Synthesis, characterization, and properties of anthracene-bridged bimetallic ruthenium vinyl complexes [rucl(co)(pme3) 3]2(μ-CH=CH-anthracene-CHdCH)

Article abstract of DOI:10.1021/om200622q

Four anthracene-based bimetallic ruthenium vinyl complexes, in which two ruthenium units are attached at different positions (the 9,10-, 1,5-, 2,6-, and 1,8-positions) of the anthracene moiety, have been synthesized by treating the appropriate anthracene-based ethynes with [RuHCl(CO)-(PPh₃) ₃]. These bimetallic complexes have been thoroughly characterized by NMR, X-ray diffraction, and elemental analysis. According to the single-crystal X-ray structures, the 2,6-disubstituted ruthenium vinyl complex has a more planar structure compared with the 9,10-disubstituted complex, possibly because it has less steric hindrance. Furthermore, we have investigated the optical electronic properties of these complexes, such as their UV/vis absorption spectra, fluorescence spectra, and electrochemical properties. The optical electronic results indicated that the 2,6-disubstituted ruthenium vinyl complex displayed the strongest fluorescence emission due to the more planar structure of its organic conjugated bridge, and the electrochemical studies showed that the two ruthenium centers displayed obvious differences in electronic communication when they are located at different positions on the anthracene unit, with the 9,10-and 1,8-disubstituted ruthenium vinyl complexes exhibiting better electronic communication and higher stability of the mixed-valence complex than the 1,5-and 2,6-disubstituted complexes. 2011 American Chemical Society.

Full text of DOI:10.1021/om200622q

ARTICLE
pubs.acs.org/Organometallics
Synthesis, Characterization, and Properties of
Anthracene-Bridged Bimetallic Ruthenium Vinyl Complexes
[RuCl(CO)(PMe3)3]2(μ-CHdCH-anthracene-CHdCH)
Ya-Ping Ou, Chuanyin Jiang, Di Wu, Jianlong Xia, Jun Yin,* Shan Jin, Guang-Ao Yu, and Sheng Hua Liu*
Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University,
Wuhan 430079, People’s Republic of China
S Supporting Information
b
ABSTRACT: Four anthracene-based bimetallic ruthenium vinyl
complexes, in which two ruthenium units are attached at
different positions (the 9,10-, 1,5-, 2,6-, and 1,8-positions) of
the anthracene moiety, have been synthesized by treating the
appropriate anthracene-based ethynes with [RuHCl(CO)-
(PPh3)3]. These bimetallic complexes have been thoroughly
characterized by NMR, X-ray diffraction, and elemental analysis.
According to the single-crystal X-ray structures, the 2,6-disub-
stituted ruthenium vinyl complex has a more planar structure
compared with the 9,10-disubstituted complex, possibly because
it has less steric hindrance. Furthermore, we have investigated
the optical electronic properties of these complexes, such as their
UV/vis absorption spectra, fluorescence spectra, and electro-
chemical properties. The optical electronic results indicated that the 2,6-disubstituted ruthenium vinyl complex displayed the
strongest fluorescence emission due to the more planar structure of its organic conjugated bridge, and the electrochemical studies
showed that the two ruthenium centers displayed obvious differences in electronic communication when they are located at different
positions on the anthracene unit, with the 9,10- and 1,8-disubstituted ruthenium vinyl complexes exhibiting better electronic
communication and higher stability of the mixed-valence complex than the 1,5- and 2,6-disubstituted complexes.
’ INTRODUCTION
Polycyclic aromatic hydrocarbons (PAHs), as classical con-
jugated systems, have been widely applied in organic semicon-
ductor materials, such as organic light-emitting diodes (OLEDs),
field-effect transistors (FETs), and solar cells.7 Acenes, as the
simplest PAHs, have been widely used as optical electronic
materials for electronic devices, due to their simple synthesis
and easy functionalization.8 In the field of organometallic mo-
lecular wires, acenes have been applied as organic bridging units,
and their mediation of electron transfer has been investigated.
For example, some research groups have reported naphthylene-
and anthracene-based bimetallic complexes and have studied
their electron-transfer properties.9 Recently, Yip also described
tetracene-based bimetallic complexes.10 However, from a survey
of the literature, we noted that the metal atoms were often
introduced at the active sites of the acene, such as the 1,4-
positions of naphthylene, the 9,10-positions of anthracene, and
the 5,12-positions of tetracene, presumably because of the ease of
synthesis. In contrast, the introduction of metal atoms at the
terminal positions of the acene, such as the 1,5-, 2,6-, and 1,8-
positions of anthracene, is synthetically challenging. Recently,
Molecular wires provide the theoretical and technological
foundations of molecular electronic devices and have been widely
applied in the development of molecular-level electronic
computers.1 Molecular wires based on conjugated organic mol-
ecules have attracted increasing attention as a result of their easy
functionalization, convenient controllability, and low cost of
organic molecules. Usually, the conjugated organic molecules
have been directly linked to electrode surfaces as the simplest
method for evaluating electron transfer, although this is incon-
venient to perform on a large scale.2 Therefore, as models of
molecular wires, linear conjugated organic molecules with two
redox-active organometallic termini, in which two metal atoms
are linked by a conjugated organic bridge ligand, can be
advantageously applied in investigations of electron transfer by
electrochemical methods.3 Consequently, there have been many
studies on conjugated organometallic molecular wires in recent
years. The electronic interaction between the two redox-active
metal centers mainly depends on the conjugated organic bridge
ligand.4 Previous research in this area has mainly focused on
linear conjugated metal complexes with sp- and sp2-hybridized
organic bridges, such as oligoethynyl-5 and oligovinyl-bridged6
metal complexes.
