Design and synthesis of ruthenium oligothienylacetylide complexes. New materials for acoustically induced nonlinear optics

Article abstract of DOI:10.1021/om049236s

A series of new donor-π-acceptor ruthenium acetylide systems built around thiophene-based π-conjugating spacers of different lengths have been developed. Comparison of the linear and third-order nonlinear optical properties of these donor-π-acceptor chromophores shows that the elongation of the oligothiophene-based spacer or further introduction of a double bond leading to a dithienylethylene spacer produces a considerable bathochromic shift of the absorption maximum together with a dramatic enhancement of the molecular cubic hyperpolarizability. Furthermore acoustically induced second-harmonic generation (AISHG) has been observed for film composites of these complexes incorporated in PMMA matrixes and reaches values among the highest reported so far.

Full text of DOI:10.1021/om049236s

Organometallics 2005, 24, 687-695
687
Design and Synthesis of Ruthenium
Oligothienylacetylide Complexes. New Materials for
Acoustically Induced Nonlinear Optics
Jean-Luc Fillaut,*,† Johann Perruchon,† Philippe Blanchard,‡ Jean Roncali,‡
Ste´phane Golhen, Magali Allain,‡ Anna Migalsaka-Zalas,§ Ivan V. Kityk,| and
Bouchta Sahraoui*,§
Institut de Chimie de Rennes, Organome´talliques et Catalyse: Chimie et Electrochimie
Mole´culaires, CNRS UMR 6509, Universite´ de Rennes 1, Campus de Beaulieu,
35042 Rennes Cedex, France, Laboratoire CIMMA, UMR CNRS 6200, Universite´ d’Angers,
2 Boulevard Lavoisier, 49045 Angers Cedex, France, Laboratoire de Chimie du Solide et
Inorganique Mole´culaire, UMR 6511 CNRS, Institut de Chimie de Rennes, Universite´ de
Rennes 1, Campus Beaulieu 35042, Rennes Cedex, France, Laboratoire POMA,
CNRS UMR 6136, Universite´ d’Angers, 2 Boulevard Lavoisier, 49045 Angers Cedex, France,
and Institute of Physics WSP, University of Czestochowa, Al. Armii Krajowej 13/15,
PL-42217 Czestochowa, Poland
Received October 4, 2004
A series of new donor-π-acceptor ruthenium acetylide systems built around thiophene-
based π-conjugating spacers of different lengths have been developed. Comparison of the
linear and third-order nonlinear optical properties of these donor-π-acceptor chromophores
shows that the elongation of the oligothiophene-based spacer or further introduction of a
double bond leading to a dithienylethylene spacer produces a considerable bathochromic
shift of the absorption maximum together with a dramatic enhancement of the molecular
cubic hyperpolarizability. Furthermore acoustically induced second-harmonic generation
(AISHG) has been observed for film composites of these complexes incorporated in PMMA
matrixes and reaches values among the highest reported so far.
Introduction
able dipolar molecules, metal fragments are directly
incorporated in the same plane as the π-conjugated
pathway, which meets the requirements for the design
of push-pull chromophores with large second-harmonic
generation (SHG) efficiencies.7 As for organic extended
conjugated π-systems,8 theoretical and experimental
studies of σ-acetylide complexes have shown that large
second-order hyperpolarizability (â) characterizing the
molecular NLO efficiency depends on the strength of the
donor, i.e., the metal, and acceptor groups and on the
extent of the π-conjugated pathway. Moreover it has
been suggested that the enhancement of metal-carbon
multiple-bond character could enhance second-order
nonlinear response.9 Analogously to metallocenes, the
metal acts as the donor group of the donor-π-acceptor
structure and the second-order nonlinearity can be
related to low-energy MLCT excitations. Noteworthy
Carbon-rich organometallics1 containing rigid π-con-
jugated chains are important targets for the investiga-
tion of electron-transfer processes,2 the formation of
liquid crystalline materials,1,3 and the construction of
molecular devices4 and novel materials for nonlinear
optics (NLO).5 Among them, σ-acetylide complexes
represent one of the most widely investigated classes
of second-order NLO metal complexes.6 In these polariz-
* To whom correspondence should be addressed. E-mail: jean-
luc.fillaut@univ-rennes1.fr. Fax: +33 223 23 69 39 (J.-L.F.). E-mail:
bouchta.sahraoui@univ-angers.fr. Fax: +33 241 73 52 16 (B.S.).
† Institut de Chimie de Rennes, Universite´ de Rennes 1
‡Laboratoire CIMMA, Universite´ d'Angers.
Laboratoire de Chimie du Solide et Inorganique Mole´culaire,
Universite´ de Rennes 1.
§ Laboratoire POMA, Universite´ d’Angers.
|University of Czestochowa.
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10.1021/om049236s CCC: $30.25 © 2005 American Chemical Society
Publication on Web 01/13/2005

688 Organometallics, Vol. 24, No. 4, 2005
Fillaut et al.
Scheme 1
σ-acetylides, with an almost linear M-CtC-R struc-
ture, give rise to a better coupling between the metal
and the π-conjugated path and, hence, to larger optical
nonlinearities. In this regard ruthenium(II) acetylide
derivatives are among the most investigated alkynyl
systems,9,10 the ruthenium-alkynyl fragment being a
powerful donor, which can compete with the strongest
organic donors.11
Finally, recent studies identified these systems as
powerful third-order NLO chromophores.6c,12,13 These
studies tend to indicate that it would be preferable to
emphasize extended conjugated spacers rather than the
strength of donor or acceptor groups of linear D-π-A
structures.
abilities.15 These performances can be related to the
moderate resonance energy of thiophene, which allows
a better π-electron delocalization than, for example,
benzene-containing spacers.16 The results of electro-
chemical, linear optical, and cubic NLO measurements
of the resulting ruthenium acetylide derivatives in
solution will be described herein. We will also consider
the use of these oligothienyl ruthenium derivatives as
D-π-A chromophores in poled polymers.17 Acoustically
induced nonlinear optical properties18 of these organo-
metallic systems incorporated within polymethyl meth-
acrylate (PMMA) matrixes will be presented.
Results and Discussion
In this work, we have studied the effect of π-bridge
variation on cubic NLO properties of linear D-π-A
ruthenium acetylide systems, using a constant donor-
acceptor couple. These derivatives were constructed
using a trans-[Cl-Ru(dppe)2(-CtC)] (dppe ) diphen-
ylphosphinoethane) unit linked to a formyl group, acting
as the acceptor head, through various “π-conjugated
spacer” units. Our interest focused on thiophene-based
spacers such as oligothiophenes of various lengths and
dithienylethylene. Indeed, thiophene oligomers can be
regarded as one of the richest and more versatile
systems for building organized structures across mul-
tiple length scales. In particular thiophene-based spac-
ers are known to provide better effective conjugation
than benzenoid moieties14 and to lead to stable NLO
chromophores with very high second-order hyperpolariz-
Synthesis and Characterization of σ-Acetylide
Complexes 4a-e. New acetylenes required for the
syntheses of the alkynyl complexes 4a-e were prepared
by well-established organic synthetic procedures from
their bromo precursors (Scheme 1).
These new acetylenes were characterized by IR, UV-
vis, and NMR spectroscopy and mass spectrometry.
(14) (a) McCullough, R. D. Adv. Mater. 1998, 10, 93. (b) Roncali, J.
Chem. Rev. 1997, 97, 173. (c) Kraft, A.; Grimsdale, A. C.; Holmes, A.
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M.; Barbarella, G.; Cavallini, M.; Biscarini, F.; Maccagnani, P.; Ostoja,
P. J. Am. Chem. Soc. 2003, 125, 10266.
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(b) Wu, X.; Wu, J.; Liu, Y.; Jen, A. K.-Y. J. Am. Chem. Soc. 1999, 121,
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2391. (c) Jen, A. K.-Y.; Liu, Y.; Zheng, L.; Liu, S.; Drost, K. J.; Zhang,
Y.; Dalton, L. R. Adv. Mater. 1999, 11, 452-455. (d) Kim, O.-K.; Fort,
A.; Barzoukas, M.; Blanchard-Desce, M.; Lehn, J.-M. J. Mater. Chem.
