Intramolecular triarylmethane-triarylmethylium complexes with a naphthalene-1,8-diyl skeleton: Isolation, structure, and reactivities of the C-H-bridged carbocations

Article abstract of DOI:10.1002/chem.200700803

Isolation and low-temperature X-ray analyses of intramolecular triarylmethane-triarylmethylium complexes with a naphthalene- 1,8-diyl-type skeleton have been achieved. These bridged cations prefer a C-H localized structure both in solution and in the soli

Full text of DOI:10.1002/chem.200700803

FULL PAPER
DOI: 10.1002/chem.200700803
Intramolecular Triarylmethane–Triarylmethylium Complexes with a
Naphthalene-1,8-diyl Skeleton: Isolation, Structure, and Reactivities of the
ꢀ
C H-Bridged Carbocations
Takashi Takeda, Hidetoshi Kawai, Kenshu Fujiwara, and Takanori Suzuki*[a]
ꢀ
Abstract: Isolation and low-tempera-
ture X-ray analyses of intramolecular
triarylmethane–triarylmethylium com-
plexes with a naphthalene-1,8-diyl-type
skeleton have been achieved. These
in solution. The C H delocalized ge-
ometry is suggested to be the transi-
tion-state structure of the degenerate
rearrangement. Charge-transfer inter-
action from the triarylmethane to the
triarylmethylium units is evident in the
electronic spectra. This interaction sta-
bilizes the present cations. Low reactiv-
ity toward Brønsted acids indicates
that these species are not the reaction
intermediates in the acid-assisted long-
bond cleavage of 1,1,2,2-tetraarylace-
naphthene derivatives.
ꢀ
bridged cations prefer a C H localized
structure both in solution and in the
solid state. The bridging hydrogen un-
dergoes a facile intramolecular 1,5-hy-
dride shift from one carbon to another
Keywords: carbocations
transfer · hydride shift · neighbor-
ing-group effects · peri-interactions
·
charge
Introduction
reactivity, which prevents
their isolation for X-ray struc-
tural analyses. Although high-
level calculations have sug-
gested that the carbon-based
multicentered bonds have in-
teresting features,[4b] the theo-
retical predictions still need to
be verified experimentally.
We envisaged that incorporation of a stable carbocationic
moiety into the [C···H···C]+ unit would provide the chance
to isolate the species for the first time. Therefore, triarylme-
thyliums, such as Ph3C+ or 9-phenylacridinium,[5] were se-
lected for this purpose, and the symmetric (pseudo-symmet-
Multicentered bonds are of interest owing to their unique
nature and special properties. Electron-deficient early s- and
p-block elements are often involved in these intriguing
bonds. Representative compounds include boranes with a
Scheme 1. Geometrical parame-
ters for [C···H···C]+-bridged
cations.
three-center, two-electron (3c–2e) bond.[1] In contrast, 3c
[2]
ꢀ ꢀ
bonds of C H C are much less common, despite the pio-
neering work by the groups of Sorensen and McMurry who
+
ꢀ ꢀ
observed the delocalized [C H C] 3c–2e bond in caged
hydrocarbons in strong acidic media.[3] These bridged cat-
ions show peculiar spectral features, such as very high-field
resonance in 1H NMR and a small coupling constant (J-
ACHTREUNG
(C,H)) in 13C NMR spectra. The delocalizability of the
bridging hydrogen in the [C···H···C]+ unit has been suggest-
ed to be sensitive to the geometry of the three-atom array,[4]
which is defined by the C···H···C angle (q), the C···C dis-
tance (D), and two kinds of C···H distances (d1 and d2)
(Scheme 1). However, detailed studies of the geometry–de-
localizability relationship have been hampered by their high
ric)
triarylmethane–triarylmethylium
complexes
[Ar3C···H···CAr3]+ were formulated to explore the detailed
structure and reactivities of the novel [C···H···C]+-bridged
carbocations. The naphthalene-1,8-diyl skeleton has attract-
ed considerable attention owing to the significant peri-inter-
action between the two subunits at the 1,8-positions.[6] To fa-
cilitate [C···H···C]+ bridging despite the sterically hindered
triarylmethane-type structure, a series of cations (1) with
this arylene spacer were designed and synthesized in this
study. In acridan–acridinium complexes 1a–c+, the
[C···H···C]+ bridging geometry can be finely tuned by re-
placing the acenaphthene-5,6-diyl and acenaphthylene-5,6-
diyl skeletons by naphthalene-1,8-diyl, which provides infor-
mation on the relationship between the properties and the
[a] T. Takeda, Dr. H. Kawai, Prof. K. Fujiwara, Prof. T. Suzuki
Department of Chemistry, Faculty of Science, Hokkaido University
Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan)
Fax : (+81)11-706-2714
E-mail: tak@sci.hokudai.ac.jp
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
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7915

bridging distances (D, d1, and d2). The thermodynamic sta-
bility (pKR+) of the cationic moiety might also perturb the
delocalizability of the bridging hydrogen. Thus, dianisylme-
thylium (1d+) or diphenylmethylium (1e+) is substituted
for the acridinium unit in 1a+.[7] In this report, we describe
the isolation and detailed geometrical investigation of 1a-e+
[8]
.
Scheme 2. Two possible structures for [C···H···C]+-bridged cations.
ed by Gabbaï and Wang as a short-lived intermediate for
the acid-promoted long-bond fission of 1,1,2,2-tetraanisyl-
AHCTREaUNG cenaphthene (2d) to form the corresponding dication
[12]
3d2+
.
While direct protonation[3b,13] of the long C C
ꢀ
bond[14] with a raised sigma-orbital level is an attractive
idea, we have obtained experimental results[15] that suggest
that molecular oxygen is involved in this type of bond cleav-
age.[16] Because the direct conversion of acenaphthene 2 by
protonation or the partial hydride addition of dications 32+
seems to be unreliable for the isolation of novel cations 1+
in pure form, we planned the synthetic routes shown in
Schemes 3 and 4, in which the neutral precursors are con-
verted in the final stage into the desired cations by quaterni-
(1a–c+) or under dehydrating conditions (1d+ and
zation ACHTREUNG
1e+). In the former case, 1a–c+ could be generated under
nonacidic conditions, and thus the bridged cations would
remain intact in the reaction mixtures even if they were sen-
sitive to acidic conditions, as proposed.[12]
We started our preparation of acridan–acridinium com-
plex 1a+ from 1,8-dibromoacenaphthene.[17] Under modified
conditions,[18] the Stille reaction with 9-trimethylstannylacri-
dine gave diacridine 4a, which was selectively mono-N-me-
thylated with MeOTf. Hydride addition by using NaBH4
gave precursor 5a. Final quaternization with MeOTf pro-
ceeded smoothly, and the desired cation 1a+ was obtained
as a stable dark-green OTfꢀ salt. Similar reactions starting
with peri-fused dibromides[19,20] gave 1b
ACTHERNGU[OTf] and 1cACHTREUNG[OTf].
Cations with the deuterium bridge, [D1]1a–c+, were ob-
tained by using NaBD4 instead of NaBH4 in the reduction
step.
Encouraged by the successful isolation of 1a–c+, bridged
cations 1d+ and 1e+ with a cationic unit that has a smaller
+
pKR value were prepared from 8-diarylmethylnaphthoic
After starting this work,[9] important papers on the bridg-
ed cations [Si···H···Si]+ and [P···H···P]+ with the same naph-
thalene-1,8-diyl arylene spacer were published,[10] which
allows comparisons with our purely organic counterpart. It
would be particularly interesting to determine whether the
bridging hydrogen in cations 1 prefers the localized position
acids 6d and 6e.[21,22] Methyl ester 7d was treated with ani-
syllithium to give carbinol 8d. Under dehydrating condi-
tions, acid treatment gave 1dACHTRE[UNG BF4] as a surprisingly stable
dark-red solid. Though less stable than 1d+, cationic hydro-
carbon 1e+ was also generated from 8e[23] and isolated as a
ꢀ
moisture-sensitive dark-green BF4 salt. Cations 1d+ and
(form A in Scheme 2) or the delocalized position (form B)
1e+ were stable under acidic conditions, which is in contrast
to the assumption[12] that 1d+ would have been transformed
into dication 3d2+ upon contact with acid.
+
ꢀ ꢀ
to better understand the nature of [C H C] 3c–2e bond-
ing.[11]
Preferred geometry in solution—variable temperature NMR
1
Results and Discussion
(VT-NMR) analyses and deuterium labeling: The H NMR
spectra of acridan–acridinium complexes 1a–cCAHTRE[UNG OTf] in
CD2Cl2 are C2v-symmetric at room temperature with only
one N-methyl resonance at d=3.91, 3.94, and 3.99 ppm, re-
Generation and isolation of [C···H···C]+-bridged cations: A
bridged cation with a [C···H···C]+ unit was recently postulat-
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Chem. Eur. J. 2007, 13, 7915 –7925

Triarylmethane–triarylmethylium Complexes
FULL PAPER
spectively. This observation can be rationalized by assuming
either a rapid degenerated 1,5-hydride shift (form A) or de-
localized 3c–2e bond formation (form B). With a decrease
in temperature, most of the resonances became broad.
Sharp Cs-symmetric spectra were obtained for 1b+ and 1c+
at ꢀ908C with two distinct N-methyl resonances at d=4.81
(acridinium) and 3.13 ppm (acridan) for 1b+, and 4.86 and
3.16 ppm for 1c+, respectively (Figure 1), although that of
Figure 1. VT-NMR spectra of 1c
d) ꢀ65, and e) ꢀ858C.
A
1a+ is just on the edge of coalescence at this temperature.