Received: July 11, 2011
Published: October 11, 2011
r
2011 American Chemical Society
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Abru~na reported a series of bipyridine ruthenium complexes
differently substituted at the 1,5-, 2,6-, and 2,7-positions.9b In our
recent work, we reported a series of anthracene quinone based
bimetallic ruthenium vinyl complexes (Scheme 1), in which the
ruthenium atoms were attached at the 1,4-, 1,5-, 2,6-, and 1,8-
positions of the anthracene quinone.11 The electrochemical
properties of these complexes showed that the interaction
between the two metal centers was not very obvious. This
research inspired us to explore the properties of 9,10-, 1,5-,
2,6-, and 1,8-disubstituted anthracene bimetallic ruthenium vinyl
complexes. In the work described herein, we have designed and
synthesized four bimetallic ruthenium vinyl complexes incorpor-
ating anthracene units (Scheme 2), in which the ruthenium
atoms were introduced at the 9,10-, 1,5-, 2,6-, and 1,8-positions of
anthracene through vinyl bridges. These bimetallic complexes
have been thoroughly characterized by NMR, X-ray diffraction,
and elemental analysis. Furthermore, we have investigated their
UV/vis absorption and fluorescence spectra, as well as their
electrochemical properties. Their optical electronic properties
indicated that the 2,6-disubstituted ruthenium vinyl complex
displayed the strongest fluorescent emission, while the electro-
chemical studies showed that two ruthenium centers located at
different positions on the anthracene unit had markedly different
degrees of electronic communication, with the 9,10- and 1,8-dis-
ubstituted ruthenium vinyl complexes exhibiting better electro-
nic communication and greater stability of the mixed-valence
system than the 1,5- and 2,6-disubstituted complexes.
catalyst. The respective bis[(trimethylsilyl)ethynyl]anthracenes
3aꢀd were obtained in yields of 47ꢀ85%. After the TMS groups
were removed in methanolic KOH solution, the bis(ethynyl)-
anthracenes 4aꢀd were obtained in yields of 39ꢀ86%. The
bis(ethynyl)anthracenes 4aꢀd were then reacted with the
ruthenium hydride complex [RuHCl(CO)(PPh3)3] to give
the insertion products [(PPh3)2Cl(CO)Ru]2(μ-CHdCH-ant-
CHdCH), which were not isolated because these five-coordi-
nated complexes are air-sensitive, especially in solution. Thus,
PMe3 was added directly to give the corresponding six-coordi-
nated complexes 1aꢀd. These complexes were characterized by
1H, 13C, and 31P NMR. Although complexes 1aꢀd have similar
structures, the resonance signals such as those of the CHdCH
1
protons in the H NMR spectra and of PMe3 in the 31P NMR
spectra displayed obvious differences, which can be attributed
to the differences in substitution positions on the anthracene
moiety. Fortunately, we were able to obtain single-crystal X-ray
structures of the 9,10- and 2,6-disubstituted anthracene bime-
tallic ruthenium vinyl complexes 1a,c.
X-ray Structures of 1a,c. Single crystals of complexes 1a,c
suitable for X-ray analysis were obtained by slow diffusion of
hexane into solutions in dichloromethane and chloroform,
respectively. The single-crystal X-ray structures of complexes
1a,c are depicted in Figures 1 and 2, respectively. The crystal-
lographic details are given in Table 1. Selected bond distances
and angles for 1a,c are presented in Tables 2 and 3, respectively.
According to the crystal structure of complex 1a in Figure 1A, its
C11ꢀC12 and C27ꢀC28 bond lengths are 1.335 and 1.318 Å,
respectively. These bond lengths lie between those of carbonꢀ
carbon single and triple bonds, indicating that they correspond to
carbonꢀcarbon double bonds. Furthermore, we found these
carbonꢀcarbon double bonds to be in a trans configuration. As
shown in Figure 1, two carbonꢀcarbon double bonds are not
coplanar with the anthracene moiety, possibly because of steric
hindrance. The two dihedral angles between the planes defined
by C11ꢀC12ꢀC13 and C28ꢀC27ꢀC20 with respect to the
central benzene ring of the anthracene moiety are 40.76 and
66.80°, respectively, further confirming that the anthracene and
vinyl units are not coplanar, as shown in Figure 1B.
’ RESULTS AND DISCUSSION
Syntheses and Characterization. The general synthetic
route for the preparation of anthracene-based bimetal ruthenium
vinyl complexes 1aꢀd is outlined in Scheme 3. The regioiso-
meric anthracene bromides or iodides 2aꢀd were selected as
starting materials to perform Sonogashira coupling reactions
with (trimethylsilyl)acetylene in the presence of a Pd/Cu
Scheme 1. Anthraquinone-Based Binuclear Ruthenium
Vinyl Complexes
In Figure 2, the C11ꢀC12 and C11aꢀC12a bond lengths in
complex 1c are both seen to be 1.318 Å, indicating that they
correspond to carbonꢀcarbon double bonds and are in a trans
configuration. At the same time, the Ru1ꢀRu1a distance in
complex 1c is 15.924 Å, which is longer than that in complex 1a
Scheme 2. Anthracene-Based Binuclear Ruthenium Vinyl Complexes 1aꢀd
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Scheme 3a
a Reaction reagents and conditions: (i) TMSA, Pd(PPh3)4, CuI, toluene or THF/Et3N; (ii) KOH, THF/MeOH; (iii) RuHCl(CO)(PPh3)3, PMe3,
CH2Cl2.
Figure 1. Single-crystal structure of complex 1a: (A) top view; (B) side view; (C) packing view.
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Figure 2. Single-crystal structure of complex 1c: (A) top view; (B) side view; (C) packing view.
(11.847 Å). According to Figure 2A, complex 1c has a very
symmetrical structure. Furthermore, in comparison with our
reported single-crystal structure of [{Ru(PMe3)2(CO)Cl}2(μ-
CHdCH-Aq-CHdCH-1,5)] (Aq = anthraquinone),11 the core
ligand anthracene has a planar rigid structure; the anthracene and
vinyl units are also coplanar in Figure 2B. Such coplanarity of the
anthracene and vinyl units is favorable for forming strong πꢀπ
interactions between molecules.
UV/vis Absorption and Fluorescence Spectra. Figure 3A
shows the UV/vis absorption spectra of complexes 1aꢀd in
CH2Cl2 at room temperature. According to the data in Table 4,
the 9,10-, 1,5-, and 1,8-disubstituted ruthenium vinyl complexes
1a,b,d exhibited three very similar absorption bands. However,
the 2,6-disubstituted ruthenium vinyl complex 1c showed a
completely different UV/vis absorption spectrum. For example,
complexes 1a,b,d showed a rather intense electronic transition at
about 275 nm, while the intense electronic transition of complex
1c appeared at 327 nm. Moreover, the absorption maxima of
complex 1c showed obvious red shifts, which indicated that the
2,6-disubstituted complex 1c had more extensive conjugation. In
addition, the other broad absorption bands of complexes 1aꢀd at
400ꢀ500 nm can be attributed to MLCT (metal-to-ligand
charge transfer), which is similar to that for bimetal complexes
of anthraquinone-based bridging ligands.11
result of its greater conjugation and the coplanarity of the organic
bridge. In general, increasing the molecular rigidity and copla-
narity will increase the fluorescence intensity and improve the
fluorescence quantum yield, which is possibly attributed to an
increase in π-electronic conjugation. Furthermore, the coplanar-
ity of the conjugated anthracene-based vinyl bridge was favorable
for molecular packing, which was in good agreement with the
single-crystal X-ray structure. In Figure 2C, the packing view of
the 2,6-disubstituted ruthenium vinyl complex shows a highly
ordered intermolecular interaction, while no such interaction is
observed in the packing view of the 9,10-disubstituted ruthenium
vinyl complex 1a, as shown in Figure 1C.