1999, 9, 2227 (e) Cai, C.; Liakatas, I.; Wong, M.-S.; Bo¨sch, M.;
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Lett. 1999, 1, 1847. (f) Wu, I.-Y.; Lin, J. T.; Luo, J.; Li, C.-S.; Tsai, C.;
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(10) Hurst, S.; Lucas, N. T.; Cifuentes, M. P.; Humphrey, M. G.;
Samoc, M.; Luther-Davies, B.; Asselberghs, I.; Van Boxel, R.; Persoons,
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Toupet, L.; Dixneuf, P. H. Inorg. Chim. Acta 1998, 272, 188. (b)
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3851.
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246, 89.
(12) (a) Hurst, S. K.; Cifuentes, M. P.; Morrall, J. P. L.; Lucas, N.
T.; Whittall, I. R.; Humphrey, M. G.; Asselberghs, I.; Persoons, A.;
Samoc, M.; Luther-Davies, B.; Willis, A. C. Organometallics 2001, 20,
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Organomet. Chem. 2002, 642, 259. (c) Hurst, S. K.; Humphrey, M. G.;
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G. A.; Willis A. C. J. Organomet. Chem. 2003, 670, 56.
(17) For general reviews on poled polymer NLO materials, see: (a)
Marks, T. J.; Ratner, M. A. Angew. Chem., Int. Ed. Engl. 1995, 34,
155. (b) Burland, D. M.; Miller, R. D.; Walsh, C. A. Chem. Rev. 1994,
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and Applications; John Wiley and Sons: New York, 1997. (e) Bauer-
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Organometallics 2002, 21, 2024.
(18) Nelson, D. F.; Lax, M. Phys. Rev. B 1971, 3, 2795.

Ruthenium Oligothienylacetylide Complexes
Organometallics, Vol. 24, No. 4, 2005 689
Scheme 2
itored by 31P NMR spectroscopy. These vinylidenes were
then cleaned by ether to remove the excess of free
acetylene, before deprotonation with triethylamine
(methylene chloride, room temperature, 1 h). The re-
sulting alkynyl compounds were purified by a silica gel
chromatography column (diethyl ether as eluent) and
crystallized using a methylene chloride/hexane biphasic
systems. Complexes 4a-e were isolated as red crystal-
line powders in approximately 80% yields. All the
spectroscopic data of compounds 4a-e are consistent
with their proposed structures. 31P NMR spectra of all
complexes contain one singlet resonance, consistent with
the trans geometry at the ruthenium center. The
chemical shifts of the CR (141.5-154.5 ppm) and Câ
carbons (106.8-115.8 ppm) of the (Ru-CRtCâ) in the
13C NMR spectra are not significantly sensitive to
changes in the acetylide ligands. However the larger
upfield shift (154.5 ppm) of CR in 4b reveals that a slight
contribution of a cumulenic form is perceptible in this
complex that includes the shortest conjugated chain.15f
The IR spectra of these complexes display a single
characteristic ν(CtC) absorption band (2040-2030
cm-1) whose values are lower than those of the corre-
sponding terminal or Me3Si-substituted acetylide ligands
as usually observed for acetylide ruthenium com-
plexes.20,21 The 1H and 13C NMR spectra of 4a-e show
features pertaining to the heteroaromatic and formyl
groups: for instance, the E configuration of the central
carbon-carbon double bond of the dithienylethylene
Table 1. Selected Bond Lengths (Å) and Bond
Angles (deg) for 1e
bond lengths (Å)
bond angles (deg)
Br-C(6)
1.871(8)
1.34(1)
1.40(1)
1.35(1)
1.43(1)
1.33(1)
1.42(1)
1.37(1)
1.38(1)
1.35(1)
1.52(1)
1.08(1)
C(1)-C(2)-C(7)
128.7(7)
127.5(7)
108.9(6)
120.6(5)
130.5(7)
122.0(5)
109.4(6)
128.6(7)
91.1(4)
C(5)-C(6)
C(4)-C(5)
C(3)-C(4)
C(1)-C(3)
C(1)-C(2)
C(2)-C(7)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C(10)-C(11)
O-C(11)
C(2)-C(1)-C(3)
S(1)-C(3)-C(4)
S(1)-C(3)-C(1)
C(1)-C(3)-C(4)
S(2)-C(7)-C(2)
S(2)-C(7)-C(8)
C(2)-C(7)-C(8)
C(7)-S(2)-C(10)
S(2)-C(10)-C(9)
S(2)-C(10)-C(11)
O-C(11)-C(10)
112.3(6)
120.7(5)
127.7(8)
(E)-1-(5-Bromo-2-thienyl)-2-(5-formyl-2-thienyl)ethene
(1e) was prepared differently from the procedure de-
scribed in the literature.15f,19 Thus, selective bromina-
tion of formyldithienylethylene15a in the presence of
N-bromosuccinimide in DMF readily afforded compound
1e in 69% yield. Slow evaporation of a solution of 1e in
a mixture of dichloromethane and hexane gave crystals
of good quality for X-ray determination. In the crystal,
molecule 1e adopts a fully planar conformation and the
central carbon-carbon double bond shows an E config-
uration (Figure 1). Although these results concern the
solid state, compound 1e appears to be an excellent
candidate for its use as π-conjugating spacer for NLO
since it exhibits the entire requirement for an optimal
electronic delocalization. Important bond lengths and
angles are displayed in Table 1.
The synthetic methodologies employed for the prepa-
ration of the new ruthenium derivatives have been
adapted from previously reported procedures.20 The
reaction of acetylenes 3a-e and [cis-(Cl)(PPh2CH2CH2-
PPh2)2Ru][TfO]20b in methylene chloride at room tem-
perature for 20 h resulted in the formation of interme-
diate vinylidenes. Their complete formation was mon-
1
fragment in 4e is ascertained by a H NMR doublet at
6.77 (1 H, 3JHH ) 16 Hz) corresponding to one proton of
the trans-CHdCH unit, the second H being masked by
the phenyl groups of the dppe ligands. In each case, the
respective molecular ion peaks [M]+ were detected by
electron impact mass spectroscopy.
X-ray Structure of trans-[Ru(4-CtC-th-CHdCH-
th-CHO)(Cl)(dppe)2], 4e. An X-ray diffraction analysis
of 4e (th ) 2,5-substituted thiophene) confirmed the
composition of this complex and especially the E
configuration of the central double bond of the dithie-
nylethylene fragment. The relevant bond lengths and
angles for 4e are displayed in Table 2. An ORTEP
plot of 4e with atom-labeling scheme is displayed in
Figure 2.
The crystal structure consists of discrete dimeric
molecules in which π-stacking between thiophene car-
boxaldehyde fragments of two molecules of 4e results
in a centrosymmetric packing (Figure 3), suggesting
that no bulk second-order NLO responses would be
observed.
(19) (a) Manecke, G.; Ha¨rtel, M. Chem. Ber. 1973, 106, 655. (b)
Justin Thomas, K. R.; Lin, J. T.; Lin, K.-J. Organometallics 1999, 18,
5285.
(20) (a) Touchard, D.; Haquette, P.; Guesmi, S.; Pichon, L. L.;
Daridor, A.; Toupet, L.; Dixneuf, P. H. Organometallics 1997, 16, 3640.
(b) Touchard, D.; Dixneuf, P. H. Coord. Chem. Rev. 1998, 178-180,
409.
(21) Zhu, Y.; Millet, D. B.; Wolf, M. O.; Rettig, S. J. Organometallics
1999, 18, 1930.
Figure 1. Top (a) and side (b) ORTEP views of 1e showing
50% probability displacement ellipsoids and the atom
numbering.

690 Organometallics, Vol. 24, No. 4, 2005
Fillaut et al.
Figure 2. ORTEP drawing of 4e, showing the atom
numbering. Hydrogen atoms are omitted for clarity. Ther-
mal ellipsoids are drawn at the 50% probability level.
Table 2. Selected Bond Lengths (Å) and Bond
Angles (deg) for 4e
Figure 3. X-ray crystal structure of 4e, showing the
packing of individual molecules (dotted line).
bond lengths (Å)
bond angles (deg)
thienyl rings being nearly coplanar, contributing to the
extent of conjugation in the ruthenium complex 4e.
