Bimetallic ruthenium complexes: Synthesis, characterization, and the effect of appending long carbon chains to their bridges

Article abstract of DOI:10.1021/om901025q

A series of binuclear ruthenium complexes [RuCl(CO)(PMe₃) ₃]₂(μ-CH=CH-Ar-CH=CH) (Ar = C₆H ₂(OR)₂-2,5; R = CH₃ (4a), ⁿC ₄H₉ (4b), ⁿC₆H1₃ (4c), ⁿC₈H₁₇ (4d), ⁿC₁₀H21 (4e), ⁿC₁₂H₂₅ (4f), ⁿC ₁₄H₂₉ (4g)), [RuCl(CO)(PMe₃)₃] ₂(μ-CH=CH-Ar-≡-Ar-CH=CH) (Ar = C₆H ₂(R)₂-2,5; R = OCH₃ (10a), OⁿC ₈H₁₇ (10b), H (10c)), and [RuCl(CO)(PMe₃) ₃]₂Cu-CH=CH-Ar-≡-Ar-≡-ArCH=CH) (Ar = C ₆H₂(R)₂-2,5; R = OCH₃ (13a), O ⁿC₈H₁₇ (13b), H (13c)) have been synthesized. These complexes have been characterized by elemental analysis, NMR, and UV/vis spectrophotometry. The structures of 4b and 4d have been determined by X-ray crystallography. Electrochemical studies have shown that long carbon chains attached to the bridges of the complexes facilitate the stability of mixed-valence bimetallic ruthenium complexes.

Full text of DOI:10.1021/om901025q

1150 Organometallics 2010, 29, 1150–1156
DOI: 10.1021/om901025q
Bimetallic Ruthenium Complexes: Synthesis, Characterization, and the
Effect of Appending Long Carbon Chains to Their Bridges
Xiang-Hua Wu, Jin Hua Liang, Jian-Long Xia, 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
Received November 26, 2009
A series of binuclear ruthenium complexes [RuCl(CO)(PMe3)3]2(μ-CHdCH-Ar-CHdCH)
n
n
n
n
n
(Ar = C6H2(OR)2-2,5; R = CH3 (4a), C4H9 (4b), C6H13 (4c), C8H17 (4d), C10H21 (4e), C12H25
(4f), nC14H29 (4g)), [RuCl(CO)(PMe3)3]2(μ-CHdCH-Ar-t-Ar-CHdCH) (Ar = C6H2(R)2-2,5; R =
OCH3 (10a), OnC8H17 (10b), H (10c)), and [RuCl(CO)(PMe3)3]2(μ-CHdCH-Ar-t-Ar-t-Ar-
CHdCH) (Ar = C6H2(R)2-2,5; R = OCH3 (13a), OnC8H17 (13b), H (13c)) have been synthesized. These
complexes have been characterized by elemental analysis, NMR, and UV/vis spectrophotometry. The
structures of 4b and 4d have been determined by X-ray crystallography. Electrochemical studies have shown
that long carbon chains attached to the bridges of the complexes facilitate the stability of mixed-valence
bimetallic ruthenium complexes.
Introduction
mixed-valence metal species and is a critical measure to
evaluate electronic delocalization along the conjugated mo-
lecular backbones in mixed-valence metal species.1e The
question then arises as to how this attenuation might be
Linear conjugated organometallic complexes in which two
redox-active transition metal moieties are connected by
molecule-based wires have been extensively investigated.1-5
Understanding of charge-transfer processes at the nanoscale
level has attracted intense interest recently.6 However, elec-
tronic coupling between two electroactive groups decays
dramatically with increasing length of the bridging ligands,
as in [(η5-C5Me5)Re(NO)(PPh3)2(CtC)n] (n = 2, ΔE= 0.53 V;
n = 3, ΔE = 0.38 V; n = 4, ΔE = 0.28 V; n = 5, ΔE = 0.20 V;
n=6,ΔE=0.19V;n=8,ΔE=0.09V;n=10,ΔE<0.07V).7
The wave separation or potential difference (ΔE1/2) is repre-
sentative of the thermodynamic stability of the corresponding
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*Corresponding author. E-mail: chshliu@mail.ccnu.edu.cn.
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r
pubs.acs.org/Organometallics
Published on Web 02/10/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 5, 2010 1151
Scheme 1
Scheme 2
prevented. In this context, some research groups have re-
cently reported that intermetallic electronic communication
between the two ferrocene centers could be enhanced by
incorporating metal moieties such as [Ru(dppm)2]8 or
[Pt2(dppm)],9 and more especially [Ru2(DMBA)4],10 where
DMBA is N,N0-dimethylbenzamidinate. This suggests that
some conjugated complexes incorporating metal moieties
may act as better electronic conductors than their all-carbon
analogues.
Previously, we reported that electronic coupling between
two Ru centers could be fine-tuned by modification of a 1,4-
diethenylphenylene bridging ligand and that the attachment
of an electron-releasing substituent (such as OCH3) facili-
tated electron coupling.5e Pelter et al. reported that two OR
groups on a benzene unit greatly enhanced the solubility
of such oligomers as well as their electronic effects.11 To
probe the efficiency of charge transfer across the molecular
fragment -Ar-, electron-releasing OR substituents with
alkyl chains of different lengths have been introduced. To
understand the electronic effects of these substituents at the
nanoscale level with a view to limiting the attenuation of
electronic coupling between two Ru centers with increasing
length of the molecular wire, some oligomeric binuclear
complexes have been prepared. The electrochemical proper-
ties of these binuclear complexes have been investigated by
voltammetric techniques.
