Synthesis, characterization, and substituent effects of binuclear ruthenium vinyl complexes [RuCl(CO(PMe3)3]2 (μ-CHd=CH-Ar-CHd=CH)

Article abstract of DOI:10.1021/om900018y

A series of binuclear ruthenium vinyl complexes [RuCl(CO)(PMe3)3]2(w-CH=CH- Ar-CH=CH) (Ar = C6H4 (6a), C6H3CH3 (6b), C6H3OCH3 (6c), C6F(6d), C6H3Q (6e), C6H3Br (6f), C6H3CN (6g), C6H3NO2 (6h), C6H2(CH3)2-2,5 (6i), C6H2(OCH3)2-2,5 (6j), C6H2(F)2-2,5 (6k),

Full text of DOI:10.1021/om900018y

2450
Organometallics 2009, 28, 2450–2459
Synthesis, Characterization, and Substituent Effects of Binuclear
Ruthenium Vinyl Complexes
[RuCl(CO)(PMe3)3]2(µ-CHdCH-Ar-CHdCH)
Xiang Hua Wu, Shan Jin, Jin Hua Liang, Zi Yong Li, 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
ReceiVed January 9, 2009
A series of binuclear ruthenium vinyl complexes [RuCl(CO)(PMe3)3]2(µ-CHdCH-Ar-CHdCH) (Ar
) C6H4 (6a), C6H3CH3 (6b), C6H3OCH3 (6c), C6H3F (6d), C6H3Cl (6e), C6H3Br (6f), C6H3CN (6g),
C6H3NO2 (6h), C6H2(CH3)2-2,5 (6i), C6H2(OCH3)2-2,5 (6j), C6H2(F)2-2,5 (6k), C6H2(CF3)2-2,5 (6l), and
C6H3CF3 (6m)) have been prepared. The respective products have been characterized by elemental analyses,
NMR spectrometry, and UV/vis spectrophotometry. The structures of 6h, 6i, and 6j have been established
by X-ray crystallography. Electrochemical studies have revealed that intermetallic electron communication
between the two Ru centers may be fine-tuned by modification of the bridging spacers, that is, by
introducing one or two substituent groups on the 1,4-diethenylphenylene bridge. Electron-releasing
substituents have been found to facilitate electron communication between the two metal centers.
described herein, a series of binuclear ruthenium complexes
[RuCl(CO)(PMe3)3]2(µ-CHdCH-Ar-CHdCH), in which the
1,4-diethenylphenylene bridge bears one or two substituent
Introduction
In the emerging field of molecular electronics, the promise
of “tuning” the electronic properties of materials has motivated
investigations into the dependence of electronic structure on the
functional groups present. For example, electron transfer in
organometallic complexes can be perturbed to different extents
by electroactive end groups in conjunction with various saturated
or conjugated bridges. The effectiveness of this perturbation is
highly dependent on the medium, the molecular topology, the
nature of the metal complex, and whether the connecting bridge
groups are electron-rich or -deficient, bulky or flexible, long-
or short-chain, and oxidizable or reducible. By judicious control
of these parameters, molecular wires exhibiting quite different
electronic properties have been investigated.1
Highly unsaturated rigid -(Ct C)n- and -(CdC)n- bridges
offer extended π-systems and have been recognized as being
particularly efficient in facilitating electronic transfer.2-4 In this
context, a vast number of mono- and bimetallic complexes with
polyynediyl or polyacetylene bridges have been extensively
studied.5-24 For example, as model complexes designed to aid
understanding of the influence of substituents on the bonding
properties within the metal-acetylide backbone, mononuclear
metal (Fe or Ru) σ-arylacetylides [(η2-dppe)(η5-C5Me5)M(Ct C)-
1,4-(C6H4)X] have recently been reported by Paul and Bruce et
al.4 Previously, substituent effects in a series of M2(DAvF)4 (M
) Mo, Ni, Ru, Rh; DAvF ) diarylformamidinate) and
Ru2(DMBA)4 (DMBA ) N,N′-dimethylbenzamidinate)bime-
tallic complexes were studied by Ren et al.25 Chen et al. have
also shown that the electronic properties of binuclear ruthenium
polyynediyl complexes largely depend on the ancillary ligands
present; intermetallic electronic communication was found to
be favored by introducing an electron-donating substituent, but
attenuated by an electron-withdrawing substituent.5a
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In contrast, there have been few studies on the influence of
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* Corresponding author. E-mail: chshliu@mail.ccnu.edu.cn.
10.1021/om900018y CCC: $40.75
2009 American Chemical Society
Publication on Web 03/25/2009

Binuclear Ruthenium Vinyl Complexes
Organometallics, Vol. 28, No. 8, 2009 2451
Scheme 1
Scheme 2
Scheme 3
protecting groups with dilute aqueous KOH in MeOH/THF or
with K2CO3 in MeOH/CH2Cl2, while 5a and 5b were obtained
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groups, has been synthesized. The variation in the electrochemi-
cal properties of these binuclear ruthenium complexes on
varying the vinyl bridging ligands has been investigated by
voltammetric techniques in order to study the influence of the
substituents on the electronic communication between the two
Ru centers.
Results and Discussion
Syntheses and Characterization. Substituted 1,4-diethynyl-
benzene derivatives were synthesized by a sequence of coupling
and deprotection reactions. The trimethylsilyl-protected bis-
(ethynyl) ligand precursors were synthesized by the palladium-
catalyzed coupling of trimethylsilylethyne with dibromo/
diiodoaryls (Scheme 1).26 Under these conditions, compounds
2a-k were obtained in yields ranging from 10 to 85%. In the
case of trifluoromethyl substituents, however, this reaction did
not proceed satisfactorily. We therefore devised another ap-
proach to access the mono- and bis-trifluoromethyl-substituted
derivatives and found that the protected diethynylbenzenes 4a
and 4b could be conveniently obtained by the coupling of 1l
and 1m with 2-methylbut-3-yn-2-ol (Scheme 2).27 The ligand
precursors were smoothly converted into the corresponding
diterminal alkynes 3a-k by removal of the trimethylsilyl

2452 Organometallics, Vol. 28, No. 8, 2009
Wu et al.
by treating 4a and 4b with NaOH in toluene. Diethynylbenzenes
3a-k and 5a,b were characterized by elemental analyses and
nylbenzenes 3a-k and 5a,b were reacted with the ruthenium
hydride complex [RuHCl(CO)(PPh3)3] to give the insertion
products [(PPh3)2Cl(CO)Ru]2(µ-CHdCH-Ar-CHdCH), which
were not isolated because they are air-sensitive, especially in
solution. PMe3 was then added to give the corresponding six-
coordinated complexes 6. These complexes were characterized
by NMR. The PMe3 ligands in 6 are meridionally coordinated
to ruthenium, as indicated by an AM2 pattern in the 31P{1H}
NMR spectrum. The 1H NMR spectrum (in CDCl3) of 6a
features the two Ru-CH proton signals at δ ) 7.96 ppm (6i,
7.88; 6j, 7.88; 6k, 8.10; 6l, 8.25), this chemical shift being
similar to that found in [RuCl(CO)(PMe3)3]2(µ-(CHdCH)n).5d,g,h
However, two different Ru-CH proton signals are observed in
the spectra of the other monosubstituted binuclear complexes.
For example, the 1H NMR spectrum of 6h displays the Ru-CH
signals at δ ) 8.11 and 8.26 ppm, respectively, which may be
attributed to the asymmetrical structure of this complex. Two
different Ru-CdCH proton signals are also observed in the
spectra of monosubstituted vinyl complexes. The vinylic proton
is in a trans geometry and the acetylene is cis-inserted into the
Ru-H bond, as confirmed by the X-ray structures of 6h, 6i,
and 6j (Figures 1-3). Similar ruthenium complexes [Ru-
Cl(CO)(PiPr3)3]2(µ-CHdCH-C6H4-CHdCH),28 [RuHCl(CO)(P-
Ph3)3]2 (µ-CHdCH-C6H4-CHdCH),29 [Fc(CHdCH)3RuCl(CO)-
(PMe3)3],5c 1,3,5-[Cl(CO)(PMe3)3RuCHdCH]3C6H3,5f and
[RuCl(CO)(PiPr3)3]4(HCdCHC6H4)(CdC)30 have recently been
reported.