The observed temperature-dependent spectral changes sug-
gest that the bridging hydrogen is localized on one of the C9
carbons in solution and fluctuates between two equivalent
sites. The chemical shift of this hydrogen (08C) is d=4.00
and 3.90 ppm for 1a+ and 1b+, respectively; that of 1c+
was not clearly seen owing to peak overlap. These values
are close to those of precursor 5a–c (d=4.52, 4.36, and
4.43 ppm, respectively), but are far different from the very
high-field values that are characteristic of delocalized 3c–2e
bonding hydrogens.[3f,4a,24]
Scheme 3. Preparation of acridan–acridinium complexes 1a–c+: a) 9-tri-
methylstannylacridine, [PdACHTER(UNG PPh3)4], CuO, N,N-dimethylformamide,
1408C; b) MeOTf, CH2Cl2 (for 4a and 4b) or MeOTf, 2,6-di-tert-butyl-4-
methylpyridine (for 4c), PhH 238C; c) NaBH4, EtOH, 238C; d) MeOTf,
2,6-di-tert-butyl-4-methylpyridine, PhH, 238C; e) NaBD4, EtOH, 238C.
Tf=trifluoromethanesulfonyl.
The 13C NMR spectra of 1b+ and 1c+ at ꢀ908C are also
consistent with Cs-symmetric form A and exhibit two dis-
tinct resonances for C9: d=163.63 and 42.33 ppm for 1b+,
and 161.6 and 37.9 ppm for 1c+, respectively. The 13C–1H
coupling constants (126 Hz for 1b+ and 128 Hz for 1c+, re-
spectively) are comparable to those of corresponding pre-
cursors 5b and 5c (128 Hz for 5b, 129 Hz for 5c, respective-
ly), which indicates the full bonding character between the
bridging hydrogen and one of the C9 carbons. We measured
2
the H NMR spectrum of [D1]1a–c+ with a bridging deuteri-
um atom in order to perform the Dd test (1H, 2H) of
Altman and Forsen.[25] The very small values (ꢀ0.01ꢁ
ꢀ0.02 ppm at ꢀ608C) indicate a deep double-minimum po-
tential for the bridging hydrogen. These results clearly show
that acridan–acridinium complexes 1a–c+ prefer a C H lo-
calized geometry (form A) in solution.
ꢀ
Scheme 4. Preparation of Ar2CH-Ar2C+ complexes 1d+ and 1e+:
a) CH2N2, diethyl ether/THF 238C; b) AnLi, diethyl ether, ꢀ788C (for
7d) or PhLi, THF, ꢀ788C (for 7e); c) Aqueous HBF4, trifluoroacetic an-
hydride, CH2Cl2, 238C. THF=tetrahydrofuran. An=4-methoxyphenyl.
The facile 1,5-hydride shift is the most characteristic pro-
cess in these cations, and the energy barriers (DG°) were
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7917

T. Suzuki et al.
+
determined by VT-NMR analyses. The value for 1b+ in
CD2Cl2 is 9.6 kcalmolꢀ1 (Tc =ꢀ558C for N-methyl protons
at 300 MHz). In more polar and Lewis basic [D6]acetone, a
larger value of 10.1 kcalmolꢀ1 was obtained (Tc =ꢀ438C),
which suggests that the transition state is less polar than that
for 1b+ owing to charge delocalization over the two acri-
dine-based subunits. When deuterium is substituted for the
bridging hydrogen, the barrier increases as expected. The
values for [D1]1b+ (10.4 kcalmolꢀ1 in CD2Cl2; 10.7 kcal
molꢀ1 in [D6]acetone) correspond to the marginal primary
isotope effect (kH/kD ꢁ2.5). Thus, tunneling effects are not
important for the hydride shift in 1b+.
with those for 1a–c+. This indicates, regardless of pKR for
the cationic moiety, that triarylmethane–triarylmethylium
complexes 1+ prefer a C H localized geometry of form A.
ꢀ
The bridging hydrogen undergoes a rapid 1,5-shift, whose
energy barrier depends on the [C···H···C]+ geometry. Com-
pared with the acridine-based cation 1a+, cations 1d+ and
1e+ with Ar2C units exhibit a larger DG° value, which can
be accounted for by considering the wider separation of
C···C in 1d,e+ than in 1a+ (see below).
Preferred geometry in the solid state (X-ray analyses) and
as isolated species (theoretical calculation): The detailed
geometrical parameters of the present cations were success-
fully obtained by X-ray analyses of all of the salts of 1a–e+.
They are the first series of experimentally determined struc-
The activation barriers of the hydride shift in 1c+ show a
similar trend in terms of solvent effects (1c+ =10.1 kcal
molꢀ1 in CD2Cl2; 10.9 kcalmolꢀ1 in [D6]acetone) as well as
isotope effects ([D1]1c+ =10.6 kcalmolꢀ1 in CD2Cl2;
11.7 kcalmolꢀ1 in [D6]acetone). All of the values are slightly
larger than the corresponding values for 1b+ and [D1]1b+,
which shows that the change of the peri-bridge from ethano
to etheno induces perturbation of the [C···H···C]+ geometry.
As confirmed by comparisons of X-ray structures (see
below), the C···C distance (D) is slightly wider in 1c+
[3.031(4) Š] than in 1b+ [3.004(4) Š], which is responsible
for the increase in DG° for the 1,5-shift. In the case of 1a+
[D=2.951(9) Š], the separation of two acridine-based subu-
nits at the 1,8-positions of naphthalene is noticeably narrow-
er owing to the lack of a bridge on the opposite peri-posi-
tion,[26] so that the 1,5-shift should be much faster than in
1b+ and 1c+.
tures
for
the
degenerately-rearranged/delocalized
[C···H···C]+-bridged cations.[11] By conducting the measure-
ments at low temperatures, the parameters were determined
with sufficient accuracy, and the bridging hydrogen atoms
were located on the D maps. No positional disorders were
observed around the [C···H···C]+ bridge.
Regardless of their different packing arrangements, one
of the acridine units in 1a–c+ has a planar acridinium with
an sp2-hybridized C9 carbon (sum of C-C-C bond angles=
359.8–360.18), whereas the other is a butterfly-shaped acri-
dan unit with an sp3-hybridized C9 (342.0–343.58, Table 1,
Figure 2, Figures S6–S8). The latter values are close to that
found for the acridan unit of precursor 5a (343.08) deter-
The 1H NMR spectrum of naphthalene derivative 1a
ACHTRE[UNG OTf]
Table 1. List of geometrical parameters in 1a–e+ determined by X-ray
analyses of their OTfꢀ or BF4 salts and those estimated by calculations
shows essentially the same features and temperature-de-
pendence as those of 1b+ and 1c+, but the much lower Tc
corresponds to a smaller DG° value (8.4 kcalmolꢀ1 for
[D1]1a+ in [D6]acetone, Tc =ꢀ808C). For 1a+ or even for
[D1]1a+ in CD2Cl2, Tc is very close to or even lower than
the freezing point of the solvent, suggesting that DG° is less
than 8 kcalmolꢀ1 in these cases. The smaller energy barrier
for the hydride shift corresponds to the greater flexibility of
the naphthalene skeleton, which allows two acridine-based
subunits to come closer to achieve a low-energy transition-
state geometry with a narrower C···C separation. Based on
the observed solvent effects for the series of 1a–c+ and
[D1]1a–c+, it is highly probable that the transition state for
the degenerated 1,5-hydride shift of 1+ (form A) adopts a
geometry close to that of the charge-delocalized form B.
Not only acridan–acridinium complexes 1a–c+, but also
1d+ and 1e+, show temperature-dependent NMR spectra:
C2v-symmetric above Tc and Cs-symmetric below Tc. The O-
methyl groups of 1d+ resonate at d=3.99 (dianisylmethy-
lium) and 3.90 ppm (dianisylmethyl) below Tc of ꢀ558C
ꢀ
(B3LYP/6-31G*).
D
d1
1a+ X-ray 2.951(9) 2.12(5) 0.97(6) 158(4) 359.8
calcd 2.999 2.047 1.102 142.7 359.3
1b+ X-ray 3.004(4) 2.13(3) 1.03(3) 140(2) 360.0
calcd 3.008 2.148 1.102 141.6 359.7
1c+ X-ray 3.031(4) 2.19(3) 0.99(4) 141(3) 360.1
d2
q
ꢀC-C+-C ꢀC-CH-C
342.9
339.1
343.5
339.1
342.0
338.8
339.7
337.4
337.7
337.5
338.0
calcd 3.110
X-ray 3.082(10) 2.39(4) 0.91(5) 133(4) 359.8
X-ray 3.041(10) 2.15(7) 1.22(7) 127(5) 359.6
2.170
1.102
141.6 359.6
+
+
1d1
1d2
calcd 3.180
1e+ X-ray 3.051(3) 2.35(2) 0.95(2) 130(2) 359.6
calcd 3.200 2.585 1.090 114.8 359.8
2.539
1.090
116.6 359.6
(300 MHz), which correspond to
a
DG° value of
9.8 kcalmolꢀ1 in CD2Cl2. In [D6]acetone, DG° was deter-
mined to be 10.4 kcalmolꢀ1. For 1e+ with phenyl substitu-
ents, DG° was estimated from the coalescence of naphtha-
lene protons (9.6 kcalmolꢀ1 in CD2Cl2). The bridging hydro-
gen appeared at d=5.47 and 5.30 ppm for 1d+ and 1e+, re-
spectively, which are shifted slightly downfield compared
Figure 2. ORTEP drawings of bridged cations 1a+ (left), 1b+ (middle),
and 1c+ (right) in OTfꢀ salts. The counteranion, crystallization solvent (if
any), and hydrogen atoms, except for the bridging one, are omitted for
clarity.
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Triarylmethane–triarylmethylium Complexes
FULL PAPER
mined by X-ray analysis. In the case of 1dCAHTREU[GN BF4] and 1e-
ACHTREUNG[BF4], the two Ar2C units again have different shapes: one
is methylium with Csp2 (sum of C-C-C bond angles=359.6–
359.88) and the other is methyl with a Csp3 carbon (337.4–
339.78, Figure 3, Figures S9–S10). In the crystal, there are no
signs of a 1,5-shift of the bridging hydrogen.
