Synthesis of Re(I) complexes bearing tridentate 2,6-bis(7′-azaindolyl)phenyl ligand with green emission properties

Article abstract of DOI:10.1016/j.jorganchem.2004.02.023

The Re(I) complexes bearing 2,6-bis(7^′-azaindolyl)phenyl ligand as a tridentate ligand were synthesized by treatment with Re₂(CO)₁₀. The structures of the complexes were confirmed by X-ray crystallography. Both 7-azaindolyl ligands of Re(I) complexes are present in butterfly forms. The Re-C_ipso bonds showed a partial double bond character by π back-donation between the phenyl moiety and Re atom. In THF solution at room temperature, these complexes exhibited green emission (λ_em=510 nm), which is considered to be attributable to MLCT (dz²(Re) →π* (7^′-azaindolyl group)) transition containing π→π^* (7^′-azaindolyl group) transition.

Full text of DOI:10.1016/j.jorganchem.2004.02.023

Journal of Organometallic Chemistry 689 (2004) 1665–1674
www.elsevier.com/locate/jorganchem
Synthesis of Re(I) complexes bearing tridentate
2,6-bis(70-azaindolyl)phenyl ligand with green emission properties
a
a,c,
b
a,c,
*
Kazuyasu Tani , Hidehiro Sakurai *, Hiroyuki Fujii , Toshikazu Hirao
a
Handai Frontier Research Center, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565-0871, Japan
b
SANYO Electric Co., Ltd., 1-18-13, Hashiridani, Hirakata, Osaka 573-8534, Japan
c
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565-0871, Japan
Received 26 November 2003; accepted 24 February 2004
Abstract
The Re(I) complexes bearing 2,6-bis(70-azaindolyl)phenyl ligand as a tridentate ligand were synthesized by treatment with Re-
2(CO)10. The structures of the complexes were confirmed by X-ray crystallography. Both 7-azaindolyl ligands of Re(I) complexes are
present in butterfly forms. The Re–Cipso bonds showed a partial double bond character by p back-donation between the phenyl
moiety and Re atom. In THF solution at room temperature, these complexes exhibited green emission (kem ¼ 510 nm), which is
considered to be attributable to MLCT (dz2(Re) ! pꢀ (70-azaindolyl group)) transition containing p ! pꢀ (70-azaindolyl group)
transition.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Re(I) complex; Tridentate ligand; Azaindole; Emission
1. Introduction
emission [9], and luminescent probe in curing of epoxy
resins [10]. Despite a number of studies on the com-
plexes bearing bidentate N; N0-chelating ligands, only
few papers on the tridentate counterparts have been
reported [11]. Surprisingly, to the best of our knowledge,
only one report appeared on Re complexes containing a
Re-carbon bond with a tridentate ligand [12]. In general,
Re-carbon bond formation requires severe reaction
conditions due to the low reactivity of Re species. For
example, the complexes bearing N^C type ligands such
as ppy (2-phenylpyridine) were synthesized by treatment
with Re(CO)5Cl in the presence of a proton sponge,
although the yields were very low [13]. Another method
involves the utilization of alkyl Re species (R ¼ CH3 or
PhCH2), which is generated by Na–Hg reduction of
Re(CO)5X followed by the reaction with alkyl halide
[14].
Cyclometallated compounds bearing nitrogen-con-
taining ligands have attracted considerable interest as a
consequence of the wide range of their potential appli-
cations in many areas including organic synthesis [1],
homogeneous catalysis [2], and photochemistry [3]. In
addition, the strong r donation through a metal–carbon
bond increases the electron density on the metal center,
resulting in low-energy metal-to-ligand charge transfer
[5].
Group 7, especially, Re complexes have been studied
for photochemistry. Among them, the Re(CO)3(N^N)X
type complexes (N^N: a bidentate N; N0-chelating ligand
such as 2,20-bipyridine or 1,10-phenanthroline, and
X ¼ Cl, Br) have been used in a variety of processes
including photochemical reduction of CO2 [6], chemo-
luminescence [7], electrochemiluminescence [8], exciplex
Use of a pincer ligand leads to the metal insertion
into C–X (X ¼ H, halide, MeO) under mild reaction
conditions, providing more stable complexes by chela-
tion to metal [4]. These facts prompted us to investigate
the synthesis and photoluminescent properties of the
Re(I) complex bearing an N–C–N type tridentate ligand.
* Corresponding authors. Tel.: +81-6-68797413; fax: +81-6-
68797415.
E-mail addresses: hsakurai@chem.eng.osaka-u.ac.jp (H. Sakurai),
hirao@chem.eng.osaka-u.ac.jp (T. Hirao).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.02.023

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K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
Table 1
Synthesis of bis(7-azaindolyl)phenyl-rhenium complexes 3a–g
No. Isolated yield (%)
3a 74
R
H
F
Cl
3b
3c
3d
3e
3f
62
65
81
68
72
85
Br
CF3
MeO
3g
Fig. 1. Re(I) complex bearing tridentate 2,6-bis(70-azaindolyl) phenyl
ligend.
We adopted a tridentate ligand containing a benzene
moiety as r-donor and two 7-azaindolyl groups as p-
acceptor (Fig. 1). 7-Azaindolyl derivatives is known to
provide the fluorescence [15] or luminescence properties
[16,17].
to pale yellow microfine crystals in 62–85% isolated
yields (Table 1). In these reactions, neither the additives
such as a proton sponge nor the preparation of R–
Re(CO)5 (R ¼ CH3 or PhCH2) species were required.
Thus-obtained complexes 3a–g were fully characterized
by spectroscopic data, mass spectra, and elemental
analyses.
2. Results and discussion
2.1. Synthesis of Re(I) complexes 3
Selected spectroscopic data for the complexes 3a–g
are summarized in Table 2. In a solution state, two
m(CBO) bands were observed around 2006 cmꢁ1 as a
sharp absorption and around 1890 cmꢁ1 as a broad
absorption. In contrast, the IR spectra of all Re(I)
complexes 3a–g in a solid state showed three bands at
1995–2002 (sharp), 1879–1890 (broad), and 1860–1882
cmꢁ1 (broad) in the m(CBO) frequency region. These
bands are assigned to the three IR-active CO stretching
modes (2a0 þ a00) of this type of complexes possessing Cs
symmetry [18]. In the 13C NMR spectra, the Re(I)
complexes 3a–g showed two signals at 198.27 ꢂ 0.25 and
195.92 ꢂ 0.24 ppm due to axial and equatorial CO car-
bon atoms, respectively, suggesting that the complexes
possess symmetry in solution [19]. Although the m(CBO)
stretching frequencies in Re(4,40-R2-bipy)(CO)3Cl were
shifted to higher wavenumber due to the electron-with-
drawing group [20], such significant shift effect induced
by the substituent of 3a–g was not detected in both so-
lution and solid states.
