5 T. Suzuki, H. Higuchi, T. Tsuji, J. Nishida, Y. Yamashita and
T. Miyashi, Chemistry of Nanomolecular Systems, Chapter 1, Dynamic
Redox Systems, eds. T. Nakamura, T. Matsumoto, H. Tada and
K. Sugiura, Springer, Berlin, 2003.
6 G. Quinkert, W. -W. Wiersdorff, M. Finke, K. Opitz and F. -G. von der
Haar, Chem. Ber., 1968, 101, 2302.
7 According to PM3 calculations on model compounds, 9,10-bis(diphenyl-
methylene)-9,10-dihydrophenanthrene 1’ (Ar ~ Ph) has a smaller heat of
formation (192.25 kcal mol21) than the corresponding cyclobutene
derivative, 1,2-dihydro-1,1,2,2-tetraphenylcyclobuta[l]phenanthrene 3’
(208.12 kcal mol21). Although 9,9a-dihydro-9,9,10-triphenylanthracene
is much more stable than 7,7,8,8-tetraphenyl-oQDM or 1,1,2,2-
tetraphenylbenzocyclobutene,6 this is not the case for the dibenzo
analogues. The dihydroanthracene-type isomer was predicted to have the
higher heat of formation (216.18 kcal mol21) than 1’ and 3’, probably
due to the steric repulsion between phenyl substituents and fused benzene
rings.
8 J. L. Stavinoha, G. W. Phillips, T. A. Puckette and T. J. Devon, Eur. Pat.
326268, 1989 (Chem. Abstr., 1990, 112, 98823z).
1
9 Physical data of new compounds are as follows. 1: mp 97–98 uC, H
NMR (acetone-d6) d 7.89 (2 H, d, J ~ 7.5 Hz), 7.29 (2 H, dd, J ~ 7.5,
7.5 Hz), 7.14 (2 H, d, J ~ 7.5 Hz) 6.75–6.83 (16 H, m), 3.84 (6 H, s), 3.72
(6 H, s); UV–Vis (MeCN) lmax 325sh (log e 4.04), 276 (4.67), 239 (4.75)
nm. 121(BF42)2: mp 172–174 uC, 1H NMR (CD3CN) d 9.07 (2 H, d, J ~
8.4 Hz), 7.94 (2 H, dd, J ~ 8.4, 8.4 Hz), 7.54–7.60 (10 H, m), 7.41 (2 H,
d, J ~ 8.4 Hz), 7.06 (8 H, AA’XX’), 4.03 (12 H, s); UV–Vis (MeCN)
Fig. 1 ORTEP drawing of 1 determined by X-ray analysis of CHCl3 solvate
at 2150 uC.
l
max 550sh (log e 4.50), 502 (4.76), 366 (4.11), 272 (4.48), 254 (4.65) nm. 2:
mp 191–192 uC, 1H NMR (CDCl3) d 7.23 (2 H, d, J ~ 7.5 Hz), 7.15 (2 H,
dd, J ~ 7.5, 7.5 Hz), 7.06 (4 H, AA’XX’), 6.95 (2 H, dd, J ~ 7.5, 7.5 Hz),
6.83–6.88 (6 H, m), 6.77 (4 H, AA’XX’), 6.43 (2 H, s), 6.43 (4 H,
AA’XX’), 3.79 (6 H, s), 3.70(6 H, s).
¯
10 Crystal data for 1?(CHCl3)2: C46H38Cl6O4, M 867.52, tetragonal I4
3
˚
˚
(No. 82), a ~ 27.728(4), c ~ 11.005(2) A, U ~ 8461.0(1) A , Dc
(Z ~ 8) ~ 1.362 g cm21, T ~ 123 K, m ~ 4.49 cm21. The final R value
is 0.052 for 3232 independent reflections with I w 3sI and 509
˚
parameters. Esds for bond lengths and angles are 0.006–0.008 A and 0.4–
0.5u for non-hydrogen atoms. Due to the orientational disorder of the
solvent in the crystal, several positional parameters were fixed in the final
least-squares cycle. CCDC 237042. Data for 2 : C44H38O4, M 630.78,
Fig. 2 Continuous changes in the UV–Vis spectrum of 1 (3 mL, 1.52 6
1025 mol dm23 in MeCN containing 0.5 mol dm23 Bu4NBF4) upon
orthorhombic Pbca (No. 61), a ~ 10.1566(7), b ~ 18.671(1), c ~
constant-current electrochemical oxidation (28 mA, 10 min interval) to 121
.