The PL efficiency (ΦPL) of complexes 1aꢀd in CH2Cl2
solutions was measured by using quinine sulfate (ca. 1 ꢁ 10ꢀ5
M solution in 0.1 M H2SO4, assuming ΦPL of 0.55) as a standard.
Electrochemical Properties. The interaction between the
two metal centers linked via an anthracene-based vinyl bridge
was examined by electrochemical methods. Cyclic voltammetry
(CV) and square-wave voltammetry (SWV) were used to study
the electrochemical behavior of complexes 1aꢀd (in 0.1 M
Bu4NPF6 in CH2Cl2). Cyclic and square-wave voltammograms
(CVs and SWVs) for complexes 1aꢀd are depicted in Figure 4.
As shown in Figure 4A, all of the complexes underwent two
successive single-electron oxidation processes in CH2Cl2 and
exhibited two pairs of independent single-electron oxidation
waves, corresponding to oxidation of RuII,II to RuII,III and
then of RuII,III to RuIII,III, respectively. For complex 1a, the potential
difference ΔE was 393 mV with a corresponding Kc value of
4.57 ꢁ 106 when the two ruthenium terminal groups were
attached at the active 9,10-positions of anthracene, which
indicated that electron density can be easily transferred from
one ruthenium center to the other. Furthermore, in comparison
Subsequently, the fluorescence properties of complexes 1aꢀd
were investigated in dichloromethane solution (2 ꢁ 10ꢀ5 mol/
L) at room temperature. From the fluorescence properties of
complexes 1aꢀd shown in Figure 3B, it can be seen that the
complexes 1a,b,d displayed very weak fluorescence. In compar-
ison with complexes 1a,b,d, the 2,6-disubstituted ruthenium
vinyl complex 1c showed very strong fluorescence properties
and the highest fluorescence quantum yield, presumably as a
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Table 1. Crystal Data and Data Collection and Refinement
Table 3. Selected Bond Lengths (Å) and Angles (deg) for 1c
Parameters for 1a,ca
bond length (Å)
bond angle (deg)
complex 1a
complex 1c
formula
fw
C38H68Cl2O2P6Ru2 C42H70Cl14O2P6Ru2
C(11)ꢀC(12)
1.318(10)
1.495(10)
1.369(10)
1.430(9)
1.390(10)
2.085(6)
C(11)ꢀC(12)ꢀC(13)
126.6(7)
118.8(6)
132.1(6)
86.5(2)
1013.77
298(2)
1491.24
298(2)
C(12)ꢀC(13)
C(13)ꢀC(14)
C(14)ꢀC(15)
C(16)ꢀC(19)
Ru(1)ꢀC(11)
C(14)ꢀC(15)ꢀC(16)
C(12)ꢀC(11)ꢀRu(1)
C(11)ꢀRu(1)ꢀP(1)
C(11)ꢀRu(1)ꢀP(2)
C(11)ꢀRu(1)ꢀP(3)
temp (K)
cryst syst
space group
a (Å)
monoclinic
P21/c
monoclinic
P21/n
178.8(2)
84.0(2)
17.5343(11)
13.9458(9)
21.0762(13)
90.00
10.3117(19)
12.025(2)
27.538(5)
90.00
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
this bimetallic ruthenium complex displayed better electron
transfer, with a potential difference ΔE of 396 mV, as shown in
Table 5. According to the electrochemical data for complexes
1aꢀd, we found that the different positions of attachment of the
two ruthenium centers on the anthracene affects electronic
communication, with the 9,10- and 1,8-disubstituted ruthenium
vinyl complexes displaying stronger metalꢀmetal electron trans-
fer and greater stability of the mixed-valence system than the 1,5-
and 2,6-disubstituted complexes, possibly due to the lengths of
the conjugation pathways between the ruthenium centers. In
addition, from electrochemical properties of two bimetal com-
plexes containing different core ligands, we find the following:
(1) anthraquinone-based 1,5-Aq-diRu, 2,6-Aq-diRu, 1,8-Aq-
diRu, ΔE = 75 mV, 2,6-Aq-diRu has no clear sign of peak
separation, 100 mV, respectively; (2) anthracene-based 1,5-
Ant-diRu, 2,6-Ant-diRu, 1,8-Ant-diRu, ΔE = 250, 224, 396 mV,
respectively. We also found that these anthracene-based ruthe-
nium vinyl complexes had better electronic communication in
comparison with the anthracene quinone based ruthenium vinyl
complexes described in our previous report.11 This can be
attributed to two reasons: one is that the electron-withdrawing
carbonyl decreases the electronic interaction between the two
metal centers and the other is that, according to the crystal
structures of two series of bimetal complexes, the rigidity and
coplanarity of the anthracene bridging ligand are stronger than
those of the anthraquinone bridging ligand and lead to increasing
interaction between the two metal centers.
109.0590(10)
90.00
97.221(4)
90.00
V (Åꢀ3
)
4871.2(5)
4
3387.5(11)
2
Z
Dcalcd (g cmꢀ3
)
1.382
1.462
F(000)
2088
1508
cryst size (mm)
0.16 ꢁ 0.12 ꢁ 0.10 0.16 ꢁ 0.12 ꢁ 0.10
radiation, Mo Kα (Å)
abs coeff (mmꢀ1
0.710 73
0.710 73
1.170
)
0.956
θ range (deg)
1.78ꢀ25.50
48 568
1.85 to 25.01
19 848
total no. of rflns
no. of indep rflns
9057 (0.1216)
5969 (0.0671)
5969/0/307
0.0873
no. of data/restraints/params 9057/0/469
final R
0.0732
Rw
0.1333
0.1818
R (all data)
0.1315
0.1098
Rw (all data)
goodness of fit/F2
largest diff peak, hole (e Åꢀ3
a w = 1/[σ2(Fo)2 + (aP)2 + bP], where P = (Fo2 + Fc2)/3.