Bis(70-azaindolyl)benzene derivatives 2a–g were syn-
thesized by Ullmann coupling of the bromobenzene
derivatives 1 with 7-azaindole as shown in Scheme 1
[16]. Complexation was carried out by treatment of 2a–g
with Re2(CO)10 in diglyme under refluxing conditions.
During the reaction, the solution color changed color-
less to brown. The solvent was removed in vacuo, and
the resulting solid was washed with CH2Cl2 or purified
by column chromatography on silica gel to give bis(70-
azaindolyl)benzene-rhenium complexes 3a–g as colorless
2.2. X-ray crystallography
The recrystallization of 3a, 3b, 3e, and 3f from mixed
solvents of DMSO/MeOH at room temperature gave the
crystals for X-ray analysis. The crystal data are collected
in Table 3. Although these crystals are not isomorphous,
their forms are quite similar. These structures are shown
in Fig. 2, and some important structural data are listed
in Table 4. Although both 7-azaindolyl ligands of Pd(II)
and Pt(II) complexes are perpendicular to one another
for central metal [17], those in Re(I) complexes are
present in butterfly forms.
Scheme 1.

K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
1667
Table 2
Selected spectroscopic data for complexes 3a–g
13C NMR CBO (ppm)a
FT-IR mCBO (cmꢁ1
)
Solidb
Solutionc
3a
3b
3c
3d
3e
3f
196.12
195.68
195.92
195.90
195.89
195.83
196.09
198.59
198.17
198.18
198.02
198.02
198.42
198.48
1995
2002
2000
1999
2002
1996
1995
1885
1893
1890
1887
1888
1879
1883
1870
1882
1867
1868
1880
1860
1863
2004
2005
2006
2006
2007
2003
2005
1889
1889
1891
1889
1894
1889
1890
3g
a DMSO-d6.
b KBr.
c CH2Cl2.
Table 3
Crystallographic data for 3a, 3b, 3e, and 3f
3a
3b
3e
3f
Formula
C23H1303N4Re
579.59
C23H1203N4FRe
597.58
C24H1203N4F3Re
647.59
C24H1504N4Re
609.61
Triclinic
Formula weight
Crystal System
Space Group
Orthorhombic
Pbca (No. 61)
14.6890(3)
14.1024(3)
18.7407(3)
Monoclinic
C2=m (No. 12)
14.0228(7)
15.7368(8)
9.2122(4)
Monoclinic
P21=n (No. 14)
6.7078(4)
ꢁ
P1 (No. 2)
ꢀ
a ðAÞ
7.2731(4)
8.3609(6)
17.238(1)
89.065(3)
81.051(3)
82.535(3)
1026.7(1)
2
ꢀ
b ðAÞ
22.297(1)
14.439(1)
ꢀ
c ðAÞ
a ð°Þ
b ð°Þ
c ð°Þ
103.533(2)
90.437(1)
3
ꢀ
Volume (A )
3882.1(1)
8
1976.5(2)
4
2159.6(2)
4
Z
Dcalc (g cmꢁ3
)
1.983
62.98
269
2.008
61.96
269
1.992
56.91
269
1.972
59.62
l (Mo Ka) (cmꢁ1
)
T (K)
269
0.031
0.101
Ra
Rw
0.041
0.123
0.022
0.071
0.048
0.138
b
P
P
a R ¼ jjFoj ꢁ jFcjj= jFoj.
h
i
1=2
P
P
2
2
b Rw
¼
wðFo2 ꢁ Fc2Þ = wðFo2Þ
.
The Re atom is linked to two carbon atoms of CO
ligand and two nitrogen atoms of the bis(70-azaind-
olyl)phenyl ligand on the equatorial plane, and adopts
an approximately octahedral coordination. In order to
maintain the octahedral structure, Re(1) atom in these
tances were reported in Re(CO)4(N^C) (N^C ¼ ppy:
ꢀ
2.163(7) A [13c], meppy: 2.168(5) A [13d], thpy: 2.16(2)
ꢀ
ꢀ
A [13b]). These distances are slightly longer than those
of Re@C double bonds (2.125(9) A) reported for neutral
or cationic Re–CO alkylidene complexes [21] and
ꢀ
ꢀ
complexes locates 0.5 A below the N(1)–N(2)–N(3)–
shorter than typical r-type Re–C single bonds
ꢀ
(2.2211(6) A) reported for neutral or anionic Re–CO
N(4) plane, being in contrast to Re atom in
Re(CO)4(N^C) nearly on the plane of phenyl-pyridine
[13]. The dihedral angles of the benzene moiety and 70-
azaindolyl groups are about 40° in all cases. Trans effect
is observed in the CO ligand of 3a, i.e. the distance
(Re(1)–C(21)) between Re and CO carbon in axial po-
complexes [22]. This indicates that a partial double bond
character is caused by p back-donation between the
phenyl moiety and Re atom.
2.3. Absorption and luminescence spectra
ꢀ
sition is about 0.07 A longer than those in equatorial
positions (Re(1)–C(22) and Re(1)–C(23)). In contrast,
Photophysical properties, especially luminescence
profiles, of d6-Re(I) complexes are of interest. The ab-
sorption and luminescent data of ligands 2a–g and
complexes 3a–g at 298 K are summarized in Table 5.
Fig. 3 shows UV–vis spectra of 3a–g in THF. All ligands
exhibited strong absorptions between 200 and 300 nm,
assignable to p ! pꢀ transitions. For complexes 3a–g,
two shoulders of low intensity were clearly observed at
axial Re–CO distance in 3b (R ¼ F) and 3e (R ¼ CF3) is
ꢀ
0.05 A shorter than those in equatorial positions.
However, the distance of Re(1)–C(21) in 3f (R ¼ MeO)
is very close to the corresponding Re–C distances of
other two CO ligands.
ꢀ
The Re(1)–C(1) distances (2.154(4)–2.165(4) A) in 3a,
3b, 3e, and 3f are nearly the same. The analogous dis-

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K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
Fig. 2. ORTEP drawing of Re(I) complexes (a) 3a, (b) 3b, (c) 3e, and (c) 3f. Hydrogen atoms are omitted for clarity. The atoms are drawn with 50%
probability thermal ellipsoids.