1
by H and 13C NMR spectrometry.
The general synthetic route for the preparation of binuclear
ruthenium vinyl complexes is outlined in Scheme 3. Diethy-
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X-ray Structures of 6h, 6i, and 6j. The molecular structures
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Organometallics 2008, 27, 3321.

Binuclear Ruthenium Vinyl Complexes
Organometallics, Vol. 28, No. 8, 2009 2453
Figure 1. Molecular structure of 6h.
Figure 2. Molecular structure of 6i.
Figure 3. Molecular structure of 6j.
σ-bonding. The molecular structure of 6h is asymmetric due to
the presence of one NO2 group on the benzene ring, which
prevents coplanarity of the carbon atoms of the µ-CHdCH-Ar-
CHdCH unit, as shown in Figure 1. The dihedral angle between
the double bond contiguous to the NO2 group and the benzene
ring is 15.73°. The carbon atoms of the benzene ring are nearly
coplanar, with a dihedral angle between C(1)/C(2)/C(3) and
C(1)/C(4)/C(5)/C(6) of 1.89°. The Ru1 · · · Ru2 distance is 11.497
Å. The molecular structures of 6i and 6j are centrosymmetric,
as shown in Figures 2 and 3. The compounds contain two Ru
centers linked by a µ-CHdCH-Ar-CHdCH bridge (Ar )
C6H2(CH3)2-2,5 (6i), C6H2(OCH3)2-2,5 (6j)). The two Ru centers
are related by a pseudo-C2 rotation axis. The Ru1 · · · Ru1a
distances in complexes 6b and 6c are 11.922 and 11.919 Å,
respectively, which are slightly longer than that in complex 6h.
The carbon atoms of the µ-CHdCH-Ar-CHdCH units are
nearly coplanar, with dihedral angles between the core benzene
ring and the two vinyl groups of 5.23° (in 6i) and 3.9° (in 6j),
respectively. The two double bonds are in the trans configu-
ration. The Ru-C and C(R)-C(ꢀ) bond distances in complexes
6h, 6i, and 6j are within the ranges of those reported for other
ruthenium vinyl complexes.31 The overall geometry about the
two ruthenium centers in 6h, 6i, and 6j closely resembles that
in the bimetallic ruthenium complexes [RuCl(CO)(PMe3)3]2-
(µ-(CHdCH)n).5b,d,g,h It is worth noting that the vinyl groups
are essentially coplanar with Cl-Ru-CO. Such coplanarity of
the vinyl group and CO is to be expected, due to the strong
π-interaction between these ligands and the metal centers in
such a conformation.5b,d,g,h,32 The three complexes adopt the
same crystal system and space group, as can be seen in
Table 1.
Electronic Absorption Spectroscopy. The electronic proper-
ties of this series of vinyl bimetallic complexes have been
investigated by optical absorption spectroscopy. A rather intense
(31) See for example: (a) Torres, M. R.; Santos, A.; Perales, A.; Ros, J.
J. Organomet. Chem. 1988, 353, 221. (b) Romero, A.; Santos, A.; Vegas,
A. Organometallics 1988, 7, 1988. (c) Lo´pez, J.; Romero, A.; Santos, A.;
Vegas, A.; Echavarren, A. M.; Noheda, P. J. Organomet. Chem. 1989, 373,
249. (d) Alcock, N. W.; Hill, A. F.; Melling, R. P. Organometallics 1991,
10, 3898. (e) Wakatsuki, Y.; Yamazaki, H.; Kumegawa, N.; Satoh, T.; Satoh,
J. Y. J. Am. Chem. Soc. 1991, 113, 9604.
(32) Choi, S. H.; Bytheway, I.; Lin, Z.; Jia, G. Organometallics 1998,
17, 3974.

2454 Organometallics, Vol. 28, No. 8, 2009
Wu et al.
Table 1. Crystal Data, Date Collection, and Refinement Parameters for 6h, 6i, and 6j
6h
6i
6j
formula
fw
C30H61Cl2NO4P6Ru2
958.66
C32H66Cl2O2P6Ru2
941.71
C32H66Cl2O4P6Ru2
973.71
temp (K)
cryst syst
space group
a (Å)
b (Å)
c (Å)
295(2)
monoclinic
P2(1)/n
9.9338(5)
35.9326(17)
13.3665(12)
90.00
111.814(10)
90.00
295(2)
monoclinic
P2(1)/n
9.4873(5)
11.1223(6)
21.9002(11)
90
97.0950(10)
90
2293.2(2)
2
292(2)
monoclinic
P2(1)/n
9.5551(4)
11.5199(5)
21.7440(9)
90.00
97.3350(10)
90.00
R (deg)
ꢀ (deg)
γ (deg)
V (Å-3
)
4429.5(5)
4
1.438
2373.86(17)
2
1.362
Z
Dcalcd (g cm-3
)
1.364
cryst size (mm)
F(000)
0.30 × 0.20 × 0.20
0.40 × 0.03 × 0.01
0.23 × 0.20 × 0.20
1968
972
1004
diffractometer
radiation
KappaCCD
Mo KR
KappaCCD
Mo KR
1.009
KappaCCD
Mo KR
abs coeff (mm-1
θ range (deg)
hkl range
)
1.050
0.980
1.74-27.00
-11 to 12 -43 to 45 -17 to 17
49 729
1.87-27.00
1.89-27.00
-11 to 12 -13 to 14 -27 to 27
-12 to 12 -14 to 14 -24 to 27
total no. of rflns
20 559
18 249
no. of unique rflns
no. of obsd rflns (I > 2σ(I)
no. of restraints/params
a, b for Wa
9638
7398
0/424
0.0711, 2.0601
0.0556
4969
4051
0/209
0.0624, 2.9242
0.0453
5161
4429
0/218
0.0597, 1.8048
0.0515
final R
Rw
0.1277
0.1074
0.1074
R (all date)
0.0754
0.0615
0.0515
Rw (all date)
0.1382
1.030
0.952, -0.672
0.1268
1.065
0.693, -0.794
0.1177
1.079
0.979, -0.498
goodness of fit/F2
largest diff peak, hole (e Å-3
)
a
2
W ) 1/[σ2(Fo)2 + (aP)2 + bP], where P ) (Fo + Fc2)/3.
Table 2. UV-vis Data for [RuCl(CO)(PMe3)3]2-
(µ-CHdCH-Ar-CHdCH) Complexes 6 in CH2Cl2
Table 3. Electrochemical Data for Complexes 6a-6ma
c
complex
E1/2(A) ∆Ep ib/ifb E1/2(B) ∆E1/2
Kcd
complex
abs, nm (10-3ꢀ, M-1 cm-1
)
6a (R1 ) R2 ) H)
0.30
0.24
0.19
0.33
0.37
0.37
0.46
0.52
0.20
0.10
0.41
0.57
0.42
0.079 0.91
0.086 0.74
0.075 0.73
0.076 0.74
0.090 0.63
0.077 0.61
0.068 0.33
0.088 0.36
0.078 0.72
0.077 0.72
0.071 0.59
0.087 0.35
0.075 0.70
0.59
0.54
0.50
0.59
0.61
0.61
0.66
0.71
0.50
0.46
0.64
0.75
0.64
0.29 8.0 × 104
0.30 1.2 × 105
0.31 1.7 × 105
0.26 2.5 × 104
0.24 1.1 × 104
0.24 1.1 × 104
0.20 2.4 × 103
0.19 1.6 × 103
0.30 1.2 × 105
0.35 8.2 × 105
0.23 7.7 × 103
0.18 1.1 × 103
0.22 5.2 × 103
6b (R1 ) H, R2 ) CH3)
6c (R1 ) H, R2 ) OCH3)
6d (R1 ) H, R2 ) F)
6e (R1 ) H, R2 ) Cl)
6f (R1 ) H, R2 ) Br)
6g (R1 ) H, R2 ) CN)
6h (R1 ) H, R2 ) NO2)
6i (R1 ) R2 ) CH3)
6j (R1 ) R2 ) OCH3)
6k (R1 ) R2 ) F)
6a (R1 ) R2 ) H)
335 (10.6)
340 (15.9)
345 (15.6)
344 (15.8)
344 (15.7)
343 (15.5)
339 (7.6)
338 (15.3),434 (2.9)
337 (11.7)
357 (11.5)
349 (13.8)
350 (13.7)
343 (15.4)
6b (R1 ) H, R2 ) CH3)
6c (R1 ) H, R2 ) OCH3)
6d (R1 ) H, R2 ) F)
6e (R1 ) H, R2 ) Cl)
6f (R1 ) H, R2 ) Br)
6g (R1 ) H, R2 ) CN)
6h (R1 ) H, R2 ) NO2)
6i (R1 ) R2 ) CH3)
6j (R1 ) R2 ) OCH3)
6k (R1 ) R2 ) F)
6l (R1 ) R2 ) CF3)
6m (R1 ) H, R2 ) CF3)
6l (R1 ) R2 ) CF3)
6m (R1 ) H, R2 ) CF3)
a Potential data were determined in CH2Cl2 containing 1mmol dm-3
compound and 0.1 mol dm-3 Bu4NPF6. The Ag Ag+ electrode (internal
solution: 0.01 mol dm-3 AgNO3
+
0.1 mol dm-3 Bu4NPF6 in
electronic transition (except in the case of 6g) is seen for these
vinyl complexes in the region 330-440 nm (Table 2). For all
of the complexes, energetic transitions are observed above 350
nm, which can be attributed to π-π* ligand-centered transitions.
