First introduction of an azulenyl group into the bismuth and antimony center. Synthesis and structure of azulenylbismuthanes and their difluorides

Article abstract of DOI:10.1021/om040053f

A nonalternant organyl ligand derived from azulene, a 1,3-dichloro-2- azulenyl group, is introduced for the first time into the bismuth and antimony center. Conversion of the azulenylbismuthanes into the pentacoordinated difluorides by xenon difluoride promotes the π-polarization of the azulene nucleus, which is detected as a color change in solution as well as changes in the chemical shifts of the ¹³C NMR spectra. A similar tendency is observed in the antimony congeners. The X-ray crystallographic study of (1,3-dichloro-2-azulenyl)-diphenylbismuth difluoride (20b) reveals that intermolecular π-π stacking takes place between the azulenyl groups through the interaction of the five-membered ring with the seven-membered ring. This may reflect the more polarized azulenyl group of the difluorides, which strengthens the stacking interaction.

Full text of DOI:10.1021/om040053f

6176
Organometallics 2004, 23, 6176-6183
First Introduction of an Azulenyl Group into the
Bismuth and Antimony Center. Synthesis and Structure
of Azulenylbismuthanes and Their Difluorides
A. F. M. Mustafizur Rahman, Toshihiro Murafuji,* Kei Kurotobi, and
Yoshikazu Sugihara*
Department of Chemistry, Faculty of Science, Yamaguchi University,
Yamaguchi 753-8512, Japan
Nagao Azuma
Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
Received April 12, 2004
A nonalternant organyl ligand derived from azulene, a 1,3-dichloro-2-azulenyl group, is
introduced for the first time into the bismuth and antimony center. Conversion of the
azulenylbismuthanes into the pentacoordinated difluorides by xenon difluoride promotes
the π-polarization of the azulene nucleus, which is detected as a color change in solution as
well as changes in the chemical shifts of the 13C NMR spectra. A similar tendency is observed
in the antimony congeners. The X-ray crystallographic study of (1,3-dichloro-2-azulenyl)-
diphenylbismuth difluoride (20b) reveals that intermolecular π-π stacking takes place
between the azulenyl groups through the interaction of the five-membered ring with the
seven-membered ring. This may reflect the more polarized azulenyl group of the difluorides,
which strengthens the stacking interaction.
Chart 1
Introduction
Construction of organometallics based on nonalter-
nant conjugation has been receiving increasing interest.1
Formation of a σ- or π-type coordinate bond between a
metal center and nonalternant ligands is considered to
endow molecules with a significant change of the
properties that are markedly different from those given
by the coordination of alternant ligands since the
resonance stabilization of nonalternant conjugation is
smaller than that of alternant conjugation.2 Thus, we
have revealed a unique structure of boron complex 1
comprised of nonalternant 8-methylamino-3-phenyl-1-
azaazulene, in which the nonalternant conjugation in
the 1-azaazulene skeleton is destroyed through the
intramolecular boron-nitrogen coordinate bond.1d
Azulene, a nonalternant hydrocarbon and isomer of
alternant naphthalene, is physicochemically character-
ized by high electron affinity, low ionization potential,
and low aromatic resonance energy, together with the
dipole moment vector whose negative end is toward its
five-membered ring (Scheme 1). Despite such unique-
ness of the electronic structure, the organometallic
species bearing an azulenyl group as a ligand of the
metal center have been very limited. In particular, there
Scheme 1
(1) (a) Matsubara, K.; Ryu, K.; Maki, T.; Iura, T.; Nagashima, H.
Organometallics 2002, 21, 3023. (b) Arce, A. J.; De Sanctis, Y.; Galarza,
E.; Garland, M. T.; Gobetto, R.; Machado, R.; Manzur, J.; Russo, A.;
Spodine, E.; Stchedroff, M. J. Organometallics 2001, 20, 359. (c) Nitta,
M.; Mitsumoto, Y.; Yamamoto, H. J. Chem. Soc., Perkin Trans. 1 2001,
1901. (d) Sugihara, Y.; Murafuji, T.; Abe, N.; Takeda, M.; Kakehi, A.
New J. Chem. 1998, 1031.
(2) (a) Dewer, M. J. S.; De Llano, C. J. Am. Chem. Soc. 1969, 91,
789. (b) Sugihara, Y.; Hashimoto, R.; Fujita, H.; Abe, N.; Yamamoto,
H.; Sugimura, T.; Murata, I. J. Chem. Soc., Perkin Trans. 1 1995, 2813.
are few examples of the σ-type species,3 although
azulenes are known to coordinate with transition metal
centers to form a π-complex.1a,b,4 The reason is at-
tributed to the lack of suitable methods for preparing
σ-anions such as azulenyllithium or azulenyl-Grignard
10.1021/om040053f CCC: $27.50 © 2004 American Chemical Society
Publication on Web 11/23/2004

Azulenylbismuthanes and Their Difluorides
Organometallics, Vol. 23, No. 26, 2004 6177
Scheme 2
Scheme 3
reagents, the generation of which has so far not been
achieved. Very recently, we were successful for the first
time in generating σ-anions 3 and 4, starting from 1,3-
dichloroazulene 2 (Scheme 1).5 Herein, we report the
first introduction of an azulenyl group into the bismuth
center, that is, the synthesis and structural character-
ization of azulenylbismuthanes 7-10 and their difluo-
rides 18-20, together with their antimony congeners.
at the bismuth atom. The structure of 8 was confirmed
by the reaction with phenylmagnesium bromide giving
9.
Results and Discussion
Dichloro- and chlorobismuthanes underwent substi-
tution smoothly with 3 to afford the corresponding
mixed bismuthanes 9 and 10, respectively (Scheme 3).
Next, azulenyllithium 3 was applied to the reaction with
an electrophile of the group 15 homologue. When
antimony(III) chloride was allowed to react with 3,
unlike the case of bismuth(III) chloride, the ratio of
chlorostibine 12 relative to 11 considerably increased,
reflecting the difference of the Lewis acidity between
the bismuth and antimony atoms. Similar reaction with
dichloro- and chlorostibines6 afforded the corresponding
stibines 13 and 14.
