7a—H7a	0.999	C7b—H7b	0.998
C8a—C9a	1.390 (2)	C8b—C9b	1.389 (2)
C8a—H8a	0.999	C8b—H8b	0.999
C9a—H9a	0.999	C9b—H9b	0.999
C1a—N1a—C4a	126.1 (1)	C1b—N1b—C4b	127.3 (2)
C1a—N1a—H1a	116 (1)	C1b—N1b—H1b	116 (1)
C4a—N1a—H1a	113 (1)	C4b—N1b—H1b	116 (1)
N1a—C1a—C2a	121.5 (1)	N1b—C1b—C2b	122.6 (1)
N1a—C1a—C3a	120.0 (1)	N1b—C1b—C3b	119.3 (2)
C2a—C1a—C3a	118.4 (1)	C2b—C1b—C3b	118.0 (2)
C1a—C2a—C3a^i	120.4 (1)	C1b—C2b—C3b^ii	120.5 (2)
C1a—C2a—H2a	120.4	C1b—C2b—H2b	120.1
C3a^i—C2a—H2a	119.2	C3b^ii—C2b—H2b	119.4
C1a—C3a—C2a^i	121.2 (2)	C1b—C3b—C2b^ii	121.5 (2)
C1a—C3a—H3a	119.8	C1b—C3b—H3b	119.4
C2a^i—C3a—H3a	119.0	C2b^ii—C3b—H3b	119.1
N1a—C4a—C5a	118.2 (1)	N1b—C4b—C5b	119.3 (1)
N1a—C4a—C9a	123.0 (1)	N1b—C4b—C9b	122.3 (2)
C5a—C4a—C9a	118.8 (2)	C5b—C4b—C9b	118.3 (1)
C4a—C5a—C6a	120.6 (1)	C4b—C5b—C6b	120.6 (2)
C4a—C5a—H5a	119.9	C4b—C5b—H5b	120.3
C6a—C5a—H5a	119.5	C6b—C5b—H5b	119.0
C5a—C6a—C7a	120.6 (2)	C5b—C6b—C7b	120.9 (2)
C5a—C6a—H6a	119.5	C5b—C6b—H6b	119.4
C7a—C6a—H6a	119.9	C7b—C6b—H6b	119.7
C6a—C7a—C8a	118.8 (2)	C6b—C7b—C8b	118.6 (2)
C6a—C7a—H7a	121.2	C6b—C7b—H7b	120.9
C8a—C7a—H7a	120.0	C8b—C7b—H7b	120.5
C7a—C8a—C9a	121.2 (1)	C7b—C8b—C9b	121.4 (2)
C7a—C8a—H8a	118.9	C7b—C8b—H8b	119.1
C9a—C8a—H8a	119.9	C9b—C8b—H8b	119.5
C4a—C9a—C8a	120.0 (1)	C4b—C9b—C8b	120.0 (2)
C4a—C9a—H9a	120.4	C4b—C9b—H9b	120.4
C8a—C9a—H9a	119.6	C8b—C9b—H9b	119.6

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