For the nitro complex 6h, an additional broader and less intense
transition is detected near 430 nm. The summarized absorptions
account for the yellow colors of 6a-g and 6i-m and the
unusual purple color of the complex 6h.
acetonitrile; salt bridge: 0.1 mol dm-3 Bu4NPF6 in CH2Cl2) was used as
a reference. b ib/if ) ibackward/iforward c ∆E1/2 ) E1/2(B) - E1/2(A) denotes
the potential difference between redox processes
and B. d The
.
A
comproportionation constants, Kc, were calculated by the formula Kc
)
exp(∆E1/2/25.69) at 298 K.33
and then of Ru2II,III to Ru2III,III. The first redox process of complex
6a is reversible, with ib/if being 0.91(Table 3). When the
substituent group is a strong electron-withdrawing group, the
first redox process of complexes 6g, 6h, and 6l are irreversible
at high positive potential. However, when the substituent group
is a electron-donor group or a weak electron-withdrawing group
(F, Cl, and Br), these complexes undergo a quasi-reversible one-
eletron oxidation at moderately positive potential during the first
redox process. The oxidation and reduction current peaks are
typically separated by 80 ( 10 mV (Table 3). The second redox
process of these complexes is irreversible.
Electrochemistry. The redox behavior of the binuclear
complexes 6a-m (1 mM in CH2Cl2) has been investigated by
cyclic voltammetry and square-wave voltammetry techniques
with 0.1 M n-Bu4NPF6 as the supporting electrolyte; pertinent
data are compiled in Table 3. Plots of the cyclic voltammogram
(CV) and the square-wave voltammogram (SWV) for some
complexes 6 are depicted in Figures 4 and 5. All of the
complexes 6a-m undergo two consecutive, chemically and
electrochemically one-electron oxidation processes, giving rise
to redox waves A and B (Table 3) in the potential region from
As shown in Table 3, for complex 6a with 1,4-diethenylphe-
nylene as the spacer, the ∆E1/2 is 0.29 V with the corresponding
Kc being 8.0 × 104. This rather large Kc for 6a is indicative of
0.10 to 0.75 V, corresponding to oxidation of Ru2II,II to Ru2
II,III

Binuclear Ruthenium Vinyl Complexes
Organometallics, Vol. 28, No. 8, 2009 2455
Figure 4. Cyclic voltammograms (CV) of complexes 6c, 6a, and
6h in CH2Cl2/Bu4NPF6 at ν ) 0.1 V s-1. Square-wave voltammo-
grams (SWV) at f ) 10 Hz. Potentials are given relative to the
Ag/Ag+ standard.
Figure 5. Cyclic voltammograms (CV) of complexes 6j, 6a, and
6l in CH2Cl2/Bu4NPF6 at ν ) 0.1 V s-1. Square-wave voltammo-
grams (SWV) at f ) 10 Hz. Potentials are given relative to the
Ag/Ag+ standard.
strong electronic communication transmitted through the 1,4-
diethenylphenylene bridge. The voltammetric features of the
other complexes showed an apparent dependence on the
substituents attached to the 1,4-diethenylphenylene unit of
the bridging ligands. When the substituent was weakly electron-
donating, such as methyl (complex 6b, with ∆E1/2 being 0.30
V and the corresponding Kc being 1.2 × 105), both the oxidation
and reduction couples were cathodically shifted and the
electronic interaction was slightly increased (Figure 4). As a
strongly electron-donating group, methoxyl proved to be even
more favorable for electron communication than methyl (com-
plex 6c, for which the ∆E1/2 is 0.31 V and the corresponding
Kc is 1.7 × 105). By comparison of the ∆E1/2 and Kc values
(Table 3), it can be seen that in 6d, 6g, 6h, and 6m, in which
one electron-withdrawing substituent is attached to the 1,4-
diethenylphenylene unit, the electronic communication rapidly
decreases with increasing electron-withdrawing strength of these
substituents (NO2 > CF3 > CN > F). Interestingly, careful
examination of the ∆E1/2 and Kc values for complexes 6d, 6e,
and 6f (Table 3) reveals that they show the opposite trend of
the above. That is to say, a gradual decrease in ∆E1/2 from 0.26
V (6d) to 0.24 V (6e) to 0.240 V (6f) was observed. The Kc
values show a similar downward trend. For the monosubstituted
complexes, the maximal ∆E1/2 difference between the complex
bearing the most electron-releasing substituent (6c) and that
bearing the most electron-withdrawing substituent (6h) is about
120 mV, and the respective Kc values show a decrease of about
2 orders of magnitude.
For complexes 6i-l, in which two substituent groups are
attached to the 1,4-diethenylphenylene unit, the ∆E1/2 values
are 0.30, 0.35, 0.23, and 0.18 V, and the corresponding Kc values
are 1.2 × 105, 8.2 × 105, 7.7 × 103, and 1.1 × 103, respectively
(Table 3). These data illustrate that the electronic communication
is rapidly attenuated with decreasing electron-releasing power
of the substituents on the 1,4-diethenylphenylene unit (OCH3
> CH3 > F > CF3), which is consistent with the conclusion
reached for the monosubstituted complexes mentioned above.
For the disubstituted complexes, the maximal ∆E1/2 difference
between the complex bearing the most electron-releasing
substituents (6j) and that bearing the most electron-withdrawing
substituents (6l) is 0.17 V, and the respective Kc values show a
decrease of about 3 orders of magnitude (Figure 5; Table 3).
As shown in Table 3, the ∆E1/2 difference between 6j and
6a is 0.06 V, which is larger than the difference of 0.02 V
between 6c and 6a. The same trend is observed between 6l and
6a as well as between 6m and 6a, and their ∆E1/2 differences
are 0.11 and 0.07 V, respectively. The results indicate the ∆E1/2
(33) (a) Vedova-Brook, N.; Matsunaga, N.; Sohlberg, K. Chem. Phys.
2004, 299, 89. (b) Xiao, X. Y.; Nagahara, L. A.; Rawlett, A. M.; Tao, N. J.
J. Am. Chem. Soc. 2005, 127, 9235. (c) Aviram, A.; Ratner, M. Chem.
Phys. Lett. 1974, 29, 277.

2456 Organometallics, Vol. 28, No. 8, 2009
Wu et al.
diethynyl-2-nitrobenzene (3h),39 1,4-diethynyl-2,5-dimethylbenzene
(3i),41 1,4-diethynyl-2,5-dimethoxybenzene (3j),40,42 and 1,4-
diethynyl-2,5-difluorobenzene (3k)40 were prepared by the proce-
dures described in literature methods.
and Kc values of the complexes bearing two strong electron-
donating substituents are significantly higher than those of their
monosubstituted counterparts, and the ∆E1/2 and Kc values of
the complexes bearing two strong electron-withdrawing sub-
stituents are significantly lower than those of their monosub-
stituted counterparts. This explains why disubstitution has a
greater effect than monosubstitution.