Results and Discussion
Syntheses and Characterization. Substituted 1,4-diethynyl-
benzene derivatives 3a-g were synthesized by a sequence of
coupling and deprotection reactions according to methods
reported in the literature. Compound 9a was obtained by
multiple Sonogashira couplings and selective deprotections
(Supporting Information). The starting reagent 1,4-diiodo-
2,5-dimethoxybenzene (1a)12 was subjected to monoiodo
coupling with 2-methyl-3-butyn-2-ol to afford 5a.13 The
remaining iodo substituent in 5a was subsequently coupled
with trimethylsilylethyne, also under Sonogashira condi-
tions, to give 6a. Selective deprotection of the trimethylsilyl
protecting group with K2CO3 in MeOH/CH2Cl2 gave the
corresponding terminal alkyne 7a. Compound 7a was then
coupled with the previously prepared iodide 5a to afford 8a.
(6) (a) Adams, D. M.; Brus, L.; Chidsey, C. E. D.; Creager, S.; Creutz,
C.; Kagan, C. R.; Kamat, P. V.; Lieberman, M.; Lindsay, S.; Marcus,
R. A.; Metzger, R. M.; Michel-Beyerle, M. E.; Miller, J. R.; Newton,
M. D.; Rolison, D. R.; Sankey, O.; Schanze, K. S.; Yardley, J.; Zhu,
X. Y. J. Phys. Chem. B 2003, 107, 6668. (b) Barbara, P. F.; Meyer, T. J.;
Ratner, M. A. J. Phys. Chem. 1996, 100, 13148. (c) Nitzan, A.; Ratner, M. A.
Science 2003, 300, 1384.
(7) (a) Horn, C. R.; Martin-Alvarez, J. M.; Gladysz, J. A. Organo-
metallics 2002, 21, 5386. (b) Horn, C. R.; Gladysz, J. A. J. Eur. Inorg.
Chem. 2003, 2211. (c) Dembinski, R.; Bartik, T.; Bartik, B.; Jaeger, M.;
Gladysz, J. A. J. Am. Chem. Soc. 2000, 122, 810. (d) Brady, M.; Weng, W.;
€
Zhou, Y.; Seyler, J. W.; Amoroso, A. J.; Arif, A. M.; Bohme, M.; Frenking,
G.; Gladysz, J. A. J. Am. Chem. Soc. 1997, 119, 775.
(8) (a) Levanda, C.; Bechgaard, K.; Cowan, D. O. J. Org. Chem.
1976, 41, 2700. (b) Zhu, Y.; Clot, O.; Wolf, M. O.; Yap, G. P. J. Am. Chem.
Soc. 1998, 120, 1812. (c) Jones, N. D.; Wolf, M. O.; Giaquinta, D. M.
Organometallics 1997, 16, 1352.
(9) Yip, J. H. K.; Wu, J.; Wong, K.-Y.; Ho, K. P.; Pun, C. S.-N.;
Vittal, J. J. Organometallics 2002, 21, 5292.
(10) (a) Xu, G. L.; DeRosa, M. C.; Crutchley, R. J.; Ren, T. J. Am.
Chem. Soc. 2004, 126, 3728. (b) Xu, G. L.; Crutchley, R. J.; DeRosa, M. C.;
Pan, Q. J.; Zhang, H. X.; Wang, X. P.; Ren, T. J. Am. Chem. Soc. 2005, 127,
13354. (c) Xi, B.; Xu, G.-L.; Fanwick, P. E.; Ren, T. Organometallics 2009,
28, 2338.
(11) Pelter, A.; Jones, D. E. J. Chem. Soc., Perkin Trans. 1 2000, 2289.
(12) Waybright, S. M.; Singleton, C. P.; Wachter, K.; Murphy, C. J.;
Bunz, U. H. F. J. Am. Chem. Soc. 2001, 123, 1828.
(13) Sasaki, T.; Tour, J. M. Tetrahedron Lett. 2007, 48, 5821.

1152 Organometallics, Vol. 29, No. 5, 2010
Wu et al.
Scheme 3
˚
Table 2. Selected Bond Lengths (A) and Angles (deg) for 4b and 4d
Table 1. Crystal Data, Data Collection, and Refinement Para-
meters for 4b and 4d
4b
4d
4b
4d
C(11)-C(12)
C(12)-C(13)
C(13)-C(14)
C(13)-C(15)
C(140)-O(100)
C(16 )-O(1 )
C(15)-O(2)
O(2)-C(16)
C(10)-Ru(1)
C(11)-Ru(1)
1.317(8)
1.478(8)
1.404(8)
1.373(9)
1.395(9)
1.372(10)
1.333(5)
1.478(5)
1.393(5)
1.414(5)
formula
fw
C
38H78Cl2O4P6Ru2
C46H94Cl2O4P6Ru2
1170.07
200(2)
tetragonal
P42/n
25.1492(7)
25.1492(7)
9.6436(6)
90.00
1057.86
299(2)
temp (K)
cryst syst
space group
tetragonal
P42/n
25.6226(7)
25.6226(7)
9.6058(5)
90.00
˚
1.385(4)
1.394(6)
1.824(4)
2.102(3)
a (A)
˚
b (A)
˚
c (A)
1.801(9)
2.105(5)
β (deg)
-3
˚
V (A
Z
)
6306.4(4)
4
1.114
0.0911, 0.0000
0.0715
0.1640
0.1199
0.1806
1.003
6099.4(4)
4
1.274
0.0742, 5.4310
0.0514
0.1355
0.0614
0.1435
0.110
C(12)-C(11)-Ru(1)
C(11)-C(12)-C(13)
C(12)-C(13)-C(14)
C(13)-C(14)-O(10)
C(13)-C(15)-O(2)
C(10)-Ru(1)-C(11)
C(11)-Ru(1)-Cl(1)
C(11)-Ru(1)-Cl(2)
179.2(8)
128.5(7)
121.3(6)
112.9(9)
132.3(3)
126.6(3)
123.6(3)
Dcalcd (g cm-3
a, b for Wa
final R
)
119.2(3)
90.51(15)
87.36(11)
Rw
R (all data)
Rw (all data)
90.3(3)
goodness of fit/F2
87.58(17)
a W = 1/[σ2(Fo)2 þ (aP)2 þ bP], where P = (Fo þ Fc2)/3.