Ru(1)-P(1)
2.3641(10)
2.3770(10)
2.3863(10)
2.3875(10)
2.5099(10)
1.990(4)
1.197(5)
1.419(5)
1.380(6)
1.403(6)
1.349(7)
1.436(6)
1.326(7)
1.449(7)
1.372(8)
1.394(8)
1.374(8)
1.461(8)
1.216(8)
C(53)-Ru(1)-Cl
79.3(1)
175.3(3)
177.2(4)
129.5(4)
121.3(3)
109.1(3)
113.5(5)
92.7(2)
114.4(4)
110.2(3)
122.7(4)
127.0(4)
129.1(5)
127.0(5)
129.3(5)
120.3(4)
113.3(5)
112.5(5)
126.7(6)
110.4(4)
91.9(3)
Ru(1)-P(4)
Ru(1)-P(2)
Ru(1)-P(3)
Ru(1)-Cl
C(54)-C(53)-Ru(1)
C(53)-C(54)-C(55)
C(56)-C(55)-C(54)
C(54)-C(55)-S(1)
C(56)-C(55)-S(1)
C(55)-C(56)-C(57)
C(58)-S(1)-C(55)
C(58)-C(57)-C(56)
C(57)-C(58)-S(1)
C(59)-C(58)-S(1)
C(57)-C(58)-C(59)
C(60)-C(59)-C(58)
C(59)-C(60)-C(61)
C(62)-C(61)-C(60)
C(60)-C(61)-S(2)
C(61)-C(62)-C(63)
C(64)-C(63)-C(62)
C(63)-C(64)-C(65)
C(62)-C(61)-S(2)
C(64)-S(2)-C(61)
C(63)-C(64)-S(2)
C(65)-C(64)-S(2)
O(1)-C(65)-C(64)
Absorption Properties of Complexes 4. The elec-
tronic absorption spectra show broad bands with λmax
at 420, 450, 500, 510, and 530 nm for 4a, 4b, 4c, 4d,
and 4e (Table 3), which were attributed to MLCT
transitions.12a,24 Replacing the phenyl spacer as in 4a
by thienyl moieties in 4b-e notably diminishes the
HOMO-LUMO gap, due to an enhanced conjugation.
Increasing conjugation in complexes 4b-d through the
introduction of more thienyl rings leads to an electronic
transition of lower energy and an increase in the molar
absorption coefficients. However, the extent of the
induced red-shift decreases with increasing number of
thienyl units. Thus, a red-shift of ca. 50 nm is observed
from 4b to 4c, whereas the shift is only ca. 10 nm from
4c to 4d, corresponding to an increasing saturation of
conjugation25 in these complexes. However, the satura-
tion of conjugation is less sensitive in the complex 4e:
a red-shift of ca. 30 nm is observed from 4c to 4e (to be
compared to 10 nm from 4c to 4d). Replacing the
terthiophene spacer as in 4d by a dithienylethylene
moiety significantly lowers the HOMO-LUMO gap.
Electrochemical Studies of Complexes 4. To get
a deeper insight into the mutual donor-acceptor elec-
tronic influence from the ruthenium alkynyl moiety to
the formyl end-group through the different spacers, we
studied the redox properties of the complexes 4a-e by
cyclic voltammetry. The results are presented in Table
3. The compounds exhibit two reversible one-electron
oxidation waves in their cyclic voltammograms in the
range 0.0-1.8 V vs SCE. The first wave (ranging from
0.60 for 4a to 0.39 V vs SCE for 4d) was assigned to
the metal-centered Ru(II/III) oxidation for all these
compounds. The second wave can be attributed either
to a Ru(III/IV) oxidation (4a) or to the oxidation of the
thiophene-based spacers (4b-e). In 4a, this wave at E1/2
Ru(1)-C(53)
C(53)-C(54)
C(54)-C(55)
C(55)-C(56)
C(56)-C(57)
C(57)-C(58)
C(58)-C(59)
C(59)-C(60)
C(60)-C(61)
C(61)-C(62)
C(62)-C(63)
C(63)-C(64)
C(64)-C(65)
O(1)-C(65)
111.9(4)
121.4(5)
122.2(7)
Most bond lengths and angles about the Cl-Ru-
C(53)-C(54)-C(55) units in this structure are classical.
The Cl-Ru, Ru-C(53), and C(54)-C(55) data for this
complex fall within the range of those previously
reported for related octahedral trans-bis(bidentate phos-
phine)ruthenium alkynyl complexes.12a,21,22 Of particu-
lar interest for NLO merit is the coplanarity of dithie-
nylethylene units in the alkynyl ligand. Coplanarity,
along with efficient delocalization, is important for
maximizing NLO response in the present complexes.23
The dihedral angle formed by the planes of the thienyl
rings in 4e (3.5(3)°) is close to coplanarity. It is interest-
ing to compare this value with that in the precursor 1e,
in which the corresponding angle was evaluated to be
1.6°. The global structure of the dithienylethylene
spacer is then almost conserved from 1e to 4e, with the
(22) Lebreton, C.; Touchard, D.; Le Pichon, L.; Daridor, A.; Toupet,
L.; Dixneuf P. H. Inorg. Chim. Acta 1998, 272, 188.
(23) McDonagh, A. M.; Whittall, I. R.; Humphrey, M. G.; Skelton,
B. W.; White, A. H. J. Organomet. Chem. 1996, 519, 229.
(24) Naulty, R. H.; McDonagh, A. M.; Whittall, I. R.; Cifuentes, M.
P.; Humphrey, M. G.; Houbrechts, S.; Maes, J.; Persoons, A.; Heath,
G. A.; Hockless, D. C. R. J. Organomet. Chem. 1998, 563, 137.
(25) Meier, H. Chem. Eur. J. 2004, 10, 360.

Ruthenium Oligothienylacetylide Complexes
Organometallics, Vol. 24, No. 4, 2005 691
Table 3. Electronic Absorption and Cyclic Voltammetric Data for Complexes 4a-e
λmax (nm)a
E1/2 (V)b
[∆E(mV)]
E1/2 (V)
[∆E(mV)]
compound
[ꢀ (104 M-1 cm-1)]
trans-[Ru(4-CtCC6H4CHO)Cl(dppe)2] (4a)
420 [1.3]
450 [2.7]
500 [2.6]
510 [3.2]
530 [5.5]
0.60 [80]
0.62 [80]
0.46 [80]
0.39 [80]
0.41 [80]
1.40c [100]
1.35d [100]
1.20d [100]
0.99d [100]
1.06d [100]
trans-[Ru(2,5-CtCC-th-CHO)Cl(dppe)2] (4b)
trans-[Ru(2,2′,5,5′-CtC-th-th-CHO)Cl(dppe)2] (4c)
trans-[Ru(2,2′,5,5′,2′′,5′′-CtC-th-th-th-CHO)Cl(dppe)2] (4d)
trans-[Ru(-CtC-th-(E)CHdCH-th-CHO)Cl(dppe)2] (4e)
a All measurements as CH2Cl2 solutions. b Conditions: CH2Cl2; Pt-wire auxiliary, Pt working, and SCE reference electrodes; ferrocene/
ferrocenium couple located at 0.46 V [[∆E(mV) ) 80]. c RuIII/IV. d Thiophene-centered oxidation.
Table 4. Cubic Nonlinear Optical Responses for
organic chromophores. Not surprisingly, these results
are consistent with that of M. G. Humphrey, which
demonstrated an electronic origin for cubic nonlinear-
ities in the metal-acetylide complexes.29 Significant
extension of the π-system on proceeding from 4c, to 4d,
to 4e results in a further increase in γ. Complex 4e has
the largest γ response for this series of complexes: the
present data complement the results obtained for linear
absorption, indicating that electronic communication
through the dithienylethylene-linked spacer (complex
4e) is the most efficient in this series.30 These data also
suggest that extending π-delocalization in similar sys-
tems must be carried out in order to give a minimal
aromatic character on the π-conjugated bridge.