The geometrical data for [C···H···C]+ distances clearly
show that the bridging hydrogen is localized on one of the
C9 carbons as in form A. The ratios of the C···H distances
(d1/d2) are in the range of 1.8–2.6, which is similar to the 3c–
ꢀ
4e-type bridged cation (1.8) with a C H localized geome-
try.[2] Thus, not only in solution, but also in the crystal, the
Figure 4. HOMO (left) and LUMO (right) of 1a+ calculated at the
B3LYP/6-31G* level.
preferred geometry of the bridged cations 1+ is the C H lo-
ꢀ
calized structure (form A).
Redox and spectral properties:
Voltammetric analyses of acri-
dan–acridinium complexes 1a–
c+ show that they exhibit mod-
erate electrochemical ampho-
tericity
(Esum =EoxꢀEred
ꢁ1.4 V, Table 2). The close
proximity of the donor–accept-
or units at the peri positions
induces intramolecular CT in-
teraction between them. Weak
but significant absorptions in
+
+
ꢀ
Figure 3. ORTEP drawings of bridged cations 1d1 (left), 1d2 (middle), and 1e+ (right) in BF4 salts. The
counteranion, crystallization solvent (if any), and hydrogen atoms, except for the bridging one, are omitted for
clarity.
Further inspection of the geometrical data in Table 1
Table 2. Redox potentials of 1a–c+ measured in MeCN[a]
.
shows that the C···C separation (D) correlates with the
Compound
Ered [V]
Eox [V]
energy barrier of the hydride shift (DG°) in solution. Thus,
1a+
1b+
1c+
ꢀ0.49
ꢀ0.55
ꢀ0.48
+0.90
+0.81
+0.85
among the acridine-based cations 1a–c+, larger values of D
and DG° are found for the acenaphthene and acenaphthy-
lene derivatives 1b+ and 1c+ with the bridge at the opposite
peri-position. The effects are more evident in 1c+, which
has a shorter etheno bridge. Among the naphthalene-1,8-
diyl derivatives, the 1,5-hydride shift is much more facile in
1a+ than in 1d+ and 1e+ because 1d+ and 1e+ have larger
D values owing to the propeller-shaped Ar2C+ units.
[a] E/V versus SCE, 0.1m Et4NClO4, Pt electrode, scan rate 100 mVsꢀ1
.
the long-wavelength region up to 750 nm (logeꢁ3, Figure 5,
Figure S11) are assigned to the CT absorption bands of 1a–
c+, and the optically determined HOMO–LUMO gaps
Theoretical calculations for 1a–e+ (B3LYP/6-31G*) nicely
reproduced the observed solid-state structures with two dif-
ferently shaped diarylmethane units (Table 1). We found no
ꢀ
energy-minimized structure for the C H delocalized form B.
Thus, the preference for form A is not the result of crystal-
packing forces or solvation effects, but rather more as a
result of the intrinsic nature of cations 1+. In accordance
with such an unsymmetric geometry, the coefficients in the
LUMO are mainly localized on the acridinium–diarylmethy-
lium unit, whereas those in the HOMO are localized on the
acridanyl–diarylmethyl unit (Figure 4, Figures S1–S5). A
considerable portion of the coefficient is located on the
bridging hydrogen. Furthermore, the unsymmetric geometry
of bridged cations enables a p-type charge-transfer (CT) in-
teraction from the diarylmethyl to the diarylmethylium
units, as described in the next section. In-phase interaction
ꢀ
of the C H group with the cationic moiety suggests that CT
also acts through the contact of [C···H···C]+.
Figure 5. UV/Vis spectra of 1a (c), 1b (a), and 1c (d) in MeCN.
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7919

T. Suzuki et al.
(1.65 eV in MeCN) correspond well to those obtained by
electrochemistry (ꢁ1.4 V in MeCN) and by calculation
(1.44 eV for 1a+, 1.36 eV for 1b+, and 1.33 eV for 1c+, re-
spectively).
largely depend on the torsion angle between the naphtha-
lene core and the Ph2C+ unit, and the naphthalene unit may
act as a stronger donating chromophore than Ph2CH when
1e+ adopts the metastable twisted geometry. The longer-
wavelength absorption in 1e+ than in 1d+ can be explained
by assuming the coexistence of the metastable form in solu-
tion.
One-electron reduction of bridged cations 1a–c+ is a re-
versible process in which the electron-deficient acridinium
unit accepts the extra electron (Scheme 5). The resulting
Reactivity: A dianisylmethane–dianisylmethylium bridging
species with a naphthalene-1,8-diyl skeleton (1d+) was first
postulated as a transient intermediate for the acid-promoted
ꢀ
cleavage of an elongated C C bond in 1,1,2,2-tetraanisylace-
naphthene 2d to dication 3d2+ (Scheme 6a). Reduction of
Scheme 5. Electrochemical processes of bridged cations 1+.
C
radicals 1a–c are stable under the voltammetric conditions
employed. In contrast, irreversible oxidation of the acridan
ꢀ
unit induces C H fission, as in the case of many triarylme-
thane derivatives. In fact, the return peaks were observed
after irreversible oxidation of 1a–c+, whose potentials corre-
spond to those of the reduction waves of dications
[15]
3a–c2+
.
Slightly higher values of Eox (+0.81–0.90 V) com-
pared to those of the corresponding arylacridans without an
acridinium unit (ꢁ+0.78 V (irreversible) for 5a–c) might be
related to CT interaction through the hydrogen bridge.
In the case of cation 1d+ with four anisyl groups, an intra-
molecular CT band is not so evident in MeCN owing to the
very strong local absorption of a dianisylmethylium chromo-
phore (lmax =500 nm, loge 5.47 for An2C+Ph).[7] The absorp-
tion tail at ꢁ700 nm is attributed to CT from An2CH to the
An2C+ units. The observed shoulder at ꢁ590 nm in CH2Cl2
might be attributed to CT in 1d+ (Figure 6, Figure S12).The
CT band is clearly seen for 1e+ (lmax =594 nm in MeCN)
owing to the higher-energy absorption for a Ph2C+ unit (Fig-
ure S13), which is red-shifted to 609 nm in CH2Cl2. Such sol-
vent effects indicate that the ground state of 1+ is more
polar than the excited state. The orbital coefficients in the
HOMO of 1e+ without electron-donating heteroatoms
Scheme 6. a) Previously proposed intermediacy of bridged cation 1d+
during interconversion of 2d and 3d2+ (ref. [12]); b) Reactivities of iso-
lated salt of 1d+ (this study); c) Acid-assisted oxidation of 2a and 2b
and 1a and 1b+ (this study).
3d2+ with LiBHEt3 was also assumed to form 1d+, which
might be further converted to 2d. The proposed conversions
involve acid-promoted hydride abstraction and hydride-pro-
moted deprotonation steps for the bridged cation 1d+,
which are peculiar types of reactions. Successful isolation of
the species in question (1d+), as well as its analogues now
enables us to experimentally examine whether bridged cat-
ions 1+ exhibit such exotic reactivities as previously pro-
posed by Gabbaï and Wang.[12]
Although 2d was shown to convert into dication 3d2+
upon treatment with HBF4, the bridged cation 1d+ is stable
under similar conditions. In fact, treatment with HBF4/tri-
fluoroacetic anhydride is used to generate 1d+ from precur-
sor 8d. Treatment of bridged cation 1d+ with NaBH4 gave
labile hydride adduct 9d in a high yield (Scheme 7), whereas
Figure 6. UV/Vis spectra of 1d+ (a) and 1e+ (c) in MeCN.
7920
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 7915 –7925

Triarylmethane–triarylmethylium Complexes
FULL PAPER
1d+ >1e+. At the same time, the hydride-accepting proper-
ties of the diarylmethylium unit decrease in the same order.
The difference in delocalizability between symmetric
[Si···H···Si]+[10a] and unsymmetric [C···H···C]+ can be ac-
counted for mainly by the difference in atomic radii.
Changes in electronegativity and the ease of hyperconjuga-
tion may also play a role. However, the former may not be
important owing to counterbalancing effects, as discussed
+
for a changing pKR in the [C···H···C]+ unit. This research
Scheme 7. Hydride reduction of bridged cations 1b–d+ to adducts 9b–d.
shows that studies on isolable triarylmethane–triarylmethyli-
um complexes should provide deeper insight into 3c bonds
between carbon and hydrogen, thanks to the finely tunable
geometry, the details of which can be determined precisely
by X-ray analyses. We are currently studying intramolecular
LiBHEt3 did not work as well and gave only intractable ma-
terial. This is also in sharp contrast to the reported reactivity
[12]
of 3d2+
.
Thus, it is highly questionable as to whether 1d+
ꢀ
is involved in the reactions in Scheme 6a. Hydride adducts
9b and 9c were also obtained by treating 1b+ and 1c+ with
NaBH4.
C H bridged carbocations with much smaller C···H separa-
tion (d1, d2) by the use of an arylene spacer other than a
naphthalene-1,8-diyl-type skeleton.