320 and 370 nm. The former absorption is assigned to
p ! pꢀ transition of the ligand. On the basis of previous
spectral studies on Re(I) complexes, the lower absorp-
tion shoulder of 3a–g at around 370 nm may be assigned
On the other hand, these complexes in a solid state
emitted with orange luminescence. Thin films of the
complexes 3a–g on glass plates were prepared by sub-
limation under high vacuum (4 ꢃ 10ꢁ2 Pa). Absorption
maxima of about 320 nm in solution states of 3a–g
were 25 nm red-shifted in thin film states. Other ab-
sorption maxima were nearly the same. However, ab-
sorption maxima of p–pꢀ and MLCT bands for 3a–g
were nearly the same in a solid state, suggesting the
substituent on benzene ring influences neither to p–pꢀ
nor to MLCT absorption. Emission maxima (kex ¼ 370
nm) appeared between 550 and 580 nm, which are
20–30 nm red-shifted from the solution state emission
(Fig. 5). These emission processes are due to MLCT
(dz2(Re) ! pꢀ (70-azaindolyl group)) transition. Con-
tribution of p ! pꢀ (70-azaindolyl group) transition
cannot be excluded. Emission maxima of all complexes
3a–g in a solid state are blue-shifted compared with
those in a solution state. These observations may be
attributed to emission arising from 70-azaindolyl group,
which participates in the intermolecular p interactions
to
a
spin-allowed metal-to-ligand charge-transfer
(MLCT) d(Re) ! pꢀ transition [23].
Emission spectra were measured at 298 K in THF
solution. As shown in Fig. 4, broad emission bands were
observed at k ¼ 510 nm for all the complexes 3a–g in
degassed THF solution upon excitation at k ¼ 370 nm.
These complexes 3a–g emitted a green color at room
temperature. These emissions were not observed in ox-
ygen saturated solution. In addition, 2a–g exhibited no
emission when excited at 370 nm. These findings also
support that the emission may be due to d(Re) ! pꢀ
(ligand) MLCT excited state. To the best of our
knowledge, these complexes appear to be the first ex-
amples for neutral Re(I) complexes containing the
Re(I)–C bond, which exhibit luminescence in THF at
298 K. Substitution group on the benzene ring of 3a–g
did not affect the emission wavelength.

K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
1669
Table 4
Selected bond lengths (A) and angles (°) for 3a, 3b, 3e, and 3f
2.4. DFT calculation
ꢀ
3a
3b
3e
3f
In a solution state, emission maxima were found to be
nearly the same wavenumber for all complexes 3a–g. It
might be due to the same initiative process in 3a–g. In
order to understand the nature of the luminescence
properties, DFT calculation for 3a–g was studied at the
B3LYP level [24] with the Gaussian 98 program [25].
The HOMO of 3a mostly consists of the d(z2) orbital of
Re(I) atom and the p orbital of the trans CO (Fig. 6).
The HOMO-1 and HOMO-2 orbitals of 3a spread over
70-azaindolyl group. The interaction between r orbital
of phenyl ipso-carbon and orbital of Re(I) atom is in
lower energy level. Other complexes 3b, 3e, and 3f
possess the similar orbital pattern. LUMO and
LUMO+1 orbitals of 3a, 3b, 3e, and 3f do not spread
over the central benzene ring significantly, but over both
70-azaindolyl groups. Therefore, electron-withdrawing
or donating effect on LUMO or LUMO+1 is limited.
Thus, the green emission of complexes 3 is most likely
due to MLCT (dz2(Re) ! pꢀ (70-azaindolyl group))
transition containing p ! pꢀ (70-azaindolyl group)
transition.
Bond lengths
Re(1)–C(1)
Re(1)–C(21)
Re(1)–C(22)
Re(1)–C(23)
Re(1)–N(2)
Re(1)–N(4)
N(1)–C(2)
2.165(4) 2.154(4) 2.155(7)
1.960(5) 1.957(6) 1.938(8)
1.888(4) 1.900(4) 1.935(9)
2.159(6)
1.937(6)
1.915(7)
1.920(6)
2.197(4)
2.203(5)
1.900(5)
2.215(4) 2.203(3) 2.204(7)
2.206(4) 2.207(6)
1.891(8)
1.450(5) 1.425(4) 1.422(10) 1.439(7)
1.444(6) 1.428(10) 1.436(8)
N(3)–C(6)
Bond angles
C(1)–Re(1)–C(21)
C(1)–Re(1)–N(2)
C(1)–Re(1)–N(4)
C(1)–Re(1)–C(22)
C(1)–Re(1)–C(23)
N(2)–Re(1)–N(4)
N(2)–Re(1)–C(22)
C(22)–Re(1)–C(23)
N(4)–Re(1)–C(23)
C(21)–Re(1)–N(2)
C(21)–Re(1)–N(4)
C(21)–Re(1)–C(22)
C(21)–Re(1)–C(23)
173.4(2) 173.3(2) 176.0(3)
173.9(2)
82.1(2)
82.1(2)
94.0(2)
91.9(2)
93.8(2)
88.9(2)
86.5(3)
90.4(2)
94.1(2)
93.4(2)
90.7(3)
92.3(3)
81.5(1)
82.7(1)
93.0(2)
96.2(2)
95.4(1)
87.9(2)
88.4(2)
88.1(2)
92.9(2)
94.6(2)
90.2(2)
89.6(2)
82.2(1)
82.3(3)
81.4(3)
92.8(3)
93.9(3)
93.5(1)
93.9(1)a 92.7(2)
88.9(1) 89.8(3)
87.8(6)b 87.8(4)
89.3(3)
93.2(2)
94.6(3)
96.3(3)
89.6(4)
89.4(3)
91.3(2)
Torsion angles
C(2)–C(1)–Re(1)–N(2) 43.7(3)
C(6)–C(1)–Re(1)–N(4) 39.7(4)
C(1)–C(2)–N(1)–C(13) 38.5(6)
C(1)–C(6)–N(3)–C(20) 34.6(7)
41.9(4)
35.9(5)
43.6(6)
137.0(6)
35(1)
45.8(5)
140.1(5)
25.3(8)
23.8(8)
160.3(5)
3. Summary
31(1)
In summary, the synthesis and structure of Re(I)
complexes bearing bis(70-azaindolyl)phenyl ligand are
described here. Their molecular structures were deter-
mined by X-ray crystallography to indicate the octahe-
dral coordination through the two carbon atoms of CO
and two nitrogen atoms of the bis(70-azaindolyl)phenyl
ligand in the equatorial plane with the one carbon atom
Re(1)–C(1)–C(2)–C(3) 172.6(3) 171.9(3) 168.3(6)
a N(2)–Re(1)–N(2)*, *X; ꢁY ; Z.
b C(22)–Re(1)–C(22)*, *X; ꢁY ; Z.
in the solid state. This interaction may lower LUMO
and LUMO+1 levels in a solid state compared with
those in a solution state.