Halogenation. Triarylbismuthanes undergo prefer-
ential halogenation at the bismuth atom with sulfuryl
chloride or xenon difluoride to give triarylbismuth
dihalides in high yields. Unlike the aryl groups of
benzenoid hydrocarbon, the azulenyl groups of 7 are
considered to be reactive toward halogenation since the
azulene nucleus undergoes electrophilic substitution at
the five-membered ring (1- and 3-positions) and suffers
from nucleophilic addition at the seven-membered ring
(4-, 6-, and 8-positions) owing to the π-polarization. A
preliminary reaction of 2 with sulfuryl chloride (1 equiv)
in THF at 0 °C immediately produced brown, intractable
substances and a small amount of 2 remained (con-
firmed by TLC), suggesting destruction of the conjuga-
tion in the azulene nucleus by sequential chlorination.
When 7 was allowed to react with sulfuryl chloride
under the same conditions, however, no such tendency
Synthesis of Azulenylbismuthanes and their
Homologues of Antimony. To know the difference in
reactivity among anionic species 3-5, we initially tried
the reaction of the respective anions (ca. 3 equiv) with
bismuth(III) chloride (1 equiv). When azulenyllithium
3 was allowed to react with bismuth(III) chloride,
bismuthane 7 preferentially formed together with minor
chlorobismuthane 8 in 72 and 15% yields [based on
bismuth(III) chloride], respectively (Scheme 2). In con-
trast, the distribution of 7 and 8 was reversed when
azulenyl-Grignard 4 was used. Thus, 8 formed as a main
product (56%) along with 7 (12%), and in addition, 2
was obtained in 36% yield (based on 6), reflecting the
lowered nucleophilicity of 4. An attempted reaction of
π-anion 5 resulted in the complete recovery of 2. The
diethylamino group of 5 seems to coordinate with Lewis
acidic bismuth(III) chloride to promote the elimination
of this group from the azulene nucleus since the π-anion
reacts with iodine to produce 6 in moderate yield. These
results clarify the efficiency of 3 for the bismuth-carbon
bond formation. Despite the reactive bismuth-chlorine
bond, 8 is resistant to aqueous workup, although chlo-
robismuthanes are usually sensitive toward hydrolysis
(3) (a) Kurotobi, K.; Tabata, H.; Miyauchi, M.; Murafuji, T.; Sugi-
hara, Y. Synthesis 2002, 1013. (b) Kurotobi, K.; Miyauchi, M.;
Takakura, K.; Murafuji, T.; Sugihara, Y. Eur. J. Org. Chem. 2003,
3663. (c) Ito, S.; Okujima, T.; Morita, N. J. Chem. Soc., Perkin Trans.
1 2002, 1896.
(4) Edelmann, F.; Behrens, U. Chem. Ber. 1978, 111, 3001.
(5) Kurotobi, K.; Tabata, H.; Miyauchi, M.; Mustafizur Rahman, A.
F. M.; Migita, K.; Murafuji, T.; Sugihara, Y.; Shimoyama, H.; Fujimori,
K. Synthesis 2003, 30.
(6) Nunn, M.; Sowerby, D. B.; Wesolek, D. M. J. Organomet. Chem.
1983, 251, C45.

6178 Organometallics, Vol. 23, No. 26, 2004
Mustafizur Rahman et al.
Scheme 4
groups (-117.95 and -139.85 ppm in 19 and 20b,
respectively), while those of 20 were little affected by
the p-substituents. Such behavior of 18 may be ascribed
to the anisotropic effect of the chlorine atoms. Compari-
son of 18 with 7 by UV/vis spectroscopy in chloroform
revealed that the absorbance (ꢀ) of the longest wave-
length absorption band (λmax ) ca. 640 nm) due to the
charge transfer absorption of the azulene nucleus is
larger in 18 (1540) than in 7 (1210). This tendency was
commonly observed through the comparison of the
difluorides with the parent bismuthanes and, further-
more, through the comparison of 11 with 17. The ꢀ value
of 8 was approximately comparable to that of 9 (890 and
830, respectively). This indicates that the polarization
of the azulene nucleus is enhanced in the higher
oxidation state of the metal center.7 To know the
influence of the metal center on the polarization,
antimony congeners 21-23 were synthesized and their
ꢀ values were compared with those of 18, 19, and 20b.
The value of 21 (1500) is comparable to that of 18, and
this tendency is seen between 22 and 19 and between
23 and 20b. The values of stibines 11-14 are close to
those of the bismuth congeners. These findings suggest
that the electronic effect of the antimony center is quite
similar to that of the bismuth center.
Scheme 5
13C NMR Study. Table 1 shows the chemical shifts
(δC) of ring carbons of azulenylbismuthanes 7-10 and
their difluorides together with those of 2. An outstand-
ing spectroscopic feature is in the chemical shifts of the
azulene nucleus. The C1 signals of 10 exhibited down-
field shift with increasing electron-withdrawing ability
of the p-substituents, suggesting the inductive effect by
the aryl groups. The signals due to the seven-membered
ring carbons of the bismuthanes showed chemical shifts
almost identical to those of 2. In contrast, the azulene
ring carbons of 20 were little affected by the p-substit-
uents but were governed by the effect of introduction of
the fluorine atoms. Thus, the signals due to the C1 and
C2 atoms appeared more upfield, while those due to the
seven-membered ring carbons were observed more
downfield, relative to the parent 10. Interestingly, the
tendency of the downfield shift was marked in the C4
and C6 atoms rather than in the C5 atoms. These
findings clarify the change in the conjugation of the
azulene nucleus accompanied by the change in the
geometry of the bismuth atom. Namely, the π-polariza-
tion of the azulene nucleus is pronounced in 20 com-
pared to the parent 10. This is in good accord with the
finding deduced from the UV/vis studies of these
compounds. The upfield shifts of the C1′ and C2′ atoms
and the downfield shift of the C3′ and C4′ atoms in 20
show the π-polarization in the benzene rings.8 Table 2
shows the chemical shifts (δC) of ring carbons of azule-
nylstibines. A similar tendency was observed in the
antimony congeners. Except for the ipso carbons, the
chemical shifts of the antimony derivatives are quite
similar to those of the bismuth congeners.