0.1512
0.1917
1.036
1.182
)
1.337, ꢀ0.772
0.871, ꢀ1.154
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 1a
bond length (Å)
bond angle (deg)
In conclusion, we have designed and synthesized four bime-
tallic ruthenium vinyl complexes containing an anthracene unit,
to which ruthenium subunits were attached at the 9,10-, 1,5-, 2,6-,
and 1,8-positions through vinyl bridges. The UV/vis absorption
spectra, fluorescence spectra, and electrochemical properties of
the complexes have been studied in detail. Their optical electro-
nic properties indicated that the 2,6-disubstituted ruthenium
vinyl complex displayed the strongest fluorescence emission
because of highly ordered intermolecular interactions. The
electrochemical studies showed that different locations of the
two ruthenium centers on the anthracene unit led to obvious
differences in electronic communication, with the 9,10- and 1,8-
disubstituted ruthenium vinyl complexes exhibiting better electro-
nic communication and higher stability of the mixed-valence
system than the 1,5- and 2,6-disubstituted complexes, possibly
due to the lengths of the conjugation pathways between the
ruthenium centers. Therefore, our studies highlight an interesting
difference in the properties of regioisomerically substituted acenes.
In this specific case, our research forms the basis for designing and
constructing larger π-system architectures as organic bridges in
organometallic molecular wires and should be helpful in under-
standing the electron transfer between different sites.
C(11)ꢀC(12)
1.335(8)
1.486(8)
1.489(8)
1.319(8)
1.839(9)
2.109(6)
C(11)ꢀC(12)ꢀC(13)
130.9(6)
125.8(6)
130.8(5)
176.60(19)
82.74(18)
86.39(18)
C(12)ꢀC(13)
C(20)ꢀC(27)
C(27)ꢀC(28)
Ru(1)ꢀC(10)
Ru(2)ꢀC(28)
C(28)ꢀC(27)ꢀC(20)
C(12)ꢀC(11)ꢀRu(1)
C(11)ꢀRu(1)ꢀP(1)
C(11)ꢀRu(1)ꢀP(2)
C(11)ꢀRu(1)ꢀP(3)
with the 9,10-disubstituted anthracene-based ethynyl bimetallic
ruthenium complexes, the bimetallic ruthenium vinyl complex
1a performed better.9 At the same time, the more extensive π
system of complex 1a led to better electronic interaction between
the ruthenium centers than we have reported for [RuCl(CO)-
(PMe3)3]2(μ-CHdCH-Ar-CHdCH) with 4,40-diethynylphe-
nyl as the spacer (ΔE = 296 mV, Kc = 1.04 ꢁ 105).12 However,
when the ruthenium subunits were attached to the two terminal
rings of the anthracene unit, the 1,5- and 2,6-disubstituted
complexes 1b,c showed lower potential differences ΔE (250
mV for complex 1b and 224 mV for complex 1c), while the data
for the 1,8-disubstituted ruthenium complex 1d confirmed that
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Figure 4. (A) Cyclic voltammograms (CV) of complexes 1aꢀd in
CH2Cl2/Bu4NPF6 at v = 0.1 V sꢀ1 and (B) square-wave voltammograms
(SWV) of complexes 1aꢀd at f = 10 Hz.
Table 5. Electrochemical Data for Complexes 1aꢀd
Ep1 (V)a
ip,a/ip,c
Ep2 (V)c
ΔE (mV)b
Kcd
b
complex
1a
1b
1c
1d
0.197
0.430
0.374
0.420
0.45
0.62
0.46
0.52
0.580
0.680
0.598
0.816
393
250
224
396
4.57 ꢁ 106
1.73 ꢁ 104
6.27 ꢁ 103
5.15 ꢁ 106
a From cyclic or square-wave voltammetry in 0.1 M CH2Cl2/n-Bu4NPF6
solutions at a scan rate of 100 mV/s for CV and 10 Hz for SWV.
b Anodic/cathodic peak current ratios. c Peak potential differences ΔE =
Ep ꢀ Ep . d The comproportionation constants, Kc, were calculated by
2
1
the formula Kc = exp(ΔE1/2/25.69) at 298 K.
Figure 3. (A) UVꢀvis absorption spectrum of compounds 1aꢀd
in CH2Cl2. (B) Fluorescence spectra of compounds 1aꢀd (2 ꢁ
10ꢀ5 mol/L) in CH2Cl2.
1,5-diiodoanthracene (2b),14 2,6-diiodoanthracene (2c),15,16 and 1,8-
diiodoanthracene (2d)17 were prepared by the procedures described in
the literature.
Synthesis of Bis((trimethylsilyl)ethynyl)anthracene. 9,10-
Bis((trimethylsilyl)ethynyl)anthracene (3a).18 To a stirred solution of
9,10-dibromoanthracene (2a; 1.0 g, 3.9 mmol), CuI (0.07 g, 0.39 mmol),
and Pd(PPh3)4 (0.45 g, 0.39 mmol) in triethylamine (60 mL) and THF
(100 mL) under an argon atmosphere was added (trimethylsilyl)-
acetylene (0.95 g, 9.75 mmol), and the mixture at 60 °C was refluxed
for 20 h. The cold solution was filtered through a bed of Celite. The
filtrate was evaporated under reduced pressure and purified by silica gel
column chromatography (petroleum ether) to give a red solid (0.91 g,
Table 4. Absorption Characteristics and Fluorescence
Quantum Yields of Complexes 1aꢀd in CH2Cl2 (2 ꢁ
10ꢀ5 mol/L)
absorption λmax (nm)/10‑4εmax
emission
λmax (nm) 102ΦPL
complex
(cm‑1 M‑1)
1a
1b
1c
244 (5.18), 276 (5.80), 437 (1.94)
245 (3.53), 276 (6.37), 423 (1.35)
264 (1.65), 314 (4.06), 327 (7.02),
348 (1.15) 366 (1.59), 386 (1.97),
420 (0.85), 442 (0.86)
545
486
475
0.062
0.236
0.897
1
85%). H NMR (400 MHz, CDCl3): δ (ppm) 0.42 (s, 18H, SiCH3),
7.60 (dd, J = 3.6 Hz, 4H), 8.57 (dd, J = 3.6 Hz, 4H).
1,5-Bis((trimethylsilyl)ethynyl)anthracene (3b).19 The procedure
for 3b was similar to that for 3a: 2b (1.0 g, 2.32 mmol), CuI (0.046 g,
0.24 mmol), Pd(PPh3)4 (0.28 g, 0.24 mmol), triethylamine (60 mL),
THF (60 mL), (trimethylsilyl)acetylene (0.56 g, 5.8 mmol). Yield: 0.60
g (70%) of a light yellow solid. 1H NMR (400 MHz, CDCl3): δ (ppm)
0.39 (s, 18H, SiCH3), 7.44 (t, J = 6.8 Hz, 2H), 7.75 (d, J = 6.8 Hz, 2H),
8.07 (d, J = 8 Hz, 2H), 8.88 (s, 2H).