We independently observed acid-promoted fission of ex-
ꢀ
tremely long C C bonds in bis(spiroacridan)-type acenaph-
thenes 2a and 2b, and higher reactivities were observed for
2b with stronger electron-donating properties. Even a weak
Brønsted acid, such as acetic acid, worked effectively to
transform 2b into the corresponding dication 3b2+
(Scheme 6c).[15] When the cleavage reactions of 2a and 2b
Experimental Section
General: 1H and 13C NMR spectra were recorded at 300, 400, or
500 MHz and 75, 100, or 125 MHz, respectively, at 238C unless indicated
otherwise. 2H NMR spectra were recorded at 77 MHz. 13C–1H coupling
constants were measured by an HSQC method. IR spectra were recorded
in KBr disks. Mass spectra were recorded in the EI mode or the FAB
mode. Column chromatography was performed on silica gel of particle
size 40–63 mm and aluminum oxide. UV/Vis spectra were measured in
spectrograde solvents. 1,8-Dibromonaphthalene,[17] 5,6-dibromoacenaph-
thene,[19] 5,6-dibromoacenaphthylene,[20] 8-dianisylmethyl-1-naphthoic
acid[21] and (8-diphenylmethyl-1-naphthyl)diphenylmethanol[22,23] were
prepared following known procedures. Other reagents and solvents were
obtained from commercial sources and purified prior to use. Preparation
1
were followed over time by H NMR spectroscopy, no reso-
nances assignable to bridged cations 1a+ and 1b+ were ob-
served. Another set of experiments indicated that the trans-
formation of 1a+ and 1b+ into dications 3a2+ and 3b2+ ac-
tually occurred, but the reactions were much slower than for
2a and 2b under similar conditions. Furthermore, the con-
version of 2a and 2b into 3a2+ and 3b2+, respectively, was
prevented under deaerated conditions. We concluded that
and X-ray analyses of 1a
liminary communication.[9a]
Preparation of 1c[OTf]: Methyl triflate (57 mL, 500 mmol) was added to a
ACHRTUNEG[OTf] and 1bACHTRE[UNG OTf] salts were reported as a pre-
ꢀ
the acid-promoted C C bond fission of 1,1,2,2-tetraarylace-
naphthenes 2 to the dications 32+ proceeds by acid-assisted
oxidation in which molecular oxygen acts as an actual oxi-
dant. This is also the case for the conversion of bridged cat-
ions 1+ to 32+ under aerated acidic conditions.
AHCTREUNG
solution of 9-[6-(10-methylacridan-9-yl)acenaphthylene-5-yl]acridine (5c,
26 mg, 50 mmol) in dry benzene (10 mL). After stirring for 40 min at
238C under argon, the resulting mixture was filtered and washed with di-
ethyl ether to give 1cACHTRE[UNG OTf] (23 mg, 67%) as a dark green solid. M.p.
1
215–2168C; H NMR (CD2Cl2): d=7.91 (brdd, J=7.0 Hz, 2H), 7.68–7.43
(br m, 10H), 7.30 (s, 2H), 7.11–6.92 (br s, 8H) 4.07–3.90 (br s, 7H); IR
(KBr): n˜ =3085, 3032, 2893, 1608, 1588, 1579, 1550, 1479, 1461, 1443,
1386, 1372, 1341, 1272, 1256, 1224, 1193, 1165, 1029, 866, 848, 752, 709,
691, 637, 573, 518 cmꢀ1; UV/Vis (CH3CN): lmax (e)=231 (55600), 263
(69900), 326 (16400), 342 (13900), 358 (12600), 430 nm (5800 mꢀ1 cmꢀ1);
LR-MS (FAB): m/z (%): 538 (34), 537 ([M]+, 65), 194 (35), 154 (bp), 138
(33), 137 (58), 136 (81); HRMS (FAB): m/z: found: 537.2355; calcd for
C40H29N2: 537.2330; elemental analysis calcd (%) for C41H29F3N2O3S: C
71.71, H 4.26, N 4.08; found C 72.08, H 4.54, N 3.52.
Conclusion
The present results demonstrate that intramolecular triaryl-
methane–triarylmethylium complexes 1a–e+ with a naph-
ꢀ
thalene-1,8-diyl-type skeleton can be best described as C H
bridged cations with a localized geometry (form A) that ex-
hibit a facile 1,5-hydride shift and a significant degree of CT
interaction. As shown by the much larger DG° values for a
hydride shift in 1b+ and 1c+ than in 1a+, small differences
in the geometry of the [C···H···C]+ unit (d1, d2, D, and q)
Other hydrogen-bridged cations 1a
a similar manner from 5a and 5b, respectively.
1a
[OTf]: Yield: 78%, dark green solid; m.p. 193–1958C; 1H NMR
ACHRTUNEG[OTf] and 1bACHRTE[UGN OTf] were prepared in
AHCTREUNG
([D6]acetone, ꢀ308C): d=8.46 (d, J=8.1 Hz, 2H), 7.87 (t, J=7.5 Hz,
2H), 7.72–7.53 (m, 10H), 7.08 (t, J=7.5 Hz, 4H), 6.98 (d, J=8.1 Hz,
4H), 4.11 (s, 1H), 4.06 (s, 6H); IR (KBr): n˜ =3107, 3034, 2919, 1609,
1589, 1579, 1549, 1479, 1461, 1342, 1275, 1262, 1224, 1193, 1160, 1030,
774, 753, 713, 691, 655, 637, 629, 517 cmꢀ1; UV/Vis (CH3CN): lmax (e)=
221 (71900), 262 (63100), 289 (15000), 344 (7200), 363 (12500), 434 nm
(4800 mꢀ1 cmꢀ1); LR-MS (FAB): m/z (%): 515 (22), 514 (44), 513 ([M]+,
bp), 194 (51); HRMS (FAB): m/z: found: 513.2324; calcd for C38H29N2:
513.2325; elemental analysis calcd (%) for C39H29F3N2O3S+0.33C6H6: C
71.50, H 4.54, N 4.07; found: C 71.24, H 4.79, N 3.92.
drastically change the behavior of the bridged cations
+
whereas the electronic nature of the cationic unit (pKR
)
has little, if any, effect. The latter point was evident when
we compared DG° values for 1a+, 1d+, and 1e+. This can
be explained by considering two counterbalancing electronic
factors that increase and decrease the delocalizability of the
bridging hydrogen. One is an increase in the hydride-donat-
ing properties of a diarylmethane unit in the order 1a+ >
Chem. Eur. J. 2007, 13, 7915 –7925
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7921

T. Suzuki et al.
1b
A
mental analysis calcd (%) for C40H35O4BF4+0.5H2O: C 71.12, H 5.37;
([D6]acetone, ꢀ108C): d=7.81–7.57 (brs, 8H), 7.64 (d, J=7.0 Hz, 2H),
7.50 (d, J=7.0 Hz, 2H), 7.18–6.94 (brs, 8H), 4.10 (brs, 6H), 4.00 (s, 1H),
3.65 (s, 4H); H NMR ([D6]acetone, ꢀ858C): d=8.98 (d, J=9.4 Hz, 2H),
found C 71.07, H 5.30.
Preparation of 1eACHTRE[UNG BF4]: Aqueous HBF4 (40%, 100 mL, 640 mmol) was
1
added to a solution of (8-diphenylmethyl-1-naphthyl)diphenylmethanol[23]
(30 mg, 62.9 mmol) in dry CH2Cl2/trifluoroacetic anhydride (3 mL/
500 mL). After stirring for 10 min at 238C, the mixture was diluted with
dry diethyl ether and the resulting precipitates were filtered and washed
8.55 (brdd, J=9.4, 7.3 Hz, 2H), 8.15(d, J=8.6 Hz, 2H), 7.99 (brdd, J=
8.6, 7.3 Hz, 2H), 7.78 (d, J=7.2 Hz, 1H), 7.68 (d, J=7.2 Hz, 1H), 7.53 (d,
J=7.3 Hz, 1H), 7.45 (d, J=7.3 Hz, 1H), 7.03 (brdd, J=8.3, 7.3 Hz, 2H),
6.82 (d, J=8.3 Hz, 2H), 6.50 (t, J=7.3 Hz, 2H), 5.96 (d, J=7.3 Hz, 2H),
5.16 (s, 3H), 4.19 (s, 1H), 3.66 (d, J=8.3 Hz, 4H), 3.25 (s, 3H); IR
(KBr): n˜ =3111, 3070, 3037, 2921, 2888, 1607, 1590, 1577, 1547, 1462,
1385, 1343, 1277, 1262, 1224, 1187, 1155, 1045, 1032, 866, 752, 638, 574,
517 cmꢀ1; UV/Vis (CH3CN): lmax (e)=210 (72300), 232 (79700), 262
(84300), 304 (19100), 361 (14100), 426 nm (5500 mꢀ1 cmꢀ1); LR-MS
(FAB): m/z (%): 540 (45), 539 ([M]+, bp), 194 (51); HRMS (FAB): m/z:
found: 539.2484; calcd for C40H31N2: 539.2482.; elemental analysis calcd
(%) for C39H29F3N2O3S+0.50H2O C 70.57, H 4.62, N 4.01; found C 70.69,
H 4.61, N 4.09.
with diethyl ether to give 1eACHTREU[NG BF4] (12.7 mg, 37%) as a dark green solid.
M.p. 198–1998C; 1H NMR (CD2Cl2): d=8.42 (dd, J=8.1, 1.4 Hz, 2H),
7.71 (dd, J=8.1, 7.5 Hz, 2H), 7.65 (t, J=7.9 Hz, 4H), 7.37 (t, J=7.9 Hz,
8H), 7.31 (dd, J=7.5, 1.4 Hz, 2H), 6.82 (d, J=7.9 Hz, 8H), 5.30 (s, 1H);
IR (KBr): n˜ =3068, 3022, 2847, 1578, 1552, 1497, 1480, 1451, 1443, 1425,
1389, 1351, 1322, 1281, 1238, 1210, 1186, 1088, 1051, 994, 791, 768, 754,
736, 710, 698, 671, 552 cmꢀ1; UV/Vis (CH3CN): lmax (e)=212 (55200, sh),
234 (28700, sh), 337 (6800), 400 (16900), 587 nm (9600 mꢀ1 cmꢀ1); LR-MS
(FAB): m/z (%):460 (43), 439 ([M]+, bp), 458 (13), 291 (12), 289 (16),
215 (14), 167 (43), 165 (16), 154 (37), 137 (19), 136 (31); HRMS (FAB):
m/z: found: 459.2106; calcd for C36H27: 459.2113; elemental analysis calcd
(%) for C36H27BF4+0.5H2O: C 77.85, H 5.08; found C 77.73, H 5.07.