Table 5
UV–vis spectra and luminescent data for ligands 2a–g and complexes 3a–ga
THF solutionb
Thin film
No.
kmax (nm) log e
Emission kmax (nm)c
kmax (nm) log e
Emission kmax (nm)d
2a
2b
2c
2d
2e
2f
221 (4.54), 239 (4.67), 259 (4.78), 294 (4.43)
224 (4.50), 239 (4.59), 262 (4.76), 292 (4.47)
222 (4.53), 238 (4.62), 263 (4.78), 291 (4.50)
222 (4.60), 237 (4.58), 264 (4.87), 291 (4.50)
223 (4.46), 238 (4.49), 265 (4.76), 291 (4.49)
220 (4.28), 257 (4.68), 291 (4.23)
358
354
347
344
342
362
356
2g
226 (4.48), 264 (4.77), 290 (4.48)
3a
3b
3c
3d
3e
3f
220 (4.71), 239 (4.79), 258 (4.69), 322 (4.21), 370 (3.71) 512
223 (4.67), 238 (4.71), 260 (4.63), 322 (4.15), 371 (3.64) 512
274, 344, 370
274, 343, 370
275, 342, 370
276, 345, 370
277, 344, 370
280, 345, 370
276, 346, 370
555
583
566
583
548
578
549
219 (4.65), 253 (4.70), 322 (4.09), 371 (3.74)
217 (4.64), 258 (4.59), 326 (3.99), 372 (3.66)
216 (4.57), 251 (4.55), 318 (4.00), 367(3.62)
223 (4.66), 257 (4.58), 320 (4.09), 371 (3.61)
511
511
509
517
3g
a 298 K.
221 (4.68), 235 (4.66), 263 (4.87), 313 (4.31), 371 (3.69) 517
b 5 ꢃ 10ꢁ5 M in THF solution.
c Excitation kmax 300 nm for 2a–g and excitation kmax 370 nm for 3a–g.
d Excitation kmax 370 nm.

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K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
Fig. 3. UV–vis spectra of complexes 3a–g in 5 ꢃ 10ꢁ5 M THF solution
at 298 K.
Fig. 5. The emission spectra of complexes 3a–g in thin film at 298 K.
Fig. 6. HOMO, LUMO, and LUMO+1 of 3a.
4. Experimental section
4.1. General procedures
Fig. 4. The luminescence spectra of complexes 3a–g in 5 ꢃ 10ꢁ5
M
THF solution at 298 K.
All reagents and solvents were purchased from com-
mercial sources and were further purified by the stan-
dard methods, if necessary. Melting points were
determined on a Yanagimoto Micromelting Point Ap-
paratus and were uncorrected. Infrared spectra were
of CO and one carbon atom of benzene moiety in axial
axis. These complexes 3a–g emitted at k ¼ 510 nm, when
excited at k ¼ 370 nm, and showed green luminescence
in THF solution. DFT calculation suggests that these
emission processes are due to MLCT (dz2(Re) ! pꢀ (70-
azaindolyl group)) transition containing p ! pꢀ (70-
azaindolyl group) transition.
1
obtained with a JASCO FT/IR-480 plus. The H NMR
(300 MHz) and 13C NMR (75.3 MHz) spectra were re-
corded on a Varian MERCURY 300 (300 MHz) spec-
trometer. Mass spectra were run on a JEOL JMS-
DX303HF mass spectrometer. UV–vis spectra were

K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
1671
obtained by using a Hitachi U-3500 spectrophotometer
at 5 ꢃ 10ꢁ5 M concentration in THF at 298 K. Emission
spectra were taken on a Shimadzu RF-5300PC spec-
trofluorophotometer at 5 ꢃ 10ꢁ5 M concentration in
THF at 298 K. THF was purchased from KANTO
Chemical Co., Ins. Thin films were prepared by subli-
mation on ULVAC VPC-410 at 65 A and 4 ꢃ 10ꢁ2 Pa.
Emission spectra of thin films on glass were taken on a
Shimadzu RF-5300PC spectrofluorophotometer at 298
K. The molecular structures were established by using
the crystallographic coordination of the complexes 3a,
3b, 3e, and 3f. LanL2DZ basis set for Re and 6-31G(d)
basis sets for the other elements were used. The orbital
diagrams were generated with the Chem3D program.
All contour values are ꢂ0.045 au.
NMR (CDCl3) d 6.67 (d, J ¼ 3:6 Hz, 2H), 7.17 (dd,
J ¼ 7:8 Hz, 4.8 Hz, 2H), 7.60 (d, J ¼ 3:6 Hz, 2H), 7.62
(dd, J ¼ 7:8 Hz, 1.6 Hz, 1H), 7.98 (dd, J ¼ 7:8 Hz, 1.6
Hz, 2H), 7.98 (dd, J ¼ 7:8 Hz, 1.6 Hz, 2H), 8.27 (t,
J ¼ 1:6 Hz, 1H), 8.39 (dd, J ¼ 4:8 Hz, 1.6 Hz, 2H). 13C
NMR (CDCl3) 102.59, 108.05 (d, J ¼ 25 Hz), 113.57 (d,
J ¼ 2:9 Hz), 117.09, 121.80, 127.13, 129.16, 140.13 (d,
J ¼ 12:3 Hz), 143.60, 147.33, 162.96 (d, J ¼ 245 Hz)
ppm. GC-MS (m=z) 328 (Mþ). HRMS Found: 328.1123.
C20H13N4F Calc.: 328.1124.
4.2.3. 1,3-Bis(70-azaindolyl)-5-chlorobenzene (Cl-Bab-
H, 2c)
1,3-Dibromo-5-chlorobenzene (1.35 g, 5.00 mmol), 7-
azaindole (1.77 g, 15.0 mmol), K2CO3 (2.07 g, 15.0
mmol), and cupric sulfate hydrate (0.031 g, 0.12 mmol)
were mixed and heated at 180 °C for 10 h under argon.