2
distances and angles for 4b and 4d are presented in Table 2.
The molecular structures of 4b and 4d are depicted in
Figures 1 and 2, respectively. The rod-like binuclear ruthe-
nium arrays in 4b and 4d consist of two [(PMe3)3Cl(CO)Ru]
end-groups linked by a μ-CHdCH-Ar-CHdCH (Ar =
C6H2(OC4H9)2-2,5 (4b), C6H2(OC8H17)2-2,5 (4d)) carbon
chain through Ru-C σ-bonding. The molecular structures
of 4b and 4d are centrosymmetric, and some C atoms in the
OR groups are disordered. The two Ru centers are related by
a pseudo-C2 rotation axis. The distances of two Ru atoms in
The 2-hydroxy-2-propyl fragments were removed by reflux-
ing 8a in toluene in the presence of sodium hydroxide to give
the corresponding diterminal alkyne 9a. Following the above
procedures, compounds 5b-9b were prepared analogously.
Twofold Sonogashira reaction of 5a with the diterminal
alkyne 3a gave 11a. Treatment of the latter compound with
NaOH in toluene afforded the diterminal alkyne 12a
(Supporting Information). Likewise, compounds 11b and
12b were obtained under the same conditions.
Reactions of the diethynylaryls 3a-g, 9a-c, and 12a-c
with the ruthenium hydride complex [RuHCl(CO)(PPh3)3]
afforded the corresponding insertion products [(PPh3)2Cl-
(CO)Ru]2(μ-CHdCH-Ar-CHdCH), [(PPh3)2Cl(CO)Ru]2-
(μ-CHdCH-Ar-t-Ar-CHdCH), and [(PPh3)2Cl(CO)-
Ru]2(μ-CHdCH-Ar-t-Ar-t-Ar-CHdCH),respectively,
which were not isolated because they are air-sensitive, espe-
cially in solution. PMe3 was then added to give the corre-
sponding six-coordinated complexes 4a-g, 10a-c, and
13a-c, respectively (Schemes 1, 2, and 3). These complexes
were characterized by NMR. The PMe3 ligands in all of these
bimetallic complexes are meridionally coordinated to ruthe-
nium, as indicated by an AM2 pattern in the 31P{1H} NMR
spectra.
˚
complexes 4b and 4d are 11.913 and 11.906 A, respectively,
˚
both of which are shorter than that of 11.919 A in complex
4a.5e The carbon atoms of the two CHdCH units and
benzene ring are nearly coplanar, with dihedral angles
between the core benzene ring and the two vinyl groups of
4.63° in 4b and 6.10° in 4d, respectively. The overall geometry
about the two ruthenium centers in 4b and 4d closely
resembles that in the bimetallic ruthenium complexes
[RuCl(CO)(PMe3)3]2(μ-(CHdCH)n)5f,h,i and [RuCl(CO)-
(PMe3)3]2(μ-CHdCH-C6H2(R)2-2,5-CHdCH) (R = CH3,
OCH3).5e The two complexes adopt the same crystal system
and space group, as can be seen in Table 1, which are distinct
from those of complex 4a.
Electronic Absorption Spectroscopy. The electronic prop-
erties of the present bimetallic complexes were investigated
by optical absorption spectroscopy. For complexes 4b-g,
but not for 4a, a rather intense electronic transition is seen at
around 349 nm (Table 3), which can be attributed to π-π*
X-ray Structures of 4b and 4d. The molecular structures of
4b and 4d were determined by X-ray crystallography. The
crystallographic details are given in Table 1. Selected bond

Article
Organometallics, Vol. 29, No. 5, 2010 1153
Figure 1. Molecular structure of 4b.
Table 4. Electrochemical Data for Complexes 4a-g in CH2Cl2
a
b
Kc
complex
E1/2(A)
E1/2(B)
ΔE1/2
4a
4b
4c
4d
4e
4f
0.10
0.07
0.07
0.08
0.10
0.12
0.11
0.46
0.44
0.44
0.45
0.47
0.49
0.48
0.35
0.37
0.37
0.37
0.37
0.37
0.37
8.2 ꢀ 105
1.8 ꢀ 106
1.8 ꢀ 106
1.8 ꢀ 106
1.8 ꢀ 106
1.8 ꢀ 106
1.8 ꢀ 106
4g
a ΔE1/2 = E1/2(B) - E1/2(A) denotes the potential difference between
redox processes A and B. b The comproportionation constants, Kc, were
calculated by the formula Kc = exp(ΔE1/2/25.69) at 298 K.14
Electrochemistry. The redox behavior of the present bime-
tallic complexes (1 mM in CH2Cl2 or THF) was investigated
by cyclic voltammetry and square-wave voltammetry tech-
niques with 0.1 M nBu4NPF6 as the supporting electrolyte.