1d
245 (3.49), 274 (5.57), 421 (0.97)
494
0.153
’ EXPERIMENTAL SECTION
General Materials. All manipulations were carried out at room
temperature under a nitrogen atmosphere using standard Schlenk
techniques, unless otherwise stated. Solvents were predried, distilled, and
degassed prior to use, except those for spectroscopic measurements, which
were of spectroscopic grade. The reagent 9,10-dibromoanthracene (2a)
was commercially available. The starting materials RuHCl(CO)(PPh3)3,13
2,6-Bis((trimethylsilyl)ethynyl)anthracene (3c).19 The procedure
for 3c was similar to that for 3a, with THF being replaced by toluene:
2c (2.0 g, 4.65 mmol), CuI (0.09 g, 0.46 mmol), Pd(PPh3)4 (0.54 g,
0.46 mmol), triethylamine (60 mL), THF (100 mL), (trimethylsilyl)-
acetylene (0.56 g, 11.6 mmol). Yield: 1.02 g (59%) of a light yellow solid.
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1H NMR (400 MHz, CDCl3): δ (ppm) 0.31 (s, 18H, SiMe3), 7.46 (dd,
J = 7.2 Hz, 2H), 7.91 (dd, J = 8.8 Hz, 2H), 8.14 (s, 2H), 8.30 (s, 2H).
1,8-Bis((trimethylsilyl)ethynyl)anthracene (3d).20 The procedure of
3d was similar to that for 3a, with triethylamine being replaced by
diisopropylamine: 2d (1.5 g, 3.49 mmol), CuI (0.068 g, 0.35 mmol),
Pd(PPh3)4 (0.41 g, 0.35 mmol), diisopropylamine (60 mL), THF
(100 mL), (trimethylsilyl)acetylene (0.85 g, 8.7 mmol). Yield: 0.61 g
(47%) of a yellow solid. 1H NMR (400 MHz, CDCl3): δ (ppm) 0.46 (s,
18H, SiMe3), 7.49 (t, J = 7.6 Hz, 2H), 7.86 (d, J = 6.8 Hz, 2H), 8.04 (d,
J = 8.4 Hz, 2H), 8.48 (s, 1H), 9.39 (s, 1H).
Synthesis of Diethynylanthracene. 9,10-Diethynylanthra-
cene (4a).21 9,10-Bis((trimethylsilyl)ethynyl)anthracene (3a; 0.5 g,
1.35 mmol) was dissolved in a mixture of THF and methanol (30 mL,
1/1, v/v). Potassium hydroxide (0.16 g, 2.84 mmol) was added, and the
reaction mixture was stirred at room temperature for 2 h. The reaction
mixture was diluted with dichloromethane and washed with brine. The
organic layer was dried over Na2SO4, and the solvent was removed in
vacuo. The crude product was purified by chromatography (petroleum
ether/dichloromethane 8/1). Yield: 0.2 g (66%) of a carmine solid. 1H
NMR (400 MHz, CDCl3): δ (ppm) 4.07 (s, 2H, CtCH), 7.61 (dd, J =
3.6 Hz, 4H), 8.60 (dd, J = 3.6 Hz, 4H).
36H, PMe3), 1.52 (d, J(PH) = 6.8 Hz, 18H, PMe3), 7.39 (t, J(HH) = 7.6
Hz, 2H), 7.52ꢀ7.55 (m, 2H, ant-CHd), 7.56 (d, J(HH) = 6.8 Hz, 2H),
7.80 (d, J(HH) = 8.4 Hz, 2H), 8.26ꢀ8.33 (m, 2H, Ru-CHd), 8.34 (s,
2H). 13C NMR (100 MHz, CDCl3): δ (ppm) 16.88 (t, J = 15.7 Hz,
PMe3), 20.23 (d, J = 20.6 Hz, PMe3), 120.18, 122.60, 123.25, 125.34,
128.95, 131.38, 132.11, 138.79 (ant-CHd), 169.91 (Ru-CHd), 202.52
(CO). 31P NMR (160 MHz, CDCl3): δ (ppm) ꢀ17.55 (t, J = 22.6 Hz,
PMe3), ꢀ5.68 (d, J =22.6 Hz, PMe3). Anal. Calcd for C38H66Cl2O2P6Ru2:
C, 45.02; H, 6.56. Found: C, 45.19; H, 6.48.
[{Ru(PMe3)2(CO)Cl}2(μ-CHdCH-ant-CHdCH-2,6)] (1c). Yield: 0.110 g,
50%. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.41 (t, J(PH) = 3.6 Hz, 36H,
PMe3), 1.48 (d, J(PH) = 7.6 Hz, 18H, PMe3), 6.79ꢀ6.82 (m, 2H, ant-
CHd), 7.58 (s, 2H), 7.58 (d, J(HH) = 8.8 Hz, 2H), 7.82 (d, J(HH) = 8.4
Hz, 2H), 8.17 (s, 2H), 8.28ꢀ8.34 (m, 2H, Ru-CHd). 13CNMR(100MHz,
CDCl3): δ (ppm) 16.62 (t, J = 15.3 Hz, PMe3), 20.09 (d, J = 21.0 Hz,
PMe3), 121.40, 123.48, 124.81, 127.58, 130.79, 131.95, 135.23, 137.26 (ant-
CHd), 167.30 (RuꢀCHd), 202.43 (CO). 31P NMR (160 MHz, CDCl3):
δ (ppm) ꢀ21.12 (t, J = 21.12 Hz, PMe3), ꢀ9.57 (d, J = 22.72 Hz, PMe3).
Anal. Calcd for C38H66Cl2O2P6Ru2: C, 45.02; H, 6.56. Found: C, 44.89;
H, 6.81.