Acoustically Induced Second-Order Nonlinear-
ity Measurements. Incorporating organometallic
chromophores within optically transparent and electri-
cally neutral polymers may be considered as a way to
achieve promising materials for second-order optical
effects.17 Therefore, we investigated the inclusion of the
organometallic complexes 4b-e within polymethyl-
methacrylate (PMMA) matrixes in order to get proc-
essable materials. Samples S4c-e were prepared by
mixing 4 g of PMMA (Mw ) 120 000) and 0.035 g of the
different complexes 4c-e in solution in chloroform. The
inclusion of complexes 4 was obtained by slow evapora-
tion of the solvent. UV-visible measurements on films
of these samples deposited on glass ascertained the
inclusion of complexes 4 in the PMMA matrixes, as
indicated by broad absorptions bands at 500, 510, and
530 nm for S4c, S4d, and S4e, which are close to that
observed for the corresponding parent complexes. IR
spectra that display characteristic ν(CtC) (2038-2041
cm-1) and ν(CHdO) (1586-1593 cm-1) absorption bands
confirmed their presence. Then, we investigated acous-
tically induced nonlinear optical properties of these
samples. Acoustically induced second-harmonic genera-
tion (AISHG) is related with physical effects at the
atomic scale that can result from interactions of phonons
with the electron subsystem of ionic or polarizable
molecules in the solid state. In particular, it was
established31 that electron-hole and electron-phonon
interactions could result in a local asymmetry.32 The
resulting spatial non-centrosymmetry would be thus at
the origin of the observed NLO responses. Acoustically
induced SHG18,33 was first observed in composites
Complexes 4b-ea
C × 10-4
R
ø 3 × 1020 ø 3 /R × 10-18 γ × 1044
compound (M L-1
)
(cm-1
)
(m2/V2)
(m3/V2)
(m5/V2)
4b
4c
4d
4e
CS2
2.8
2.6
2.4
2.5
≈ 0
7.8
5.1
12.9
13.7
1.94
0.40
1.20
2.10
2.50
5.1
1.5
4.9
23
19
9.1
15
10.4
4.7 × 10-5
a All measurements in THF solutions. R ) linear absorption
coefficient, ø 3 ) third-order susceptibility, ø 3 /R ) merit factor, γ
) second-order hyperpolarizability.
) 1.40 V can only be assigned to the Ru(III/IV) oxida-
tion. In complexes 4b-e,21 as the potentiel E1/2 of this
second wave significantly decreases (from 1.35 for 4b
to 0.99 V vs SCE for 4d) as the length of the π-spacer
increases, it was assigned to the oxidation of the
thiophene-based spacers by analogy with previous re-
ports on both oligothiophenes26 and alkynyl-ruthenium
derivatives bearing oligothiophene groups.21
The extent of the communication between the electron-
donating and -accepting termini can be evaluated by
comparing the E1/2 values of the electrochemically
reversible one-electron Ru(II/III) oxidation in complexes
4a-e. The effect of the acceptor on the oxidation of the
metal center is highly dependent on the length of the
π-bridge (Table 3). In particular, the half-wave poten-
tials (E1/2) of the Ru(II/III) oxidation are negatively
shifted through insertion of thienyl rings (from 4b to
4c or 4d) or an additional double bond (4e). Moreover,
the donor effect of the oligothienyl spacers apparently
counterbalances the acceptor effect of the formyl end
as the separation of the termini increases. For instance,
the Ru(II/III) oxidation in complex 4e becomes close to
that of trans-[Ru(4-CtC-C6H5)Cl(dppe)2] (E1/2 ) 0.45
V vs SCE).27
Third-Order Nonlinearity Measurements. Third-
order nonlinearities for the complexes 4b-e were evalu-
ated by degenerate four-wave mixing measurements
(DFWM)28 at 532 nm in chloroform solutions (0.3 g/L).
Details of the measurements and theoretical approach
are given in the Supporting Information. We found that
the molecules 4a-e exhibit large third-order hyper-
polarizability (γ) values (approximately 105 times larger
than those of CS2, which is a reference material for
DFWM) (Table 4).
Extension of the acetylide ligand from the one-ring
spacer in 4b to the two-ring system 4c leads to a large
increase in γ, which parallels results observed in all-
(29) Whittall, I. R.; Humphrey, M. G.; Samoc, M.; Swiatkiewicz, J.;
Luther-Davies, B. Organometallics 1995, 14, 5493.
(30) Roncali, J. Acc. Chem. Res. 2000, 33, 147.
(31) (a) Bussmann-Holder A.; Buttner, H. Nature 1992, 360, 541.
(b) Dalal, N.; Klymachyov, A.; Bussmann-Holder, A. Phys. Rev. Lett.
1998, 81, 5924. (c) Sahraoui, B.; Kityk, I. V.; Nguyen Phu, X.;
Hudhomme, P.; Gorgues, A. Phys. Rev. B 1999, 59, 9229.
(32) Bielincher, V. I.; Sturman, B. I. Usp. Fiz. Nauk 1980, 130, 415.
(33) Majchrowski, A.; Kityk, I. V.; Kasperczyk, J.; Łukasiewicz, T.;
Mefleh, A. Mater. Lett. 2001, 50, 146.
(26) Jestin, I.; Fre`re, P.; Blanchard, P.; Roncali, J. Angew. Chem.
Int. Ed. 1998, 37, 942.
(27) McDonagh, A. M.; Cifuentes, M. P.; Humphrey, M. G.; Hou-
brechts, S.; Persoons, A. J. Organomet. Chem. 2000, 610, 71.
(28) Sahraoui, B.; Rivoire, G. Opt. Commun. 1997, 138, 109.

692 Organometallics, Vol. 24, No. 4, 2005
Fillaut et al.
Table 5. Maximal AIOSHG Values for Complexes
4c-e Included in PMMA Matrixes and for Selected
Ferroelectric and Photorefractive Crystals
nonlinear dependences of the AISHG on acoustical
power as well as sensitivity to morphological phase
transformation, indicate that the origin of the observed
phenomenon results from a spatial non-centrosymmetry
induced by phonons interacting with the electron sub-
systems.36
To compare our results with that of typical ferro-
electric and photorefractive crystals, similar AISHG
measurements were done for several of these crystals.
The corresponding maximal second-order susceptibili-
ties ø(2) were evaluated by varying acoustical strengths
at different temperatures (Table 5). The maximal value
of the AIOSHG (0.8 pm/V) for complex 4c incorporated
in the PMMA matrixes is then comparable with the
values for these nonlinear optical single crystals. We
continue this study to determine the factors that could
improve the AISHG responses. These results will be
published in due course.
compound
ø(2) (pm/V)
T (K)a
4cb
0.80
0.27
0.64
0.17
0.36
0.12
0.61
4.2
4.2
4.2
106
153
92
4db
4eb
Ba2NaNb5O15
Bi4Ge3O12
LiNbO3
Pb3Ge5O12
4.2
a Temperature at which the measurement was achieved. b 0.035
g of 4 incorporated in 4 g of PMMA.
containing large-size nanocrystallites and in ferroelec-
tric photorefractive crystals.34
We investigated AISHG in the σ-acetylide complexes
4c-e incorporated within PMMA matrixes in the form
of plates with thickness within 1.4 mm. The experimen-
tal setup for the AISHG measurements is fully described
in the Supporting Information. The acoustical signal
power has been applied to the sample by LiNbO3
piezoelectric acoustical transducers, which allow varying
acoustical frequencies (80 Hz to 1.1 MHz). A pulsed
mode-locked YAB-Gd3+ laser (λ ) 1.76 µm, power about
25 MW; pulse duration about 15 ps) was used as a
source of optical second-harmonic generation (funda-
mental laser beam).
The observed effect was maximal for parallel direc-
tions of the acoustical wave polarization and fundamen-
tal light beam polarization, with effective second-order
susceptibility ø(2) as high as 0.8 pm/V for 4c (Table 5).
It should also be stressed that when similar experiments
were carried out in the absence of acoustic signal, we
did not observe any nonlinear response.
The differences in the order for the observed values
(4c > 4e > 4d) and the order for the linear optical and
third-order NLO measurements (4e > 4d > 4c) were
unexpected. Actually, the AISHG data seem to be
inconsistent with the effect of an extension of the
π-conjugation pathway. To better understand these
differences, a new set of experiments was performed.
We thus observed a substantial influence of the angle
Φ between the sample surface and laser beam polariza-
tion on the second-order nonlinear optical output signal
stimulated by the acoustical field. Thus, the output
AISHG intensities increase with increasing the effective
thickness of the sample, by rotating it with respect to
the light beam propagation. On the other hand, maximal
increase was observed at acoustical power densities
about 1.2 W/cm2 with increasing differences for 4e
compared to 4c,d.