Complexes 4b-g in CH2Cl2 undergo two successive one-
electron oxidation processes, giving rise to redox waves A
and B (Table 4) in the potential region 0.06-0.50 V
II,III
(Figure S1), corresponding to oxidation of Ru2II,II to Ru2
and then of Ru2
to Ru2III,III. As shown in Table 4, for
II,III
Figure 2. Molecular structure of 4d.
complex 4b, with two OC4H9 groups attached to the 1,4-
diethenylphenylene spacer unit, the ΔE1/2 is 0.37 V, with the
corresponding Kc being 1.8 ꢀ 106. Compared with the ΔE1/2
(0.35 V) and Kc value (8.2 ꢀ 105) of complex 4a, the OC4H9
group is apparently even more favorable for the stability of
the mixed-valence complex than the OCH3 group. However,
by comparison of the ΔE1/2 and Kc values of complexes 4c-g
(Table 4), it is found that the stability of the mixed-valence
complex is not enhanced further with a further increase of n
to give longer OCnH2nþ1 moieties.
Complex 10c in CH2Cl2 undergoes two one-electron irre-
versible processes, with ΔEp being 0.08 V and the corre-
sponding Kc being 22.5 (Table 5). Compared to the
voltammetric features of the complex [RuCl(CO)(PMe3)3]2-
(μ-CHdCH-C6H4-CHdCH), for which the ΔE1/2 value is
0.29 V and the Kc value is 8.0 ꢀ 104,5e it is clear that the
stability of the mixed-valence complex is rapidly attenuated
on increasing the length of the bridging ligand. However, if
OCH3 groups are introduced on the -Ar- unit, as in
complex 10a, both the oxidation and reduction couples are
cathodically shifted and the stability of the mixed-valence
complex is slightly increased (ΔE1/2 = 0.09 V), which may
be attributed to the electron-donating property of the OCH3
group. On going to the OC8H17-bearing structure 10b, which
displays two resolved one-electron redox couples for the two
Ru centers, the separation of redox couples increases further
Table 3. UV-Vis Data for Binuclear Complexes 4a-g, 10a-c,
and 13a-c in CH2Cl2
abs, nm
(10-4ε, M-1 cm-1
)
complex
4a
4b
4c
4d
4e
4f
4g
10a
10b
10c
13a
13b
13c
357 (1.15)5e
350 (16.4)
349 (16.5)
349 (16.5)
350 (16.3)
349 (18.1)
349 (18.1)
372 (2.0)
388 (5.6)
415 (6.4)
376 (2.3)
394 (4.7)
418 (8.4)
ligand-centered transitions. Compared with the absorption
spectrum of the unsubstituted complex 10c, the absorption
maxima of the substituted complexes 10a and 10b show
bathochromic shifts and the intensities of the bands are
increased. The above results are supported by comparison
of the absorption spectra of complexes 13a-c. A red-shift
and an increase in intensity are observed upon extension of
the π-system of the bridging spacer.

1154 Organometallics, Vol. 29, No. 5, 2010
Wu et al.
Table 5. Electrochemical Data for Complexes 10a-c in CH2Cl2
difference of 0.02 V between 4d and 4a. The above results
indicate that the introduction of long carbon chains on the
bridges facilitates the stability of mixed-valence complexes.
We suggest that the enhanced stability of mixed-valence
complexes is not entirely attributable to the electron-donat-
ing property of the OC8H17 group. To some extent, the four
OC8H17 groups in complex 10b are expected to act like a
“coating”, protecting the “bare” bridging ligand from the
effects of the medium, i.e., the bulk solution, thereby pre-
venting the loss of charge transfer.15 That is to say, for the
OC8H17-bearing structure, the enhanced stability of the
mixed-valence complex is to some extent attributable to its
shielding effect besides its electronic effect. Therefore, com-
plexes such as 10b may be viewed as potential insulated
organometallic molecular wires.
a
b
Kc
complex
E1/2(A)
E1/2(B)
ΔE1/2
10a
10b
10c
0.36
0.34
0.58
0.45
0.46
0.66
0.09
0.12
33.2
1.1 ꢀ 102
0.08c
22.5
a ΔE1/2 = E1/2(B) - E1/2(A) denotes the potential difference between
redox processes A and B. b The comproportionation constants, Kc, were
calculated by the formula Kc = exp(ΔE1/2/25.69) at 298 K.14 c ΔEp value.
The above results are supported by comparison of the
voltammetric features of complexes 13a-c in CH2Cl2
(Supporting Information, Figures S2 and S3 and Table S1).
These three complexes all undergo one-electron oxidation
processes. Upon appending the electron-donating OCnH2nþ1
groups, both the oxidation and reduction couples are cath-
odically shifted and the redox process changes from irrever-
sible to quasi-reversible. The square-wave voltammogram
(Figure S3) analyses for complexes 13a-c show that the
wave width increases following the introduction of the
OCnH2nþ1 groups and clearly predict the presence of two
unresolved (overlapping) one-electron redox couples with a
ΔE1/2 value of approximately 80 mV for the OC8H17-bearing
structure. The electrochemical properties of complexes 4a-d
and 10a,b have also been investigated in THF. The results
show a similar long carbon chain effect in THF to that in
CH2Cl2 (Table S2 and Table S3).
Conclusions
We have reported here the synthesis, characterization, and
electrochemical properties of a series of binuclear ruthenium
vinyl complexes 4a-g and six oligomeric binuclear ruthe-
nium complexes (10a-c, 13a-c). Electrochemical studies
have shown that long carbon chains attached to the bridges
of the complexes facilitate the stability of mixed-valence
complexes. We suggest that the introduction of long carbon
chains on the bridge causes a shielding effect besides the
electronic effect.
