4500 J. Am. Chem. Soc., Vol. 119, No. 19, 1997
Wienk and Janssen
slowly added to a solution of N,N′-diphenyl-1,3-benzenediamine (0.18
g, 0.7 mmol) in diphenyl ether (15 mL) at room temperature. After
15 min of stirring, 4-iodo-N,N-diphenylaniline (0.52 g, 1.4 mmol) and
copper(I) iodide (13 mg, 0.07 mmol) were added, and the mixture was
heated to 200 °C for 48 h. After cooling, ethyl acetate (50 mL) was
added and the reaction mixture was filtered over hyflo, washed with a
saturated aqueous solution of ammonium chloride, and dried over
magnesium sulfate. Evaporation of the solvent, flash column chro-
matography (SiO2, hexane/CHCl3 3:1 to 2:1) and recrystallization from
benzene afforded pure 1 (0.32 g, 61%) as white crystals: mp 216-
218 °C; 1H NMR (CDCl3) δ 6.68 (2H, dd, J ) 8.0 and 2.0 Hz, HA-4),
6.86 (1H, t, J ) 2.0 Hz, HA-2), 6.94-7.01 (14H, m, HB-4, HC-2, HC-3,
HD-4), 7.06-7.12 (13H, m, HA-5, HB-2, HD-2), 7.19 (12H, m, HB-3,
HD-3); 13C NMR (CDCl3) δ 117.43 (CA-4), 118.57 (CA-2), 122.40 (CB-
4, CD-4), 123.69 (CB-2), 123.77 (CD-2), 125.33 (CC-3), 125.56 (CC-2),
129.08 (CB-3), 129.17 (CD-3), 129.65 (CA-5), 142.58 (CC-1), 142.96
(CC-4), 147.57 (CB-1), 147.87 (CD-1), 148.60 (CA-1). Anal Calcd for
C54H42N4: C, 86.83; H, 5.67; N, 7.50. Found: C, 86.76; H, 5.78; N,
7.66. ES-MS m/z (M+) calcd 746.3, obsd 746.3.
that acid doping is an efficient method to arrive at the required
intermediate oxidation state of secondary meta-para aniline
oligomers. ESR spectroscopy has provided insight into the spin
distribution and the nature of the intramolecular spin-spin
interaction of the various redox states of the meta-para aniline
oligomers. High-spin states have been observed for all aniline
oligomers in the intermediate oxidation state, despite the
extended delocalization within the p-phenylenediamine units.
Due to this delocalization, the zero-field splitting parameter D
is small compared to high-spin molecules with more localized
unpaired electrons like carbenes and triarylmethyl radicals.23
We stress, however, that no direct relation exists between the
zero-field splitting and the exchange energy (|2J|), which
determines the actual energy gap between the high-spin and
low-spin states. Variable-temperature ESR measurements on
all high-spin meta-para aniline oligomers presented in this
study reveal Curie behavior of the signal intensity between 4
and 100 K. This indicates that the high-spin state is a low-
energy state, either corresponding to the ground state or as part
of a (near) degeneracy with a low-spin state.
Summarizing, we have shown that polaronic triplet di(cation
radical)s 12•2+ and 72•2+ can be generated by oxidative or acid
doping of neutral precursors. Moreover, we have demonstrated
that these triplet di(cation radical) structures can successfully
be extended to higher spin multiplicities in one and two
dimensions. The chemical stability of the cationic oligoradicals
and their intramolecular ferromagnetic spin-spin interaction
confirm the feasibility of the concept of alternating meta and
para aniline oligomers as building blocks for future polaronic
ferromagnetic polymers.