Temperature-dependent measurements of the AISHG
also show a drastic increase of the output signal at
temperatures below 45 K. Such behavior can be associ-
ated with the optical SHG temperature dependence
during the structural phase transition in disordered
material.35 Moreover, the AISHG signal correlates well
with the temperature behavior of differential scanning
calorimetry. These experimental data, particularly the
Concluding Remarks
The present work reports a high-yield synthetic access
to a new series of alkynyl ruthenium donor-π-acceptor
complexes bearing oligothiophene-conjugating bridges.
Complexes 4a-e present third-NLO activity. The γ
maxima follow the same order as the absorption ener-
gies. Absorption and third-order nonlinear properties
increase by extending the effective conjugation in this
series of complexes. In addition, acoustically induced
second-harmonic generation has been observed for films
of the complexes 4c-e incorporated in PMMA matrixes.
The actual AISHG values are comparable with that
observed for the well-known ferroelectric and photo-
refractive crystals. Therefore, these complexes can be
considered as attractive candidates for SHG applications
and in the perspective of molecular materials for optical
communication systems.
Experimental Section
General Information. Reactions were carried out using
standard Schlenk techniques, under an inert atmosphere.
Solvents were dried and distilled according to standard
procedures.37 The following were prepared by literature pro-
cedures: bromodithiophenecarboxaldehyde (1c),38 bromoter-
thiophenecarboxaldehyde (1d),39 4-ethynylbenzaldehyde,39 and
trans-[RuCl(dppe)2][OTf].20b Column chromatography was car-
ried out on Merck silica gel 60 (70-230 ASTM) or Merck
alumina oxide 90 active basic (activity grade II, 70-230 mesh
ASTM). Microanalyses were carried out at the Center for
Microanalyses of the CNRS at Lyon-Solaise, France. Routine
NMR spectra were recorded using a Bruker DPX 200 spec-
trometer. High-field NMR spectra experiments were performed
on a multinuclear Bruker WB 300 instrument or a Bruker
Avance DRX 500. Chemical shifts are given in parts per million
relative to tetramethylsilane (TMS) for 1H and 13C NMR
spectra and H3PO4 for 31P NMR spectra. Electrochemical data
were acquired with a computer-controlled Autolab PG start
30 potentiostat utilizing the GPES program version 4.7.
(36) (a) Majchrowski, A.; Mija, J. Mater. Sci. Eng. A 1993, 173, 19.
(b) Liu, Q.; Zhao, X.; Tanaka, K.; Narazaki, A.; Hirao, K.; Gan, F. Opt.
Commun. 2001, 198, 187.
(37) Leonard, J.; Lygo, B.; Procter, G. Advanced Practical Organic
Chemistry, 2nd ed.; Blackie Academic & Professional: New York, 1995.
(38) Wei, Y.; Wang, B.; Tian, J. Tetrahedron Lett. 1995, 36, 665.
(39) Austin, W. B.; Bilow, N.; Kelleghan, W. J.; Lau, K. S. Y. J. Org.
Chem. 1981, 46, 2280.
(34) (a) Majchrowski, A. I.; Kityk, V.; Lukasiewicz, T.; Mefleh, A.;
Benet, S. Opt. Mater. 2000 15 (1), 51. (b) Majchrowski, A.; Mefleh, A.;
Lee, R.; Makowska-Janusik, M.; Kasperczyk, J.; Kityk, I. V.; Ber-
dowski, J.; Benet, S. Nonlinear Opt. 2000, 24, 335 (c) Dalal, N.;
Klymachyov, A.; Bussmann-Holder, A. Phys. Rev. Lett. 1998, 81, 5924.
(35) Napieralski, J. Ferroelectrics 1999, 220, 17.

Ruthenium Oligothienylacetylide Complexes
Organometallics, Vol. 24, No. 4, 2005 693
Electrochemical experiments were performed with 10-4
M
5′-Trimethylsilylethynyl-[2,2′]bithiophene-5-carbalde-
hyde (2c). From 2.73 g of 5′-bromo-[2,2′]bithiophene-5-car-
baldehyde,39 2.38 g of compound (2c) was obtained as a
yellowish solid in 82% yield. 1H NMR (CDCl3, 200 MHz, δ
methylene chloride solution of the complexes in a standard
three-electrode system (platinum working/auxiliary electrode
and SCE reference electrode). Bu4NPF6 [0.1 M] was used as
the supporting electrolyte. Scan rates were typically 100 mV
s-1. Transmittance-FTIR spectra were recorded using a Bruker
IFS 28 spectrometer or a Perkin-Elmer 841 spectrophotometer
by using samples embedded in KBr disks or thin films between
NaCl plates. UV-vis spectra were recorded on a UVIKON
spectrometer. Secondary ion (SI) mass spectra were recorded
on a VG ZAB 2SEQ spectrometer (30 kV Cs+ ions, current 1
mA, accelerating potential 8 kV, matrix o-nitrophenyloctyl
ether or m-nitrobenzylic alcohol) and electron impact (EI),
including high-resolution (HR), mass spectra on a VG Autospec
instrument (70 eV electron energy, 8 kV accelerating potential)
at the Centre de Mesures Physiques de l’Ouest, Rennes,
France. Peaks are reported as m/z (assignment, relative
intensity).
3
ppm): 9.86 (s, 1H, CHO), 7.65 (d, 1H, JHH ) 4 Hz), 7.24 (d,
1H, 3JHH ) 4 Hz), 7.19 (d, 1H, 3JHH ) 4 Hz), 7.15 (d, 1H, 3JHH
) 4 Hz), 0.26 (s, 9H). 13C{1H} NMR (CDCl3, 50 MHz, δ ppm):
183.22, 146.82, 142.91, 142.90, 138.11, 137.89, 134.21, 126.40,
125.18, 102.30, 97.23, -0.10; IR (KBr): νC≡C 2142.6 cm-1, νCd
1636 cm-1. UV/vis (CH2Cl2): λmax 378 nm (ꢀ 3500 mol-1
L
)
O
cm-1). MS (EI): m/z calcd [M]+ ) 290.0255; m/z found [M]+
290.0258.
5′′-Trimethylsilylethynyl-[2,2′;5′,2′′]terthiophene-5-car-
baldehyde (2d). From 3.55 g of 5′′-bromo-[2,2′;5′,2′′]ter-
thiophene-5-carbaldehyde,39 2.61 g of compound (2d) was
obtained as a yellow-orange solid in 70% yield. 1H NMR
(CDCl3, 200 MHz, δ ppm): 9.92 (s, 1H, CHO), 7.74 (d, 1H, 3JHH
) 6 Hz), 7.33 (d, 1H, 3JHH ) 4 Hz), 7.31 (d, 1H, 3JHH ) 4 Hz),
3
3
7.21 (d, 1H, JHH ) 4 Hz), 7.19 (d, 1H, JHH ) 4 Hz), 7.12
(d, 1H, JHH ) 4 Hz), 0.32 (s, 9H). 13C{1H} NMR (CDCl3, 50
3
Synthesis of (E)-1-(5-Bromo-2-thienyl)-2-(5-formyl-2-
thienyl)ethene (1e). A solution of N-bromosuccinimide (0.40
g, 2.25 mmol) in DMF (15 mL) was added dropwisely over a
period of 45 min to a solution of 5-[(E)-2-(2-thienyl)vinyl]-
thiophene-2-carbaldehyde15a (0.45 g, 2.04 mmol) in DMF
(50 mL) cooled to 0 °C under N2 in the absence of light. The
mixture was stirred for 18 h at room temperature and
concentrated, and the residue was diluted with CH2Cl2 (200
mL). The organic phase was washed with water (2 × 75 mL),
dried over MgSO4, and evaporated to dryness. The residue was
triturated with pentane, and the mixture was filtered, leading
to a yellow-brown solid, which was further purified by chro-
matography on silica gel (eluent: CH2Cl2/cyclohexane, 7:3) to
give a yellow powder (0.42 g, 69% yield). An analytical sample
was recrystallized from a mixture of CH2Cl2 and hexane,
affording yellow crystals. Mp: 129-130 °C (lit. 129-131 °C).19a
1H NMR (CDCl3, 500.13 MHz, δ ppm): 9.85 (s, 1H, CHO); 7.64
MHz, δ ppm): 182.64, 146.66, 141.99, 138.44, 137.85, 137.55,
135.31, 133.77, 127.13, 125.34, 124.46, 124.19, 123.04, 101.52,
97.24, 0.10. IR (KBr): νC≡C 2144 cm-1; νCdO 1634 cm-1. MS
(EI): m/z calcd [M]+ ) 372.0132; m/z found [M]+ ) 372.0142.