Synthesis of 1,4-Diethynylbenzene Derivatives. 2-Methyl-1,4-
bis(2-(trimethylsilyl)ethynyl)benzene (2b). 1,4-Dibromo-2-me-
thylbenzene (0.5 g, 2.0 mmol), PdCl2(PPh3)2 (0.14 g, 0.2 mmol),
and CuI (0.038 g, 0.2 mmol) were dissolved in tetrahydrofuran (30
mL) and diisopropylamine (1 mL). Then (trimethylsily)acetylene
(0.43 g, 4.4 mmol) was added to the stirred solution. The reaction
mixture was stirred at 40 °C for 24 h. The solvent was then
evaporated, and dichloromethane was added to the residue and
extracted with brine and water. The organic phases were dried with
Na2SO4. The crude product was purified by chromatography
(Petroleum ether) to give 0.39 g (69% yield) of monoyne and 0.05 g
(10% yield) of diyne (2b) as a yellow solid.
The result above showed the electronic communication
between the metal centers is largely substituent independent.
Attaching one or two electron-donating groups to the 1,4-
diethenylphenylene unit favors metal-metal communication,
whereas electron-withdrawing groups have the opposite effect.
The result is in good agreement with the theoretical estimation
by Vedova-Brook et al.33a and experimental results by Tao et
al.33b The chemical nature of a substituent can shift the frontier
molecular orbital (FMO) and alter the electron transport
efficiency through the molecule.33c In the presence of an
electron-withdrawing substituent, the bridging ligand should be
more positive and therefore less favorable for electronic
communication between their two metal residues. Conversely,
in the presence of an electron-donating substituent, the bridging
ligand should be more negatively charged and more favorable
for electronic communication. Chen5a and Touchard1u reported
the electrochemical studies of {(bph)(PPh3)2Ru}2{Ct C-Ar-
Ct C} (bph ) N-(benzoyl)-N′-(picolinylidene) hydrazine) and
trans-[Cl(dppe)2RudCdCdCH-Ar-CHdCdCdRu(dppe)2-
Cl](PF6)2 (Ar ) C4H2S, C6H4) and found the electron-richer
thiophene ring (pyrrole) can enhance the electron communications.
Diadduct: Anal. Calcd for C17H24Si2: C, 71.76; H, 8.50. Found:
1
C, 71.64; H, 8.31. H NMR (600 MHz, CDCl3): δ 0.24 (s, 9H,
SiCH3), 0.25 (s, 9H, SiCH3), 2.39 (s, 3H, CH3), 7.21 (d, J ) 7.8
Hz, 1H, Ph-H), 7.30 (s, 1H, Ph-H), 7.34 (d, J ) 8.4 Hz, 1H, Ph-
H). 13C{1H} NMR (150 MHz, CDCl3): δ -0.08, -0.02, 20.37,
95.68, 100.18, 103.51, 104.81, 122.93, 123.12, 128.97, 131.88,
132.73, 140.48.
2-Methoxy-1,4-bis(2-(trimethylsilyl)ethynyl)benzene (2c). To
a solution of 1,4-diiodo-2-methoxybenzene43 (0.736 g, 2.05 mmol),
CuI (38 mg, 0.2 mmol), and Pd (PPh3)2Cl2 (140 mg, 0.2 mmol) in
50 mL of triethylamine was added (trimethylsilyl)acetylene (0.603
g, 6.14 mmol). The mixture was stirred at room temperature for
15 h. After removal of the solvent in vacuo, the desired product
was separated from the starting material using silica gel with
petroleum ether as eluent to yield 0.524 g (85%) of a brown solid.
Anal. Calcd for C17H24OSi2: C, 67.94; H, 8.05. Found: C, 68.23;
H, 8.25. 1H NMR (600 MHz, CDCl3): δ 0.26 (s, 18H, SiMe3), 3.86
(s, 3H, OCH3), 6.93 (s, 1H, Ph-H), 7.00 (d, J ) 1.2 Hz, 1H, Ph-
H), 7.34 (d, J() 7.8 Hz, 1H, Ph-H). 13C{1H} NMR (150 MHz,
CDCl3): δ -0.14, -0.02, 55.80, 95.92, 100.33, 100.72, 104.62,
112.82, 113.73, 124.16, 124.28, 133.81, 159.77.
2-Chloro-1,4-bis(2-(trimethylsilyl)ethynyl)benzene (2e). Simi-
lar coupling procedures to those in 2e were adopted using 1,4-
dibromo-2-chlorobenzene (0.54 g, 2.0 mmol) to obtain a pale yellow
solid in 78% yield. Anal. Calcd for C16H21ClSi2: C, 63.01; H, 6.94.
Found: C, 63.46; H, 6.59. 1H NMR (600 MHz, CDCl3): δ 0.24 (s,
9H, SiCH3), 0.27 (s, 9H, SiCH3), 7.25 (dd, J1 ) 1.8 Hz, J2 ) 1.2
Hz, 1H, Ph-H), 7.39 (d, J ) 7.8 Hz, 1H, Ph-H), 7.47 (d, J ) 1.2
Hz, 1H, Ph-H). 13C{1H} NMR (150 MHz, CDCl3): δ -0.21, -0.19,
97.60, 100.91, 102.14, 103.08, 123.05, 124.35, 129.69, 132.29,
133.18, 135.92.
Conclusions
We have reported here the synthesis, characterization, and
electrochemical properties of a series of vinyl binuclear
ruthenium complexes. Electrochemical studies have revealed
that all of these vinyl complexes display two successive Ru-
based one-electron processes and that intermetallic electronic
communication between the two Ru centers may be fine-tuned
by modification of the 1,4-diethenylphenylene bridging ligand.
It has clearly been demonstrated that electron-releasing sub-
stituents facilitate electron communication between the two Ru
centers.
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 measure-
ments, which were of spectroscopic grade. The reagents ethynyl-
trimethylsilane, 2-methylbut-3-yn-2-ol, 1,4-bis(trifluoromethyl)ben-
zene, 1,4-dibromo-2-methylbenzene (1b), 1,4-dibromo-2-fluoro-
benzene (1d), 1,4-dibromo-2-chlorobenzene (1e), 1,4-dibromo-2,5-
difluorobenzene (1k), and 1,4-dibromo-2-(trifluoromethyl)benzene
(1m) were purchased from Alfa Aesar. Others were commercially
available. The starting materials RuHCl(CO)(PPh3)3,34 1,4-diiodo-
2-methoxybenzene (1c),35 2-bromo-1,4-diiodobenzene (1f),36 2,5-
diiodobenzonitrile (1g),37 1,4-bis(trifluoromethyl)-2,5-diiodobenzene
(1l),38 2-bromo-1,4-bis(2-(trimethylsilyl)ethynyl)benzene (2f),36 1,4-
diethynylbenzene (3a),39 1,4-diethynyl-2-fluorobenzene (3d),40 1,4-
2,5-Bis(2-(trimethylsilyl)ethynyl)benzonitrile (2g). Similar cou-
pling procedures as in 2e were adopted using 2,5-diiodobenzonitrile
(0.70 g, 2.0 mmol) to obtain a pale yellow solid in 60% yield. Anal.
Calcd for C17H21NSi2: C, 69.90; H, 7.16; N, 4.74. Found: C, 69.44;
1
H, 7.04; N, 4.49. H NMR (600 MHz, CDCl3): δ 0.25 (s, 9H,
SiCH3), 0.29 (s, 9H, SiCH3), 7.48 (d, J ) 7.8 Hz, 1H, Ph-H), 7.56
(38) Kim, Y. M.; Whitten, J. E.; Swager, T. M. J. Am. Chem. Soc. 2005,
127, 12122.
(39) Jr., D. W.; Dirk, S. M.; Maya, F.; Tour, J. M. Tetrahedron 2003,
59, 2497.
(40) Khan, M. S.; Al-Mandhary, M. R. A.; Al-Suti, M. K.; Corcoran,
T. C.; Al-Mahrooqi, Y.; Attfield, J. P.; Feeder, N.; David, W. I. F.;
Shankland, K.; Friend, R. H.; Ko¨hler, A.; Marseglia, E. A.; Tedesco, E.;
Tang, C. C.; Raithby, P. R.; Collings, J. C.; Roscoe, K. P.; Batsanov, A. S.;
Stimson, L. M.; Marder, T. B. New J. Chem. 2003, 27, 140.