Experimental Section
General Materials. All manipulations were carried out at
room temperature under a nitrogen atmosphere using standard
Schlenk techniques, unless otherwise stated. Solvent were pre-
dried, distilled, and degassed prior to use, except those for
spectroscopic measurements, which were of spectroscopic
grade. The starting materials RuHCl(CO)(PPh3)3,16 3b,11 3c,17
3d,18 3e,19 3f,20 and 4a5e were prepared by the procedures
described in literature methods. The synthesis of 2g, 3g,
6a-9a, 5b-9b, 11a, 12a, 11b, and 12b is shown in the Supporting
Information.
Figure 3. Cyclic voltammograms (CV) of complexes 10c, 10a,
and 10b in CH2Cl2/Bu4NPF6 at υ = 0.1 V s-1. Square-wave
voltammograms at f = 10 Hz. Potentials are given relative to the
Ag|Agþ standard.
(15) Chen, P.; Meyer, T. J. Chem. Rev. 1998, 98, 1439.
(16) Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, M. F.;
Wonchoba, E. R.; Parshall, G. W. Inorg. Synth. 1974, 15, 45.
(17) Zhou, C.-Z.; Liu, T.; Xu, J.-M.; Chen, Z.-K. Macromolecules
2003, 36, 1457.
(18) Weder, C.; Wrighton, M. S. Macromolecules 1996, 29, 5157.
(19) Shirai, Y.; Zhao, Y.; Cheng, L.; Tour, J. M. Org. Lett. 2004, 6,
2129.
to a quite large ΔE1/2 value of 0.12 V, as shown in Figure 3
and Table 5. Upon appending the electron-donating
OCnH2nþ1 groups, the redox processes change from irrever-
sible to quasi-reversible. The ΔE1/2 difference between com-
plex 10b and complex 10a is 0.03 V, which is larger than the
(20) Moroni, M.; Moigne, J. L.; Luzzati, S. Macromolecules 1994, 27,
562.
(14) Richardson, D. E.; Taube, H. Inorg. Chem. 1981, 20, 1278.

Article
General Synthesis of Binuclear Ruthenium Complexes. To a
Organometallics, Vol. 29, No. 5, 2010 1155
PMe3), 1.67-1.69 (m, 4H, CH2), 1.73-1.78 (m, 4H, CH2), 3.92
(t, J = 6.4 Hz, 4H, OCH2), 6.92-6.98 (m, 2H, Ph-CHd), 7.02
(s, 2H, Ph-H), 7.79-7.86 (m, 2H, Ru-CHd). 13C NMR (100
MHz, CDCl3): δ 13.92, 16.37 (t, J = 14.8 Hz, PMe3), 19.98 (d,
J = 20.5 Hz, PMe3), 22.42, 26.02, 29.11, 29.36, 29.65, 31.67,
69.89, 10.97, 128.16, 128.73, 149.01, 161.56, 202.09 (CO). IR
(KBr, cm-1): 1925 (CO), 1550, 1467, 1422 (CdC aryl, vinyl).
4g: Yellow solid, yield: 0.49 g, 73%. Anal. Calcd for
C58H118Cl2O4P6Ru2: C, 52.05; H, 8.89. Found: C, 52.31; H,
9.10. 31P NMR (160 MHz, CDCl3): δ -19.41 (t, J = 21.1 Hz,
suspension of RuHCl(CO)(PPh3)3 (0.76 g, 0.80 mmol) in
CH2Cl2 (30 mL) was slowly added a solution of diethynylaryls
(4a-g, 10a-c, and 13a-c) (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.
4b: Yield: 0.32 g, 77%. Anal. Calcd for C38H78Cl2O4P6Ru2:
C, 43.14; H, 7.43. Found: C, 43.41; H, 7.53. 31P NMR
(160 MHz, CDCl3): δ -21.10 (t, J = 21.1 Hz), -9.35 (d, J =
21.1 Hz). 1H NMR (400 MHz, CDCl3): δ 0.94 (t, J = 6.4 Hz,
6H, CH3), 1.40 (t, J = 3.2 Hz, 36H, PMe3), 1.47 (d, J = 6.8 Hz,
18H, PMe3), 1.60-1.66 (m, 4H, CH2), 1.72-1.79 (m, 4H, CH2),
3.94 (t, J = 6.4 Hz, 4H, OCH2), 6.93-7.00 (m, 2H, Ph-CHd),
7.04 (s, 2H, Ph-H), 7.80-7.87 (m, 2H, Ru-CHd). 13C NMR
(100 MHz, CDCl3): δ 13.82, 16.56 (t, J = 14.8 Hz, PMe3), 20.01
(d, J = 20.1 Hz, PMe3), 22.40, 31.70, 69.65, 110.05, 128.24,
128.77, 149.06, 162.04, 202.18 (CO). IR (KBr, cm-1): 1918 (CO),
1556, 1469, 1421 (CdC aryl, vinyl).