(E)-1-(5-Trimethylsilylethynyl-2-thienyl)-2-(5-formyl-
2-thienyl)ethene (2e).15f A total of 2.33 g of compound 2e
was obtained as a yellow solid in 74% yield from 2.99 g of E-1-
(5-bromo-2-thienyl)-2-(5-formyl-2-thienyl)ethene, 1e. 1H NMR
3
(CDCl3, 200 MHz, δ ppm): 9.84 (s, 1H), 7.65 (d, 1H, JHH ) 4
3
3
Hz), 7.16 (d, 1H, JHH ) 15.8 Hz), 7.12 (d, 1H, JHH ) 4 Hz),
3
3
7.11 (d, 1H, JHH ) 4 Hz), 6.97 (d, 1H, JHH ) 4 Hz), 6.96
(d, 1H, JHH ) 15.8 Hz), 0.31 (s, 9H). 13C{1H} NMR (CDCl3,
3
50 MHz, δ ppm): 182.96, 151.89, 143.01, 142.15, 137.69,
133.99, 128.36, 127.43, 125.55, 123.94, 121.52, 101.76, 97.89,
0.26. IR (KBr): νC≡C 2146 cm-1; νCdO 1632 cm-1. MS (EI): m/z
calcd [M]+ ) 316.0412; m/z found [M]+ ) 316.0400.
General Procedure for the Preparation of 3b-e. To a
stirred solution of 5 mmol of the trimethylsilyl-protected
acetylene derivatives 2b-e in 30 mL of THF was added 7.5
mmol of Bu4NF (solution 1 M/THF, 7.5 mL). The mixture was
stirred for 1 h at room temperature and concentrated, and the
residue was diluted with diethyl ether (3 × 50 mL) and washed
with water (3 × 30 mL). The organic phase was dried over
MgSO4, filtered, and pumped dry. The resulting organic
compound was dissolved in 5 mL of diethyl ether and filtered
through a silica gel column with diethyl ether to afford 3b-e
in good yields.
3
3
(d, 1H, JHH ) 3.9 Hz); 7.13 (d, 1H, JHH ) 15.4 Hz); 7.11 (d,
3
3
1H, JHH ) 3.9 Hz); 6.98 (d, 1H, JHH ) 3.9 Hz); 6.89 (d, 1H,
3JHH ) 15.4 Hz); 6.87 (d, 1H, JHH ) 3.9 Hz). 13C{1H} NMR
3
(CDCl3, 125.7 MHz, δ ppm): 182.39, 151.37, 142.88, 141.78,
137.05, 130.89, 128.21, 126.74, 124.95, 120.63, 113.26. IR
(KBr): νCdO 1654 cm-1
.
Synthesis of Ligands 2a-e. General Procedure for the
Preparation of Trimethylsilyl-Protected Acetylene (2b-
e). To a mixture of PdCl2(PPh3)2 (175 mg, 0.25 mmol) and CuI
(95 mg, 0.5 mmol) in 40 mL of THF were added successively
10 mmol of the corresponding bromo derivatives 1b-e, 11
mmol of trimethylsilyl acetylene (1.56 mL), and 40 mL of
triethylamine.40 The resulting mixture was stirred for 24 h at
room temperature. The dark solution was pumped dry, and
the resulting black solid was extracted with pentane (4 × 50
mL) and further purified by chromatography on silica gel
(eluent pentane). The resulting solution was dried over MgSO4,
filtered, and pumped dry to afford 2b-e as powdery solids.
5-Ethynylthiophene-2-carbaldehyde (3b).15f From 1.04
g of 5-trimethylsilylethynylthiophene-2-carbaldehyde, 2b, 572
mg of 3b was obtained as a brown solid in 84% yield. 1H NMR
(CDCl3, 200 MHz, δ ppm): 9.86 (s, 1H), 7.63 (d, 1H, 3JHH ) 4
3
Hz), 7.31 (d, 1H, JHH ) 4 Hz), 3.57 (s, 1H). 13C{1H} NMR
(CDCl3, 50 MHz, δ ppm): 180.20, 142.89, 139.41, 135.69,
122.30, 84.52, 77.40. IR (KBr): νC≡C 2140 cm-1; νCdO 1634 cm-1
.
)
MS (EI): m/z calcd [M]+ ) 135.9983; m/z found [M]+
135.9999
5′-Ethynyl-[2,2′]bithiophene-5-carbaldehyde (3c).15f From
1.45 g of 5′-trimethylsilylethynyl-[2,2′]bithiophene-5-carbal-
dehyde, 2c, 972 mg of compound 3c was obtained as a
brownish solid in 89% yield. 1H NMR (CDCl3, 200 MHz, δ
5-Trimethylsilylethynylthiophene-2-carbaldehyde (2b).
A total of 1.75 g of compound 2b was obtained as a white-
brown solid in 84% yield from 1.91 g of 5-bromothiophene-2-
carbaldehyde. 1H NMR (CDCl3, 200 MHz, δ ppm): 9.81 (s, 1H,
CHO), 7.59 (d, 1H, 3JHH ) 3.9 Hz), 7.24 (d, 1H, 3JHH ) 3.9 Hz),
0.23 (s, 9H). 13C{1H} NMR (CDCl3, 50 MHz, δ ppm): 179.20,
142.29, 139.51, 133.13, 123.08, 100.30, 95.13, -0.10; IR
(KBr): νC≡C 2148.9 cm-1, νCdO 1673 cm-1. UV/vis (CH2Cl2): λmax
(ꢀ) 328 nm (2600 mol-1 L cm-1).
3
ppm): 9.93 (s, 1H), 7.74 (d, 1H, JHH ) 4 Hz), 7.25 (d, 1H,
3JHH ) 4 Hz), 7.21 (s, 2H), 3.53 (s, 1H). 13C{1H} NMR (CDCl3,
50 MHz, δ ppm): 182.99, 146.24, 142.73, 137.85, 137.66,
134.63, 126.12, 125.29, 123.87, 84.06, 76.74. IR (KBr): νC≡C
2143 cm-1; νCdO 1630 cm-1. MS (EI): m/z calcd [M]+
217.9860; m/z found [M]+ ) 217.9871.
)
5′′-Ethynyl-[2,2′;5′,2′′]terthiophene-5-carbaldehyde (3d).
From 1.86 g of 5′′-trimethylsilylethynyl-[2,2′;5′,2′′]terthiophene-
5-carbaldehyde, 3d, 976 mg of compound 3d was obtained as
(40) (a) Kim, J. P.; Masai, H.; Sonogashira, K.; Hagihara, N. Inorg.
Nucl. Chem. Lett. 1970, 6, 181. (b) Sonogashira, K.; Yatake, T.; Tohda,
Y.; Takahashi, S.; Hagihara, N. J. Chem. Soc., Chem. Commun. 1977,
291. (c) Sonogashira, K.; Fujikura, Y.; Yatake, T.; Takahashi, S.;
Hagihara, N. J. Organomet. Chem. 1978, 145, 101.
1
a yellowish solid in 65% yield. H NMR (CDCl3, 200 MHz, δ
3
ppm): 9.93 (s, 1H), 7.74 (d, 1H, JHH ) 6 Hz), 7.34 (d, 1H,

694 Organometallics, Vol. 24, No. 4, 2005
Fillaut et al.
3
3
3JHH ) 4 Hz), 7.32 (d, 1H, JHH ) 4 Hz), 7.22 (d, 1 H, JHH
)
trans-[Ru(2,2′,5,5′-CtC-th-th-CHO)Cl(dppe)2] (4c). From
130 mg of 2c and 542 mg of [cis-(Cl)(dppe)2Ru][TfO], 466 mg
of compound 4c was obtained as a red-brownish powdery solid
in 81% yield. 1H NMR (CDCl3, 300 MHz, δ ppm): 9.87 (s, 1H),
3
3
4 Hz), 7.21 (d, 1 H, JHH ) 4 Hz), 7.14 (d, 1 H, JHH ) 4 Hz),
3.50 (s, 1 H). 13C{1H} NMR (CDCl3, 50 MHz, δ ppm): 182.90,
146.85, 138.45, 137.77, 135.74, 134.51, 132.41, 127.95, 127.37,
125.76, 124.76, 124.40, 122.58, 83.33, 76.49. IR (KBr): νC≡C
3
7.69 (d, 1H, JHH ) 4.0 Hz), 7.42-7.03 (m, 42H, dppe and th.