(41) McQuade, D. T.; Kim, J. S.; Swager, T. M. J. Am. Chem. Soc.
2000, 122, 5885.
(34) Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, M. F.;
Wonchoba, E. R.; Parshall, G. W. Inorg. Synth. 1974, 15, 45.
(35) Mangel, T.; Eberhardt, A.; Scherf, U.; Bunz, U. H. F.; Mu¨llen, K.
Macromol. Rapid Commun. 1995, 16, 571.
(36) Morin, J.-F.; Shirai, Y.; Tour, J. M. Org. Lett. 2006, 8, 1713.
(37) Yamaguchi, Y.; Ochi, T.; Wakamiya, T.; Matsubara, Y.; Yoshida,
Z. Org. Lett. 2006, 8, 717.
(42) Dirk, S. M.; Jr., D. W. P.; Chanteau, S.; Kosynkin, D. V.; Tour,
J. M. Tetrahedron 2001, 57, 5109.
(43) Mangel, T.; Eberhardt, A.; Scherf, U.; Bunz, U. H. F.; Mu¨llen, K.
Macromol. Rapid Commun. 1995, 16, 571.

Binuclear Ruthenium Vinyl Complexes
Organometallics, Vol. 28, No. 8, 2009 2457
(d, J ) 7.8 Hz, 1H, Ph-H), 7.69 (s, 1H, Ph-H). 13C{1H} NMR (150
MHz, CDCl3): δ -0.47, -0.39, 99.09, 100.17, 101.92, 104.12,
115.94, 116.33, 123.80, 126.16, 132.25, 135.15, 135.46.
(600 MHz, CDCl3): δ 1.63 (s, 12H, CH3), 7.81 (s, 2H, Ph-H).
13C{1H} NMR (150 MHz, CDCl3): δ 30.85, 65.64, 102.71, 120.95,
123.24, 128.47, 131.25, 134.37.
1,4-Diethynyl-2-methylbenzene (3b). 2-Methyl-1,4-bis(2-(tri-
methylsilyl)ethynyl)benzene (0.93 g, 3.3 mmol) was dissolved in
a mixture of dichloromethane and methanol (40 mL, 1:1, v/v).
Powdered potassium carbonate (4.1 g, 30 mmol) was added, and
the reaction mixture was stirred at room temperature for 12 h. The
reaction mixture was diluted with dichloromethane and washed with
brine. The organic layer was dried over NaSO4, and the solvent
removed in vacuo. The crude product was purified by chromatog-
raphy (petroleum ether). Yield: 0.38 g (84%) of pale yellow solid.
Anal. Calcd for C11H8: C, 94.25; H, 5.75. Found: C, 94. 52; H,
1,4-(2-Trifluoromethyl-1,4-phenylene)bis(2-methylbut-3-yn-
2ol) (4b). Similar coupling procedures as in 4a were adopted using
1,4-dibromo-2-(trifluoromethyl)benzene (0.6 g, 2.0 mmol) to obtain
a brownish-red oil in 85% yield. Anal. Calcd for C17H17F3O2: C,
1
65.80; H, 5.52. Found: C, 65.63; H, 5.35. H NMR (600 MHz,
CDCl3): δ 1.61 (s, 6H, CH3), 1.62 (s, 6H, CH3), 7.44 (m, 2H, Ph-
H), 7.64 (d, J ) 1.2 Hz, 1H, Ph-H). 13C{1H} NMR (150 MHz,
CDCl3): δ 30.79, 31.8, 65.30, 77.68, 80.23, 83.90, 97.03, 101.10,
120.40, 122.77, 128.69, 133.51, 133.93.
1,4-Diethynyl-2,5-bis(trifluoromethyl)benzene (5a). Compound
4a (0.62 g, 2.0 mmol) and NaOH (1.0 g, excess) were added to
toluene (30 mL) in a flask. Then the reaction mixture was refluxed
for 24 h. The solvent was evaporated and the residue was purified
with flash column chromatography over silica gel, eluted with
petroleum ether, to give 5a as a yellow solid (0.33 g, 63%). Anal.
Calcd for C12H4F6: C, 54.98; H, 1.54. Found: C, 55.30; H, 1.89.
1H NMR (600 MHz, CDCl3): δ 3.55 (s, 2H, t CH), 7.90 (s, 1H,
Ph-H). 13C{1H} NMR (150 MHz, CDCl3): δ 77.83, 86.49, 120.99,
121.27, 123.09, 132.22, 135.09.
1,4-Diethynyl-2-(trifluoromethyl)benzene (5b). Similar depro-
tection procedures in 5a were adopted to obtain a brownish-red
solid in 64% yield. Anal. Calcd for C11H5F3: C, 68.05; H, 2.60.
Found: C, 67.89; H, 2.80. 1H NMR (600 MHz, CDCl3): δ 3.24 (s,
1H, t CH), 3.46 (s, 1H, t CH), 7.57 (m, 2H, Ph-H), 7.76 (d, J )
1.2 Hz, 1H, Ph-H). 13C{1H} NMR (150 MHz, CDCl3): δ 78.94,
80.61, 81.65, 84.78, 120.52, 121.93, 122.86, 123.74, 129.49, 132.40,
134.69.
Synthesis of Binuclear Rutheniun Complexes (6). 1,4-[RuCl-
(CO)(PMe3)3CHdCH]2C6H4 (6a). To a suspension of RuH-
Cl(CO)(PPh3)3 (0.762 g, 0.80 mmol) in CH2Cl2 (30 mL) was slowly
added a solution of 1,4-diethynylbenzene (0.063 g, 0.50 mmol) in
CH2Cl2 (10 mL). The reaction mixture was stirred for 30 min to
give a red solution. Then a 1 M THF solution of PMe3 (4.0 mL,
4.0 mmol) was added to the red solution. The mixture was stirred
for another 15 h. The solution was filtered through a column of
Celite. The volume of the filtrate 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. Yield: 0.26 g, 70%. Anal. Calcd for
C30H62Cl2O2P6Ru2 · C6H12: C, 43.33; H, 7.48. Found: C, 43.04; H,
7.69. 31P{1H} NMR (160 MHz, CDCl3): δ -21.01 (t, J ) 21.1
Hz), -9.35 (d, J ) 21.1 Hz). 1H NMR (400 MHz, CDCl3): δ 1.39
(t, J ) 3.2, 36H, PMe3), 1.45 (d, J ) 6.8, 18H, PMe3), 6.54 (m,
2H, Ar-CHd), 7.25 (s, 2H, Ar-H), 7.96 (m, 2H, Ru-CHd). 13C{1H}
NMR (150 MHz, CDCl3): δ 16.56(t, J ) 15.2 Hz, PMe3), 20.13
(d, J ) 20.55 Hz, PMe3), 124.34, 134.86, 137.79, 164.72, 202.48
(CO). IR (KBr, ν in cm-1): 1915 (CO), 1554, 1420 (CdC aryl,
vinyl).
1
5.66. H NMR (600 MHz, CDCl3): δ 2.44 (s, 3H, CH3), 3.17 (s,
1H, t CH), 3.39 (s, 1H, t CH), 7.28 (d, J ) 8.4 Hz, 1H, Ph-H),
7.36 (s, 1H, Ph-H), 7.42 (d, J ) 7.8 Hz, 1H, Ph-H). 13C{1H} NMR
(150 MHz, CDCl3): δ 20.28, 78.62, 81.89, 83.75, 83.22, 122.25,
122.45, 129.15, 132.29, 132.89, 140.69.
1,4-Diethynyl-2-methoxybenzene (3c). Methanol (20 mL) and
aqueous KOH (7 mL, 20%) were added at room temperature to a
stirred solution of 2-methoxy-1,4-bis(2-(trimethylsiyl)ethynyl)ben-
zene (0.30 g, 1.0 mmol) in tetrahydrofuran (40 mL), and the reaction
mixture was stirred for 2 h. After removal of the solvent in vacuo,
the desired product was separated from starting material using silica
gel with petroleum ether as eluent to yield 0.119 g (76%) of a brown
solid. Anal. Calcd for C11H8O: C, 84.59; H, 5.16. Found: C, 84.36;
1
H, 5.79. H NMR (600 MHz, CDCl3): δ 3.17 (s, 1H, t CH), 3.38
(s, 1H, t CH), 3.89 (s, 3H, OCH3), 6.89 (s, 1H, Ph-H), 7.05 (d, J
) 1.2 Hz, 1H, Ph-H), 7.39 (d, J ) 7.8 Hz, 1H, Ph-H). 13C{1H}
NMR (150 MHz, CDCl3): δ 55.87, 78.82, 79.46, 82.78, 83.09,
112.09, 113.98, 123.69, 124.32, 133.89, 160.09.