4c: Yellow solid, yield: 0.27 g, 48%. Anal. Calcd for
C42H86Cl2O4P6Ru2: C, 45.28; H, 7.78. Found: C, 45.61; H,
8.06. 31P NMR (162 MHz, CDCl3): δ -22.20 (t, J = 18.1 Hz),
-10.33 (d, J = 18.1 Hz). 1H NMR (400 MHz, CDCl3): δ 0.88
(t, J = 6.4 Hz, 6H CH3), 1.23-1.31 (m, 8H, CH2), 1.40 (t, J =
3.2 Hz, 36H, PMe3), 1.47 (d, J = 3.2 Hz, 18H, PMe3), 1.62-1.67
(m, 4H, CH2), 1.73-1.80 (m, 4H, CH2), 3.93 (t, J = 6.4 Hz, 4H,
OCH2), 6.92-7.00 (m, 2H, Ph-CHd), 7.03 (s, 2H, Ph-H),
7.80-7.87 (m, 2H, Ru-CHd). 13C NMR (100 MHz, CDCl3): δ
13.84, 16.31 (t, J = 15.2 Hz, PMe3), 19.94 (d, J = 20.2 Hz,
PMe3), 22.30, 25.65, 29.54, 31.46, 69.85, 109.95, 128.10, 128.64,
148.96, 162.38, 202.06 (CO). IR (KBr, cm-1): 1921 (CO), 1555,
1468, 1422 (CdC aryl, vinyl).
1
PMe3), -7.64 (d, J = 21.1 Hz, PMe3). H NMR (400 MHz,
CDCl3): δ 0.88 (t, J = 6.4 Hz, 6H, CH3), 1.23-1.25 (m, 40H,
CH2), 1.39 (t, J = 3.2 Hz, 36H, PMe3), 1.47 (d, J = 6.8 Hz, 18H,
PMe3), 1.63-1.68 (m, 4H, CH2), 1.73-1.80 (m, 4H, CH2), 3.92
(t, J = 6.4 Hz, 4H, OCH2), 6.92-7.00 (m, 2H, Ph-CHd), 7.02
(s, 2H, Ph-H), 7.78-7.86 (m, 2H, Ru-CHd). 13C NMR (100
MHz, CDCl3): δ 13.88, 16.31 (t, J = 15.3 Hz, PMe3), 19.93 (d,
J = 20.1 Hz, PMe3), 22.39, 25.99, 29.0, 29.40, 31.63, 69.81,
109.89, 128.13, 128.72, 148.97, 201.90 (CO). IR (KBr, cm-1):
1926 (CO), 1550, 1469, 1423 (CdC aryl, vinyl).
10a: Yellow solid, 0.42 g, 82%. Anal. Calcd for C42H74Cl2O6-
P6Ru2: C, 44.49; H, 6.58. Found: C, 44.65; H, 6.83. 31P NMR
(160 MHz, CDCl3): δ -20.68 (t, J = 22.5 Hz, PMe3), -8.73 (d,
J = 22.5 Hz, PMe3). 1H NMR (600 MHz, CDCl3): δ 1.40 (t, J =
3.6 Hz, 36H, PMe3), 1.47 (d, J = 6.6 Hz, 18H, PMe3), 3.80 (s,
6H, OCH3), 3.91 (s, 6H, OCH3), 6.93-6.97 (m, 2H, PH-CHd),
6.98 (s, 2H, Ph-H), 7.02 (s, 2H, Ph-H), 8.13-8.17 (m, 2H,
Ru-CHd). 13C NMR (100 MHz, CDCl3): δ 13.90, 16.30 (t, J =
15.2 Hz, PMe3), 19.76 (d, J = 20.9 Hz, PMe3), 56.46, 90.09,
107.35, 108.32, 116.14, 127.87, 131.68, 148.27, 154.47, 169.10,
201.93 (CO). IR (KBr, cm-1): 1918 (CO), 1561, 1533, 1485,
1464, 1420 (CdC aryl, vinyl).
10b: Yellow solid, 0.15 g, 22%. Anal. Calcd for C70H130
-
Cl2O6P6Ru2: C, 55.07; H, 8.58. Found: C, 55.23; H, 8.61. 31P
NMR (160 MHz, CDCl3): δ -20.48 (t, J = 22.5 Hz, PMe3),
-8.54 (d, J = 22.5 Hz, PMe3). 1H NMR (400 MHz, CDCl3): δ
0.86 (t, J = 6.8 Hz, 12H, CH3), 1.40 (t, J = 3.2 Hz, 36H, PMe3),
1.25-1.26 (m, 32H, CH2), 1.44-1.45 (m, 8H, CH2), 1.48 (d, J =
6.8 Hz, 18H, PMe3), 1.74-1.84 (m, 8H, CH2), 3.90 (m, 4 Hz,
OCH2), 4.03 (m, 4 Hz, OCH2), 6.86-6.93 (m, 2H, PhCHd), 6.97
(s, 2H, Ph-H), 7.02 (s, 2H, Ph-H), 8.04-8.12 (m, 2H,
RuCHd). 13C NMR (100 MHz, CDCl3): δ 13.94, 16.34 (t,
J = 15.2 Hz, PMe3), 19.76 (d, J = 20.5 Hz, PMe3), 22.48,
25.91, 26.02, 29.06, 29.15, 29.24, 29.36, 29.49, 31.62, 31.68,
66.02, 69.82, 79.78, 90.20, 109.73, 117.29, 128.34, 131.84,
147.96, 154.13, 167.82, 201.98 (CO). IR (KBr, cm-1): 1922
(CO), 1561, 1533, 1493, 1467, 1419 (CdC aryl, vinyl).