was observed. Thus, the reaction proceeded quickly
(within 5 min), and a greenish product considered to be
15 was confirmed by TLC together with 1,2,3-trichlo-
roazulene 16 and 2 (Scheme 4). Isolation of the product
failed owing to decomposition in solution. Eventually,
most of the azulenyl groups were recovered in the form
of 16 and 2 (57 and 22% yields, respectively). In
contrast, when 11 was chlorinated similarly, the color
of the solution immediately changed from greenish blue
to deep green, giving dichloride 17 quantitatively. These
results show that the chlorination of the lone pair on
the bismuth and antimony atoms precedes that of the
azulene nucleus. Furthermore, dichloride 15 is ther-
mally less stable and easily suffers from decomposition
through the fission of the bismuth-carbon bonds. It is
known that the geometry of triarylbismuth difluorides
is much more stabilized than that of triarylbismuth
dichlorides due to the apicophilicity of the more elec-
tronegative fluorine atoms in the apical positions of the
trigonal bipyramidal structure. On adding xenon dif-
luoride to a solution of 7 in THF, a color change similar
to that observed in the chlorination of 11 took place and
green solids of difluoride 18 gradually separated out
(Scheme 5). Compound 18 is thermally stable in both
solid and solution. The 19F NMR spectrum of 18 showed
that the signal due to the fluorine atoms appears at δF
-88.30 in DMSO-d6, which caused confusion when
compared with the value of triphenylbismuth difluoride
(δF -153.28) in the same solvent. To know the reason
for such a marked difference, bismuthanes 9 and 10
were similarly fluorinated and 19 and 20 were charac-
terized by their 19F NMR spectra. Comparison of 19 with
20b revealed that the fluorine signals showed an upfield
shift with a decrease in the number of the azulenyl
(7) The coordination number-photophysical property relationships
for the tri(9-anthryl)derivatives of boron, silicon, phosphorus, and
bismuth, see: (a) Yamaguchi, S.; Akiyama, S.; Tamao, K. J. Am. Chem.
Soc. 2000, 122, 6335. (b) Yamaguchi, S.; Akiyama, S.; Tamao, K. J.
Am. Chem. Soc. 2001, 123, 11372. (c) Yamaguchi, S.; Akiyama, S.;
Tamao, K. J. Am. Chem. Soc. 2000, 122, 6793. (d) Yamaguchi, S.;
Akiyama, S.; Tamao, K. J. Organomet. Chem. 2002, 646, 277. (e)
Yamaguchi, S.; Shirasaka, T.; Tamao, K. Organometallics 2002, 21,
2555.

Azulenylbismuthanes and Their Difluorides
Organometallics, Vol. 23, No. 26, 2004 6179
Table 1. 13C NMR Spectral Data of Azulenylbismuthanes and Difluorides in DMSO-d6
C1
C2
C3
C4
C5
C6
C1′
C2′
C3′
C4′
2
132.56
a
113.16
122.88
121.50
122.42
122.64
122.64
122.44
122.40
116.50
116.35
116.42
116.56
116.84
132.56
133.00
133.68
133.23
133.33
133.39
133.49
133.60
132.40
132.30
132.39
132.37
132.48
135.73
134.62
133.87
134.21
134.01
134.13
134.25
134.40
139.01
138.49
138.60
138.57
138.45
124.69
124.51
124.04
124.38
124.27
124.29
124.27
124.50
126.67
126.41
126.54
126.48
126.43
141.73
141.23
140.30
140.89
140.76
140.81
140.98
141.09
144.97
144.47
144.57
144.61
144.55
7
8
9
a
165.10
164.08
165.40
167.22
168.81
a
158.57
159.22
158.88
159.80
156.58
147.12
157.45
157.11
165.20
a
144.08
154.59
154.62
162.80
139.80
139.73
138.39
140.35
139.24
135.26
135.25
133.93
135.35
134.47
130.23
116.29
130.36
130.30
126.50
132.20
117.21
132.01
131.53
128.25
127.94
159.07
127.68
132.84
128.23
132.98
162.27
132.50
137.32
131.98
10ab
10b
10c
10dc
19d
20ab,d
20bd
20cd
20dc,d
c
a Not observed. b The chemical shift of the methyl carbon: δ 54.98 (10a) and 55.97 (20a). JCF ) around 3.7(q), 32(q), and 273(q) for
2
3
C3′, C4′, and CF3, respectively. The chemical shift of the CF3 carbon: δ 124.72 (10d) and 123.81 (20d). d The JCF and JCF couplings of
the fluorine atoms attached to the bismuth atom were not detected in the azulenyl and phenyl ring carbons.
Table 2. 13C NMR Spectral Data of Azulenylstibines and Difluorides in DMSO-d6
C1
C2
C3
C4
C5
C6
C1′
C2′
C3′
C4′
11
140.18
141.88
141.95
137.19
139.43
121.48
120.94
121.25
117.42
116.22
132.46
132.62
132.84
132.65
132.45
135.20
134.91
135.02
138.80
138.26
124.88
124.81
124.82
126.29
126.16
142.16
142.78
143.64
145.02
144.48
13
134.30
136.49
137.46
136.39
128.78
128.95
129.26
128.89
14
21a
23b
133.10
135.25
130.25
133.03
2
3
a The JCF and JCF couplings of the fluorine atoms attached to the antimony atom were not detected in the azulenyl and phenyl ring
b 2
3
carbons.
J
) 13.9(t) for the C1′ and JCF ) 4.6(t) for the C2′.