2-Chloro-1,4-diethynylbenzene (3e). Similar desilylation pro-
cedures in 3b were adopted to obtain an off-white solid in 83%
yield. Anal. Calcd for C10H5Cl: C, 74.79; H, 3.14. Found: C, 74.37;
1
H, 3.46. H NMR (600 MHz, CDCl3): δ 3.21 (s, 1H, t CH), 3.46
(s, 1H, t CH), 7.32 (dd, J ) 1.2 Hz, 1H, Ph-H), 7.46 (d, J ) 6.4
Hz, 1H, Ph-H), 7.52 (d, J ) 0.6 Hz, 1H, Ph-H). 13C{1H} NMR
(150 MHz, CDCl3): δ 79.75, 80.21, 81.67, 84.16, 122.51, 123.81,
130.02, 132.56, 133.65, 136.12.
2-Bromo-1,4-diethynylbenzene (3f). Similar desilylation pro-
cedures in 3b were adopted to obtain an off-white solid in 73%
yield. Anal. Calcd for C10H5Br: C, 58.57; H, 2.46. Found: C, 58.79;
1
H, 2.64. H NMR (600 MHz, CDCl3): δ 3.12 (s, 1H, t CH), 3.38
(s, 1H, t CH), 7.25 (dd, J1 ) 0.6 Hz, J2 ) 1.2 Hz, 1H, Ph-H), 7.34
(d, J ) 7.8 Hz, 1H, Ph-H), 7.60 (d, J ) 0.6 Hz, 1H, Ph-H). 13C{1H}
NMR (150 MHz, CDCl3): δ 80.35, 81.43, 81.48, 83.64, 123.80,
124.60, 125.14, 130.48, 133.56, 135.55.
2,5-Diethynylbenzonitrile (3g). Similar desilylation procedures
in 3b were adopted to obtain a white solid in 85% yield. Anal.
Calcd for C11H5N: C, 87.40; H, 3.33; N, 9.27. Found: C, 87.76; H,
3.61; N, 9.08. 1H NMR (600 MHz, CDCl3): δ 3.31 (s, 1H, t CH),
3.60 (s, 1H, t CH), 7.56 (d, J ) 6.0 Hz, 1H, Ph-H), 7.63 (d, J )
7.8 Hz, 1H, Ph-H), 7.75 (s, 1H, Ph-H). 13C{1H} NMR (150 MHz,
CDCl3): δ 79.09, 80.67, 81.55, 85.63, 116.11, 116.26, 123.39,
125.66, 132.92, 135.58, 135.77.
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3CH3 (6b). The synthesis
is similar to 6a, with 1,4-diethynylbenzene being replaced by 1,4-
diethynyl-2-methylbenzene. Yellow solid, yield: 0.31 g, 83%. Anal.
Calcd for C31H64Cl2O2P6Ru2: C, 40.13; H, 6.95. Found: C, 40. 45;
H, 7.26. 31P{1H} NMR (240 MHz, CDCl3): δ -19.14 (t, J ) 21.9
1
Hz, PMe3), -7.38 (d, J ) 21.9 Hz, PMe3). H NMR (600 MHz,
1,4-(2,5-Bis(trifluoromethyl)-1,4-phenylene)bis(2-methylbut-
3-yn-2ol) (4a). To a solution of 1,4-bis(trifluoromethyl)-2,5-
diiodobenzene (0.93 g, 2.0 mmol), CuI (38 mg, 0.2 mmol), and Pd
(PPh3)2Cl2 (140 mg, 0.2 mmol) in 30 mL of diisopropylamine was
added 2-methylbut-3-yn-2-ol (1.0 mL, 10.0 mmol). The mixture
was refluxed for 24 h. After removal of the solvent in vacuo, the
desired product was separated from starting material using silica
gel with petroleum ether/dichloromethane (1:1, v/v) as eluent to
give the product as a yellow solid: 0.67 g (88%). Anal. Calcd for
C18H16F6O2: C, 57.15; H, 4.26. Found: C, 57.34; H, 4.58. 1H NMR
CDCl3): δ 1.39 (t, J ) 3.0 Hz, 36H, PMe3), 1.47 (d, J ) 6.0 Hz,
18H, PMe3), 2.37 (s, 3H, CH3), 6.50 (m, 1H, ArCHd), 6.74 (m,
1H, ArCHd), 7.09 (d, J ) 7.8 Hz, 2H, Ph-H), 7.44 (d, J ) 7.8 Hz,
1H, Ph-H), 7.89-7.97 (m, 2H, RuCHd). 13C{1H} NMR (150 MHz,
CDCl3): δ16.50(t, J ) 14.55 Hz, PMe3), 20.15 (d, J ) 20.10 Hz,
PMe3), 53.34, 122.22, 123.91, 125.76, 131.90, 132.10, 134.86,
136.51, 137.49, 162.02, 163.85, 202.37 (CO). IR (KBr, ν in cm-1):
1919 (CO), 1552, 1419 (CdC aryl, vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3OCH3 (6c). The syn-
thesis is similar to 6a, with 1,4-diethynylbenzene being replaced

2458 Organometallics, Vol. 28, No. 8, 2009
Wu et al.
by 1,4-diethynyl-2-methoxybenzene. Yellow solid, yield: 0.33 g,
87%. Anal. Calcd for C31H64Cl2O3P6Ru2: C, 39.45; H, 6.84. Found:
C, 39.72; H, 6.52. 31P{1H} NMR (160 MHz, CDCl3): δ-19.66 (t,
J ) 21.9 Hz, PMe3), -7.93 (d, J ) 21.9 Hz, PMe3). 1H NMR (600
MHz, CDCl3): δ 1.38 (t, J ) 2.4 Hz, 36H, PMe3), 1.47 (d, J ) 6.6
Hz, 18H, PMe3), 3.84 (s, 3H, OCH3), 6.51 (m, 1H, ArCHd), 6.83
(m, 1H, ArCHd), 6.87 (d, J ) 6.6 Hz, 1H, Ph-H), 6.90 (d, J ) 7.2
Hz, 1H, Ph-H), 7.42 (d, J ) 8.4 Hz, 1H, Ph-H), 7.89 (m, 1H,
RuCHd), 7.94 (m, 1H, RuCHd). 13C{1H} NMR (150 MHz,
CDCl3): δ 16.54(t, J ) 14.55 Hz, PMe3), 20.09 (d, J ) 20.10 Hz,
PMe3), 55.84, 106.98, 117.31, 124.44, 127.43, 128.45, 134.98,
138.60, 154.73, 162.30, 202.33 (CO). IR (KBr, ν in cm-1): 1921
(CO), 1549, 1423 (CdC aryl, vinyl).
127.42, 128.35, 132.60, 135.07, 137.51, 139.77, 168.43, 173.93,
201.85 (CO). IR (KBr, ν in cm-1): 1920 (CO), 1552, 1420 (CdC
aryl, vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3NO2 (6h). The synthesis
is similar to 6a, with 1,4-diethynylbenzene being replaced by 1,4-
diethynyl-2-nitrobenzene. Purple solid, yield: 0.28 g, 74%. Anal.
Calcd for C30H61Cl2NO4P6Ru2: C, 37.50; H, 6.61; N, 1.46. Found:
C, 37.71; H, 6.58; N, 1.38. 31P{1H} NMR (160 MHz, CDCl3): δ
-21.82 (t, J ) 22.7 Hz, PMe3), -10.37 (d, J ) 22.7 Hz, PMe3).