[{Ru(PMe3)2(CO)Cl}2(μ-CHdCH-ant-CHdCH-1,8)] (1d). Yield:
0.048 g, 21%. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.44 (t,
J(PH) = 3.6 Hz, 36H, PMe3), 1.49 (d, J(PH) = 8.8 Hz, 18H, PMe3),
7.39 (t, J(HH) = 7.6 Hz, 2H), 7.56ꢀ7.60 (m, 2H, ant-CHd), 7.61 (d,
J(HH) = 7.2 Hz 2H), 7.74 (d, J(HH) = 8 Hz, 2H), 8.35 (s, 1H),
8.44ꢀ8.50 (m, 2H, RuꢀCHd), 9.40 (s, 1H). 13C NMR (100 MHz,
CDCl3): δ (ppm) 16.92 (t, J = 15.4 Hz, PMe3), 20.15 (d, J = 20.8 Hz,
PMe3), 120.61, 124.44, 125.48, 127.92, 128.79, 130.87, 131.81, 133.68,
139.23 (ant-CHd), 171.46 (RuꢀCHd), 201.93 (CO). 31P NMR (160
MHz, CDCl3): δ (ppm) ꢀ19.81 (t, J = 22.56 Hz, PMe3), ꢀ8.05 (d, J =
22.56 Hz, PMe3). Anal. Calcd for C38H66Cl2O2P6Ru2: C, 45.02; H, 6.56.
Found: C, 44.79; H, 6.61.
1,5-Diethynylanthracene (4b).22 The procedure for 4b was similar
to that for 4a: 3b (0.33 g, 0.89 mmol), potassium hydroxide (0.12 g, 2.16
mmol), THF (20 mL), methanol (20 mL). The crude product was
purified by chromatography (petroleum ether/dichloromethane 8/1).
Yield: 0.16 g (78%) of a light yellow solid. 1H NMR (400 MHz, CDCl3):
δ (ppm) 3.59 (s, 2H, CtCH), 7.45 (t, J = 7.2 Hz, 2H), 7.78 (d, J = 7.2
Hz, 2H), 8.09 (d, J = 8.8 Hz, 2H), 8.93 (s, 2H).
2,6-Diethynylanthracene (4c).22 The procedure for 4c was similar to
that for 4a: 3c (0.21 g, 0.57 mmol), potassium hydroxide (0.08 g, 1.36
mmol), THF (30 mL), methanol (30 mL). The crude product was
purified by chromatography (petroleum ether/dichloromethane 2/1).
Yield: 0.11 g (86%) of a light yellow solid. 1H NMR (400 MHz, CDCl3):
δ (ppm) 3.23 (s, 2H, CtCH), 7.49 (dd, J = 8.8 Hz, 2H), 7.95 (dd, J = 8.8
Hz, 2H), 8.19 (s, 2H), 8.35 (s, 2H).
Crystallographic Details. Single crystals of complexes 1a,c sui-
table for X-ray analysis were obtained by slow diffusion of hexane into a
solution of dichloromethane and chloroform, respectively. Crystals with
approximate dimensions of 0.16 ꢁ 0.12 ꢁ 0.10 mm3 for 1a and 0.16 ꢁ
0.12 ꢁ 0.10 mm3 for 1c were mounted on glass fibers for diffraction
experiments. Intensity data were collected on a Nonius Kappa CCD
diffractometer with Mo Kα radiation (0.710 73 Å) at room temperature.
The structures were solved by a combination of direct methods
(SHELXS-97)23 and Fourier difference techniques and refined by full-
matrix least squares (SHELXL-97).24 All non-H atoms were refined
anisotropically. The hydrogen atoms were placed in ideal positions and
refined as riding atoms. Further crystal data and details of the data
collection are summarized in Table 1. Selected bond distances and
angles are given in Tables 2 and 3, respectively.
1,8-Diethynylanthracene (4d).21 The procedure for 4d was similar to
that for 4a: 3d (0.5 g, 1.35 mmol), flaky potassium hydroxide (0.18 g,
3.24 mmol), THF (20 mL), methanol (20 mL). The crude product was
purified by chromatography (pure petroleum ether). Yield: 0.12 g (39%)
of a yellow solid. 1H NMR (400 MHz, CDCl3): δ (ppm) 3.62 (s, 2H,
CtCH), 7.45 (t, J = 7.6 Hz, 2H), 7.79 (d, J = 6.8 Hz, 2H), 8.03 (d, J = 8.4
Hz, 2H), 8.45 (s, 1H), 9.44 (s, 1H).
General Synthesis of Binuclear Ruthenium Complexes11.
To a suspension of RuHCl(CO)(PPh3)3 (0.42 g, 0.44 mmol) in CH2Cl2
(20 mL) was slowly added a solution of the corresponding diethynylan-
thracene (0.05 g, 0.22 mmol) in CH2Cl2 (5 mL). The reaction mixture
was stirred for 30 min to give a red solution. Then a 1 M THF solution of
PMe3 (2.2 mL, 2.2 mmol) was added to the red solution. The mixture
was stirred for another 20 h. The solution was reduced to ca. 2 mL under
vacuum. Addition of hexane (30 mL) to the residue produced a yellow
solid, which was collected by filtration, washed with hexane, and dried
under vacuum.
[{Ru(PMe3)2(CO)Cl}2(μ-CHdCH-ant-CHdCH-9,10)] (1a). Yield:
0.120 g, 54%. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.52 (t, J(PH) =
2.4 Hz, 36H, PMe3), 1.54 (d, J(PH) = 3.2 Hz, 18H, PMe3), 7.31 (dd,
J(HH) = 3.6 Hz, 4H), 7.52ꢀ7.58 (m, 2H, ant-CHd), 7.71ꢀ7.78 (m, 2H,
RuꢀCHd), 8.60 (dd, J(HH) = 3.2 Hz, 4H). 13C NMR (100 MHz,
CDCl3): δ (ppm) 17.40 (t, J = 14.9 Hz, PMe3), 20.04 (d, J = 20.6 Hz,
PMe3), 123.19, 127.11, 128.67, 133.14, 135.85 (ant-CHd), 170.80 (Ru-
CHd), 202.41 (CO). 31P NMR (160 MHz, CDCl3): δ (ppm) ꢀ19.58
(t, J = 22.56 Hz, PMe3), ꢀ7.80 (d, J = 22.56 Hz, PMe3). Anal. Calcd for
C38H66Cl2O2P6Ru2: C, 45.02; H, 6.56. Found: C, 45.15; H, 6.67.
[{Ru(PMe3)2(CO)Cl}2(μ-CHdCH-ant-CHdCH-1,5)] (1b). Yield: 0.117
g, 52%. 1H NMR (400 MHz, CDCl3): δ (ppm) 1.46 (t, J(PH) = 3.6 Hz,
1
Physical Measurements. H, 13C, and 31P NMR spectra were
collected on a Varian Mercury Plus 400 spectrometer (400 MHz) or on a
Varian Mercury Plus 600 spectrometer (600 MHz). 1H and 13C NMR
chemical shifts are relative to TMS, and 31P NMR chemical shifts are
relative to 85% H3PO4. Elemental analyses (C, H, N) were performed
with a Vario ElIII Chnso instrument. UVꢀvis spectra were recorded on a
PDA spectrophotometer by quartz cells with a path length of 1.0 cm.