N-[4-(Diphenylamino)phenyl]-N,N′-diphenyl-1,3-benzenedi-
amine (2). In a procedure similar to the synthesis of 1, N,N′-diphenyl-
1,3-benzenediamine (0.78 g, 3 mmol) was reacted with n-BuLi, 4-iodo-
N,N-diphenylaniline (1.11 g, 3 mmol), and copper(I) iodide (0.04 g,
0.2 mmol). Flash column chromatography (SiO2, hexane/CHCl3 3:1
to 2:1) afforded 1 (0.29 g, 13%) and 2 (0.65 g, 43%) as a gray solid:
mp 178 °C; 1H NMR (CDCl3) δ 5.6 (1H, bs, NH), 6.63 (1H, m, HA-6),
6.66 (1H, m, HA-4), 6.77 (1H, t, J ) 2.1 Hz, HA-2), 6.89 (1H, tt, J )
7.3 and 1.1 Hz, HB′-4), 6.9-7.0 (9H, m, HB′-2, HC-2, HC-3, HB-4, HD-
4), 7.05-7.15 (7H, m, HA-5, HB-2, HD-2), 7.15-7.25 (8H, m, HB-3,
HD-3, HB′-3); 13C NMR (CDCl3) δ 111.58 (CA-4), 112.67 (CA-2), 116.00
(CA-6), 117.61 (CB′-2), 120.82 (CB′-4), 122.36 (CD-4), 122.52 (CB-4),
123.69 (CD-2), 124.03 (CB-2), 125.42 (CC-3), 125.63 (CC-2), 129.15
(CB-3, CD-3), 129.22 (CB′-3), 129.84 (CA-5), 142.73, 142.82, 142.89,
143.78 (CA-3, CB′-1, CC-1, CC-4), 147.66 (CB-1), 147.82 (CD-1), 148.96
(CA-1).
Experimental Section
General Methods. Commercial grade reagents were used without
further purification. Solvents were purified, dried, and degassed
following standard procedures. Synthesis of 4-iodo-N,N-diphenyl-
aniline,13 N,N′,N′′-triphenyl-1,3,5-benzenetriamine,24 and 5-811 have
been reported previously. NMR spectra were recorded on a Bruker
AM-400 spectrometer, chemical shifts are relative to TMS for 1H and
13C NMR spectra. Cyclic voltammograms were recorded with 0.1 M
tetrabutylammonium hexafluorophosphate as supporting electrolyte
(unless stated otherwise) using a Potentioscan Wenking POS73
potentiostat. The working electrode was a platinum disc (0.2 cm2),
the counterelectrode was a platinum plate (0.5 cm2), and the reference
electrode was a saturated calomel electrode calibrated against a Fc/
Fc+ couple. The UV-vis-near IR spectra were recorded on a Perkin
Elmer Lambda 900 spectrophotometer with a sealed 10 mm cuvette.
ESR spectra were recorded on a Bruker ER 200D spectrometer,
operating with an X-band standard or TMH cavity, interfaced to a
Bruker Aspect 3000 data system. Temperature was controlled by a
Bruker ER4111 variable-temperature unit between 100 and 370 K or
by an Oxford 3120 temperature controller combined with an ESR900
continuous flow cryostat in the range of 4-100 K. Saturation of the
ESR signal during variable-temperature experiments was avoided by
using low microwave powers, i.e., 200 nW for the ∆MS ) (1 transition
and 1 mW for the ∆MS ) (2 transition, which is well within the range
where signal intensity is proportional to the square root of the
microwave power at 4 K. For intensity measurements, the spectra were
base line corrected. Powder ESR spectrum simulations were carried
out with a spin Hamiltonian incorporating the electron Zeeman term
and the dipolar spin-spin coupling. The g value was assumed to be
isotropic. Unresolved hyperfine couplings were generally treated using
different Gaussian line widths for the three principal directions.
N,N′-Bis[4-(diphenylamino)phenyl]-N,N′-diphenyl-1,3-benzene-
diamine (1). n-Butyllithium (1.0 mL 1.6 M in hexane, 1.6 mmol) was
N,N′-Bis{3-[N-(diphenylamino)phenyl-N-phenylamino]phenyl}-
N,N′-diphenyl-1,4-benzenediamine (3). To a solution of 2 (0.46 g,
1.1 mmol) in diphenyl ether (10 mL) were added sodium hydride (0.05
g, 2 mmol), 1,4-diiodobenzene (0.17 g, 0.5 mmol), and copper(I) iodide
(20 mg, 0.1 mmol), and the mixture was heated to 200 °C for 48 h.