1H NMR (400 MHz, CDCl3): δ 1.41 (t, J ) 3.2 Hz, 36H, PMe3),
1.47 (d, J ) 6.8 Hz, 18H, PMe3), 6.53 (m, 1H, Ar-CHd), 6.84 (m,
1H, Ar-CHd), 7.43-7.56 (m, 3H, Ar-H), 8.21 (m, 1H, Ru-CHd),
8.29 (m, 1H, Ru-CHd). 13C{1H} NMR (150 MHz, CDCl3): δ
16.71(t, J ) 14.55 Hz, PMe3), 20.02 (d, J ) 20.15 Hz, PMe3),
119.06, 126.99, 127.71, 128.64, 131.32, 132.68, 138.06, 146.48,
170.58, 202.04 (CO). IR (KBr, ν in cm-1): 1919 (CO), 1515, 1419
(CdC aryl, vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3F (6d). The synthesis is
similar to 6a, with 1,4-diethynylbenzene being replaced by 1,4-
diethynyl-2-fluorobenzene. Yellow solid, yield: 0.28 g, 74%. Anal.
Calcd for C30H61Cl2FO2P6Ru2: C, 38.67; H, 6.60. Found: C, 38.59;
H, 6.30. 31P{1H} NMR (240 MHz, CDCl3): δ -19.04 (t, J ) 21.9
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H2-2,5-(CH3)2 (6i). The
synthesis is similar to 6a, with 1,4-diethynylbenzene being replaced
by 1,4-diethynyl-2,5-dimethylbenzene. Yellow solid, yield: 0.17 g,
46%. Anal. Calcd for C32H66Cl2O2P6Ru2: C, 40.81; H, 7.06. Found:
C, 40.23; H, 7.01. 31P{1H} NMR (160 MHz, CDCl3): δ -22.12 (t,
1
Hz, PMe3), -7.42 (d, J ) 21.9 Hz, PMe3). H NMR (600 MHz,
CDCl3): δ 1.39 (t, J ) 3.0 Hz, 36H, PMe3), 1.47 (d, J ) 7.2 Hz,
18H, PMe3), 6.50 (m, 1H, ArCHd), 6.73 (m, 1H, ArCHd), 6.97
(t, J ) 7.2 Hz, 1H, Ar-H), 7.43 (t, J ) 7.2 Hz, 1H, Ar-H),
8.00-8.07 (m, 2H, RuCHd). 13C{1H} NMR (150 MHz, CDCl3):
δ 16.56(t, J ) 14.55 Hz, PMe3), 20.07 (d, J ) 20.10 Hz, PMe3),
110.07, 120.11, 124.91, 125.71, 133.81, 139.19, 157.99, 159.60,
165.79, 166.31, 202.23 (CO). IR (KBr, ν in cm-1): 1916 (CO),
1553, 1418 (CdC aryl, vinyl).
1
J ) 21.1 Hz, PMe3), -10.43 (d, J ) 21.1 Hz, PMe3). H NMR
(400 MHz, CDCl3): δ 1.40 (t, J ) 3.2 Hz, 36H, PMe3), 1.47 (d, J
) 6.8 Hz, 18H, PMe3), 2.34 (s, 6H, CH3), 6.74 (m, 2H, Ar-CHd),
7.25-7.52 (m, 2H, Ar-H), 7.88 (m, 2H, Ru-CHd). 13C{1H} NMR
(100 MHz, CDCl3): δ 16.69 (t, J ) 15.3 Hz, PMe3), 19.69, 20.26
(d, J ) 20.6 Hz, PMe3), 125.54, 129.83, 132.45, 136.32, 162.91,
202.58 (CO). IR (KBr, ν in cm-1): 1919 (CO), 1550, 1421 (CdC
aryl, vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3Cl (6e). The synthesis
is similar to 6a, with 1,4-diethynylbenzene being replaced by
2-chloro-1,4-diethynylbenzene. Yellow solid, yield: 0.34 g, 89%.
Anal. Calcd for C30H61Cl3O2P6Ru2: C, 38.00; H, 6.48. Found: C,
37.59; H, 6.16. 31P{1H} NMR (240 MHz, CDCl3): δ-19.04 (t, J
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H2-2,5-(OCH3)2 (6j). The
synthesis is similar to 6a, with 1,4-diethynylbenzene being replaced
by 1,4-diethynyl-2,5-dimethoxybenzene. Yellow solid, yield: 0.27 g,
68%. Anal. Calcd for C32H66Cl2O4P6Ru2: C, 39.47; H, 6.83. Found:
C, 39.43; H, 7.21. 31P{1H} NMR (160 MHz, CDCl3): δ -22.05 (t,
1
) 21.9 Hz, PMe3), -7.45 (d, J ) 21.9 Hz, PMe3). H NMR (600
MHz, CDCl3): δ 1.38 (t, J ) 3.0 Hz, 36H, PMe3), 1.47 (d, J ) 6.6
Hz, 18H, PMe3), 6.47 (m, 1H, ArCHd), 6.92 (m, 1H, ArCHd),
7.12 (d, J ) 1.2 Hz, 1H, Ar-H), 7.24 (d, J ) 1.8 Hz, 1H, Ar-H),
7.45 (d, J ) 7.8 Hz, 1H, Ar-H), 8.02-8.11 (m, 2H, RuCHd).
13C{1H} NMR (150 MHz, CDCl3): δ 16.60(t, J ) 14.55 Hz, PMe3),
20.07 (d, J ) 20.10 Hz, PMe3), 122.75, 124.62, 124.80, 130.47,
133.46, 134.62, 138.84, 153.80, 165.31, 167.66, 202.22 (CO). IR
(KBr, ν in cm-1): 1922 (CO), 1545, 1421 (CdC aryl, vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3Br (6f). The synthesis
is similar to 6a, with 1,4-diethynylbenzene being replaced by
2-bromo-1,4-diethynylbenzene. Yellow solid, yield: 0.28 g, 71%.
Anal. Calcd for C30H61BrCl2O2P6Ru2: C, 36.30; H, 6.19. Found:
C, 35.95; H, 5.73. 31P{1H} NMR (240 MHz, CDCl3): δ -19.11 (t,
J ) 21.9 Hz, PMe3), -7.48 (d, J ) 21.9 Hz, PMe3). 1H NMR (600
MHz, CDCl3): δ 1.38 (t, J ) 3.0 Hz, 36H, PMe3), 1.47 (d, J ) 3.6
Hz, 18H, PMe3), 6.46 (m, 1H, ArCHd), 6.87 (m, 1H, ArCHd),
7.16 (d, J ) 7.8 Hz, 1H, Ar-H), 7.42 (s, 1H, Ar-H), 7.44 (s, 1H,
Ar-H), 7.99-8.06 (m, 2H, RuCHd). 13C{1H} NMR (150 MHz,
CDCl3): δ 16.50(t, J ) 14.55 Hz, PMe3), 19.93 (d, J ) 20.10 Hz,
PMe3), 121.69, 123.09, 123.34, 125.70, 127.83, 133.20, 136.07,
139.09, 165.63, 168.05, 202.09 (CO). IR (KBr, ν in cm-1): 1921
(CO), 1541, 1420 (CdC aryl, vinyl).
1
J ) 21.1 Hz, PMe3), -10.22 (d, J ) 21.1 Hz, PMe3). H NMR
(400 MHz, CDCl3): δ 1.40 (t, J ) 3.2 Hz, 36H, PMe3), 1.47 (d, J
) 6.8 Hz, 18H, PMe3), 3.89 (s, 6H, OCH3), 6.88 (m, 2H, Ar-CHd),
7.04 (s, 2H, Ar-H), 7.88 (m, 2H, Ru-CHd). 13C{1H} NMR (150
MHz, CDCl3): δ 16.61(t, J ) 15.0 Hz, PMe3), 20.17 (d, J ) 20.10
Hz, PMe3), 57.46, 109.24, 128.58, 128.58, 149.82, 164.59, 202.29
(CO). IR (KBr, ν in cm-1): 1918 (CO), 1548, 1421 (CdC aryl,
vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H2-2,5-F2 (6k). The syn-
thesis is similar to 6a, with 1,4-diethynylbenzene being replaced
by 1,4-diethynyl-2,5-difluorobenzene. Yellow solid, yield: 0.32 g,
85%. Anal. Calcd for C30H60F2Cl2O2P6Ru2: C, 37.97; H, 6.37.