CF
Table 3. Selected Bond Lengths (Å) and Angles
(deg) for 7 and 20b
X-ray Structure Analysis of Bismuthane 7 and
Difluoride 20b. To know how the azulenyl group
attached to the bismuth(III) and -(V) centers behaves
in solid, X-ray structure analysis was carried out for 7
and 20b (Tables 3 and 4 and Figures 1-3). The bismuth
center of 7 has a pyramidal configuration (Figure 1) and
is surrounded by the six chlorine atoms with distances
of 3.493(6)-4.033(5) Å, which are all within the sum of
the van der Waals radii (4.04 Å). The partially larger
bond angles around the bismuth center are due to the
steric bulkiness of the azulenyl groups. The enhanced
stability of chlorobismuthane 8 may be mainly at-
tributed to the intramolecular interaction and kinetic
stabilization by these chlorine atoms. The bismuth
center of 20b possesses a trigonal bipyramidal geometry
with the fluorine atoms and the carbon atoms of the
azulenyl and phenyl groups in the apical and equatorial
positions, respectively (Figure 2). An outstanding struc-
tural feature is seen in the crystal structure of 20b. An
intermolecular π-π stacking is observed between the
azulenyl groups9 through the interaction of the five-
membered ring with the seven-membered ring, with the
7
20b
Bi-C(1)
Bi-C(11)
Bi-C(21)
2.23(2)
2.27(2)
2.26(2)
Bi-C(1)
2.15(2)
2.19(2)
2.19(2)
2.27(1)
2.189(9)
1.40(2)
1.40(2)
1.42(2)
1.47(2)
1.31(2)
1.32(3)
1.44(3)
1.41(2)
1.36(2)
1.39(2)
1.37(2)
115.5(6)
117.4(6)
127.1(6)
178.5(4)
Bi-C(11)
Bi-C(17)
Bi-F(1)
Bi-F(2)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(3)-C(9)
C(4)-C(5)
C(5)-C(6)
C(6)-C(7)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C(1)-C(10)
1.38(2)
1.41(3)
1.41(3)
1.50(3)
1.39(3)
1.33(3)
1.33(3)
1.38(3)
1.39(3)
1.38(3)
1.42(2)
92.6(6)
99.2(7)
100.6(6)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(3)-C(9)
C(4)-C(5)
C(5)-C(6)
C(6)-C(7)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C(1)-C(10)
C(1)-Bi-C(11)
C(1)-Bi-C(21)
C(11)-Bi-C(21)
C(1)-Bi-C(11)
C(1)-Bi-C(17)
C(11)-Bi-C(17)
F(1)-Bi-F(2)
shortest interatomic distance of 3.54(2) Å between the
C4 and C9 atoms (Figure 3). While the azulenyl group
is approximately coplanar with the equatorial plane
[C2-C1-Bi-C17 ) 166(1)°], the two phenyl groups lie
perpendicular to this plane as if they surround the
azulenyl groups of the neighboring molecules. This
(8) π-Polarization is observed in diaryltrifluorosilicates. Thus, the
ipso carbons attached to the pentacoordinate silicon appear more
downfield compared to those of the parent tetracoordinate silanes. This
is attributed to the π-inductive effect induced by the electronic fields
of the charged substituents. The upfield shift of the ipso carbons in
the pentacoordinate antimony and bismuth halides may be ascribed
to this π-inductive effect. For the π-polarization of the silicates, see:
Tamao, K.; Hayashi, T.; Ito, Y. Organometallics 1992, 11, 182.
(9) Sterically protected phosphaethenes bearing an azulenyl group
at the ethene carbon, see: Yasunami, M.; Ueno, T.; Yoshifuji, M.;
Okamoto, A.; Hirotsu, K. Chem. Lett. 1992, 1971.

6180 Organometallics, Vol. 23, No. 26, 2004
Mustafizur Rahman et al.
Table 4. Crystallographic Parameters for 7
and 20b
7‚THF
20b
empirical formula
fw
color, habit
cryst dimens (mm)
cryst syst
a (Å)
C
34H23BiCl6O
C22H15BiCl2F2
597.24
869.25
green, prismatic
green, prismatic
0.33 × 0.28 × 0.18 0.25 × 0.13 × 0.13
monoclinic
12.063(6)
21.085(7)
12.721(7)
92.81(4)
3231(2)
P21/n (#14)
4
monoclinic
8.030(6)
16.78(1)
15.44(2)
97.2(1)
2064(3)
P21/c (#14)
4
1.922
1128.00
88.06
55.4
8.0
b (Å)
c (Å)
â (deg)
V (Å3)
space group
Z
Dcalc (g cm-3
)
1.786
1680.00
59.69
55.0
32.0
1.47 + 0.30 tan θ
7991; 7428
F000
µ(Mo KR) (cm-1
2θmax (deg)
)
scan rate (deg min-1
scan width (deg)
no. of rflns measd
total; unique
)
1.52 + 0.30 tan θ
5263; 4749
no. of observns
no. of variables
5078 (I > 0.00σ(I)) 2953 (I > 0.00σ(I))
369
0.141; 0.191
1.01
0.001
244
b
residuals: R;a Rw
0.096; 0.117
1.18
goodness of fit indicator
max. shift/error in final
cycle
0.000
Figure 2. ORTEP drawing of 20b showing the atomic
numbering scheme. The thermal ellipsoids are drawn at
the 50% probability level.
max. and min. peaks
4.01; -3.85
2.11; -2.19
in final diff map (e-/Å3)
2
2
2
2
2
a R ) ∑(Fo - Fc )/∑Fo
.
b Rw ) [∑w(Fo - Fc )2/∑w(Fo2)2]1/2; w
) 1/σ2(Fo2).
Figure 3. Crystal structure of 20b.
Experimental Section
General Comments. All reactions were carried out under
argon unless otherwise noted. THF and diethyl ether were
distilled from calcium hydride under nitrogen before use.
Bismuth(III) chloride and antimony(III) chloride were purified
Figure 1. ORTEP drawing of 7 showing the atomic
numbering scheme. The thermal ellipsoids are drawn at
the 50% probability level. A THF molecule is omitted for
clarity.
1
by refluxing with thionyl chloride. H and 13C NMR spectra
were recorded in CDCl3 or DMSO-d6 on a Bruker AVANCE
400S spectrometer with TMS as an internal standard. 19F
NMR spectra were measured in DMSO-d6 on a Bruker
AVANCE 400S spectrometer with benzotrifluoride (δF -64.0)
as an internal standard. UV/vis spectra were measured in
CHCl3 by means of a Shimadzu UV-1600PC spectrophotom-
eter. 1,3-Dichloroazulene 2 was synthesized by the chlorination
of azulene with NCS.
stacking interaction was not observed in 7, although the
bismuth center possesses three azulenyl groups. The
difference in the crystal structures of 7 and 20b may
reflect the enhanced polarization in the azulene nucleus
of the latter, which strengthens the stacking interaction.
In conclusion, this work shows a potential utility of
nonalternant azulenes not only as σ-ligands of the metal
center but also as key building blocks for the construc-
tion of supramolecular systems composed of organome-
tallics based on the π-π interaction.