2144 cm-1; νCdO 1628 cm-1. MS (EI): m/z calcd [M]+
299.9737; m/z found [M]+ ) 299.9729.
)
3
groups), 6.05 (d, 1H, JHH ) 4.0 Hz), 2.73 (m, 8H, CH2 dppe).
13C{1H} NMR (CDCl3, 75 MHz, δ ppm): 182.26 (CHO), 141.52
2
5-[2-(5-Ethynylthiophen-2-yl)vinyl]thiophene-2-car-
baldehyde (3e).15f From 1.58 g of 5-[2-(5-trimethylsilylethy-
nylthiophen-2-yl)vinyl]thiophene-2-carbaldehyde (2e), 978 mg
of compound (3e) was obtained as a deep yellow solid in 80%
(quint., Ru-CtC, JPC ) 15.9 Hz), 143.88 and 148.73 (Cquat
,
thiophene), 139.60 and 137.90 (CH, thiophene), 136.10 and
1
135.95 (quint., Cipso, | JPC + 3JPC| ) 12 Hz, dppe phenyl groups),
134.49, 133.93, 128.99, 127.43, and 127.10 (CH, dppe phenyl
groups), 130.51 and 128.51 (Cquat, thiophene), 126.45 and
122.01 (CH, thiophene), 106.98 (s, Ru-CtC), 30.61 (quint.,
1
yield. H NMR (CDCl3, 200 MHz, δ ppm): 9.85 (s, 1H), 7.65
3
3
(d, 1 H, JHH ) 4 Hz), 7.18 (d, 1 H, JHH ) 15.8 Hz), 7.17 (d,
1H, 3JHH ) 4 Hz), 7.13 (d, 1 H, 3JHH ) 4 Hz), 6.99 (d, 1H, 3JHH
1
PCH2CH2P, | JPC + 3JPC| ) 23 Hz). 31P{1H} NMR (CDCl3, 121
) 4 Hz), 6.98 (d, 1H, JHH ) 15.8 Hz), 3.45 (s, 1H). 13C{1H}
3
MHz, δ ppm): 50.01 (s, dppe). IR (KBr): νC≡C 2042 cm-1; νCdO
1587 cm-1. UV/vis (CH2Cl2): λmax (ꢀ) 270.5 nm (12 500 mol-1
L cm-1), 502.5 nm (16 500 mol-1 L cm-1). MS (LSIMS): m/z
calcd [M]+ ) 1150.1220; m/z found [M]+ ) 1150.1203. Anal.
Calcd for C63H53P4RuClS2O: C 65.76; H 4.64. Found: C 65.38;
H 4.82.
NMR (CDCl3, 50 MHz, δ ppm): 182.99, 151.75, 143.34, 142.27,
137.67, 134.42, 128.21, 127.53, 125.39, 122.67, 121.81, 83.63,
77.68. IR (KBr): νC≡C 2143 cm-1; νCdO 1631 cm-1. MS (EI): m/z
calcd [M]+ ) 244.0016; m/z found [M]+ ) 244.0007.
Synthesis of Complexes 4a-e. General Procedure. To
a mixture of [cis-(Cl)(dppe)2Ru][TfO]20b (542 mg, 0.5 mmol) and
3a-e (0.6 mmol) was added 50 mL of dichloromethane. The
resulting mixture was stirred at room temperature for 20 h,
and the solvant was pumped dry. The resulting solid was
cleaned with diethyl ether (3 × 20 mL) to eliminate the organic
reactant. The solid was dissolved in 20 mL of dichloromethane,
and 140 µL of NEt3 (101 mg, 1 mmol) was added, with rapid
stirring, at room temperature for 1 h. The resulting solution
was washed with water (2 × 50 mL), dried over MgSO4,
filtered, and pumped dry. The resulting organometallic com-
pound was dissolved in 5 mL of dichloromethane and filtered
through a silica gel column with diethyl ether. Finally, solvent
was pumped dry to afford powdery solid 4a-e in 74-95%
yields. Analytical samples of 4c-e were recrystallized from
mixtures of CH2Cl2 and hexane, affording brown to red
crystals.
trans-[Ru(-CtC-th-th-th-CHO)Cl(dppe)2] (4d). From
180 mg of 2d and 542 mg of [cis-(Cl)(dppe)2Ru][TfO], 480 mg
of 4d was obtained as a red powdery solid in 78% yield. 1H
NMR (CDCl3, 300 MHz, δ ppm): 9.91 (s, 1H), 7.94 (d, 1H, 3JHH
) 4.0 Hz), 7.84 (d, 1H, 3JHH ) 4.0 Hz, CH thiophene), 7.73 (d,
3
1H, JHH ) 4.0 Hz, CH thiophene), 7.48-7.02 (m, 42H, dppe
and th. groups), 6.13 (d, 1H, 3JHH ) 4.0 Hz), 2.74 (m, 8H, CH2
dppe). 13C{1H} NMR (CDCl3, 75 MHz, δ ppm): 182.39 (CHO),
2
142.85 (quint., Ru-CtC, JPC ) 15.9 Hz), 147.48 and 140.75
(Cquat, thiophene), 141.00 and 137.33 (CH, thiophene), 136.02
1
3
and 135.49 (quint., Cipso, | JPC + JPC| ) 12 Hz, dppe phenyl
groups), 134.48 and 134.01 (CH, dppe phenyl groups), 133.80,
132.58, 132.13, and 128.94 (Cquat, thiophene), 128.95, 127.41,
and 127.07 (CH, dppe phenyl groups), 126.04, 124.81, 123.78,
and 122.70 (CH, thiophene), 106.83 (s, Ru-CtC), 30.61
1
(quint., PCH2CH2P, | JPC
+
3JPC| ) 23 Hz. 31P{1H} NMR
trans-[Ru(4-CtCC6H4CHO)Cl(dppe)2] (4a).25 From 78
mg of acetylene derivative 2a and 542 mg of [cis-(Cl)(dppe)2Ru]-
[TfO], 504 mg of compound 4a was obtained as a yellow
powdery solid in 95% yield. 1H NMR (CDCl3, 300 MHz, δ
(CDCl3, 121 MHz, δ ppm): 50.17 (s, dppe). IR (KBr): νC≡C 2042
cm-1; νCdO 1590 cm-1. UV/vis (CH2Cl2): λmax (ꢀ) 248 nm (60 500
mol-1 L cm-1), 510 nm (32 100 mol-1 L cm-1). MS (LSIMS):
m/z calcd [M]+ ) 1232.1098; m/z found [M]+ ) 1232.1108. Anal.
Calcd for C67H55P4RuClS3O: C 63.64; H 4.56. Found: C 63.68;
H 4.69.
3
ppm): 9.79 (s, 1H, CHO), 7.51 (d, 2H, JHH ) 5.5 Hz), 7.19-
6.86 (m, 40H, dppe), 6.51 (d, 2H, 3JHH ) 5.5 Hz), 2.61 (m, 8H,
CH2 dppe). 13C{1H} NMR (CDCl3, 75 MHz, δ ppm): 191.44
trans-[Ru(-CtC-th-(E)CHdCH-th-CHO)Cl(dppe)2] (4e).