Found: C, 38.10; H, 5.97. 31P{1H} NMR (240 MHz, CDCl3):
δ-19.01 (t, J ) 21.9 Hz, PMe3), -7.51 (d, J ) 21.9 Hz, PMe3).
1H NMR (600 MHz, CDCl3): δ 1.39 (t, J ) 3.0 Hz, 36H, PMe3),
1.47 (d, J ) 6.0 Hz, 18H, PMe3), 6.71 (m, 2H, ArCHd), 7.13 (t,
J ) 8.0 Hz, 2H, Ph-H), 8.10 (m, 2H, RuCHd). 13C{1H} NMR
(150 MHz, CDCl3): δ 16.59(t, J ) 15.0 Hz, PMe3), 20.05 (d, J )
20.10 Hz, PMe3), 111.28, 124.73, 125.56, 153.20, 167.80, 201.91
(CO). IR (KBr, ν in cm-1): 1917 (CO), 1550, 1415 (CdC aryl,
vinyl).
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3CN (6g). The synthesis
is similar to 6a, with 1,4-diethynylbenzene being replaced by 2,5-
diethynylbenzonitrile. Yellow solid, yield: 0.28 g, 74%. Anal. Calcd
for C31H61NCl2O2P6Ru2: C, 39.66; H, 6.55; N, 1.49. Found: C,
39.93; H, 6.37; N, 1.14. 31P{1H} NMR (240 MHz, CDCl3): δ-19.01
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H2-2,5-(CF3)2 (6l). The syn-
thesis is similar to 6a, with 1,4-diethynylbenzene being replaced
by 1,4-diethynyl-2,5-bis(trifluoromethyl)benzene. Yellow solid,
yield: 0.32 g, 77%. Anal. Calcd for C32H60Cl2F6O2P6Ru2: C, 36.61;
H, 5.76. Found: C, 36.91; H, 5.52. 31P{1H} NMR (240 MHz,
CDCl3): δ-18.82 (t, J ) 21.9 Hz, PMe3), -7.26 (d, J ) 21.9 Hz,
1
(t, J ) 21.9 Hz, PMe3), -7.38 (d, J ) 21.9 Hz, PMe3). H NMR
(600 MHz, CDCl3): δ 1.38 (t, J ) 3.0 Hz, 36H, PMe3), 1.47 (d, J
) 5.4 Hz, 18H, PMe3), 6.49 (m, 1H, ArCHd), 6.97 (m, 1H,
ArCHd), 7.39 (s, 1H, Ar-H), 7.41 (d, J ) 6.4 Hz, 1H, Ar-H), 7.53
(d, J ) 6.4 Hz, 1H, Ar-H), 8.13 (m, 1H, RuCHd), 8.41 (m, 1H,
RuCHd). 13C{1H} NMR (150 MHz, CDCl3): δ 16.55 (t, J ) 14.55
Hz, PMe3), 19.93 (d, J ) 20.10 Hz, PMe3), 107.26, 119.52, 123.97,
1
PMe3). H NMR (600 MHz, CDCl3): δ 1.40 (t, J ) 3.0 Hz, 36H,
PMe3), 1.48 (d, J ) 7.2 Hz, 18H, PMe3), 6.90 (m, 2H, ArCHd),
7.79 (s, 1H, Ar-H), 8.25 (m, 1H, RuCHd). 13C{1H} NMR (150

Binuclear Ruthenium Vinyl Complexes
Organometallics, Vol. 28, No. 8, 2009 2459
MHz, CDCl3): δ 16.51(t, J ) 15.0 Hz, PMe3), 20.01 (d, J ) 20.10
Hz, PMe3), 123.71, 126.48, 135.52, 136.83, 168.35, 172.97, 202.05
(CO). IR (KBr, ν in cm-1): 1926 (CO), 1541, 1414 (CdC aryl,
vinyl).
Physical Measurements. Elemental analyses (C, H, N) were
1
performed by Vario ElIII Chnso. H, 13C{1H}, and 31P{1H} NMR
spectra were collected on a Varian Mercury Plus 400 spectrometer
(400 MHz) or on a Varian Mercury Plus 600 spectrometer (600
1
MHz). H, 13C NMR chemical shifts are relative to TMS, and 31P
1,4-[RuCl(CO)(PMe3)3CHdCH]2C6H3CF3 (6m). The synthesis
is similar to 6a, with 1,4-diethynylbenzene being replaced by 1,4-
diethynyl-2-(trifluoromethyl)benzene. Yellow solid, yield: 0.32 g,
82%. Anal. Calcd for C31H61Cl2F3O2P6Ru2: C, 37.93; H, 6.26.
Found: C, 37.57; H, 6.08. 31P{1H} NMR (240 MHz, CDCl3): δ
-19.07 (t, J ) 21.9 Hz, PMe3), -7.35 (d, J ) 21.9 Hz, PMe3). 1H
NMR (600 MHz, CDCl3): δ 1.39 (t, J ) 3.0 Hz, 36H, PMe3), 1.48
(d, J ) 6.0 Hz, 18H, PMe3), 6.54 (m, 1H, ArCHd), 6.89 (m, 1H,
ArCHd), 7.41 (s, 2H, Ar-H), 7.60 (d, J ) 7.8 Hz, 1H, Ar-H),
8.09-8.17 (m, 1H, RuCHd). 13C{1H} NMR (150 MHz, CDCl3):
δ 16.50 (t, J ) 15.0 Hz, PMe3), 19.93 (d, J ) 20.10 Hz, PMe3),
121.34, 123.52, 124.34, 125.71, 126.15, 129.92, 133.60, 135.81,
137.07, 165.61, 170.29, 201.89 (CO). IR (KBr, ν in cm-1): 1922
(CO), 1546, 1416 (CdC aryl, vinyl).
Crystallographic Details. Crystals suitable for X-ray diffraction
were grown from a dichloromethane of solution 6h, 6i, and 6j
layered with hexane. A crystal with approximate dimensions of
0.30 × 0.20 × 0.20 mm3 for 6h, 0.40 × 0.03 × 0.01 mm3 for 6i,
and 0.23 × 0.20 × 0.20 mm3 for 6j was mounted on a glass fiber
for diffraction experiment. Intensity data were collected on a Nonius
Kappa CCD diffractometer with Mo KR radiation (0.71073 Å) at
room temperature. The structures were solved by a combination of
direct methods (SHELXS-9744) and Fourier difference techniques
and refined by full-matrix least-squares (SHELXL-9745). All non-H
atoms were refined anisotropically. The hydrogen atoms were placed
in the 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, 3, and 4,
respectively.
NMR chemical shifts are relative to 85% H3PO4. IR spectra were
recorded on a Nicolet Avatar 360 FT-IR spectrophotometer using
KBr disks. UV-vis spectra were recorded on a PDA spectropho-
tometer by quartz cells with a path length of 1.0 cm. The
electrochemical measurements were performed on a CHI 660C
potentiostat (CHI USA). A three-electrode one-compartment cell
was used to contain the solution of the compound 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 (Bu4NPF6) concentrations
were typically 0.001 and 0.1 mol dm-3, 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 solution of 0.01 mol
dm-3 AgNO3 in acetonitrile and was incorporated into the cell with
a salt bridge containing 0.1 mol dm-3 Bu4NPF6 in CH2Cl2. All
electrochemical experiments were carried out under ambient
conditions.
Acknowledgment. The authors acknowledge financial
support from National Natural Science Foundation of China
(Nos. 20572029, 2072039, 20803027) and the Natural
Science Foundation of Hubei Province (No. 2008CDB023).
Supporting Information Available: Tables of bond distances
and angles, and X-ray crystallographic files (CIF) for 1,4-
[RuCl(CO)(PMe3)3CHdCH]2C6H3NO2(6h),1,4-[RuCl(CO)(PMe3)3-
CHdCH]2C6H2-2,5-(CH3)2 (6i), and 1,4-[RuCl(CO)(PMe3)3-
CHdCH]2C6H2-2,5-(OCH3)2 (6j). The materials are available free
of charge via the Internet at http://pubs.acs.org.
(44) Sheldrick, G. M. SHELXS-97, a program for crystal structure
solution; Go¨ttingen: Germany, 1997.
(45) Sheldrick, G. M. SHELXL-97, a program for crystal structure
refinement; Go¨ttingen, Germany, 1997.
OM900018Y