Fluorescence spectra were taken on a Fluoromax-P luminescence
spectrometer (Horiba Jobin Yvon Inc.). The electrochemical measure-
ments were performed on a CHI 660C potentiostat (CHI USA). A
three-electrode one-compartment cell was used to contain the solution
of complexes and supporting electrolyte in dry CH2Cl2. Deaeration of
the solution was achieved by argon bubbling through the solution
for about 10 min before measurement. The ligand and electrolyte
(n-Bu4NPF6) concentrations were typically 0.001 and 0.1 mol dmꢀ3
,
respectively. A 500 μm diameter platinum-disk working electrode, a
platinum-wire counter electrode, and an Ag/Ag+ reference electrode
were used. The Ag/Ag+ reference electrode contained an internal
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solution of 0.01 mol dmꢀ3 AgNO3 in acetonitrile and was incorporated
into the cell with a salt bridge containing 0.1 mol dmꢀ3 n-Bu4NPF6 in
CH2Cl2. All electrochemical experiments were carried out under ambient
conditions.
1999, 578, 76. (p) Horn, C. R.; Gladysz, J. A. J. Eur. Inorg. Chem.
2003, 2211. (q) Brady, M.; Weng, W.; Gladysz, J. A. J. Chem. Soc., Chem.
Commun. 1994, 2665.
(6) (a) Chung, M.-C.; Gu, X.; Etzenhouser, B. A.; Spuches, A. M.;
Rye, P. T.; Seetharaman, S. K.; Rose, D. J.; Zubieta, J.; Sponsler, M. B.
Organometallics 2003, 22, 3485. (b) Fox, H. H.; Lee, J. K.; Park, L. Y.;
Schrock, R. R. Organometallics 1993, 12, 759. (c) Liu, S. H.; Chen, Y.;
Wan, K. L.; Wen, T. B.; Zhou, Z.; Lo, M. F.; Williams, I. D.; Jia, G.
Organometallics 2002, 21, 4984. (d) Gao, L.-B.; Liu, S.-H.; Zhang, L.-Y.;
Shi, L.-X.; Chen, Z.-N. Organometallics 2006, 25, 506. (e) Liu, S. H.; Xia,
H.; Wen, T. B.; Zhou, Z. Y.; Jia, G. Organometallics 2003, 22, 737. (f) Liu,
S. H.; Hu, Q. Y.; Xue, P.; Wen, T. B.; Williams, I. D.; Jia, G.
Organometallics 2005, 24, 769. (g) Guillaume, V.; Mahias, V.; Mari,
A.; Lapinte, C. Organometallics 2000, 19, 1422. (h) Xia, H.; Yeung,
R. C. Y.; Jia, G. Organometallics 1998, 17, 4762. (i) Yuan, P.; Wu, X. H.;
Yu, G.; Du, D.; Liu, S. H. J. Organomet. Chem. 2007, 692, 3588.
(7) (a) Zaumseil, J.; Sirringhaus, H. Chem. Rev. 2007, 107, 1296. (b)
Lo, S.-C.; Burn, P. L. Chem. Rev. 2007, 107, 1097. (c) Anthony, J. E.
Angew. Chem., Int. Ed. 2008, 47, 452.
’ ASSOCIATED CONTENT
S
Supporting Information. CIF files giving X-ray crystallo-
b
graphic data for [{Ru(PMe3)2(CO)Cl}2(μ-CHdCH-ant-CHd
CH-9,10)] (1a) and [{Ru(PMe3)2(CO)Cl}2(μ-CHdCH-ant-
CHdCH-2,6)] (1c). This material is available free of charge via
the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: chshliu@mail.ccnu.edu.cn (S.H.L.); yinj@mail.ccnu.
edu.cn (J.Y.).
(8) (a) Han, J.; Burgess, K. Chem. Rev. 2010, 110, 2709. (b) Haas,
K. L.; Franz, K. J. Chem. Rev. 2009, 109, 4921.
’ ACKNOWLEDGMENT
(9) (a) de Montigny, F.; Argouarch, G.; Costuas, K.; Halet, J. F.;
Roisnel, T.; Toupet, L.; Lapinte, C. Organometallics 2005, 24, 4558. (b)
Vilꢀa, N.; Zhong, Y.-W.; Henderson, J. C.; Abru~na, H. D. Inorg. Chem.
2010, 49, 796. (c) Fabre, M.; Bonvoisin, J. J. Am. Chem. Soc. 2007,
129, 1434. (d) Cicogna, F.; Gaddi, B.; Ingrosso, G.; Marcaccio, M.;
Marchetti, F.; Paolucci, D.; Paolucci, F.; Pinzino, C.; Viglione, R. Inorg.
Chim. Acta 2004, 357, 2915. (e) Bertini, F.; Calucci, L.; Cicogna, F.;
Gaddi, B.; Ingrosso, G.; Marcaccio, M.; Marchetti, F.; Paolucci, D.;
Paolucci, F.; Pinzino, C. J. Organomet. Chem. 2006, 691, 2987. (f)
Hoshino, Y.; Suzuki, T.; Umeda, H. Inorg. Chim. Acta 1996, 245, 87. (g)
Sharmin, A.; Minazzo, A.; Salassa, L.; Rosenberg, E.; Alexander Ross,
J. B.; Kabir, S. E.; Hardcastle, K. I. Inorg. Chim. Acta 2008, 361, 1624. (h)
Gao, L.-B.; Zhang, L.-Y.; Shi, L.-X.; Chen, Z.-N. Organometallics 2005,
24, 1678. (i) Carano, M.; Careri, M.; Cicogna, F.; D¢Ambra, I.; Houben,
J. L.; Ingrosso, G.; Marcaccio, M.; Paolucci, F.; Pinzino, C.; Roffia, S.
Organometallics 2001, 20, 3478.
We acknowledge financial support from the National Natural
Science Foundation of China (Nos. 20931006, 21072070, 2107-
2071, and 20803027) and the Program for Changjiang Scholars
and Innovative Research Team in University (No. IRT0953).
’ REFERENCES
(1) (a) Chen, J.; Reed, M. A.; Rawlett, A. M.; Tour, J. M. Science
1999, 286, 1550–1552. (b) Feldman, A. K.; Steigerwald, M. L.; Guo, X.;
Nuckolls, C. Acc. Chem. Res. 2008, 41, 1731–1741.