Preparation of [D1]1cACHTREUNG[OTf]: Methyl triflate (130 mL, 1.1 mmol) was
added to a solution of 9-[6-(9-deuterio-10-methylacridan-9-yl)acenaph-
thylene-5-yl]acridine ([D1]5c, 60.0 mg, 115 mmol) in dry benzene (20 mL).
After stirring for 20 min at 238C under argon, the resulting mixture was
Preparation of 4c: CuO (600 mg, 7.54 mmol) and [Pd
995 mmol) were added to solution of 5,6-dibromoacenaphthylene
ACHTRE(UGN PPh3)4] (1.15 g,
a
(1.02 g, 3.30 mmol) in dry DMF (100 mL). After bubbling with argon for
30 min, the mixture was heated at 1408C under argon. After 5 min, a so-
lution of 9-trimethylstannylacridine (13, 4.52 g, 13.2 mmol) in dry DMF
(20 mL) was added at this temperature. After 21 h, 5% aqueous ammoni-
um hydroxide (100 mL) and hexane (200 mL) were added to the reaction
mixture. The resulting precipitates were filtered. The filtered solid was
extracted with CHCl3, and the extract was washed with brine and then
dried over Na2SO4. The black solid obtained by evaporation of the sol-
vent was purified by chromatography (SiO2, CHCl3/Et3N 100:1) to give
filtered and washed with diethyl ether to give [D1]1cACHTRE[UGN OTf] as a dark
green solid. M.p. 223–2258C; 1H NMR (CD2Cl2): d=7.91 (brdd, J=
7.0 Hz, 2H), 7.63–7.40 (br m, 10H), 7.30 (s, 2H), 7.09–6.89 (br s, 8H)
4.08–3.86 (br s, 6H); IR (KBr): n˜ =3085, 3032, 2970, 2926, 2881, 2822,
1637, 1624, 1608, 1579, 1549, 1462, 1386, 1376, 1339, 1272, 1240, 1224,
1193, 1165, 1151, 1029, 869, 849, 752, 710, 691, 685, 664, 637, 602, 573,
539, 518 cmꢀ1; LR-MS (FAB): m/z (%):539 (30), 538 ([M]+, 59), 154
(bp), 138 (33), 137 (59), 136 (80), 107 (31); HRMS (FAB): m/z: found:
538.2377; calcd for C40H28DN2: 538.2369.
1
4c (674 mg, 40%) as a yellow solid. M.p. 255–2588C (decomp); H NMR
Other deuterium-bridged cations [D1]1a
pared in a similar manner from [D1]5a and [D1]5b, respectively.
[D1]1a[OTf]: Yield: 68%, dark green solid; m.p. 193–1948C (decomp);
ACHRTEU[NG OTf] and [D1]1bACHTRE[UGN OTf] were pre-
(CDCl3): d=7.91 (dd, J=6.9, 1.1 Hz, 2H), 7.71 (dd, J=8.6, 0.6 Hz, 4H),
7.38–7.33 (m, 8H), 6.96 (dd, J=8.6, 0.6 Hz, 4H), 6.70 (ddd, J=8.6, 6.9,
1.1 Hz, 4H); 13C NMR (CDCl3): d=146.70, 144.87, 140.88, 134.70, 131.86,
130.08, 129.34, 129.31, 129.07, 128.87, 126.15, 124.85, 124.74, 124.20; IR
(KBr): n˜ =3070, 1556, 1540, 1515, 1460, 1436, 1408, 1154, 1011, 869, 752,
688, 603 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=329 (15400), 348 (17400), 360
(16700), 390 nm (7400 mꢀ1 cmꢀ1, sh); fluorescence (CH2Cl2, lex 360 nm):
lmax =530 nm; LR-MS (EI) m/z (%): 507 (42), 506 ([M]+, bp), 253 (21),
252 (14); HRMS (EI): m/z: found: 506.1789; calcd for C38H22N2:
ACHTREUNG
1H NMR ([D6]acetone): d=8.46 (d, J=8.3 Hz, 2H), 7.89 (brt, J=7.5 Hz,
2H), 7.70–7.50 (m, 10H), 7.08 (brt, J=7.0 Hz, 4H), 7.00 (d, J=8.1 Hz,
4H), 4.07 (s, 6H); 2D NMR ([D6]acetone, ꢀ308C): d=4.10 (brs); IR
(KBr): n˜ =3069, 3034, 1609, 1589, 1579, 1549, 1461, 1385, 1341, 1276,
1262, 1224, 1194, 1162, 1030, 753, 713, 691, 654, 637, 626, 602, 573,
517 cmꢀ1; LR-MS (FAB): m/z (%): 517 (32), 516 (26), 515 (85), 514
([M]+, bp), 513 (29), 195 (48), 136 (27); HRMS (FAB): m/z: found:
514.2388; calcd for C38H28DN2: 514.2392.
506.1783; elemental analysis calcd (%) for C38H22N2+0.25CHCl3:
C
85.64, H 4.18, N5.22; found C 85.20, H 4.32, N 5.10.
[D1]1bACHTREUNG[OTf]: Yield: 63%, dark green solid; m.p. 265–2678C (decomp);
Other diacridines 4a and 4b were prepared in a similar manner from 1,8-
1H NMR ([D6]acetone, ꢀ858C): d=8.98 (d, J=9.4 Hz, 2H), 8.55 (t, J=
8.0 Hz, 2H), 8.17 (d, J=8.6 Hz, 2H), 7.99 (t, J=8.0, 2H), 7.78 (d, J=
7.2 Hz, 1H), 7.68 (d, J=7.2 Hz, 1H), 7.53 (d, J=7.3 Hz, 1H), 7.45 (d, J=
7.3 Hz, 1H), 7.03 (t, J=7.7 Hz, 2H), 6.82 (d, J=8.3 Hz, 2H), 6.50 (t, J=
7.3 Hz, 2H), 5.96 (d, J=7.2 Hz, 2H), 5.16 (s, 3H), 3.67 (brs, 4H), 3.25 (s,
3H); 2D NMR ([D6]acetone, ꢀ108C): d=3.99 (brs); IR (KBr): n˜ =3113,
3070, 3037, 2932, 2883, 1607, 1591, 1577, 1547, 1464, 1344, 1279, 1262,
1224, 1189, 1157, 1029, 874, 751, 636, 516 cmꢀ1; LR-MS (FAB): m/z (%):
541 (45), 514 ([M]+, bp), 195 (47); HRMS (FAB): m/z: found: 540.2568;
calcd for C40H30DN2: 540.2549.
dibromonaphthalene and 5,6-dibromoacenaphthene, respectively.
4a: Yield: 23%, yellow solid; m.p. 245–2478C (decomp); 1H NMR
(CD2Cl2): d=8.24 (dd, J=8.4, 1.4 Hz, 2H), 7.67 (dd, J=8.4, 6.9 Hz, 2H),
7.52 (dd, 4H, J=8.4, 1.2 Hz), 7.29 (ddd, J=8.4, 6.6, 1.4 Hz, 4H), 7.19
(dd, J=6.9, 1.4 Hz, 2H), 6.72 (dd, J=8.4, 1.4 Hz, 4H), 6.61 (ddd, J=8.4,
6.6, 1.2 Hz, 4H). The 13C NMR could not be measured owing to the low
solubility of 4a. IR (KBr): n˜ =3045, 1558, 1540, 1517, 1436, 1145, 1014,
866, 827, 785, 752, 601 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=347 (12600), 360
(13400), 390 nm (6000 mꢀ1 cmꢀ1, sh); fluorescence (CH2Cl2, lex 360 nm)
lmax =536 nm; LR-MS (EI): m/z (%): 484 ([M]++2H, 57), 483(23),
482([M]+, bp), 241(87), 240 (65), 207 (66), 196 (60), 171 (63), 166 (64),
138 (63), 122 (61), 121 (63), 93 (64), 80 (63), 52 (58); HRMS (EI): m/z:
found: 482.1778; calcd for C36H22N2: 482.1783; elemental analysis calcd
(%) for C36H22N2+0.50CHCl3: C 80.84, H 4.18, N 5.17; found C 80.88, H
4.48, N 5.20.
Preparation of 1dACHTREUNG[BF4]: Aqueous HBF4 (40%, 265 mL, 1.74 mmol) was
added to a solution of carbinol 8d (101 mg, 174 mmol) in dry CH2Cl2/tri-
fluoroacetic anhydride (5 mL/500 mL). After stirring for 20 min, the mix-
ture was diluted with diethyl ether, and the resulting precipitates were fil-
tered and washed with diethyl ether to give 1dCAHTRE[UGN BF4] (55 mg, 47%) as a
dark red solid. M.p. 195–1968C; 1H NMR (CD2Cl2): d=8.19 (d, J=
7.7 Hz, 2H), 7.61 (dd, J=7.7, 7.3 Hz, 2H), 7.26 (dd, J=7.3, 1.1 Hz, 2H),
4b: Yield: 48%, yellow solid; m.p. 270–2728C (decomp); 1H NMR
(CDCl3): d=7.69 (d, J=8.4 Hz, 4H), 7.55 (d, J=7.0 Hz, 2H), 7.34 (ddd,
J=8.4, 6.4, 1.1 Hz, 4H), 7.25 (d, J=7.0 Hz, 2H), 6.94 (dd, J=8.6, 1.1 Hz,
4H), 6.68 (ddd, J=8.6, 6.4, 1.1 Hz, 4H), 3.74 (s, 4H); 13C NMR (CDCl3):
d=147.55, 146.71, 145.89, 140.28, 131.92, 131.76, 128.93, 128.79, 126.25,
124.94, 124.57, 119.50, 30.51; IR (KBr): n˜ =3042, 2916, 1629, 1600, 1556,
6.89 (d, J=8.8 Hz, 8H), 6.81 (d, J=8.8 Hz, 8H), 5.47 (s, 1H), 3.90ACHTRE(UNG s,
12H); IR (KBr): n˜ =2935, 2836, 1605, 1578, 1508, 1443, 1365, 1318, 1279,
1252, 1161, 1123, 1092, 1056, 1031, 998, 912, 849, 832, 814, 804, 791, 770,
623, 595, 584, 563, 540, 521 cmꢀ1
; UV/Vis (CH3CN): lmax (e)=226
(58400), 266 (12700), 282 (11300), 339 (7900), 490 nm (40700 mꢀ1 cmꢀ1);
LR-MS (FAB): m/z (%):580 (44), 579 ([M]+, bp), 307 (15), 289(11), 227
(13), 155 (14), 154 (60), 138 (16), 137 (30), 136 (45), 107 (12), 77 (11);
HRMS (FAB): m/z: found: 579.2548; calcd for C40H35O4: 579.2535; ele-
1515, 1460, 1435, 1408, 1329, 1151, 1013, 868, 745, 647, 626, 603 cmꢀ1
UV/Vis (CH2Cl2): lmax (e)=349 (12200), 360 (12900), 390 nm
(6200 mꢀ1 cmꢀ1, sh); fluorescence (CH2Cl2, lex 360 nm) lmax =525 nm; LR-
MS (EI): m/z (%): 509 (42), 508 ([M]+, bp), 254 (19); HRMS (EI): m/z:
;
7922
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 7915 –7925

Triarylmethane–triarylmethylium Complexes
FULL PAPER
found: 508.1940; calcd for C38H24N2: 508.1939; elemental analysis calcd
(%) for C38H24N2+0.33H2O: C 88.69, H 4.83, N 5.44; found C 88.42, H
4.75, N 5.41.