1,3-Dichloroazulene (2): blue solids; yield 85%; mp 85-
87 °C (lit.10 85-87 °C); 1H NMR (CDCl3) δ 7.18 (2H, t, J 10.0),
(10) Anderson, A. G., Jr.; Nelson, J. A.; Tazuma, J. J. J. Am. Chem.
Soc. 1953, 75, 4980.

Azulenylbismuthanes and Their Difluorides
Organometallics, Vol. 23, No. 26, 2004 6181
7.64 (1H, t, J 9.9), 7.65 (1H, s), 8.32 (2H, d, J 9.3); UV/vis
(CHCl3) λmax/nm (ꢀ) 241 (20420), 288 (34140), 294 (29410), 344
(3360), 352 (4520), 361 (3000), 369 (5030), 642 (380).
1,3-Dichloro-2-azulenylbis(4-trifluoromethylphenyl)-
bismuthane (10d): green solids; yield 61%; mp 135-138 °C;
1H NMR (DMSO-d6) δ 7.30 (2H, t, J 10.0, AzH), 7.71 (4H, d, J
7.9, ArH), 7.78 (1H, t, J 9.9, AzH), 8.15 (4H, d, J 7.9, ArH),
8.23 (2H, d, J 9.0, AzH); UV/vis (CHCl3) λmax/nm (ꢀ) 241
(25 820), 301 (43 360), 348 (5910), 362 (6710), 642 (380). Anal.
Calcd for C24H13BiCl2F6: C, 41.46; H, 1.88. Found: C, 41.24;
H, 1.97.
Tris(1,3-dichloro-2-azulenyl)stibine (11): green solids;
yield 55%; mp 270-271 °C; 1H NMR (DMSO-d6) δ 7.34 (6H, t,
J 9.9), 7.82 (3H, t, J 9.9), 8.27 (6H, d, J 9.6); UV/vis (CHCl3)
λmax/nm (ꢀ) 242 (48 130), 310 (158 500), 367 (25 880), 648
(1250). Anal. Calcd for C30H15SbCl6: C, 50.76; H, 2.13.
Found: C, 50.72; H, 2.15.
Chlorobis(1,3-dichloro-2-azulenyl)stibine (12): green
solids; yield 30%; mp 264-265 °C; 1H NMR (CDCl3) δ 7.17
(4H, t, J 9.0), 7.63 (2H, t, J 9.4), 8.28 (4H, d, J 9.6); due to low
solubility, measurement of 13C NMR spectrum failed; UV/vis
(CHCl3) λmax/nm (ꢀ) 242 (36 870), 308 (79 150), 364 (sh, 16 140),
648 (920). Anal. Calcd for C20H10SbCl5: C, 43.73; H, 1.83.
Found: C, 44.24; H, 1.85.
Bis(1,3-dichloro-2-azulenyl)phenylstibine (13): green
solids; yield 58%; mp 195-198 °C; 1H NMR (DMSO-d6) δ 7.31-
7.36 (7H, m), 7.72 (2H, d, J 7.7, ArH), 7.81 (2H, t, J 9.8, AzH),
8.26 (4H, d, J 9.9, AzH); UV/vis (CHCl3) λmax/nm (ꢀ) 242
(32 320), 306 (68 090), 367 (sh, 14 900), 644 (820). Anal. Calcd
for C26H15SbCl4: C, 52.48; H, 2.56. Found: C, 52.84; H, 2.50.
Generation of Azulenyllithium 3 and the Reaction
with Electrophiles. General Procedure. A typical example
is exemplified by the reaction with bismuth(III) chloride. To
a solution of lithium 2,2,6,6-tetramethylpiperidide (ca. 4.5
mmol) prepared from 2,2,6,6-tetramethylpiperidine (4.5 mmol)
and BuLi (4.5 mmol) in THF (5 mL) at -70 °C was added a
solution of 2 (3.0 mmol) in THF (3 mL) at the same temper-
ature. The color of the solution immediately turned from blue
to dark green, showing the generation of 3. To this solution
thus obtained was added a solution of bismuth(III) chloride
(1.0 mmol) in THF (5 mL), and the resulting solution was
stirred for 5 min. The reaction was quenched at -70 °C with
brine (10 mL), and the green precipitate was separated by
filtration. The filtrate was extracted with ethyl acetate (7 mL
× 3), and the combined extracts were dried over anhydrous
sodium sulfate and evaporated to leave a residue, which was
recrystallized from THF-MeOH (5:1) to give pure 7. The
precipitate was recrystallized from THF-MeOH (5:1) to give
8. Yields are based on bismuth(III) chloride.
1,3-Dichloro-2-iodoazulene (6):5 blue solids; yield 95%;
1
mp 102-103 °C; H NMR (CDCl3) δ 7.22 (2H, t, J 10.0), 7.69
(1H, t, J 9.9), 8.35 (2H, d, J 10.2); 13C NMR (CDCl3) δ 103.78,
119.58, 124.60, 132.44, 134.66, 140.09. Anal. Calcd for C10H5-
Cl2I: C, 37.19; H, 1.56. Found: C, 37.41; H, 1.50.
Tris(1,3-dichloro-2-azulenyl)bismuthane (7): green sol-
ids; yield 72%; mp 258-259 °C; 1H NMR (DMSO-d6) δ 7.30
(6H, t, J 9.9), 7.77 (3H, t, J 9.9), 8.22 (6H, d, J 9.3); UV/vis
(CHCl3) λmax/nm (ꢀ) 242 (50 870), 313 (147 290), 348 (26 660),
365 (31 320), 645 (1210). Anal. Calcd for C30H15BiCl6: C, 45.20;
H, 1.90. Found: C, 45.44; H, 2.02.
Chlorobis(1,3-dichloro-2-azulenyl)bismuthane (8): green
solids; yield 15%; mp 251-252 °C; 1H NMR (DMSO-d6) δ 7.17
(4H, t, J 9.8), 7.66 (2H, t, J 9.8), 7.96 (4H, d, J 9.8); UV/vis
(CHCl3) λmax/nm (ꢀ) 242 (38 070), 295 (70 100), 300 (69 690),
315 (77 320), 345 (13 810), 352 (sh, 14 160), 361 (16 880), 645
(890). Elemental analysis of this compound failed due to its
slow decomposition upon storage.