4d: Yellow solid, yield: 0.49 g, 84%. Anal. Calcd for
C46H94Cl2O4P6Ru2: C, 47.22; H, 8.10. Found: C, 47.41; H,
8.34. 31P NMR (160 MHz, CDCl3): δ -19.41 (t, J = 21.1 Hz,
1
PMe3), -7.63 (d, J = 21.1 Hz, PMe3). H NMR (400 MHz,
CDCl3): δ 0.87 (t, J = 6.4 Hz, 6H, CH3), 1.26-1.27 (m, 16H,
CH2), 1.39 (t, J = 3.2 Hz, 36H, PMe3), 1.47 (d, J = 6.8 Hz, 18H,
PMe3), 1.51-1.52 (m, 4H, CH2), 1.73-1.78 (m, 4H, CH2), 3.93
(t, J = 6.4 Hz, 4H, OCH2), 6.94-6.98 (m, 2H, Ph-CHd), 7.02
(s, 2H, Ph-H), 7.79-7.86 (m, 2H, Ru-CHd). 13C NMR
(100 MHz, CDCl3): δ 13.88, 16.35 (t, J = 15.2 Hz, PMe3),
19.96 (d, J = 20.5 Hz, PMe3), 22.40, 25.99, 29.97, 29.24, 29.62,
31.55, 69.89, 109.97, 128.17, 128.70, 149.00, 162.34, 202.02
(CO). IR (KBr, cm-1): 1924 (CO), 1550, 1467, 1422 (CdC aryl,
vinyl).
10c: Yellow solid, yield: 63%. Anal. Calcd for C38H66Cl2O2-
P6Ru2: C, 45.02; H, 6.56. Found: C, 44.92; H, 6.82. 31P NMR
(160 MHz, CDCl3): δ -18.96 (t, J = 22.4 Hz, PMe3), -7.23 (d,
J = 22.4 Hz, PMe3). 1H NMR (400 MHz, CDCl3): δ 1.39 (t, J =
3.2 Hz, 36H, PMe3), 1.48 (d, J = 6.8 Hz, 18H, PMe3), 6.55-6.58
(m, 2H, Ph-CHd), 7.27 (d, J = 8.0 Hz, 4H, Ph-H), 7.39 (d,
J = 8.0 Hz, 4H, Ph-H), 8.23-8.26 (m, 2H, Ru-CHd). 13C
NMR (100 MHz, CDCl3): δ 16.55 (t, J = 15.2 Hz, PMe3), 20.01
(d, J = 20.1 Hz, PMe3), 89.73, 134.26, 118.88, 124.10, 131.51,
140.65, 168.98, 202.34 (CO). IR (KBr, ν in cm-1): 1918 (CO),
1563, 1531, 1510, 1421 (CdC aryl, vinyl).
13a: Yellow solid, 0.16 g, 25%. Anal. Calcd for C52H82Cl2O8-
P6Ru2: C, 48.26; H, 6.39. Found: C, 48.34; H, 6.61. 31P NMR
(240 MHz, CDCl3): δ -19.17 (t, J = 21.1 Hz, PMe3), -7.32 (d,
J = 22.1 Hz, PMe3). 1H NMR (600 MHz, CDCl3): δ 1.41 (t, J =
3.6 Hz, 36H, PMe3), 1.48 (d, J = 6.6 Hz, 18H, PMe3), 3.80 (s,
2H, OCH3), 3.91 (s, 2H, OCH3), 3.92 (s, 2H, OCH3), 6.94-6.95
(m, 2H, Ph-CHd), 6.97 (s, 2H, Ph-H), 7.02 (s, 2H, Ph-H),
7.04 (s, 2H, Ph-H), 8.12-8.23 (m, 2H, Ru-CHd). IR (KBr,
cm-1): 1918 (CO), 1561, 1533, 1505, 1487, 1464 (CdC aryl,
vinyl).
4e: Yellow solid, yield: 0.36 g, 65%. Anal. Calcd for
C50H102Cl2O4P6Ru2: C, 48.97; H, 8.38. Found: C, 48.63; H,
8.16. 31P NMR (160 MHz, CDCl3): δ -19.04 (t, J = 21.1 Hz,
1
PMe3), -7.24 (d, J = 21.1 Hz, PMe3). H NMR (400 MHz,
CDCl3): δ 0.88 (t, J = 6.4 Hz, 6H, CH3), 1.26-1.27 (m, 24H,
CH2), 1.39 (t, J = 3.2 Hz, 36H, PMe3), 1.47 (d, J = 6.4 Hz, 18H,
PMe3), 1.57-1.59 (m, 4H, CH2), 1.76-1.77 (m, 4H, CH2), 3.92
(t, J = 6.4 Hz, 4H, OCH2), 6.93-6.97 (m, 2H, Ph-CHd), 7.02
(s, 2H, Ph-H), 7.79-7.82 (m, 2H, Ru-CHd). 13C NMR (100
MHz, CDCl3): δ 13.90, 16.34 (t, J = 15.2 Hz, PMe3), 19.95 (d,
J = 20.5 Hz, PMe3), 22.39, 25.99, 29.06, 29.28, 29.62, 31.61,
69.88, 109.95, 128.16, 128.70, 148.99, 161.96, 202.00 (CO). IR
(KBr, cm-1): 1926 (CO), 1550, 1467, 1423 (CdC aryl, vinyl).
4f: Yellow solid, yield: 0.28 g, 54%. Anal. Calcd for
C54H110Cl2O4P6Ru2: C, 50.58; H, 8.65. Found: C, 50.39; H,
8.93. 31P NMR (160 MHz, CDCl3): δ -20.52 (t, J = 21.1 Hz,
1
PMe3), -8.67 (d, J = 21.1 Hz, PMe3). H NMR (400 MHz,
CDCl3): δ 0.88 (t, J = 6.4 Hz, 6H, CH3), 1.25-1.26 (m, 32H,
CH2), 1.40 (t, J = 3.2 Hz, 36H, PMe3), 1.47 (d, J = 6.4 Hz, 18H,
13b: Yellow solid, 0.47 g, 55%. Anal. Calcd for C94H164
Cl2O8P6Ru2: C, 60.02; H, 8.79. Found: C, 60.38; H, 8.59.