From 146.6 mg of 2e and 542 mg of [cis-(Cl)(dppe)2Ru][TfO],
482 mg of compound 4e was obtained as a deep red powdery
(CHO), 142.5 (quint., Ru-CtC, 2JPC ) 15.8 Hz), 136.79 (Cquat
,
C6H4), 136.01 (quint., Cipso, | JPC + 3JPC| ) 12 Hz, dppe phenyl
1
groups), 135.41 (quint., Cipso, | JPC + 3JPC| ) 12 Hz, dppe phenyl
1
1
solid in 82% yield. H NMR (CDCl3, 300 MHz, δ ppm): 9.81
groups), 134.40 and 134.09 (CH, dppe phenyl groups), 130.82
(Cquat, phenyl), 130.24, 129.43, 129.01, 127.33, and 127.08 (CH,
dppe phenyl groups), 115.81 (Ru-CtC), 30.86 (quint., PCH2-
3
(s, 1H), 7.63 (d, 1H, JHH ) 4 Hz), 7.37-6.98 (m, 42H), 6.87
3
3
(d, 1H, JHH ) 4 Hz, CH thiophene), 6.77 (d, 1H, JHH ) 16
Hz, dCH), 2.58 (m, 8H, CH2 dppe). 13C{1H} NMR (CDCl3, 75
MHz, δ ppm): 182.30 (CHO), 153.66 (CHd), 143.29 (quint.,
Ru-CtC, 2JPC ) 15.9 Hz), 140.19 and 137.74 (Cquat thiophene),
CH2P, | JPC + 3JPC| ) 23 Hz). 31P{1H} NMR (CDCl3, 121 MHz,
1
δ ppm): 49.50 (s, dppe). IR (KBr): νC≡C 2036 cm-1; νCdO 1584
cm-1. UV/vis (CH2Cl2): λmax (ꢀ) 258 nm (19 000 mol-1 L cm-1),
423 nm (12r t900 mol-1 L cm-1). MS (LSIMS): m/z calcd [M]+
) 1062.1779; m/z found [M]+ ) 1062.1768
1
3
136.04 and 135.32 (quint., Cipso, | JPC + JPC| ) 12 Hz, dppe
phenyl groups), 134.61 (dCH), 134.49 and 134.02 (CH, dppe
phenyl groups), 133.18 (Cquat, thiophene), 129.66 (CH, thio-
phene), 129.07, 129.02, 127.44, and 127.12 (CH, dppe phenyl
groups), 127.00, 125.28, and 116.57 (CH, thiophene), 108.21
trans-[Ru(2,5-CtCC-th-CHO)Cl(dppe)2] (4b). From 82
mg of reactant 2b and 542 mg of [cis-(Cl)(dppe)2Ru][TfO], 454
mg of compound 4b was obtained as a brownish powdery solid
in 85% yield. 1H NMR (CDCl3, 300 MHz, δ ppm): 9.63 (s, 1H,
CHO), 7.47 (d, 1H, 3JHH ) 4.0 Hz), 7.44-6.96 (m, 40H, dppe),
5.99 (d, 1H, 3JHH ) 4.0 Hz), 2.65 (m, 8H). 13C{1H} NMR (CDCl3,
50 MHz, δ ppm): 181.29 (CHO), 154.47 (quint., Ru-CtC, 2JPC
) 15.9 Hz), 141.80 and 138.29 (Cquat, thiophene), 135.97 (CH,
1
3
(Ru-CtC), 30.67 (quint., PCH2CH2P, | JPC + JPC| ) 23 Hz).
31P{1H} NMR (CDCl3, 121 MHz, δ ppm): 49.44 (s, dppe). IR
(KBr): νC≡C 2038 cm-1; νCdO 1593 cm-1. UV/vis (CH2Cl2): λmax
(ꢀ) 254 nm (82 000 mol-1 L cm-1), 528 nm (55 500 mol-1
L
cm-1). MS (LSIMS): m/z calcd [M]+ ) 1176.1377; m/z found
[M]+ ) 1176.1391. Anal. Calcd for C65H55P4RuClS2O‚2CH2Cl2
(consistent with the NMR spectra and X-ray structure deter-
mination): C 59.76; H 4.42. Found: C 59.49; H 4.42.
thiophene), 135.56 and 135.19 (quint., Cipso, | JPC + 3JPC| ) 12
1
Hz, dppe phenyl groups), 134.48, 133.82, 129.14, 127.52, and
127.15 (CH, dppe phenyl groups), 126.60 (s, CH, thiophene),
1
3
X-ray Structure Determinations of 1e and 4e. Single
crystals of 1e, suitable for X-ray crystallographic analysis, were
obtained from a methylene chloride/hexane solution. Data
collection was performed at 294 K on an Enraf-Nonius MACH3
four-circle diffractometer equipped with a graphite monochro-
mator utilizing Mo KR radiation (λ ) 0.71073 Å). The structure
108.52 (s, Ru-CtC), 30.56 (quint., PCH2CH2P, | JPC + JPC
|
) 23 Hz). 31P{1H} NMR (CDCl3, 121 MHz, δ ppm): 49.12 (s,
dppe). IR (KBr): νC≡C 2032 cm-1; νCdO 1589 cm-1. UV/vis (CH2-
Cl2): λmax (ꢀ) 249 nm (49 000 mol-1 L cm-1), 450 nm (27 400
mol-1 L cm-1). MS (LSIMS): m/z calcd [M]+ ) 1068.1343; m/z
found [M]+ ) 1068.1351.

Ruthenium Oligothienylacetylide Complexes
Organometallics, Vol. 24, No. 4, 2005 695
was solved by direct methods (SIR)41 and refined on F by full
matrix least-squares techniques using MolEN package pro-
grams.42 All non-H atoms were refined anisotropically. Absorp-
tion was corrected by psi-scan technique, and the H atoms
were included in the calculation without refinement.
Crystal data for 1e: C11H7Br1O1S2, M ) 299.21, orange
prism, 0.91 × 0.74 × 0.29 mm3, monoclinic, P21/c, a ) 8.0389-
(7) Å, b ) 7.536(1) Å, c ) 18.853(2) Å, â ) 94.48(1)°, V )
1138.6(4) Å3, Z ) 4, T ) 294 K, Dcalc ) 1.74 g/cm3, GOF )
2.084, R ) 0.054 [I > 3σ(I)], R ) 0.096 (all data).
Single crystals of 4e, suitable for X-ray crystallographic
analysis, were obtained from a methylene chloride/hexane
biphasic system. Single crystals were mounted on a Nonius
four-circle diffractometer equipped with a CCD camera and a
graphite-monochromated Mo KR radiation source (λ ) 0.71073
Å). Data collection was performed at room temperature.
Effective absorption correction was performed (SCALEPACK).43
Structures were solved with SHELXS-9744 and refined with
SHELXL-9744 programs by full matrix least-squares method
on F2.
Crystal data for 4e: C67H59OCl5P4RuS2; M ) 1346.46,
triclinic, P1h, a ) 9.3070(1) Å, b ) 12.9700(2) Å, c ) 26.5840(5)
Å, R ) 84.1060(10)°, â ) 83.0280(10)°, γ ) 80.7530(10)°, V )
3132.53(8) Å3, Z ) 2, Dcalc ) 1.428 g cm-3, T ) 293 K, GOF )
1.029, R1 ) 0.0562 [8678 reflns with I > 2σ(I)], R1 ) 0.1122
(14 303 unique data).
Preparation of the Samples S4c-e. Samples S4c-e were
prepared by mixing the solution of 4 g of PMMA (Mw
)
120 000) in 300 mL of CHCl3 and 0.035 g of the different
complexes 4b,c,e in solution in chloroform (50 mL). The
inclusion of the complexes 4 was obtained by slow evaporation
of the solvent under a nitrogen flux. They were then obtained
in the form of plates with thickness within 1.4 mm by using
spin-coating techniques.
S4c: IR (KBr): νC≡C 2040 cm-1; νCdO 1586 cm-1. UV/vis: λmax
(ꢀ) 503 nm. S4d: IR (KBr): νC≡C 2042 cm-1; νCdO 1590 cm-1
.
UV/vis: λmax (ꢀ) 510 nm. S4e: IR (KBr): νC≡C 2040 cm-1; νCdO
1593 cm-1. UV/vis: λmax (ꢀ) 530 nm.
Supporting Information Available: Full details includ-
ing txt files of the crystallographic studies of compounds 1e
and 4e. Text giving experimental procedures for DFWM and
AIOSHG measurements. This material is available free of
charge via the Internet at http://pubs.acs.org.
(41) SIR92-A program for crystal structure solution. Altomare, A.;
Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl. Crystallogr.
1993, 26, 343.
(42) Crystal Structure Analysis; Molecular Enraf-Nonius (MolEN):
Delft Instruments X-ray Diffraction, B. V. Rontnenweg 1 2624 BD
Delft, The Netherlands, 1990.
(43) Otwinowski, Z.; Minor, W. Processing of X-ray Diffraction Data
Collected in Oscillation Mode. Methods in Enzymology, Macromolecular
Crystallography, part A; Carter, C. W., Sweet, R. M., Eds.; Academic
Press: New York, 1997; pp 276, 307.
OM049236S
(44) Sheldrick, G. M. SHELX97, Program for the Refinement of
Crystal Structures; University of Go¨ttingen: Germany, 1997.