Bis(1,3-dichloro-2-azulenyl)phenylbismuthane (9): green
solids; yield 73%; mp 206-207 °C; 1H NMR (DMSO-d6) δ 7.27-
7.32 (4H, m), 7.40 (2H, t, J 7.5, ArH), 7.77 (2H, t, J 9.8, AzH),
8.17 (2H, d, J 7.2, ArH), 8.20 (4H, d, J 9.8, AzH); UV/vis
(CHCl3) λmax/nm (ꢀ) 241 (40 500), 309 (89 510), 349 (sh, 17 130),
365 (18 330), 642 (830). Anal. Calcd for C26H15BiCl4: C, 46.05;
H, 2.23. Found: C, 46.56; H, 1.94.
1,3-Dichloro-2-azulenylbis(4-methoxyphenyl)bismuth-
ane (10a): green solids; yield 70%; mp 109-111 °C; 1H NMR
(DMSO-d6) δ 3.70 (6H, s), 6.95 (4H, d, J 8.4, ArH), 7.29 (2H,
t, J 9.8, AzH), 7.76 (4H, d, J 8.4, ArH), 7.77 (1H, t, J 9.9, AzH),
8.21 (2H, d, J 9.7, AzH); UV/vis (CHCl3) λmax/nm (ꢀ) 243
(45 870), 300 (63 400), 307 (62 850), 349 (sh, 9420), 365 (8610),
642 (480). Anal. Calcd for C24H19BiCl2O2: C, 46.55; H, 3.09.
Found: C, 47.08; H, 2.99.
(1,3-Dichloro-2-azulenyl)diphenylstibine (14): green
solids; yield 45%; mp 133-135 °C; 1H NMR (DMSO-d6) δ 7.32-
7.37 (8H, m), 7.50-7.52 (4H, m), 7.83 (1H, t, J 9.9, AzH), 8.28
(2H, d, J 9.4, AzH); UV/vis (CHCl3) λmax/nm (ꢀ) 242 (27 360),
299 (46 720), 329 (14 690), 645 (430). Anal. Calcd for C22H15-
SbCl2: C, 55.98; H, 3.20. Found: C, 56.31; H, 3.19.
Generation of Azulenyl-Grignard 4 and the Reaction
with Bismuth(III) Chloride. To a solution of 6 (3.0 mmol)
in THF (5 mL) was added at -30 °C a solution of i-PrMgBr
(3.6 mmol) in THF (3 mL). The color of the solution turned
from blue to bluish green, showing the generation of 4. To this
solution thus obtained was added a solution of bismuth(III)
chloride (1.0 mmol) in THF (5 mL), and the resulting solution
was stirred for 5 min. The reaction was quenched at -30 °C
with brine (10 mL), and the green precipitate was separated
by filtration. The precipitate was recrystallized from THF-
MeOH (5:1) to give 8 in 56% yield. The filtrate was extracted
with ethyl acetate (7 mL × 3), and the combined extracts were
dried over anhydrous sodium sulfate and evaporated to leave
a residue, which was recrystallized from THF-MeOH (5:1) to
give pure 7 in 12% yield. Evaporation of the filtrate after
filtration of 7 gave a residue, which was chromatographed
(silica gel; hexane) to give 2 in 36% yield.
Reaction of 8 with Phenylmagnesium Bromide. To a
solution of 8 (0.3 mmol) in THF (5 mL) was added at 0 °C a
solution of phenylmagnesium bromide (ca. 0.6 mmol) in the
same solvent (1 mL), and the reaction mixture was stirred for
3 h, during which time the temperature was raised to ambient.
The reaction was quenched with brine (3 mL), and the
resulting mixture was extracted with ethyl acetate (5 mL ×
3). The combined extracts were dried over anhydrous sodium
sulfate and evaporated to leave a residue, which was crystal-
lized from MeOH to give 9 in 95% yield.
(1,3-Dichloro-2-azulenyl)diphenylbismuthane (10b):
green solids; yield 82%; mp 111-112 °C; 1H NMR (DMSO-d6)
δ 7.29 (2H, t, J 9.9, AzH), 7.29 (2H, t, J 7.3, ArH), 7.39 (4H, t,
J 7.4, ArH), 7.78 (1H, t, J 9.9, AzH), 7.90 (4H, d, J 6.8, ArH),
8.21 (2H, d, J 9.5, AzH); UV/vis (CHCl3) λmax/nm (ꢀ) 240
(30 250), 299 (52 470), 307 (52 010), 364 (7620), 642 (400).
Anal. Calcd for C22H15BiCl2: C, 47.25; H, 2.70. Found: C,
47.15; H, 2.71.
Generation of Lithium 6-N,N-Diethylamino-6H-azu-
lenate (5) and the Reaction with Bismuth(III) Chloride.
To a solution of lithium diethylamide (ca. 3.0 mmol), prepared
from diethylamine (3.0 mmol) and BuLi (3.0 mmol) in ether
(10 mL) at -20 °C, was added a solution of 2 (3.0 mmol) in
ether (3 mL) at -70 °C. The color of the solution turned from
blue to yellow, showing the generation of 5. Then a solution
of bismuth(III) chloride (1.0 mmol) in THF (5 mL) was added
at this temperature. After 5 min the reaction was quenched
at -70 °C with brine (10 mL) and the mixture was extracted
1,3-Dichloro-2-azulenylbis(4-chlorophenyl)bismuth-
1
ane (10c): green solids; yield 65%; mp 115-117 °C; H NMR
(DMSO-d6) δ 7.29 (2H, t, J 9.8, AzH), 7.42 (4H, d, J 8.3, ArH),
7.77 (1H, t, J 9.9, AzH), 7.89 (4H, d, J 8.3, ArH), 8.21 (2H, d,
J 9.9, AzH); UV/vis (CHCl3) λmax/nm (ꢀ) 241 (38 110), 300 (sh,
52 060), 307 (52 860), 348 (sh, 7390), 363 (7930), 641 (420).
Anal. Calcd for C22H13BiCl4: C, 42.07; H, 2.09. Found: C,
42.36; H, 2.05.

6182 Organometallics, Vol. 23, No. 26, 2004
Mustafizur Rahman et al.
with ethyl acetate (7 mL × 3). The combined extracts were
dried over anhydrous sodium sulfate and evaporated to leave
a residue, from which 2 was recovered intact.