(2) Ulgut, B.; Abru~na, H. D. Chem. Rev. 2008, 108, 2721–2736.
(3) (a) Astruc, D. Acc. Chem. Res. 1997, 30, 383–391. (b) Ceccon, A.;
Santi, S.; Orian, L.; Bissello, A. Coord. Chem. Rev. 2004, 248, 683–724.
(c) Carlson, C. N.; Kuehl, C. J.; Da Re, R. E.; Veauthier, J. M.; Schelter,
E. J.; Milligan, A. E.; Scott, B. L.; Bauer, E. D.; Thompson, J. D.; Morris,
D. E.; John, K. D. J. Am. Chem. Soc. 2006, 128, 7230–7241. (d) Kaim, W.;
Sarkar, B. Coord. Chem. Rev. 2007, 251, 584–594. (e) Debroy, P.; Roy, S.
Coord. Chem. Rev. 2007, 251, 203–211. (f) Aguirre-Etcheverry, P.;
O’Hare, D. Chem. Rev. 2010, 110, 4839–4864. (g) Gleiter, R.; Werz,
D. B. Chem. Rev. 2010, 110, 4447–4488.
(10) Nguyen, M.-H.; Yip, J. H. K. Organometallics 2010, 29, 2422.
(11) Li, F.; Chen, J.; Chai, X.; Jin, S.; Wu, X.; Yu, G.-A.; Liu, S. H.;
Chen, G. Z. Organometallics 2011, 30, 1830.
(12) Wu, X. H.; Jin, S.; Liang, J. H.; Li, Z. Y.; Yu, G. A.; Liu, S. H.
Organometallics 2009, 28, 2450.
(13) Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, M. F.;
Wonchoba, E. R.; Parshall, G. W. Inorg. Synth. 1974, 15, 45.
(14) Kendall, J. K.; Shechter, H. J. Org. Chem. 2001, 66, 6643.
(15) Stone, M. T.; Anderson, H. L. Chem. Commun. 2007, 2387.
(16) Shao, M.; Chen, G.; Zhao, Y. M. Synlett 2008, 371.
(17) Goichi, M.; Segawa, K.; Suzuki, S.; Toyota, S. Synthesis 2005,
13, 2116.
(18) Nierth, A.; Kobitski, A. Yu.; Nienhaus, G. U.; J€aschke, A. J. Am.
Chem. Soc. 2010, 132, 2646.
(19) Gouloumis, A.; Gonzlez-Rodriguez, D.; Vzquez, P.; Torres, T.;
Liu, S. G.; Echegoyen, L.; Ramey, J.; Hug, G. L.; Guldi, D. M. J. Am.
Chem. Soc. 2006, 128, 12674.
(20) Ma, H.; Kang, M. S.; Xu, K. S.; Jen, A. K. Y. Chem. Mater. 2005,
17, 2896.
(21) Chmiel, J.; Neumann, B.; Stammler, H.-G.; Mitzel, N. W. Chem.
Eur. J. 2010, 16, 11906.
(22) Xia, J.-L.; Zhang, C.; Zhu, X.; Ou, Y.; Jin, G.-J.; Yu, G.-A. New J.
(4) (a) Balzani, V.; Juris, A.; Venturi, M.; Campagna, S.; Serroni, S.
Chem. Rev. 1996, 96, 759. (b) Delville, M. H. Inorg. Chim. Acta 1999,
291, 1. (c) Ceccon, A.; Santi, S.; Orian, L.; Bisello, A. Coord. Chem. Rev.
2004, 248, 683. (d) Adams, H.; Costa, P. J.; Newell, M.; Vickers, S. J.;
Ward, M. D.; Felix, V.; Thomas, J. A. Inorg. Chem. 2008, 47, 11633.
(5) (a) Horn, C. R.; Martin-Alvarez, J. M.; Gladysz, J. A. Organome-
tallics 2002, 21, 5386. (b) Bruce, M. I.; Ellis, B. G.; Low., P. J.; Skelton,
B. W.; White, A. H. Organometallics 2003, 22, 3184. (c) Gil-Rubio, J.;
Laubender, M.; Werner, H. Organometallics 2000, 19, 1365. (d) Meyer,
W. E.; Amoroso, A. J.; Horn, C. R.; Jaeger, M.; Gladysz, J. A. Organo-
metallics 2001, 20, 1115. (e) Peters, T. B.; Bohling, J. C.; Arif, A. M.;
Gladysz, J. A. Organometallics 1999, 18, 3261. (f) Sponsler, M. B.
Organometallics 1995, 14, 1920. (g) Dembinski, R.; Bartik, T.; Bartik,
B.; Jaeger, M.; Gladysz, J. A. J. Am. Chem. Soc. 2000, 122, 810. (h) Bruce,
M. I.; Low, P. J.; Costuas, K.; Halet, J.-F.; Best, S. P.; Heath, G. A. J. Am.
Chem. Soc. 2000, 122, 1949. (i) Qi, H.; Gupta, A.; Noll, B. C.; Snider,
G. L.; Lu, Y.; Lent, C.; Fehlner, T. P. J. Am. Chem. Soc. 2005, 127, 15218.
(j) Xu, G.-L.; Zou, G.; Ni, Y.-H.; DeRosa, M. C.; Crutchley, R. J.; Ren, T.
J. Am. Chem. Soc. 2003, 125, 10057. (k) Xu, G.-L.; Crutchley, R. J.;
DeRosa, M. C.; Pan, Q.-J.; Zhang, H.-X.; Wang, X.; Ren, T. J. Am. Chem.
Soc. 2005, 127, 13354. (l) Ying, J.-W.; Liu, I. P.-C.; Xi, B.; Song, Y.;
Campana, C.; Zuo, J.-L.; Ren, T. Angew. Chem., Int. Ed. 2010, 49, 954.
(m) Bruce, M. I.; Zaitseva, N. N.; Skelton, B. W.; White, A. H.
J. Organomet. Chem. 2005, 690, 3268. (n) Bruce, M. I.; Kelly, B. D.;
Skelton, B. W.; White, A. H. J. Organomet. Chem. 2000, 604, 150.
(o) Coat, F.; Guillemot, M.; Paul, F.; Lapinte, C. J. Organomet. Chem.
Chem. 2011, 35, 97.
(23) Sheldrick, G. M. SHELXS-97, a Program for Crystal Structure
Solution; University of G€ottingen: G€ottingen, Germany, 1997.
(24) Sheldrick, G. M. SHELXL-97, a Program for Crystal Structure
Refinement; University of G€ottingen, G€ottingen, Germany, 1997.
5770
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