3
35.302(2) A, U ~ 6694.5(8) A , Dc (Z ~ 8) ~ 1.252 g cm21, T ~ 153 K,
m ~ 0.79 cm21. The final R value is 0.039 for 4939 independent
reflections with I w 3sI and 433 parameters. Esds for bond lengths and
˚
˚
oxidation process have been commonly observed in the dynamic
redox pairs5 undergoing reversible C–C bond making/breaking4 or
drastic structural changes.17 Preliminary X-ray analysis on the
dicationic salt 121(I32)2 suggests that its phenanthrene unit adopts
a planar structure.18
Not only the geometries but also their colors change drastically
during the interconversion between 1 and 121. Thus, when the
electrochemical oxidation of 1 was followed using UV–Vis
spectroscopy, the continuous and clean conversion was observed
as shown in Fig. 2 with the development of a huge absorption band
in the visible region (l ~ 400–650 nm), demonstrating that this
couple can serve as a new electrochromic material with high
electrochemical bistability. Studies on other stable oQDMs are now
under way.
˚
angles are 0.002–0.003 A and 0.1–0.2u for non-hydrogen atoms. The
ORTEP drawing of 2 is given as Figure S1 in the ESI. CCDC 237043.
data in .cif format.
11 A. Ohta and Y. Yamashita, J. Chem. Soc., Chem. Commun., 1995, 1761.
12 H. Higuchi, E. Ohta, H. Kawai, K. Fujiwara, T. Tsuji and T. Suzuki,
J. Org. Chem., 2003, 68, 6605.
13 A. J. Moore, M. R. Bryce, P. J. Skabara, A. S. Datsanov,
L. M. Goldenberg and J. A. K. Howard, J. Chem. Soc., Perkin
Trans. 1, 1997, 3443; Y. Yamashita, M. Tomura, S. Tanaka and
K. Imaeda, Synth. Metal, 1999, 102, 1730; R. Carlier, P. Hapiot,
D. Lorcy, A. Robert and A. Tallec, Electrochim. Acta, 2001, 46, 3269.
14 Photoirradiation of 1 caused its isomerization to the 9,10-dihydroan-
thracene skeleton by electrocyclization and a subsequent 1,3-H shift. The
details will be published as a full paper in due course.
15 The PM3 calculation on 9,10-bis(diphenylmethylene)-9,10-dihydrophe-
nanthrene 1’ reproduced the values for these angles (59.7u and 18.8u,
respectively) so nicely that the observed solid-state structure is intrinsic to
this skeleton but not due to the crystal packing force.
16 L. Pauling, The Nature of the Chemical Bond, 3rd edn., Cornell
University Press, Ithac,a NY, 1960, p. 260.
17 D. H. Evans and R. W. Busch, J. Am. Chem. Soc., 1982, 104, 5057;
H. Kurata, T. Tanaka and M. Oda, Chem. Lett., 1999, 749.
¯
18 Crystal data: C44H36O4I6, M 1390.2, triclinic P1, a ~ 11.502(2), b ~
Notes and references
1 J. L. Segura and N. Mart´ın, Chem. Rev., 1999, 99, 3199.
2 K. Deuchert and S. Hu¨nig, Angew. Chem., Int. Ed. Engl., 1978, 17, 875.
By definition, the redox pair of A and B in Scheme 1 is assigned as the
inverse-Wurster type.
3 The first o-terphenoquinone-type redox system was reported very
recently: H. Kurata, Y. Takehara, T. Kawase and M. Oda, Chem. Lett.,
2003, 538.
4 S. Hu¨nig, M. Kemmer, H. Wenner, I. F. Perepichka, P. Ba¨uerle and
A. Emge, Chem. Eur. J., 1999, 5, 1969; S. Hu¨nig, S. Aldenkortt,
P. Ba¨uerle, C. A. Briehn, M. Scha¨ferling, I. F. Perepichka, D. Stalke and
B. Walfort, Eur. J. Org. Chem., 2002, 1603.
˚
11.612(2), c ~ 19.688(3) A, a ~ 84.567(4), b ~ 88.131(4), c ~
3
84.500(4)u, U ~ 2604.9(7) A , Dc (Z ~ 2) ~ 1.773 g cm21, T ~ 293 K.
˚
Due to the severe disorder of the iodine atoms, the R value is still quite
high (11.3%) (Fig. S2, ESI). We are now trying to obtain other dication
salts with different counter anions.
C h e m . C o m m u n . , 2 0 0 4 , 2 0 7 6 – 2 0 7 7
2 0 7 7