After cooling, ethyl acetate (50 mL) was added and the reaction mixture
was filtered over hyflo, washed with a saturated aqueous solution of
ammonium chloride, and dried over magnesium sulfate. Evaporation
of the solvent and flash column chromatography (SiO2, hexane/CHCl3
3:1 to 2:1) afforded 3 (0.28g, 51%) as a light gray solid: mp 234 °C;
1H NMR (CDCl3) δ 6.61 (2H, dd, J ) 8.0 and 2.1 Hz, HC-6), 6.65
(2H, dd, J ) 8.0 and 2.1 Hz, HC-4), 6.85 (2H, t, J ) 2.1 Hz, HC-2),
6.9-7.0 (20H, m, HA, HB-4, HD-4, HE-2, HE-3, HF-4), 7.05-7.08 (18H,
m, HB-2, HC-5, HD-2, HF-2), 7.15-7.25 (16H, m, HB-3, HD-3, HF-3);
13C NMR (CDCl3) δ 117.41 (CC-4, CC-6), 118.53 (CC-2), 122.36, 122.37
(CB-4, CD-4), 122.39 (CF-4), 123.65, 123.68 (CB-2, CD-2), 123.76 (CF-
2), 125.32 (CE-3), 125.51, 125.54 (CA-2, CE-2), 129.07 (CB-3, CD-3),
129.14 (CF-3), 129.67 (CC-5), 142.57, 142.62 (CA-1, CE-1), 142.91 (CE-
4) 147.52, 147.54 (CB-1, CD-1), 147.85 (CF-1), 148.54, 148.57 (CC-1,
CC-3). ES-MS m/z (M+) calcd for C78H60N6 1080.5, obsd 1080.5.
N,N′,N′′-Tris[4-(diphenylamino)phenyl]-N,N′,N′′-triphenyl-1,3,5-
benzenetriamine (4). To a solution of N,N′,N′′-triphenyl-1,3,5-
benzenetriamine (0.74 g, 2.0 mmol) in diphenyl ether (25 mL) were
added sodium hydride (0.25 g, 10 mmol), 4-iodo-N,N-diphenylaniline
(2.71 g, 7.3 mmol), and copper(I) iodide (0.12 g, 0.6 mmol), and the
mixture was heated to 200 °C for 48 h. After cooling, ethyl acetate
(50 mL) was added and the reaction mixture was filtered over hyflo,
washed with a saturated aqueous solution of ammonium chloride, and
dried over magnesium sulfate. Evaporation of the solvent and flash
column chromatography (SiO2, hexane/CHCl3 3:1 to 2:1) afforded pure
1
4 (0.80 g, 37%): mp 239 °C; H NMR (330 K, CDCl3) δ 6.36 (3H,
bs, HA), 6.8-6.94 (21H, m, HB-4, HC-2, HC-3, HD-4), 6.95-7.05 (18H,
m, HB-2, HD-2), 7.13 (6H, t, J ) 7.5 Hz, HB-3), 7.17 (12H, t, J ) 7.5
Hz, HD-3); 13C NMR (330 K, CDCl3) δ 112.79 (CA-2), 122.48 (CB-4),
122.51 (CD-4), 123.85 (CB-2), 123.93 (CD-2), 125.34 (CC-3), 125.69
(CC-2), 129.00 (CB-3), 129.19 (CD-3), 142.64 (CC-1), 143.24 (CC-4),
(23) (a) Wasserman, E.; Murray, R. W.; Yager, W. A.; Trozzolo, A.
M.; Smolinsky, G. J. Am. Chem. Soc. 1967, 89, 5076. (b) Itoh, K. Chem.
Phys. Lett. 1967, 1, 235. (c) Luckhurst, G. R.; Pedulli, G. F.; Tiecco, M. J.
Chem. Soc. (B) 1971, 329.
(24) Buu-Ho¨ı, Ng. Ph. J. Chem. Soc. 1952, 4346.