After being cooled to ambient temperature, the reaction
mixture was dissolved in CH2Cl2 (100 ml) and washed
with water. The organic layer was separated, dried over
MgSO4, and evaporated to dryness in vacuo. The resi-
due was purified by column chromatography on silica
gel using hexane/AcOEt (5:1, Rf ¼ 0:18) as an eluent to
give 0.388 g (23%) of 2c as a colorless solid, m.p. 185–
188 °C. IR (KBr) 3099, 1608, 1594, 1518, 1489, 1465,
1414, 1273, 1226, 892, 857, 840, 792, 771, 755, 727, 714,
676 cmꢁ1. 1H NMR (CDCl3) d 6.66 (d, J ¼ 3:8 Hz, 2H),
7.14 (dd, J ¼ 7:8 Hz, 4.7 Hz, 2H), 7.58 (d, J ¼ 3:8 Hz,
2H), 7.81 (dd, J ¼ 7:8 Hz, 1.7 Hz, 2H), 7.97 (d, J ¼ 1:9
Hz, 2H), 8.32 (t, J ¼ 1:9 Hz, 1H), 8.38 (dd, J ¼ 4:7 Hz,
1.7 Hz, 2H). 13C NMR (CDCl3) 102.61, 116.60, 117.09,
120.75, 121.74, 127.14, 129.14, 135.24, 139.92, 143.63,
147.35 ppm. HRMS Found: 344.0832. C20H13N4Cl
Calc.: 344.0829.
4.2. Synthesis of 2,6-bis(70-azaindolyl)benzene deriva-
tives
4.2.1. 1,3-Bis(70-azaindolyl)benzene (Bab-H, 2a) [16]
1,3-Dibromobenzene (0.50 ml, 4.13 mmol), 7-azain-
dole (1.47 g, 12.4 mmol), K2CO3 (1.71 g, 12.4 mmol),
and cupric sulfate hydrate (0.025 g, 0.10 mmol) were
mixed and heated at 220 °C for 5 h under argon. After
being cooled to ambient temperature, the reaction
mixture was dissolved in CH2Cl2 (100 ml) and washed
with water. The organic layer was separated, dried over
MgSO4, and evaporated to dryness in vacuo. The resi-
due was purified by column chromatography on silica
gel using hexane/AcOEt (5:1, Rf ¼ 0:18) as an eluent to
1
give 0.911 g (71%) of 2a as a colorless solid. H NMR
(CDCl3) d 6.64 (d, J ¼ 3:8 Hz, 2H), 7.12 (dd, J ¼ 7:9
Hz, 4.7 Hz, 2H), 7.60 (d, J ¼ 3:8 Hz, 2H), 7.64 (dd,
J ¼ 9:0 Hz, 7.2 Hz, 1H), 7.74 (d, J ¼ 1:8 Hz, 2H), 7.77
(t, J ¼ 1:8 Hz, 2H), 7.96 (dd, J ¼ 7:9 Hz, 1.7 Hz, 2H),
8.27 (t, J ¼ 2:1 Hz, 1H), 8.35 (dd, J ¼ 4:7 Hz, 1.7 Hz,
2H). 13C NMR (CDCl3) 101.94, 116.77, 119.24, 121.32,
121.63, 127.70, 129.04, 130.00, 139.22, 143.49, 147.38
ppm.
4.2.4. 1-(70-Azaindolyl)-3,5-dibromobenzene, 1,3-bis(70-
azaindolyl)-5-bromobenzene (Br-Bab-H, 2d) [16] and
1,3,5-tris(70-azaindolyl)benzene (Tab-H, 2g) [16]
1,3,5-Tribromobenzene (1.26 g, 4.00 mmol), 7-azain-
dole (1.89 g, 16.0 mmol), K2CO3 (2.21 g, 16.0 mmol),
and cupric sulfate hydrate (0.025 g, 0.10 mmol) were
mixed and heated at 180 °C for 8 h under argon. After
being cooled to ambient temperature, the reaction
mixture was dissolved in CH2Cl2 (200 ml) and washed
with water. The organic layer was separated, dried over
MgSO4, and evaporated to dryness in vacuo. The resi-
due was purified by column chromatography on silica
gel using hexane/AcOEt (5:1) as an eluent.
4.2.2. 1,3-Bis(70-azaindolyl)-5-fluorobenzene (F-Bab-H,
2b)
1,3-Dibromo-5-fluorobenzene (0.50 ml, 3.97 mmol),
7-azaindole (1.41 g, 11.9 mmol), K2CO3 (1.65 g, 11.9
mmol), and cupric sulfate hydrate (0.025 g, 0.10 mmol)
were mixed and heated at 200 °C for 9 h under argon.
After being cooled to ambient temperature, the reaction
mixture was dissolved in CH2Cl2 (100 ml) and washed
with water. The organic layer was separated, dried over
MgSO4, and evaporated to dryness in vacuo. The resi-
due was purified by column chromatography on silica
gel using hexane/AcOEt (2:1, Rf ¼ 0:50) as an eluent to
give 0.817 g (63%) of 2b as a colorless solid, m.p. 180–
184 °C. IR (KBr) 3140, 3104, 3040, 3010, 1616, 1591,
1522, 1483, 1434, 1412, 1360, 1272, 1208, 1180, 1040,
4.2.4.1. 1-(70-Azaindolyl)-3,5-dibromobenzene. Colorless
solid (0.553 g, 39%, Rf ¼ 0:58), m.p. 73–74 °C. IR (KBr)
3071, 1585, 1558, 1517, 1480, 1452, 1405, 1353, 1278,
1151, 1097, 847, 794, 777, 767, 756, 745, 711, 675, 657
cmꢁ1. 1H NMR (CDCl3) d 6.63 (d, J ¼ 3:9 Hz, 1H), 7.14
(dd, J ¼ 7:7 Hz, 4.7 Hz, 1H), 7.45 (d, J ¼ 3:9 Hz, 1H),
7.56–7.59 (m, 1H), 7.93 (dd, J ¼ 7:7 Hz, 1.5 Hz, 1H),
1
1002, 892, 877, 846, 791, 764, 732, 674, 516 cmꢁ1. H

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K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
7.99 (d, J ¼ 4:2 Hz, 2H), 8.37 (dd, J ¼ 4:7 Hz, 1.5 Hz,
1H). 13C NMR (CDCl3) 103.02, 117.29, 121.69, 123.05,
124.89, 126.61, 129.21, 131.22, 140.31, 143.75, 147.25
ppm. GC-MS (m=z): 352 (Mþ). HRMS Found:
348.8982. C14H9Br2N Calc.: 348.9102.
gel using hexane/AcOEt (10:1, Rf ¼ 0:18) as an eluent to
give 0.449 g (73%) of 2e as a colorless solid, m.p. 137–
138 °C. IR (KBr) 3108, 3039, 1613, 1595, 1523, 1489,
1412, 1364, 1300, 1272, 1236, 1153, 1114, 964, 889, 828,
1
798, 775, 759, 717 cmꢁ1. H NMR (CDCl3) d 6.68 (d,
J ¼ 3:6 Hz, 2H), 7.16 (dd, J ¼ 7:8 Hz, 4.7 Hz, 2H), 7.63
(d, J ¼ 3:6 Hz, 2H), 7.97 (dd, J ¼ 7:8 Hz, 1.6 Hz, 2H),
8.04 (d, J ¼ 1:2 Hz, 2H), 8.37 (dd, J ¼ 4:7 Hz, 1.6 Hz,
2H), 8.70 (t, J ¼ 1:2 Hz, 1H). 13C NMR (CDCl3) 102.90,
117.16 (q, J ¼ 3:9 Hz), 117.23, 121.31, 121.77, 125.30,
126.99, 129.22, 132.43 (q, J ¼ 33 Hz), 139.75, 143.74,
147.41 ppm. HRMS Found: 378.1089. C21H13N4F3
Calc.: 378.1092.