[D1]5a: Yield: 41%, yellow solid; m.p. 270–2718C (decomp); 1H NMR
(CDCl3): d=8.16 (dd, J=8.4, 1.2 Hz, 1H), 8.07 (d, J=8.8 Hz, 2H), 8.03
(dd, J=8.0, 1.5 Hz, 1H), 7.64 (dd, J=8.0, 7.2 Hz, 1H), 7.60–7.53 (m,
3H), 7.49 (dd, J=7.2, 1.5 Hz, 1H), 7.44 (d, J=8.6 Hz, 2H), 7.40 (dd, J=
6.6, 1.2 Hz, 1H), 7.14 (ddd, J=8.6, 6.6, 1.1 Hz, 2H), 6.86 (td, J=7.5
1.5 Hz, 2H), 6.48 (d, J=7.5 Hz, 2H), 6.40 (dt, J=7.5, 1.1 Hz, 2H), 6.10
(dd, J=7.5, 1.5 Hz, 2H), 3.04 (s, 3H); 13C NMR (CDCl3): d=148.91,
148.62, 141.78, 140.07, 135.22, 132.90, 132.56, 132.13, 131.30, 130.78,
129.92, 129.16, 128.66, 128.03, 127.19, 127.05, 126.36, 126.20, 125.24,
125.19, 124.44, 119.42, 111.05, 32.95; IR (KBr): n˜ =3056, 2958, 2926, 2872,
1625, 1605, 1589, 1556, 1539, 1514, 1459, 1439, 1343, 1301, 1261, 1209,
Preparation of 5c: A solution of methyl triflate in dry benzene (0.22m,
1.0 mL, 220 mmol) was added to a solution of 9,9’-(acenaphthylene-5,6-
diyl)diacridine (4c, 88.9 mg, 175 mmol) and 2,6-di-tert-butyl-4-methylpyri-
dine (35.8 mg, 175 mmol) in dry benzene (100 mL). The whole mixture
was stirred for 22.5 h at 238C under argon, and the resulting orange pre-
cipitates were filtered to give monomethylated acridinium OTfꢀ salt ac-
companied by a small amount of dimethylated dication salt 3c2+(OTfꢀ)2
ACHTREUNG
and pyridinium triflate. The mixture was used in the next reaction with-
out further purification. NaBH4 (110 mg, 2.9 mmol) was added to a sus-
pension of the above mixture containing monoacridinium OTfꢀ salt in
EtOH (30 mL). After stirring for 20 min at 238C, the solvent was evapo-
rated. The resulting yellow solid was suspended in water, and the mixture
was extracted with CH2Cl2. The organic layers were combined and then
washed with brine, dried over Na2SO4, and filtered. The yellow solid ob-
tained by evaporation of the solvent was purified by chromatography
(Al2O3, CH2Cl2/n-hexane 1:1) to give 5c (69 mg, 75%) as a yellow solid.
M.p. 220–2238C (decomp); 1H NMR (CDCl3): d=8.18 (d, J=8.1 Hz,
2H), 7.86 (d, J=7.0 Hz, 1H), 7.68 (d, J=7.0 Hz, 2H), 7.62 (d, J=8.1 Hz,
2H), 7.49 (d, J=7.0 Hz, 2H), 7.32–7.22 (m, 3H), 7.17 (s, 2H), 6.91 (t, J=
7.7 Hz, 2H), 6.59 (d, J=8.1 Hz, 2H), 6.40 (t, J=7.5 Hz, 2H), 6.05 (d, J=
7.5 Hz, 2H), 4.43 (s, 1H) 3.16 (s, 3H); 13C NMR (CDCl3): d=148.64,
141.50, 141.20, 138.86, 133.57, 133.29, 132.60, 132.19, 130.13, 129.48,
128.74, 128.69, 128.10, 127.46, 126.48, 126.02, 125.69, 125.59, 123.32,
119.51, 115.82, 111.63, 42.48, 32.97; IR (KBr): n˜ =3056, 3029, 2958, 2877,
2826, 1607, 1592, 1556, 1515, 1479, 1436, 1407, 1355, 1318, 1286, 1267,
1131, 865, 838, 760, 743, 674 cmꢀ1; LR-MS (EI) m/z (%):524 (19), 523
(45), 522 ([M]+, bp), 521 (26), 508 (20), 507 (47), 262 (12), 261 (28), 194
(28); HRMS (EI): m/z: found: 522.2094; calcd for C39H26N2: 522.2096; el-
emental analysis calcd (%) for C39H26N2+0.33EtOH: C 88.56, H 5.25, N
5.21; found C 88.50, H 5.60, N 5.25.
1200, 1160, 1144, 1129, 1045, 862, 783, 776, 746, 651, 638, 618, 601 cmꢀ1
;
LR-MS (EI): m/z (%): 500 (43), 499([M]+, bp), 498 (20), 484 (29), 250
(27), 195 (30); HRMS (EI): m/z: found: 499.2163; calcd for C37H25DN2:
499.2158.
[D1]5b: Yield: 77%, yellow solid; m.p. 233–2358C (decomp); 1H NMR
(CDCl3): d=8.14 (d, J=8.6 Hz, 2H), 7.67–7.58 (m, 4H), 7.47 (d, J=
6.9 Hz, 1H), 7.41 (d, J=7.2 Hz, 1H), 7.36 (d, J=7.2 Hz, 1H), 7.32 (d, J=
6.9 Hz, 1H), 7.24 (m, 2H), 6.88 (td, J=7.8, 1.5 Hz, 2H), 6.54 (d, J=
7.8 Hz, 2H), 6.40 (td, J=7.8, 0.6 Hz, 2H), 6.08 (dd, J=7.8, 1.5 Hz), 3.61–
3.52 (m, 4H), 3.12 (s, 3H); 13C NMR (CDCl3): d=148.82, 148.74, 148.06,
145.46, 141.64, 140.19, 137.87, 133.11, 132.50, 130.67, 129.97, 129.38,
128.06, 127.76, 127.51, 126.23, 125.86, 125.26, 120.84, 119.40, 118.46,
111.35, 32.94, 30.32, 30.07; IR (KBr): n˜ =3070, 3037, 2924, 2854, 1605,
1592, 1514, 1470, 1435, 1345, 1278, 1269, 1132, 874, 757, 751 cmꢀ1; LR-MS
(EI): m/z (%): 526 (50), 525 ([M]+, bp), 524 (28), 510 (28), 278 (39), 263
(36), 195 (28); HRMS (EI): m/z: found: 525.2318; calcd for C39H27DN2:
525.2314.
[D1]5c: Yield: 63%, yellow solid; m.p. 245–2488C (decomp); 1H NMR
(CDCl3): d=8.17 (dd, J=8.8 Hz, 2H), 7.81 (dd, J=7.0, 1.1 Hz, 1H), 7.66
(d, J=8.1 Hz, 2H), 7.61 (d, J=7.9 Hz, 2H), 7.47 (dd, J=7.0, 1.1 Hz, 2H),
7.30–7.20 (m, 3H), 7.13 (s, 2H), 6.88 (t, J=7.7 Hz, 2H), 6.56 (d, J=
8.1 Hz, 2H), 6.38 (t, J=7.5 Hz, 2H), 6.03 (d, J=7.7 Hz, 2H), 2.98 (s,
3H); 13C NMR (CDCl3): d=148.60, 147.75, 144.86, 141.47, 141.17, 138.83,
133.54, 132.48, 132.15, 130.09, 129.61, 129.47, 128.72, 128.66, 128.07,
127.90, 127.49, 127.44, 126.47, 126.00, 125.66, 125.58, 123.29, 119.49,
111.63, 32.92; IR (KBr): n˜ =3274, 3059, 2958, 2918, 2873, 1609, 1591,
1515, 1470, 1437, 1407, 1356, 1271, 1132, 865, 854, 760, 743, 674 cmꢀ1; LR-
MS (EI): m/z (%):525 (11), 524 (41), 523 ([M]+, bp), 522 (29), 509 (17),
508 (40) 262 (13), 262 (30), 195 (31), 149 (23); HRMS (EI): m/z: found:
523.2149; calcd for C39H25DN2: 523.2158.
Other acridan–acridine hybrids 5a and 5b were prepared in a similar
manner from 4a and 4b, respectively.