-139.85 (s); UV/vis (CHCl3) λmax/nm (ꢀ) 241 (23 300), 298
(49 700), 306 (49 700), 345 (sh, 6160), 351 (6400), 368 (4480),
642 (500). Anal. Calcd for C22H15BiCl2F2: C, 44.24; H, 2.53.
Found: C, 44.36; H, 2.65.
Chlorination of 7 with Sulfuryl Chloride. To a solution
of 7 (1.0 mmol) in THF (10 mL) was added sulfuryl chloride
(1.0 mmol) in dichloromethane (1.0 mL) at 0 °C, and the
reaction mixture was stirred for 3 h, during which time the
temperature was raised to ambient. The mixture was evapo-
rated to leave an oily residue containing insoluble substances,
which was extracted with hexane (7 mL × 3). The combined
extracts were purified by silica gel column chromatography
using hexane as eluent to give 1,3-dichloroazulene 2 (22%) and
1,2,3-trichloroazulene 16 (57%).
1,3-Dichloro-2-azulenylbis(4-chlorophenyl)bismuth di-
1
fluoride (20c): green solids; yield 68%; mp 144-146 °C; H
NMR (DMSO-d6) δ 7.51 (2H, t, J 9.9, AzH), 7.90 (4H, d, J 8.6,
ArH), 7.99 (1H, t, J 9.9, AzH), 8.25 (4H, d, J 8.6, ArH), 8.46
(2H, d, J 9.7, AzH); 19F NMR (DMSO-d6) δ -138.98 (s); UV/
vis (CHCl3) λmax/nm (ꢀ) 240 (28 440), 298 (43 200), 306 (45 310),
345 (6370), 350 (6380), 367 (4410), 642 (500). Anal. Calcd for
C22H13BiCl4F2: C, 39.67; H, 1.97. Found: C, 39.74; H, 2.15.
1,3-Dichloro-2-azulenylbis(4-trifluoromethylphenyl)-
bismuth difluoride (20d): green solids; yield 65%; mp 139-
1,2,3-Trichloroazulene (16): blue solids; yield 57%; mp
1
136-137 °C (lit.11 137 °C); H NMR (CDCl3) δ 7.28 (2H, t, J
1
141 °C; H NMR (DMSO-d6) δ 7.50 (2H, t, J 9.8, AzH), 7.98
9.8), 7.66 (1H, t, J 9.6), 8.30 (2H, d, J 10.0); 13C NMR (CDCl3)
δ 112.38, 124.81, 131.86, 134.44 (× 2), 139.58. Anal. Calcd for
C10H5Cl3: C, 51.88; H, 2.18. Found: C, 51.84; H, 2.25.
Chlorination of 11 with Sulfuryl Chloride. To a solution
of 11 (1.0 mmol) in THF (10 mL) was added sulfuryl chloride
(1.0 mmol) in dichloromethane (1.0 mL) at 0 °C, and the
reaction mixture was stirred for 3 h, during which time the
temperature was raised to ambient. The mixture was evapo-
rated to leave solids, which were crystallized from hexane-
AcOEt (5:1) to give pure 17.
Tris(1,3-dichloro-2-azulenyl)antimony dichloride (17):
green solids; yield 98%; mp 290-292 °C; 1H NMR (DMSO-d6)
δ 7.58 (6H, t, J 9.9), 8.09 (3H, t, J 10.3), 8.66 (6H, d, J 9.6);
due to low solubility, measurement of 13C NMR spectrum
failed; UV/vis (CHCl3) λmax/nm (ꢀ) 241 (50 880), 313 (173 650),
355 (26 290), 371 (16 160), 648 (1610). Anal. Calcd for C30H15-
SbCl8: C, 46.15; H, 1.94. Found: C, 46.16; H, 2.23.
Fluorination of Azulenylbismuthanes with Xenon
Difluoride. General Procedure. A typical example is ex-
emplified by the reaction of 7. To a solution of 7 (1.0 mmol) in
THF (15 mL) was added xenon difluoride (1.2 mmol) at 0 °C,
and the mixture was stirred for 3 h. Evaporation of the
resulting mixture gave a residue, which was crystallized from
MeOH to give 18.
(1H, t, J 9.9, AzH), 8.19 (4H, d, J 8.4, ArH), 8.43 (2H, d, J 9.9,
AzH), 8.49 (4H, d, J 8.4, ArH); 19F NMR (DMSO-d6) δ 61.16
(s, 6F), -140.40 (s, 2F); UV/vis (CHCl3) λmax/nm (ꢀ) 241
(20 430), 297 (39 160), 306 (40 080), 344 (5910), 349 (5880),
367 (4200), 644 (520). Anal. Calcd for C24H13BiCl2F8: C, 39.31;
H, 1.79. Found: C, 39.65; H, 1.95.
Tris(1,3-dichloro-2-azulenyl)antimony difluoride (21):
green solids; yield 94%; mp 238-240 °C; 1H NMR (DMSO-d6)
δ 7.54 (6H, t, J 9.9), 8.06 (3H, t, J 9.9), 8.60 (6H, d, J 9.6); 19
F
NMR (DMSO-d6) δ -97.98 (s); UV/vis (CHCl3) λmax/nm (ꢀ) 241
(45 450), 310 (138 280), 347 (sh, 19 970), 353 (21 330), 370
(16 480), 650 (1500). Anal. Calcd for C30H15SbCl6F2: C, 48.18;
H, 2.02. Found: C, 48.26; H, 2.14.
Bis(1,3-dichloro-2-azulenyl)phenylantimony difluo-
1
ride (22): green solids; yield 93%; mp 248-250 °C (dec); H
NMR (DMSO-d6) δ 7.51 (4H, t, J 9.9, AzH), 7.76-7.77 (3H,
m), 8.03 (2H, t, J 9.9, AzH), 8.29-8.31 (2H, m), 8.54 (4H, d, J
9.6, AzH); 19F NMR (DMSO-d6) δ -118.27 (s); due to low
solubility, measurement of 13C NMR spectrum failed; UV/vis
(CHCl3) λmax/nm (ꢀ) 242 (27 600), 299 (65 830), 309 (79 170),
346 (sh, 10 640), 353 (11 650), 370 (9360), 645 (900). Anal.