4.2.4.2. 1,3-Bis(70-azaindolyl)-5-bromobenzene (Br-Bab-
H, 2d) [16]. Colorless solid (0.499 g, 32%, Rf ¼ 0:38),
1
m.p. 212–214 °C. H NMR (CDCl3) d 6.66 (d, J ¼ 3:8
Hz, 2H), 7.14 (dd, J ¼ 7:8 Hz, 4.7 Hz, 2H), 7.58 (d,
J ¼ 3:8 Hz, 2H), 7.95 (dd, J ¼ 7:8 Hz, 1.7 Hz, 2H), 7.97
(d, J ¼ 1:9 Hz, 2H), 8.35 (t, J ¼ 1:9 Hz, 1H), 8.38 (dd,
J ¼ 4:7 Hz, 1.7 Hz, 2H). 13C NMR (CDCl3) 102.60,
117.06, 117.11, 121.70, 122.85, 123.53, 127.10, 129.10,
140.01, 143.60, 147.34 ppm.
4.2.5. 1,3-Bis(70-azaindolyl)-5-methoxybenzene (MeO-
Bab-H, 2f)
4.2.4.3. 1,3,5-Tris(70-azaindolyl)benzene (Tab-H, 2g)
[16]. Colorless solid (0.209 g, 12%, Rf ¼ 0:10), m.p.
To a suspension of 2c (0.161 g, 0.41 mmol) and cop-
per(I) bromide (0.059 g, 0.41 mmol) in DMF (0.75 ml)
was added a solution of sodium (0.095 g, 0.42 mmol)
and methanol (15 ml). The mixture was refluxed for 24
h. After being cooled to ambient temperature, the re-
action mixture was dissolved in CH2Cl2 (50 ml) and
washed with water. The organic layer was separated,
dried over MgSO4, and evaporated to dryness in vacuo.
The residue was purified by column chromatography on
silica gel using hexane/AcOEt (5:1) to give 0.119 g (85%)
of 2f as a colorless solid, m.p. 120–122 °C. IR (KBr)
3127, 3034, 2924, 1610, 1522, 1490, 1415, 1356, 1275,
1
220–222 °C. H NMR (CDCl3) d 6.67 (d, J ¼ 3:6 Hz,
3H), 7.14 (dd, J ¼ 7:7 Hz, 4.7 Hz, 3H), 7.70 (d, J ¼ 3:6
Hz, 3H), 7.97 (dd, J ¼ 7:7 Hz, 1.7 Hz, 3H), 8.34 (s, 3H),
8.36 (dd, J ¼ 4:7 Hz, 1.7 Hz, 3H). 13C NMR (CDCl3)
102.27, 116.01, 116.92, 121.79, 127.62, 129.05, 139.81,
143.56, 147.50 ppm.
4.2.4.4. 1,3-Dibromo-5-trifluoromethylbenzene (1e) [26].
A solution of 5-(trifluoromethyl)-1,3-phenylenediamine
(0.528 g, 3.00 mmol) in aq 48% HBr solution (100 ml)
was stirred for 12 h at room temperature. A solution of
sodium nitrite (1.67 g, 24 mmol) in water (50 ml) was
added dropwise to the reaction mixture over 60 min at 0
°C. After the reaction mixture was stirred at 0 °C for 30
min, a suspension of copper(I) bromide (1.38 g, 9.6
mmol) in aq 48% HBr solution (80 ml) was added
dropwise to the mixture over 1 h. After the reaction
mixture was stirred at 70 °C for 1 h, the mixture was
poured into ice water (100 ml), stirred for 30 min, and
extracted with CH2Cl2 (300 ml). The extract was washed
with water, dried over anhydrous MgSO4, and concen-
trated. The residue was chromatographed on silica gel
using hexane as an eluent to give 1e (0.554 g, 61%) as a
colorless solid; m.p. 41–43 °C. 1H NMR (CDCl3) d
7.68–7.69 (m, 2H), 7.83–7.84 (m, 1H). 13C NMR
(CDCl3) 120.38, 123.33, 127.26 (q, J ¼ 3:8 Hz), 133.56
(q, J ¼ 34 Hz), 137.47 ppm.
1
1208, 1057, 756, 708 cmꢁ1. H NMR (CDCl3) d 3.92 (s,
3H, CH3O), 6.61 (d, J ¼ 3:9 Hz, 2H), 7.11 (dd, J ¼ 7:7
Hz, 4.7 Hz, 2H), 7.40 (d, J ¼ 1:9 Hz, 2H), 7.58 (d,
J ¼ 3:9 Hz, 2H), 7.85 (t, J ¼ 1:9 Hz, 1H), 7.94 (dd,
J ¼ 7:7 Hz, 1.6 Hz, 2H), 8.36 (dd, J ¼ 4:7 Hz, 1.6 Hz,
2H). 13C NMR (CDCl3) 55.66 (CH3O), 101.84, 107.41,
111.35, 116.67, 121.59, 1127.59, 128.88, 139.83, 143.39,
147.36, 160.50 ppm. HRMS Found: 340.1320.
C21H16N4O Calc.: 340.1324.