5a: Yield: 77%, yellow solid; m.p. 280–2858C (decomp); 1H NMR
(CDCl3): d=8.16 (dd, J=8.4, 1.2 Hz, 1H), 8.08 (d, J=8.8 Hz, 2H), 8.03
(dd, J=8.0, 1.5 Hz, 1H), 7.65 (dd, J=8.0, 7.2 Hz, 1H), 7.61–7.54 (m,
3H), 7.49 (dd, J=7.2, 1.5 Hz, 1H), 7.45 (dd, J=8.4, 0.6 Hz, 2H), 7.41
(dd, J=6.6, 1.2 Hz, 1H), 7.15 (ddd, J=8.4, 6.6, 1.2 Hz, 2H), 6.87 (td, J=
7.5, 1.2 Hz, 2H), 6.48 (dd, J=7.5, 1.2 Hz, 2H), 6.40 (dd, J=7.5, 1.2 Hz,
2H), 6.10 (dd, J=7.5, 1.2 Hz, 2H), 4.52 (s, 1H), 3.04 (s, 3H); 13C NMR
(CDCl3): d=148.95, 148.57, 141.74, 140.16, 135.19, 132.90, 132.60, 132.08,
131.32, 130.79, 129.96, 129.57, 129.10, 128.66, 128.08, 127.19, 127.06,
126.36, 126.19, 125.19, 124.43, 119.41, 111.04, 43.07, 32.96; IR (KBr): n˜ =
3059, 3037, 2960, 2926, 1589, 1503, 1477, 1456, 1359, 1322, 1273, 781,
744 cmꢀ1; LR-MS (EI): m/z (%): 500 (20), 499 (46), 498 ([M]+, bp), 497
(24), 496 (22), 484 (27), 483 (55), 249 (28), 194 (48); HRMS (EI): m/z:
found: 498.2096; calcd for C37H26N2: 498.2096; elemental analysis calcd
(%) for C37H26N2+0.25H2O: C 88.33, H 5.31, N 5.57; found C 88.40, H
5.55, N 5.35.
5b: Yield: 95%, yellow solid; m.p. 220–2238C (decomp); 1H NMR
(CDCl3): d=8.16 (dd, J=8.6, 1.2 Hz, 2H), 7.65–7.58 (m, 4H), 7.46 (d, J=
7.2 Hz, 1H), 7.40 (d, J=7.5 Hz, 1H), 7.36 (d, J=7.2 Hz, 1H), 7.32 (d, J=
7.5 Hz, 1H), 7.24 (dd, J=8.6, 7.2 Hz, 2H), 6.87 (tt, J=8.1, 0.6 Hz, 2H),
6.54 (d, J=8.1 Hz, 2H), 6.39 (t, J=7.5 Hz, 2H), 6.07 (d, J=7.5, 1.1 Hz,
2H), 4.35 (s, 1H), 3.60–3.48 (m, 4H), 3.10 (s, 3H); 13C NMR (CD2Cl2):
d=148.58 (br), 148.19, 145.58, 141.24, 139.97, 132.23, 132.69, 132.22,
129.77, 129.35 (br), 127.90, 127.70, 127.40, 127.28, 126.15, 125.61, 125.25,
120.47, 119.11, 118.31, 111.51, 41.80, 32.65, 30.05, 29.76; IR (KBr): n˜ =
1606, 1590, 1461, 1346, 1266, 1131, 866, 752 cmꢀ1; LR-MS (EI): m/z (%):
525 (64), 524 ([M]+, bp), 523 (49), 510 (52), 509 (69), 328 (53), 262 (40),
194 (51), 179 (50); HRMS (EI): m/z: found: 524.2257; calcd for C39H28N2:
524.2252; elemental analysis calcd (%) for C39H28N2+0.50H2O: C 86.32,
H 5.57, N5.16; found C 86.06, H 5.43, N 5.12.
Preparation of 8d:
A solution of 8-dianisylmethyl-1-naphthoic acid
(660 mg, 1.5 mmol)[21] in THF (50 mL) was treated with an excess
amount of a solution of CH2N2 in diethyl ether. The solution was evapo-
rated to afford ester 7d. A solution of anisyllithium in THF, which was
generated from anisyl iodide (1.26 g, 5.4 mmol) and n-butyl lithium
(1.59m in n-hexane, 3.4 mL, 5.4 mmol) at ꢀ788C, was added to a solution
of ester 7d (371 mg, 899 mmol) in dry diethyl ether (40 mL). The mixture
was allowed to warm to 238C and stirred for 18 h. The mixture was dilut-
ed with water and extracted with diethyl ether. The organic layer was
washed with brine, dried over MgSO4, and evaporated. The crude prod-
uct was purified by chromatography (Al2O3) to give carbinol 8d (397 mg,
1
76%) as a pale yellow solid. M.p. 114–1168C; H NMR (CDCl3): d=7.77
(dd, J=8.1, 1.4 Hz, 1H), 7.76 (dd, J=8.1, 1.4 Hz, 1H), 7.36 (d, J=7.5 Hz,
1H) 7.17 (d, J=8.1 Hz, 1H), 7.14 (d, J=7.5 Hz, 1H), 6.89 (dd, J=7.5,
1.4 Hz, 1H), 6.83 (s, 1H), 6.73 (d, J=8.8 Hz, 4H), 6.58 (d, J=8.8 Hz,
4H), 6.41 (d, J=8.1 Hz, 4H), 3.78 (s, 6H), 3.71 (s, 6H), 3.28 (s, 1H); IR
(KBr): n˜ =3493, 3062, 3037, 2998, 2951, 2906, 2834, 1727, 1607, 1582,
1509, 1463, 1442, 1301, 1250, 1177, 1111, 1036, 823, 779, 770, 587,
554 cmꢀ1; LR-MS (FD): m/z (%):595 ([M]+, 6), 580 (13), 579 (54), 578
(bp); elemental analysis calcd (%) for C40H37O5: C 80.51, H 6.08; found
C 80.54, H 6.28.
Reaction of the bridged cation with hydride—formation of 9b: NaBH4
(46 mg, 1.2 mmol) was added to
a solution of 1bACHRTE[UNG OTf] (7.7 mg,
11.2 mmol) in EtOH (10 mL). After stirring for 4 h at 238C, the solvent
was evaporated. The resulting yellow solid was suspended in water and
extracted with CH2Cl2. The organic layers were combined and then
washed with brine, dried over Na2SO4, and filtered. The yellow solid ob-
Deuterated compounds [D1]5a–c were prepared in a similar manner to
4a–c, respectively, by using NaBD4 instead of NaBH4.
Chem. Eur. J. 2007, 13, 7915 –7925
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7923

T. Suzuki et al.
tained by evaporation of the solvent was purified by chromatography
(Al2O3, CH2Cl2/n-hexane 1:1) to give 9b (6.0 mg, 99%) as a white solid.
M.p. 228–2308C (decomp); 1H NMR (CDCl3): d=7.43 (d, J=7.5 Hz,
2H), 7.36 (d, J=7.5 Hz, 2H), 6.90 (t, J=7.5 Hz, 2H), 6.58 (d, J=7.5 Hz,
2H), 6.47 (d, J=8.8 Hz, 2H), 6.42 (t, J=7.5 Hz, 2H), 6.36 (t, J=8.8 Hz,
paratus (MoKa radiation, l=0.71070 Š). Numerical absorption correction
was applied (m=3.71 cmꢀ1). The structure was solved by the direct
method (SIR97) and refined by the full-matrix least-squares method on
F2 with anisotropic temperature factors for non-hydrogen atoms. All of
the hydrogen atoms, except for the methine proton, were located at the
calculated positions and refined with riding. The methine proton was lo-
cated in the D map and refined with isotropic temperature factors. The
final R1 and wR2 values are 0.054 (I>2sI) and 0.128 (all data) for
7678 reflections and 522 parameters.
4H), 6.13 (d, J=7.5 Hz, 2H), 6.09 (d, J=7.5 Hz, 2H), 5.77
ACHTRE(UGN s, 1H), 5.44
(s, 1H), 3.55(s, 4H), 3.21
A
ACHTREUNG
147.71, 146.23, 142.77, 142.33, 140.12, 136.15, 134.56, 131.78, 131.74,
131.57, 130.00, 128.34, 127.14, 126.79, 126.48, 126.43, 125.31, 120.05,
119.42, 118.94, 110.84, 110.00, 51.16, 45.26, 33.28, 33.22, 30.27, 29.85; IR
(KBr): n˜ =3082, 3032, 2924, 2855, 2365, 1726, 1636, 1608, 1590, 1468,
1347, 1267, 1130, 1050, 868, 747 cmꢀ1; LR-MS (EI): m/z (%):542 (17), 541
(52), 540 ([M]+, bp), 526 (23), 525 (43), 347 (13), 346 (35), 270 (13), 194
(38); HRMS (EI): m/z: found: 540.2570; calcd for C40H32N2: 540.2565; el-
emental analysis calcd (%) for C40H32N2+CH2Cl2: C78.71, H 5.48, N
4.48; found C 78.42, H 5.84, N 4.50.
Crystal data for 1cCAHTRE[UNG OTf]·CHCl3: Formula C42H30Cl3F3N2O3S, Mw 806.12,
yellow plates, 0.70”0.20”0.02 mm3, triclinic P1, a=8.288(3) Š, b=
13.908(6) Š, c=16.579(7) Š, a=109.844(6)8, b=97.679(7)8, g=
¯
90.430(7)8, V=1778.5(12) Š3,
1
A
.