Calcd for C26H15SbCl4F2: C, 49.65; H, 2.41. Found: C, 50.08;
H, 2.59.
(1,3-Dichloro-2-azulenyl)diphenylantimony difluoride
(23): green solids; yield 91%; mp 220-222 °C; 1H NMR
(DMSO-d6) δ 7.49 (2H, t, J 9.9, AzH), 7.69-7.70 (6H, m, ArH),
8.00 (1H, t, J 9.9, AzH), 8.16-8.18 (4H, m, ArH), 8.47 (2H, d,
J 9.7, AzH); 19F NMR (DMSO-d6) δ -134.31 (s); UV/vis (CHCl3)
λmax/nm (ꢀ) 240 (18 600), 290 (44 090), 305 (41 110), 353 (5750),
370 (4870), 641 (520). Anal. Calcd for C22H15SbCl2F2: C, 51.81;
H, 2.96. Found: C, 51.85; H, 2.85.
X-ray Crystallography. All measurements were made on
a Rigaku AFC5R diffractometer with graphite-monochromated
Mo KR radiation (λ ) 0.71069 Å) and a rotating anode
generator. The data were collected at 298 K using the ω-2θ
scan technique. The data were corrected for Lorentz and
polarization effects. The structures were solved by the Patter-
son method12 and expanded using Fourier techniques.13 The
non-hydrogen atoms were refined anisotropically. Neutral
atom scattering factors were taken from Cromer and Waber.14
Tris(1,3-dichloro-2-azulenyl)bismuth difluoride (18):
green solids; yield 75%; mp 191-192 °C; 1H NMR (DMSO-d6)
δ 7.36 (6H, t, J 9.9), 7.61 (3H, t, J 9.9), 8.64 (6H, d, J 9.3); 19
F
NMR (DMSO-d6) δ -88.30 (s); due to low solubility, measure-
ment of 13C NMR spectrum failed; UV/vis (CHCl3) λmax/nm (ꢀ)
241 (50 130), 311 (160 070), 346 (24 210), 351 (24 380), 368
(16 750), 645 (1540). Anal. Calcd for C30H15BiCl6F2: C, 43.15;
H, 1.81. Found: C, 43.18; H, 1.76.
Bis(1,3-dichloro-2-azulenyl)phenylbismuth difluoride
(19): green solids; yield 65%; mp 153-155 °C; 1H NMR
(DMSO-d6) δ 7.57 (4H, t, J 10.0, AzH), 7.73 (1H, t, J 7.4, ArH),
7.79 (2H, t, J 9.6, AzH), 7.91 (2H, t, J 7.7, ArH), 8.38 (2H, d,
J 7.5, ArH), 8.57 (4H, d, J 9.5, AzH); 19F NMR (DMSO-d6) δ
-117.95 (s); UV/vis (CHCl3) λmax/nm (ꢀ) 241 (34 700), 309
(92 700), 345 (15 300), 351 (15 100), 642 (950). Anal. Calcd for
C26H15BiCl4F2: C, 43.60; H, 2.11. Found: C, 43.23; H, 2.46.
1,3-Dichloro-2-azulenylbis(4-methoxyphenyl)bis-
muth difluoride (20a): green solids; yield 75%; mp 124-126
°C; 1H NMR (DMSO-d6) δ 3.84 (6H, s), 7.37 (4H, d, J 8.9, ArH),
7.45 (2H, t, J 9.0, AzH), 7.93 (1H, t, J 9.9, AzH), 8.14 (4H, d,
J 8.9, ArH), 8.40 (2H, d, J 9.6, AzH); 19F NMR (DMSO-d6) δ
-137.57 (s); UV/vis (CHCl3) λmax/nm (ꢀ) 242 (57 950), 298
(54 750), 306 (55 810), 345 (7520), 351 (7640), 369 (5110), 642
(550). Anal. Calcd for C24H19BiCl2F2O2: C, 43.86; H, 2.91.
Found: C, 44.20; H, 3.01.
(12) Fan, H.-F. SAPI91: Structure Analysis Programs with Intel-
ligent Control; Rigaku Corporation: Tokyo, Japan, 1991.
(13) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
de Gelder, R.; Israel, R.; Smits, J. M. M. DIRDIF94: The DIRDIF-94
program system, Technical Report of the Crystallography Laboratory;
University of Nijmegen: The Netherlands, 1994.
(14) Cromer, D. T.; Waber, J. T. In International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, England, 1974; Vol.
IV, Table 2.2 A.
(15) Ibers, J. A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.
(16) Creagh, D. C.; McAuley, W. J. In International Tables for X-ray
Crystallography; Kluwer Academic Publishers: Boston, 1992; Vol. C,
Table 4.2.6.8.
(1,3-Dichloro-2-azulenyl)diphenylbismuth difluoride
(20b): green solids; yield 70%; mp 152-154 °C; 1H NMR
(DMSO-d6) δ 7.51 (2H, t, J 9.9, AzH), 7.65 (2H, t, J 7.4, ArH),
7.83 (4H, t, J 7.7, ArH), 7.99 (1H, t, J 9.9, AzH), 8.23 (4H, d,
J 7.6, ArH), 8.47 (2H, d, J 9.7, AzH); 19F NMR (DMSO-d6) δ
(17) Creagh, D. C.; Hubbell, J. H. In International Tables for X-ray
Crystallography; Kluwer Academic Publishers: Boston, 1992; Vol. C,
Table 4.2.4.3.
(18) TeXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corporation, 1985 and 1999.
(11) Toda, T.; Yamanouchi, A. Bull. Chem. Soc. Jpn. 1970, 43, 2181.

Azulenylbismuthanes and Their Difluorides
Organometallics, Vol. 23, No. 26, 2004 6183
15
Anomalous dispersion effects were included in Fcalc
;
the
Supporting Information Available: Crystal data for
compounds 7 and 20b. This material is available free of charge
via the Internet at http://pubs.acs.org.
values for ∆f′ and ∆f′′ were those of Creagh and McAuley.16
The values for the mass attenuation coefficients are those of
Creagh and Hubbell.17 All calculations were performed using
the teXsan18 crystallographic software package of Molecular
Structure Corporation.
OM040053F