4.3. Synthesis of Re(I) complexes 3
4.3.1. Re(Bab)(CO)3 complex (3a)
Re2(CO)10 (111 mg, 0.17 mmol) and 2a (106 mg, 0.34
mmol) were refluxed in diglyme (10 ml) for 24 h under
argon. After the solvent was removed, the resulting
residue was washed with CH2Cl2 (15 ml) to give 147 mg
(74%) of 3a as a pale yellow solid, m.p. (dec.) 280 °C. IR
(KBr) 1995 (CO), 1885 (CO), 1869 (CO), 1518, 1429,
4.2.4.5. 1,3-Bis(70-azaindolyl)-5-trifluoromethylbenzene
(CF3-Bab-H, 2e). The compound 1e (0.492 g, 1.62
mmol), 7-azaindole (0.574 g, 4.86 mmol), K2CO3 (0.672
g, 4.86 mmol), and cupric sulfate hydrate (0.006 g) were
mixed and heated at 200 °C for 13 h under argon. After
being cooled to ambient temperature, the reaction
mixture was dissolved in CH2Cl2 (200 ml) and washed
with water. The organic layer was separated, dried over
MgSO4, and evaporated to dryness in vacuo. The resi-
due was purified by column chromatography on silica
1
1227, 803, 711 cmꢁ1. H NMR (DMSO-d6) d 6.93 (d,
J ¼ 3:8 Hz, 2H), 7.20 (t, J ¼ 7:8 Hz, 1H), 7.33 (d,
J ¼ 7:8 Hz, 2H), 7.38 (dd, J ¼ 7:6 Hz, 5.3 Hz, 2H), 8.33
(d, J ¼ 7:6 Hz, 2H), 8.53 (d, J ¼ 3:8 Hz, 2H), 9.21 (d,
J ¼ 5:3 Hz, 2H). 13C NMR (DMSO-d6) 104.55, 113.37,
118.19, 123.45, 126.24, 129.18, 132.48, 143.18, 143.50,
147.53, 149.66, 196.12 (CO), 198.59 (CO) ppm. HRMS
Found: 586.0624. C23H13N4O3Re +Hþ Calc.: 586.0624.
Anal. Found: C, 47.11; H, 2.40; N, 9.50.

K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
1673
C23H13N4O3Re ꢄ 0.3H2O Calc.: C, 47.17; H, 2.35; N,
ppm. HRMS Found: 658.9712. C23H12BrN4O3 Re + Hþ
Calc.: 658.9728. Anal. Found: C, 42.58;H, 2.09; N, 8.54.
C23H12BrN4O3Re ꢄ 0.2H2O Calc.: C, 41.72; H, 1.89; N,
8.46.
9.57.
4.3.2. Re(F-Bab)(CO)3 complex (3b)
Re2(CO)10 (111 mg, 0.17 mmol) and 2b (112 mg, 0.34
mmol) were refluxed in diglyme (10 ml) for 24 h under
argon. After the solvent was removed, the resulting
residue was purified by column chromatography on
silica gel using CH2Cl2 to give 126 mg (62%) of 3b as a
pale yellow solid, m.p. (dec.) >300 °C. IR (KBr) 2962,
2921, 2001 (CO), 1893 (CO), 1882 (CO), 1586, 1520,
1468, 1443, 1423, 1359, 1326, 1293, 1260, 1202, 1121,
1080, 1020, 960, 921, 870, 825, 802, 791, 762, 728, 718,
621 cmꢁ1. 1H NMR (DMSO-d6) d 6.95 (dd, J ¼ 3:9 Hz,
1.2 Hz, 2H), 7.32 (d, J ¼ 11 Hz, 2H), 7.49 (ddd, J ¼ 7:8
Hz, 5.4 Hz, 1.2 Hz, 2H), 8.33 (d, J ¼ 7:8 Hz, 2H), 8.52
(d, J ¼ 3:9 Hz, 2H), 9.21 (d, J ¼ 5:4 Hz, 2H). 13C NMR
(DMSO-d6) 100.67 (d, J ¼ 24 Hz), 104.99, 118.38,
123.35, 129.06, 132.52, 136.74 (d, J ¼ 14 Hz), 143.19 (d,
J ¼ 11 Hz), 147.35, 149.58, 195.68 (CO), 198.17 (CO)
ppm. HRMS Found: 599.0540. C23H12N4O3FRe Calc.:
598.0451.
4.3.5. Re(CF3-Bab)(CO)3 complex (3e)
Re2(CO)10 (111 mg, 0.17 mmol) and 2e (129 mg, 0.34
mmol) were refluxed in diglyme (10 ml) for 20 h under
argon. After the solvent was removed, the resulting
residue was purified by column chromatography on
silica gel using CH2Cl2 as an eluent to give 149 mg (68%)
of 3e as a pale yellow solid, m.p. (dec.) 270 °C. IR (KBr)
2002 (CO), 1888 (CO), 1880 (CO), 1429, 1338, 1208,
1161, 1117, 804, 734 cmꢁ1. 1H NMR (DMSO-d6) d 6.99
(d, J ¼ 3:8 Hz, 2H), 7.41 (dd, J ¼ 7:7 Hz, 5.3 Hz, 2H),
7.61 (s, 2H), 8.35 (d, J ¼ 7:7 Hz, 2H), 8.72 (d, J ¼ 3:8
Hz, 2H), 9.24 (d, J ¼ 5:3 Hz, 2H). 13C NMR (DMSO-
d6) 105.50, 108.99, 118.74, 123.63, 129.40, 132.86,
143.95, 147.64, 150.01, 195.89 (CO), 198.02 (CO) ppm
one aromatic carbon and CF3 carbon were not detective
due to the low solubility of 3e. HRMS Found: 648.0413.
C24H12F3N4O3Re Calc.: 648.0419. Anal. Found: C,
44.73; H, 2.17; N, 8.25. C24H12F3N4O3Re Calc.: C,
44.51; H, 1.87; N, 8.65.
4.3.3. Re(Cl-Bab)(CO)3 complex (3c)
Re2(CO)10 (111 mg, 0.17 mmol) and 2c (117 mg, 0.34
mmol) were refluxed in diglyme (10 ml) for 24 h under
argon. After the solvent was removed, the resulting
residue was washed with CH2Cl2 (10 ml) to give 137 mg
(65%) of 3c as a yellow solid, m.p. (dec.) >300 °C. IR
(KBr) 2000 (CO), 1890 (CO), 1867 (CO), 1561, 1468,
4.3.6. Re(MeO-Bab)(CO)3 complex (3f)
Re2(CO)10 (226 mg, 0.35 mmol) and 2f (236 mg, 0.69
mmol) were refluxed in diglyme (20 ml) for 24 h under
argon. After the solvent was removed, the resulting
residue was purified by column chromatography on
silica gel using CH2Cl2 as an eluent to give 302 mg (72%)
of 3f as a pale yellow solid, m.p. (dec.) >300 °C. IR
(KBr) 1996 (CO), 1879 (CO), 1860 (CO), 1591, 1427,
1425, 1354, 1315, 1293, 1270, 1203, 837, 792, 716 cmꢁ1
.
1H NMR (DMSO-d6) d 6.96 (d, J ¼ 3:8 Hz, 2H), 7.40
(dd, J ¼ 7:7 Hz, 5.5 Hz, 2H), 7.46 (s, 2H), 8.34 (dd,
J ¼ 7:7 Hz, 1.2 Hz, 2H), 8.59 (d, J ¼ 3:8 Hz, 2H), 9.22
(dd, J ¼ 5:5 Hz, 1.2 Hz, 2H). 13C NMR (DMSO-d6)
105.24, 112.89, 118.58, 123.59, 129.26, 130.96, 132.70,
144.05, 147.58, 149.79, 195.92 (CO), 198.18 (CO) ppm.