A
total of
7842 unique data (2qmax =558) were measured at T=93 K by a CCD ap-
paratus (MoKa radiation, l=0.71070 Š). Numerical absorption correction
was applied (m=3.781 cmꢀ1). The structure was solved by the direct
method (SIR97) and refined by the full-matrix least-squares method on
F2 with anisotropic temperature factors for non-hydrogen atoms. All of
the hydrogen atoms, except for the methine proton, were located at the
calculated positions and refined with riding. The methine proton was lo-
cated in the D map and refined with isotropic temperature factors. The
final R1 and wR2 values are 0.077 (I>2sI) and 0.252 (all data) for
7842 reflections and 520 parameters.
Other bis(diarylmethyl) derivatives 9c,d were formed upon treatment of
the salts of 1c,dACHTREUNG[OTf] with NaBH4 in a similar manner.
9c: Yield: 61%, yellow solid; m.p. 245–2478C (decomp); 1H NMR
(CDCl3): d=7.74 (d, J=6.8 Hz, 1H), 7.73 (d, J=7.2 Hz, 1H), 7.53 (d,
1H, J=6.8 Hz), 7.42 (d, J=7.2 Hz, 1H), 7.15 (d, J=1.0 Hz, 2H), 6.92 (t,
J=7.5 Hz, 2H), 6.58 (t, J=7.5 Hz, 2H), 6.50 (d, J=7.5 Hz), 6.43 (t, J=
7.5 Hz, 2H), 6.36 (t, J=7.5 Hz, 2H), 6.14 (d, J=7.5 Hz, 2H), 6.10 (d, J=
7.5 Hz, 2H), 5.82 (s, 1H), 5.52 (s, 1H), 3.21 (s, 3H), 3.20 (s,
3H);13C NMR (CDCl3): d=142.65, 141.15, 139.95, 138.78, 138.45, 135.57,
134.15, 129.73, 129.33, 128.36, 127.29, 126.75, 126.60, 125.54, 124.41,
124.24, 120.10, 119.53, 110.89, 110.15, 51.15, 45.58, 33.27; IR (KBr): n˜ =
3068, 3029, 2964, 2871, 2809, 1606, 1589, 1496, 1465, 1430, 1346, 1305,
1266, 1182, 1166, 1129, 1092, 1050, 864, 842, 743, 678, 656 cmꢀ1; LR-MS
(EI): m/z (%):540 (16), 539 (45), 538 ([M]+, bp), 525 (10), 524 (29), 523
(66), 522 (18), 521 (10), 507 (14), 344 (26), 269 (12), 195 (10), 194 (56),
179 (12); HRMS (EI): m/z: found: 538.2384; calcd for C40H30N2:
538.2409; elemental analysis calcd (%) for C40H30N2: C 89.19, H 5.61, N
5.20; found C 89.20, H 5.68, N 5.16.
9d: Yield: 90%, pale yellow solid; m.p. 196–1988C (decomp); 1H NMR
(C6D6): d=7.65 (d, J=6.8 Hz, 2H), 7.40 (dd, J=7.7, 6.8 Hz, 2H), 7.19 (d,
2H, J=7.7 Hz), 6.92 (d, J=8.8 Hz, 8H), 6.76 (s, 2H), 6.70 (d, J=8.8 Hz,
8H), 3.26 (s, 12H); IR (KBr): n˜ =3001, 2953, 2929, 2907, 2835, 1606,
1582, 1508, 1462, 1442, 1299, 1247, 1176, 1110, 1034, 857, 838, 821, 803,
781, 767, 584, 534 cmꢀ1; LR-MS (FD): m/z (%):581 (44), 580 ([M]+, bp);
HRMS (FD): m/z: found: 580.2632; calcd for C40H36O4: 580.2614; ele-
mental analysis calcd (%) for C40H36O4+H2O: C 80.24, H 6.40; found C
79.97, H 6.25.
Crystal data for 1d
0.20”0.10”0.05 mm3, monoclinic P21/c, a=16.434(4) Š, b=14.951(3) Š,
c=27.399(7) Š, b=102.634(6)8, V=6569(3) Š3, 1(Z=8)=1.348 gcmꢀ3. A
CATHERU[NG BF4]: Formula C40H35F4O4B, Mw 666.52, red blocks,
AHCTREUNG
total of 14911 unique data (2qmax =558) were measured at T=123 K by a
CCD apparatus (MoKa radiation, l=0.71070 Š). Numerical absorption
correction was applied (m=1.003 cmꢀ1). The structure was solved by the
direct method (SIR97) and refined by the full-matrix least-squares
method on F2 with anisotropic temperature factors for non-hydrogen
atoms. All of the hydrogen atoms, except for the methine protons, were
located at the calculated positions and refined with riding. The methine
protons were located in the D map and refined with isotropic tempera-
ture factors. The final R1 and wR2 values are 0.092 (I>2sI) and 0.249
(all data) for 14911 reflections and 959 parameters.
Crystal data for 1eACHTRE[UNG BF4]: Formula C36H27F4B, Mw 546.41, black blocks,
3
¯
0.40”0.25”0.20 mm , triclinic P1, a=10.227(4) Š, b=10.201(3) Š, c=
14.472(3) Š, a=71.61(3)8, b=68.91(2)8, g=85.82(3)8, V=1335.3(7) Š3,
(Z=2)=1.359 gcmꢀ3. A total of 5657 unique data (2qmax =54.28) were
1ACHTREUNG
measured at T=123 K by
a CCD apparatus (MoKa radiation, l=
0.71070 Š). Numerical absorption correction was applied (m=
0.963 cmꢀ1). The structure was solved by the direct method (SIR97) and
refined by the full-matrix least-squares method on F2 with anisotropic
temperature factors for non-hydrogen atoms. All of the hydrogen atoms,
except for the methine proton, were located at the calculated positions
and refined with riding. The methine proton was located in the D map
and refined with isotropic temperature factors. The final R1 and wR2
values are 0.068 (I>2sI) and 0.169 (all data) for 5657 reflections and
400 parameters.
X-ray analysis:CCDC 288334 (1a
[OTf]·CHCl3), CCDC 648371 (1c[OTf]·CHCl3), CCDC 648372 (1d
CCDC 648373 (1e[BF4]) contain the supplementary crystallographic data
ACHTREUNG
A
N
ACHTREUNG
ACHTREUNG
for this paper. These data can be obtained free of charge from the Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
Crystal data for 1aACHTREUNG[OTf]·acetone: Formula C43H35F3N2O4S, Mw 720.80,
Redox potential measurements: Redox potentials (Eox and Ered) were
measured by cyclic voltammetry in dry MeCN containing 0.1 moldmꢀ3
Et4NClO4 as a supporting electrolyte. Ferrocene undergoes one-electron
oxidation at +0.38 V under the same conditions. All of the values shown
in the text are shown in E/V versus SCE measured at the scan rate of
100 mVsꢀ1. A Pt disk and wire electrodes were used as the working and
counterelectrodes, respectively. The working electrode was polished by
using a water suspension of Al2O3 (0.05 mm) before use. The irreversible
3
¯
dark orange plates, 0.60”0.03”0.02 mm , triclinic P1, a=8.407(4) Š, b=
13.578(7) Š, c=15.815(8) Š, a=72.28(2)8, b=80.88(2)8, g=89.70(3)8,
ACHTREUNG
V=1695.9(14) Š3, 1(Z=2)=1.411 gcmꢀ3. A total of 6566 unique data
(2qmax =558) were measured at T=133 K by a CCD apparatus (MoKa ra-
diation, l=0.71070 Š). Numerical absorption correction was applied (m=
1.60 cmꢀ1). The structure was solved by the Patterson method and the
following expansion (DIRDIF99) and refined by the full-matrix least-
squares method on F2 with anisotropic temperature factors for non-hy-
drogen atoms. All of the hydrogen atoms, except for the methine proton,
were located at the calculated positions and refined with riding. The me-
thine proton was located in the D map and refined with isotropic temper-
ature factors. The final R1 and wR2 values are 0.081 (I>2sI) and 0.197
(all data) for 6555 reflections and 508 parameters.
halfwave potentials were estimated from the anodic peak potentials (Epa
)
as Eox =Epaꢀ0.03 or the cathodic peak potentials (Epc) as Ered =Epc +0.03.
Computational method: The DFT calculations were performed with the
Gaussian98 program package.[27] The geometries of the compounds were
optimized by the B3LYP method[28] in combination with a 6-31G* basis
set without performing frequency calculations.
Crystal data for 1bACHTREUNG[OTf]·CHCl3: Formula C43H32Cl3F3N2O3S, Mw 808.14,
3
¯
dark brown plates, 0.70”0.20”0.02 mm , triclinic P1, a=8.208(2) Š, b=
14.152(4) Š, c=16.716(5) Š, a=109.750(5)8, b=97.638(5)8, g=
90.402(3)8, V=1808.4(9) Š3,
1
(Z=2)=1.484 gcmꢀ3
.
A
total of
7678 unique data (2qmax =558) were measured at T=103 K by a CCD ap-
7924
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 7915 –7925

Triarylmethane–triarylmethylium Complexes
FULL PAPER
+
structure may be directly related to the inequivalency of the pKR
Acknowledgements
of units of Ar2C+ and Ar’2C+, see ref. [9b].
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This work was supported by a Grant-in-Aid for Scientific Research from
the Ministry of Education, Science, and Culture (No. 17655012) and from
JSPS (No. 18–4425). T.T. gratefully acknowledges a JSPS Research Fel-
lowship for Young Scientist. We thank Prof. Tamotsu Inabe (Department
of Chemistry, Faculty of Science, Hokkaido University) for the use of fa-
cilities to analyze the X-ray structures. Elemental analyses were per-
formed at the Center for Instrumental Analysis of Hokkaido University.
Mass spectra were measured by Mr. Kenji Watanabe and Dr. Eri Fukushi
at the GC-MS&NMR Laboratory (Faculty of Agriculture, Hokkaido
University).
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+
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6
Ar’) revealed that they
Received: May 26, 2007
Published online: August 27, 2007
ꢀ
adopt form A geometry, yet the preference for the C H-localized
Chem. Eur. J. 2007, 13, 7915 –7925
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7925