-

1156 Organometallics, Vol. 29, No. 5, 2010
Wu et al.
31P NMR (160 MHz, CDCl3): δ -20.43 (t, J = 22.5 Hz, PMe3),
-8.60 (d, J = 22.5 Hz, PMe3). 1H NMR (400 MHz, CDCl3): δ
0.86 (t J = 6.8 Hz, 18H, CH3), 1.26-1.27 (m, 48H, CH2), 1.39
(t, J = 3.2 Hz, 36H, PMe3), 1.47 (d, J = 6.8 Hz, 18H, PMe3),
1.48-1.49 (m, 12H, CH2), 1.72-1.86 (m, 12H, CH2), 3.91 (t,
J = 6.4, 4H, OCH2), 4.02-4.07 (m, 8H, OCH2), 6.94-6.95
(m, 2H, Ph-CHd), 6.99 (s, 4H, Ph-H), 7.03 (s, 4H, Ph-H),
8.12-8.17 (m, 2H, Ru-CHd). 13C NMR (100 MHz, CDCl3):
δ 19.96, 16.39 (t, J = 15.2 Hz, PMe3), 19.88 (d, J = 20.9 Hz,
PMe3), 22.50, 25.89, 26.04, 29.22, 29.41, 29.51, 31.73, 69.18,
69.49, 69.70, 89.27, 92.49, 108.79, 109.21, 114.25, 117.07, 117.44,
128.33, 132.48, 147.95, 153.10, 154.41, 168.97, 201.95 (CO). IR
(KBr, cm-1): 1925 (CO), 1555, 1526, 1506, 1467, 1423 (CdC
aryl, vinyl).
13c: Yellow solid, yield: 63%. Anal. Calcd for C46H70Cl2O2-
P6Ru2: C, 49.60; H, 6.33. Found: C, 49.32; H, 6.58. 31P NMR
(240 MHz, CDCl3): δ -19.04 (t, J = 21.1 Hz, PMe3), -7.29 (d,
J = 22.1 Hz, PMe3). 1H NMR (600 MHz, CDCl3): δ 1.39 (t, J =
3.6 Hz, 36H, PMe3), 1.48 (d, J = 6.6 Hz, 18H, PMe3), 6.59-6.62
(m,2H,Ph-CHd),7.29(d,J=7.8Hz,Ph-H), 7.42 (d, J=7.8Hz,
Ph-H), 7.47 (d, J = 7.8 Hz, Ph-H), 8.30-8.32 (m, 2H,
RuCHd). IR (KBr, cm-1): 1918 (CO), 1597, 1563, 1530, 1515,
1420 (CdC aryl, vinyl).
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 Table 2.
Physical Measurements. 1H, 13C{1H}, and 31P{1H} NMR
spectra were collected on a Varian Mercury Plus 400 spectro-
meter (400 MHz) or on a Varian Mercury Plus 600 spectrometer
(600 MHz). 1H and 13C{1H} NMR chemical shifts are relative to
TMS, and 31P{1H} NMR chemical shifts are relative to 85%
H3PO4. Elemental analyses (C, H, N) were performed by Vario
ElIII Chnso. IR spectra were recorded on a Nicolet Avatar 360
FT-IR spectrophotometer using KBr disks. UV-vis spectra
were recorded on a PDA spectrophotometer 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 and
THF. Deaeration of the solution was achieved by argon bub-
bling through the solution for about 10 min before measure-
ment. 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|Agþ reference electrode were used.
The Ag|Agþ reference electrode contained an internal solution
of 0.01 mol dm-3 AgNO3 in acetonitrile and was incorporated
to the cell with a salt bridge containing 0.1 mol dm-3 Bu4NPF6
in CH2Cl2. All electrochemical experiments were carried out
under ambient conditions.
Crystallographic Details. Crystals suitable for X-ray diffrac-
tion were grown from a dichloromethane of solution 4b and 4d
layered with hexane. A crystal with approximate dimensions of
0.30 ꢀ 0.20 ꢀ 0.20 mm3 for 4b and 0.23 ꢀ 0.20 ꢀ 0.20 mm3 for 4d
was mounted on a glass fiber for diffraction experiments.
Intensity data were collected on a Nonius Kappa CCD diffract-
Supporting Information Available: The synthesis of 2g, 3g,
6a-9a, 5b-9b, 11a, 12a, 11b, and 12b, tables of bond distances
and angles, and X-ray crystallographic files (CIF) for complexes
4b and 4d, and CVs of complexes 4b, 4c, 4g, and 13a-c. The
materials are available free of charge via the Internet at http://
pubs.acs.org.
˚
ometer with Mo KR radiation (0.71073 A) at room temperature.
The structures were solved by a combination of direct methods
(SHELXS-9722) and Fourier difference techniques and refined
by full-matrix least-squares (SHELXL-9723). All non-H atoms
were refined anisotropically. The hydrogen atoms were placed in
(21) Swager, T. M.; Gil, C. J.; Wrighton, M. S. J. Phys. Chem. 1995,
99, 4886.
(22) Sheldrick, G. M. SHELXS-97, a program for crystal structure
Acknowledgment. The authors acknowledge financial
support from National Natural Science Foundation of
China (Nos. 20772039, 20931006) and the Natural Science
Foundation of Hubei Province (No. 2008CDB023).
€
solution; Gottingen, Germany, 1997.
(23) Sheldrick, G. M. SHELXL-97, a program for crystal structure
€
refinement; Gottingen, Germany, 1997.