HRMS Found: 614.0144. C23H12N4O3ClRe Calc.:
614.0155. Anal. Found: C, 44.23;H, 2.14; N, 8.89.
C23H12N4O3ClRe ꢄ 0.5H2O Calc.: C, 44.34; H, 2.10; N,
8.99.
1
1361, 1203, 803 cmꢁ1. H NMR (DMSO-d6) d 3.84 (s,
3H, CH3O), 6.92 (d, J ¼ 3:9 Hz, 2H), 7.00 (s, 2H), 7.37
(dd, J ¼ 7:7 Hz, 5.4 Hz, 2H), 8.32 (dd, J ¼ 7:7 Hz, 1.4
Hz, 2H), 8.58 (d, J ¼ 3:9 Hz, 2H), 9.20 (dd, J ¼ 5:4 Hz,
1.4 Hz, 2H). 13C NMR (DMSO-d6) 55.49 (CH3O),
100.34, 104.24, 117.89, 123.19, 129.04, 132.10, 132.46,
143.14, 147.38, 149.30, 158.79, 195.83 (CO), 198.42 (CO)
ppm. HRMS Found: 611.0723. C24H15N4O4Re +Hþ
Calc.: 611.0729. Anal. Found: C, 46.55; H, 2.64; N, 8.92.
C24H15N4O4Re ꢄ 0.5H2O Calc.: C, 46.60; H, 2.61; N,
9.06.
4.3.4. Re(Br-Bab)(CO)3 complex (3d)
Re2(CO)10 (137 mg, 0.21 mmol) and 2d (164 mg, 0.42
mmol) were refluxed in diglyme (15 ml) for 24 h under
argon. After the solvent was removed, the resulting
residue was washed with CH2Cl2 (15 ml) to give 225 mg
(81%) of 3d as a yellow solid, m.p. (dec.) >300 °C. IR
(KBr): 1999 (CO), 1887 (CO), 1868 (CO), 1556, 1521,
1467, 1427, 1354, 1314, 1292, 1270, 1202, 802, 766, 728
cmꢁ1. 1H NMR (DMSO-d6) d 6.94 (d, J ¼ 3:9 Hz, 2H),
7.39 (dd, J ¼ 7:8 Hz, 5.4 Hz, 2H), 7.56 (s, 2H), 8.35 (dd,
J ¼ 7:8 Hz, 1.4 Hz, 2H), 8.60 (d, J ¼ 3:9 Hz, 2H), 9.23
(dd, J ¼ 4:5 Hz, 1.4 Hz, 2H). 13C NMR (DMSO-d6)
105.18, 115.55, 118.52, 118.86, 123.55, 123.82, 129.24,
132.65, 144.25, 147.55, 149.74, 195.90 (CO), 198.12 (CO)
4.3.7. Re(Tab)(CO)3 complex (3g)
Re2(CO)10 (196 mg, 0.30 mmol) and 2g (171 mg, 0.40
mmol) were refluxed in diglyme (30 ml) for 24 h under
argon. After the solvent was removed, the resulting
residue was purified by column chromatography on
silica gel using CH2Cl2 as an eluent to give 237 mg (93%)
of 3g as a pale yellow solid, m.p. (dec.) >300 °C. IR
(KBr) 2925, 1995 (CO), 1883 (CO), 1863 (CO), 1588,
1519, 1467, 1453, 1418, 1347, 1300, 1269, 1225, 1205,
894, 802, 765, 715 cmꢁ1. 1H NMR (DMSO-d6) d 6.74 (d,
J ¼ 3:6 Hz, 1H), 6.96 (d, J ¼ 3:8 Hz, 2H), 7.18 (dd,

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K. Tani et al. / Journal of Organometallic Chemistry 689 (2004) 1665–1674
[7] A. Vogler, H. Kunkely, Angew. Chem. Int. Ed. Engl. 20 (1981)
469.
J ¼ 8:0 Hz, 5.0 Hz, 1H), 7.40 (dd, J ¼ 7:6 Hz, 5.5 Hz,
2H), 7.82 (s, 2H), 8.05-8.10 (m, 2H), 8.28 (m, 1H), 8.35
(d, J ¼ 7:6 Hz, 2H), 8.60 (d, J ¼ 3:8 Hz, 2H), 9.26 (d,
J ¼ 5:5 Hz, 2H). 13C NMR (DMSO-d6) 101.27, 104.94,
109.44, 116.73, 118.40, 121.22, 123.53, 129.07, 129.23,
129.29, 132.61, 137.02, 141.47, 143.09, 143.38, 147.21,
147.78, 149.80, 196.09 (CO), 198.48 (CO) ppm. HRMS
Found: 697.0999 C30H17N6O3Re + Hþ Calc.: 697.0998.
Anal. Found: C, 51.77; H, 2.79; N, 11.64.
C30H17N6O3Re Calc.: C, 51.79; H, 2.46; N, 12.08.
[8] H. Kunkely, A. Merz, A. Vogler, J. Am. Chem. Soc. 105 (1983)
7241.
[9] A. Vogler, H. Kunkely, Inorg. Chim. Acta 45 (1980) L265.
[10] T.G. Kotch, A.J. Lees, S.J. Fuerniss, K.I. Papathomas, Chem.
Mater. 4 (1992) 675.
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4.4. X-ray structure analysis
€
€
€
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All measurements for 3a, 3b, 3e, and 3f were made on
a Rigaku RAXIS-RAPID imaging plate diffractometer
with graphite-monochromated Mo Ka radiation. The
structures of 3a, 3b, 3e, and 3f were solved by direct
methods and expanded using Fourier techniques. The
non-hydrogen atoms were refined anisotropically. The
H atoms were placed in idealized positions and allowed
to ride with the C atoms to which each was bonded.
Crystallographic details are given in Table 3. Crystal-
lographic data (excluding structure factors) for the
structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-224950 for 3a,
no. CCDC-224951 for 3b, no. CCDC-224952 for 3e, and
CCDC-224953 for 3f. Copies of the data can be ob-
tained free of charge on application to CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK [fax: (int) +44-1223/
336-033; email: deposit@ccdc.cam.ac.uk].
€
Stuckl, H.W. Schmalle, J. Phys. Chem. A 101 (1997) 2946;
€
(d) F.W.M. Vanhelmont, M.V. Rajasekharan, H.U. Gudel, S.C.
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€
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